University of Southern California Dissertations and Theses

Marine paleoecology during the aftermath of the end-Permian mass extinction

(USC Thesis Other)

Marine paleoecology during the aftermath of the end-Permian mass extinction

PDF

Download a page range

Download transcript

Copy asset link

Request this asset

Transcript (if available)

Content MARINE PALEOECOLOGY DURING THE AFTERMATH OF THE END-PERMIAN MASS EXTINCTION Copyright 2005 by Margaret Lee Fraiser A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (GEOLOGICAL SCIENCES) August 2005 Margaret Lee Fraiser Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 3196807 Copyright 2005 by Fraiser, Margaret Lee All rights reserved. INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. ® UMI UMI Microform 3196807 Copyright 2006 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ii ACKNOWLEDGEMENTS This research was supported by grants from the Paleontological Society, the American Museum of Natural History Lerner-Gray Fund for Marine Research, and the Geological Society of America. The Wrigley Institute for Environmental Studies and the Graduate and Professional Student Senate at USC also provided support for which I am thankful. The Department of Earth Sciences at USC unwaveringly provided financial support for much of the field work for this study and for travel to national and international meetings; I am grateful for this support and I am fortunate to have been involved with a department that so generously supports its students. A grant to David Bottjer from the USC Women in Science and Engineering Program (WISE) provided much of the financial support that enabled me to conduct field work in the western U.S.A., Italy, and Japan. Discussions with committee members Frank Corsetti, Dave Caron, Bob Douglas, Al Fischer, and Donn Gorsline over the years were fruitful and kept me thinking. Frank was generous to allow me to focus on the Noonday Dolomite for my minor project, and I am appreciative to have been a part of that study. Dr. Hiroyoshi Sano and Toshie Igawa at Kyushu University, and Dr. Tatsuo Oji, Taku Kudo, Haduka Yamagishi, and AtsushiYamamoto at the University of Tokyo provided invaluable field assistance in Japan. I thank Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Bushra Hussaini and N. Newell at the American Museum of Natural History, and D.W. Boyd at the University of Wyoming for discussions and assistance in identifying Early Triassic bivalves; Chris McRoberts at the State University of New York at Cortland provided me with unpublished list of Early Triassic bivalves. Interacting with the many PaleoLab members over the years has been a fun, learning experience. In particular, I thank Pedro Marenco, Catherine Jamet, and Steve Dornbos for field assistance in the western U.S. A. Pedro deserves special thanks for his assistance and comic relief during one field season in south-central Utah, and for enabling me to obtain many samples from the Sinbad Limestone Member. Dave Bottjer has been the ideal advisor. I will always remember the dinners after class, parties at his home, Dodgers games, and Groundlings shows. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS Acknowledgements ii List of Figures vii Abstract x CHAPTER 1: INTRODUCTION 1 The Permian-Triassic Biotic Crisis 1 Purpose 7 CHAPTER 2: TECTONIC AND GEOLOGIC SETTING OF STUDIED LOWER TRIASSIC STRATA 9 Eastern Panthalassa: Present-day western U.S.A. 13 Dinwoody Formation 13 Upper member, Thaynes Formation 16 Sinbad Limestone Member, Moenkopi Formation 19 Virgin Limestone Member, Moenkopi Formation 21 Western Paleotethys: Present-day Northern Italy 23 Werfen Formation 23 Western Panthalassa: Present-day Honshu, Japan 32 Hiraiso Formation 32 Open-ocean Panthalassa: Present-day Kyushu, Japan 33 Kamura Formation 33 CHAPTER 3: FOSSIL PRESERVATION DURING THE AFTERMATH OF THE END-PERMIAN MASS EXTINCTION: TAPHONOMIC PROCESSES AND PALAEOECOLOGICAL SIGNALS 37 The potential Early Triassic preservation bias 37 Methods 42 Preservation of Early Triassic skeletonized invertebrate benthic marine fossils 43 Environmental and ecological effects upon Early Triassic early diagenetic processes 48 Testing the quality and utility of the Lower Triassic fossil record of skeletonized invertebrate benthic marine fossils 54 Conclusions 56 CHAPTER 4: THE GLOBAL EARLY TRIASSIC BIVALVE ECOLOGIC TAKEOVER 58 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. V "The Brachiopod-Bivalve Question" 58 Purpose 63 Broad Scale Patterns of Post-Cambrian Ecological Dominance 64 Early Triassic Patterns of Ecological Dominance 68 Discussion 80 CHAPTER 5: PROLIFERATION OF EARLY TRIASSIC WRINKLE STRUCTURES 84 Introduction 84 Study Locations and Methods 87 Results 91 Depositional and Taphonomic Conditions 95 Conclusions 98 CHAPTER 6: RESTRUCTURING IN BENTHIC LEVEL-BOTTOM SHALLOW MARINE COMMUNITIES DUE TO PROLONGED ENVIRONMENTAL STRESS FOLLOWING THE END-PERMIAN MASS EXTINCTION Introduction 100 Proxies for Assessing Structural Changes in Benthic Level-Bottom Shallow Marine Paleocommunities 102 Taxonomic patterns 103 Biodiversity and taxonomic dominance among the Early Triassic skeletonized invertebrate fauna 103 Ichnogeneric diversity 104 Paleoecologic patterns 106 Relative abundance of Early Triassic skeletonized Invertebrates 106 Extent of bioturbation (ichnofabric indices) 108 Tiering 109 Benthic Bambachian megaguilds 110 Biosedimentary Structures 112 Shell beds 112 Wrinkle structures 113 Restructuring in Benthic Level-Bottom Shallow Marine Communities due to Prolonged Environmental Stress Following the End-Permian Mass Extinction 114 CHAPTER 7: THE MID-PHANEROZOIC BIOCALCIFICATION CRISIS: THE PAST IS THE KEY TO THE FUTURE 120 Introduction 120 Response of Skeletonized Marine Biota to Increases in Atmospheric C02 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. vi 121 Late Paleozoic and Early Mesozoic Increased atmospheric C 02 , Mass Extinctions, and Prolonged Ecological Degradation 122 Discussion 128 CHAPTER 8: CONCLUSIONS 129 REFERENCES 134 APPENDICES: Appendix A: Lower Triassic Localities Studied 155 Appendix B: Ecological Dominants in post-Cambrian Fossil Accumulations 162 Appendix C: Raw data from Collected Lower Triassic samples 204 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. V II LIST OF FIGURES Figure 1: Series, stages and dates for the Permian and Triassic periods. 2 Figure 2: Diversity of marine familes through the Phanerozoic. 3 Figure 3: Paleogeography of Early Triassic Earth. 4 Figure 4: 513C data for Upper Permian-Upper Triassic strata from south China. 6 Figure 5: Paleolocations of Lower Triassic strata examined. 10 Figure 6: Generalized stratigraphy of Lower Triassic strata examined. 11 Figure 7: General positions of localities of Lower Triassic strata in the western U.S.A., northern Italy, and Japan. 12 Figure 8: Maps of localities of the Dinwoody Formation examined. 14 Figure 9: Stratigraphic columns representative of the Dinwoody Formation. 15 Figure 10: Maps of localities of the upper member of the Thaynes Formation examined. 17 Figure 11: Stratigraphic column representative of the upper member of the Thaynes Formation. 18 Figure 12: Maps of localities of the Sinbad Limestone Member, Moenkopi Formation examined. 20 Figure 13: Stratigraphic column representative of the Sinbad Limestone Member of the Moenkopi Formation. 22 Figure 14: Maps of localities of the Virgin Limestone Member of the Moenkopi Formation Examined. 24 Figure 15: Stratigraphic column representative of the Virgin Limestone Member of the Moenkopi Formation. 25 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. viii Figure 16: Maps of Werfen Formation localities examined. 27 Figure 17: Stratigraphic column representative of the Werfen Formation. 28 Figure 18: Maps of localities of the Hiraiso Formation examined. 32 Figure 19: Stratigraphic columns representative of the Hiraiso Formation. 33 Figure 20: Maps of localities of the Kamura Formation examined. 35 Figure 21: Stratigraphic column representative of the Kamura Formation. 36 Figure 22: Stratigraphy of sections containing silicified Early Triassic faunas. 44 Figure 23: Paleogeography of silicified Early Triassic faunas. 45 Figure 24: Preservation of Early Triassic fossils. 47 Figure 25: Phanerozoic Evolutionary Faunas. 59 Figure 26: Phanerozoic ecological dominants. 69 Figure 27: Stratigraphy and paleogeography of ecologic study. 71 Figure 28: Dominance in Lower Triassic shell beds. 73 Figure 29: Lower Triassic fossil accumulations. 74 Figure 30: Bivalve- and brachiopod-dominated shell beds through the Phanerozoic. 75 Figure 31: Results of field analysis of Lower Triassic shell beds. 76 Figure 32: Totals from field analysis of Lower Triassic shell beds. 77 Figure 33: Common Early Triassic bivalves. 79 Figure 34: Characteristics of wrinkle structures. 85 Figure 35: Paleogeography of Early Triassic wrinkle structures. 88 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 36: Stratigraphy of Early Triassic wrinkle structures. 89 Figure 37: Photos of Cambrian and Early Triassic wrinkle structures. 90 Figure 38: Structural characteristics of paleocommunities before and after the end-Permian mass extinction. 114 Figure 39: Mid-Phanerozoic environmental and atmospheric changes. 123 Figure 40: Mid-Phanerozoic biotic changes. 124 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT x During the latest Paleozoic and earliest Mesozoic the Earth experienced the most devastating biotic crisis in the Phanerozoic history of life, the end-Permian mass extinction. Several lines of evidence indicate that physiological and chemical stresses likely linked to the cause(s) of the end- Permian mass extinction pulsed throughout its aftermath during the Early Triassic (Scythian) for 5-6 million years. However, the majority of studies on the Permian-Triassic biotic crisis are boundary-centric and focus on determining taxonomic patterns; very few studies have focused on determining the prolonged effects of these lingering environmental perturbations on the Earth’s biota. The purpose of this research was to evaluate marine paleoecology during the aftermath of the end-Permian mass extinction to test the hypothesis that, in addition to the mass extinctions, temporary and permanent ecological changes in Earth’s marine biota resulted from the prolonged latest Paleozoic-earliest Mesozoic environmental perturbations. Presented in this dissertation are: 1) a taphonomic evaluation of Early Triassic fossils; 2) a case study of ecologic/numerical dominance during the Early Triassic; 3) a study of the proliferation of microbial mats in benthic level-bottom marine subtidal environments; 4) a synthesis of temporary and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. xi permanent structural changes in benthic level-bottom marine paleocommunities; and 5) a new mechanism that is hypothesized to have been one of the causes of the Permian-Triassic marine biotic crisis. The focus on marine paleoecology during the aftermath of the end- Permian mass extinction represents a novel approach to understanding mass extinctions and the effects of global environmental changes and perturbations on Earth’s biota. This research reveals that: 1) the aftermath of the end-Permian mass extinction was as crucial as the mass extinction in shaping the evolutionary history of life on Earth; and 2) an understanding of paleoecology during the aftermaths of mass extinctions can help to constrain causal mechanisms for biotic crises. An understanding of how the Earth’s biota react to environmentally stressed intervals in Earth’s history, such as mass extinctions, will enable the present biodiversity crisis to be better managed. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 CHAPTER 1: INTRODUCTION The Permian-Triassic Biotic Crisis During the latest Paleozoic and earliest Mesozoic the Earth experienced the most devastating biotic crisis in the Phanerozoic history of life. In the marine realm, two mass extinction events punctuated the late Permian, the first eliminating 71% and the second eliminating 80% of invertebrate species at the end of the Capitanian and the end of the Changhsingian stages (Stanley and Yang, 1994) 260.4±0.7 and 252.0±0.6 million years ago respectively (Gradstein etal., 2004; Mundil etal., 2004) (Figure 1). Furthermore, over 50% of marine vertebrate and invertebrate families went extinct during the end-Permian mass extinction (Raup and Sepkoski, 1982) (Figure 2). The cause(s) of these mass extinctions are still debated and deliberated, but they are ultimately rooted in the supercontinent configuration of Pangea (Figure 3) and its disassembly by continental flood basalt volcanism (e.g., Hallam and Wignall, 1999; Wignall, 2001; Bottjer, 2004). The configuration of Pangea and the massive amounts of C 02 injected into the atmosphere by continental flood basalt volcanism are hypothesized to have led to a series of detrimental environmental consequences, including global warming, a reduced pole to equator Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 199.6±0.6 247.0 252.0±0.6 260.4±0.7 299.0±0.8 o w to e g 'i_ \— c C O C D C L Series Upper Middle Lower Lopingian Guadalupian Cisuralian Stages Rhaetian Norian Carnian Ladinian Anisian Olenekian Induan Changhsingian Wuchiapingian Capitanian Wordian Roadian Kungurian Artinskian Sakmarian Asselian Substages Spathian Smithian Dienerian Griesbachlan Figure 1: Series, stages and dates for the Permian and Triassic periods. Substages for the Lower Triassic. Dates from Gradstein et al. (2004) and Mundil et al. (2004). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. 900 E 600 ' a > c < u _Q E 13 C 300 ■ Figure 2: Diversity of marine familes through the Phanerozoic. Note the large decrease in diverstiy at the Permian/Triassic boundary indicating the end-Permian mass extinction. Modified from Sepkoski (1981). ight owner. Further reproduction prohibited without permission. lorea ’aleotethys Panthalassa Figure 3: Paleogeography of Earth's continents -2 5 0 million years ago. The location of some present-day countries during the Early Triassic is indicated. Modified from Scotese (1994). 5 temperature gradient, and sluggish ocean circulation, that facilitated massive release of CH4 (Krull etal., 2000), global marine anoxia (e.g., Wignall and Twitchett, 1996; Isozaki, 1997), hypercapnia (Knoll etal., 1996), and H2 S poisoning (Kump etal., 2005). Sedimentological, geochemical, and paleontological evidence supports these phenomena as mechanisms for the end-Permian mass extinction. Though extraterrestrial impact has been hypothesized as the cause of the end-Permian mass extinction (e.g., Becker etal., 2004), a complex scenario for the late Permian mass extinctions involving all of the previously hypothesized causes is most probable. Several lines of evidence indicate that physiological and chemical stresses likely linked to the cause(s) of the end-Permian mass extinction pulsed throughout its aftermath during the Early Triassic (Scythian) for 5-6 million years (Martin etal., 2001; Mundil etal., 2004). Data on 81 3 C isotopes indicate that the carbon cycle experienced large perturbations during the Late Permian, through the Early Triassic, and into the Middle Triassic (Baud etal., 1989; Payne etal., 2004) (Figure 4). Sedimentologic evidence in the form of originally aragonitic seafloor fans provides evidence for unusual ocean chemistry throughout the Early Triassic (Woods et al., 1999; Baud, pers. comm.) (Figure 4). The majority of studies on the Permian-Triassic biotic crisis are boundary-centric and focus on determining taxonomic patterns (e.g., Stanley Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. c ro O O 5 = ro a > to M - o < u u c a t * _ * _ D O Late Triassic Middle Triassic Early Triassic Late Permian ft! u c 0 5 *E ^ 5 0 3 c . 2 c < O'- c o Hlyrian mK Aeg. Spathian Smithian D ienerian Griesbachian Changxingian 1 < 5 0 1 O C ) ‘V _ j — s — j— ,— ,— ] — p - p - ,— , — p -2 0 2 4 6 8 6 13C,Brtl (%o) Figure 4 :81 data for Upper Permian-Upper Triassic strata from south China. Modified from Payne et al., 2004. Originally aragonite seafloor fans depicted in the Griesbachian and Spathian; data on seafloor fans from Woods et al. (1999) and A. Baud (pers. comm.). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7 and Yang, 1994) because enumerating how many and which taxonomic groups were affected during the largest mass extinction in the Phanerozoic history of life is important for understanding the broad-scale evolutionary history of life on Earth. However, very few studies have focused on determining the prolonged effects of these lingering environmental perturbations on the Earth’s biota (c.f. Schubert and Bottjer, 1995; Rodland and Bottjer, 2001; Fraiser and Bottjer, 2004). Indeed, some studies have focused on determining taxonomic patterns throughout the Early Triassic aftermath to determine the nature of taxonomic recovery following the end- Permian mass extinction (e.g., Ciriacks, 1963; Erwin, 1996; Erwin and Pan, 1996; McGowan, 2004), but taxonomic data alone are insufficient for discerning ecological patterns and processes on fine- and broad-scales (e.g., Novack-Gottshall, 2003). Furthermore, though taxonomic changes are the hallmark of mass extinctions, taxonomic and ecologic patterns during their aftermaths can be decoupled and differ in severity, and new ecological patterns established during their aftermath may actually represent their most significant results (Droser etal., 1997, 2000; Erwin, 2001). Purpose The purpose of this research was to evaluate marine paleoecology during the aftermath of the end-Permian mass extinction to test the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8 hypothesis that, in addition to the mass extinctions, temporary and permanent ecological changes in Earth’s marine biota resulted from the prolonged latest Paleozoic-earliest Mesozoic environmental perturbations. Presented here are: 1) a taphonomic evaluation of Early Triassic fossils; 2) a case study of ecologic/numerical dominance during the Early Triassic; 3) a study of the proliferation of microbial mats in benthic level-bottom marine subtidal environments; 4) a synthesis of temporary and permanent structural changes in benthic level-bottom marine paleocommunities; and 5) a new mechanism that is hypothesized to have been one of the causes of the Permian-Triassic marine biotic crisis. The focus on marine paleoecology during the aftermath of the end- Permian mass extinction represents a novel approach to understanding mass extinctions and the effects of global environmental changes and perturbations on Earth’s biota. This research reveals that: 1) the aftermath of the end-Permian mass extinction was as crucial as the mass extinction in shaping the evolutionary history of life on Earth; and 2) an understanding of paleoecology during the aftermaths of mass extinctions can help to constrain causal mechanisms for biotic crises. An understanding of how the Earth’s biota react to environmentally stressed intervals in Earth’s history, such as mass extinctions, will enable the present biodiversity crisis (Wilson, 2002) to be better managed. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9 CHAPTER 2: TECTONIC AND GEOLOGIC SETTING OF STUDIED LOWER TRIASSIC STRATA Because mass extinctions are global-scale events that result from widespread environmental perturbations (e.g., Hallam and Wignall, 1997), a field-based study on Lower Triassic strata deposited in various oceans was conducted to determine global marine paleoecology during the aftermath of the end-Permian mass extinction. Fossiliferous Lower Triassic strata deposited in level-bottom marine environments in western Palaeotethys, eastern Panthalassa, western Panthalassa, and open-ocean Panthalassa were examined in the field where they are exposed today in the western United States, northern Italy, and Japan (Figures 5, 6). The members and formations examined range from approximately 10 m (e.g., Kamura Formation, Kyushu, Japan) to nearly 700 m (e.g., Werfen Formation) in thickness, and numerous localities of each member and formation tens to hundreds of kilometers apart were measured and sampled to ensure that a range of marine depositional environments was examined (Figure 7; Appendix A). The examined strata span the entire Early Triassic in age and represent shallow marine subtidal through offshore deposition as well as continuous accumulation on an open-ocean seamount. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. I oreak Paleotethys Panthalassa Pangea Figure 5: Paleogeographic map ~ 250 million years ago showing the paleo- locations of Lower Triassic strata examined during the course of this study. Present-day locations are: 1) Western U.S.A.;2) northern Italy; 3) Japan ( Hiraiso Formation); and 4) Japan (Kamura Formation). Modified from Scotese (1994). o Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. eastern Panthalssa western Paleotethys open-ocean Panthalssa western U.S.A. N Italy Japan SE Nevada SE central Utah N central Utah ID, MT, WY Werfen & Servino Formations Kyushu Honshu Stages and Substages Moenkopi Formation Thaynes Formation Kamura Formation E arly Triassic (Scythian) Olenekian Spathian Virgin Limestone Member upper member San Lucano Member lower member Lower Red Member Cencenighe Member Timpoweap Member Val Badia Member Torrey Member Sinbad Limestone Member Nammalian Smithian Campil Member Gastropod Oolite Member Siusi Member Andraz Horizon Mazzin Member Hiraiso Formation Induan Dienerian Black Dragon Member Griesbachian Dinwoody Formation basal member mya Figure 6: Generalized stratigraphy of Lower Triassic strata examined over the course of this study. Compiled from Kummel, 1954;Blakey, 1974; Kimura et al., 1991; Broglio Loriga et al., 1990; Schubert and Bottjer, 1995;Twitchett and Wignall, 1996; Sano and Nakashima, 1997; Martin et al., 2001; F . Corsetti, pers. comm., 2003; Mundil et al., 2004) 12 Western U.S.A. \ ) Montana 1 / Idaho' J j — / Wyoming 1 I Nevada / 1 \ / Utah / J \ / 4,5,6,7,/ \ l 5 16 A |4 ^ 9 ,1 0 / V 200 km Dinwoody Formation uppper member,Thaynes Formation 1) Blacktail Creek 11) Cascade Springs 2) Flidden Pasture 12) Fall Creek 3) Gros Ventre 13) University Sinbad Limestone Member Virgin Limestone Member 4) Batten and Stokes 14) Hurricane 5) Black Box 15) Lost Cabing Springs 6) Fish Creek 16) Muddy Mountains 7) Jackass Benches 17)Ute 8) Junction 18) White Hills 9) Miners Mountain 10) Roadcut Italy Werfen Formation 1) Punta Rolle 2 )Tesero 3) Uomo 50 km Japan Hiraiso Formation D A 2) B A 3)C j 2 Kamura Formation D A 2) B X T Figure 7: General positions of localities of Lower Triassic strata in the western U.S.A., northern Italy, and Japan that were measured and from which samples were collected. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 13 Eastern Panthalassa: Present-day western U.S.A. Dinwoody Formation: The Griesbachian Dinwoody Formation outcrops in Idaho, Montana, and Wyoming of the western U.S.A. and represents the first transgression onto continental shelves exposed during the Permian (Pauli et al., 1989; Pauli and Pauli, 1994). The Dinwoody disconformably overlies the Permian Phosphoria Formation (Pauli and Pauli, 1994) and reaches over 700 m at its thickest exposures (Pauli et al., 1989). The Dinwoody represents deposition in nearshore to middle shelf marine environments (Pauli et al., 1989; Pauli and Pauli, 1994), and three localities in Montana and Wyoming were examined during the course of the study (Figure 8). In the study region, the Dinwoody is comprised primarily of olive-gray shale and siltstone beds with interbedded limestones that increase in thickness and frequency upward in the formation (Pauli et al., 1989) (Figure 9). The interbedded limestones are bioclastic wackestones, packstones, and grainstones. The most common fossils are bivalves, the inarticulate brachiopod Lingula, microgastropods, echinoid debris, ostracodes, and serpulid worm tubes; microbial mat laminations also occur in the Dinwoody. Previous authors have subdivided the Dinwoody Formation into different units based on lithology or paleontology (Newell and Kummel, 1942; Moritz, 1951; Kummel, 1954; Schock et al., 1981). However, Pauli et al. (1989) establish that Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 14 •Helena Montana H5 l Wyoming Dillon Grand Teton National Park .Beaverhead/ /f D e ll \ Nationa^ F o re st/ X * v L im a \O T 20 km Gros Ventre Wilderness Area >Jackson Figure 8: Maps of localities of the Dinwoody Formation examined in Montana and Wyoming, U.S.A. A) Localities examined in shaded areas. B) Two localities in Montana: 1) Blacktail Creek; 2) Hidden Pasture. C) One locality in Wyoming: 3) Gros Ventre. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Blacktail Creek 10m! a v v i "i_ ' r r i i ) ? E2Z2 222Z3 iznxiL::i::rri n z ra Gros Ventre l l f i l L E G E N D | § LIMESTONE | DISTAL MUDSTONE Q COVERED SECTION ^ SILTSTONE ^ PROXIMALMUDSTONE f UNGULA Figure 9: Stratigraphic columns representative of the Dinwoody Formation measured at the Blacktail Creek and Gros Ventre localities, (modified from Rodland and Bottjer,2001) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 16 formalized subdivisions based on lithology or fossil content are impractical and unjustified. Upper member, Thaynes Formation: The retreat of the Dinwoody sea during the Dienerian was met with the progradation of silty, craton-derived sediments represented by the marginal marine red beds of the Woodside and Red Peak Formations, marking the end of normal marine deposition (Pauli et al., 1989; Pauli and Pauli, 1994). Towards the west, where redbeds did not persist, strata of the Smithian-Spathian Thaynes Formation gradationally overlie the Dinwoody (Pauli et al., 1989). The Thaynes Formation outcrops in Utah, Idaho, Wyoming, and Montana of the western U.S.A.; three localities in Utah and Idaho were examined during the course of this study (Figure 10). The Thaynes Formation records two major transgressions in the Cordilleran miogeosyncline, represented by the lower and upper members respectively that are separated by the regressive, nonmarine redbeds of the middle member (Newman, 1974; Pauli et al., 1989). The upper member consists primarily of thin to thick bioclastic packstones and grainstones deposited in storm-dominated marine environments; hummocky cross stratification is recorded in thin siltsone beds (Figure 11). Bivalves, crinoids, rhynchonelliform brachiopods, and microgastropods are common. The upper Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 17 Idaho E m Utah I-80 Idaho Falls, ' Sail Lake Swan Valley 1-21 89 Provo 8 km iEH 25 km Figure 10: Maps of localities of the upper member of the Thaynes Formation examined in Idaho and Utah, U.S.A. A) Localities examined in shaded areas. B) Two localities in Utah: 1) University; 2) Cascade Springs.C) One locality in Idaho: 3) Fall Creek. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 18 600. ‘ - - .a - -.I: - - - . 1 u i^ i x r k H am b mudstone ano oeiec/ood oacxsiont. interbeddeo sandstone and s ilt s t o n t . '■*»*» ' ipc < e = and cut wave n p p le s dominate. Coated traoments, p e it-d s . burrows and encrustation; com oit. -dunaan; ct.tr: nooules, la y e r; and tensest© ), Biota ■■nctuoes “ ace T!?SSi 1 S 1 : - u - ^ Q O i e a i <«> * u m x r o ter,m oid wackestone and omdstone oase1. and pelecypod packstont '.topi a its eacneo. a 'c n :. :e b . coated and bored sh e lls, Cyclic deposition on scale. Marker bed ( tie ld ) , B iota: O © £ , ■.*> -xT u m i r i Mainly s ilt y mudstone ano pindstone. m so !!>■'. echinoid wackestone '.middle.' and o o litic oac»sicr.e (to p i. Ooids, onkoids, bioturbation and m i::s - crosslam ination common. B iota: ■&. O © - c r $ A - w f u r^ T -r m Mud- wackestone, w ith minor dolom ite. Rare isolated s ilts to n e and sandstone interbeds. Capped by th in , pelecypod packstone, Abundant b io tu rb a tio n , burrous, p eloids. chert ano coated, bored and : eached *oss:'> traoments. Minor ooids. B iota: $ 3 0 0 <*><=» V ur^j i r C 3 Echinoid packstone ano wackestone: raestene .c* nee in tra c la s ts ; near oase, Abundant coated and cores s hell traoments. "e io 'd s , :a:cispner»s ano lith o c la s ts " common. S om e c n e rt, c y c l'c :esos Marker bed. B io ta : - ^ • $ O f f i k i » - c r < *> K E Y a Pentacrinus H Pelecypod H 3 Ammonite a Crinoid 0 Algae f f l Wood a Echinoid G s l Nautiloid Bone 0 Brachiopod HI Pore ms [1 Hash [I] Ga st ro pod M Bu rrows a Li t h ociast L © l Gas t r opo d M Chert I * * * ~ ~ | Siltst one Mu ds tone c p : lO EE Lim estone BZ tzz *y Dolomite Sands tone id Gt d units L: 1 S — S R»d ®md Green P *- mottle Figure 11: Composite stratigraphic column of the upper member of the Thaynes Formation, (modified from Sikkink, 1984) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 19 member of the Thaynes Formation was measured and sampled during the course of this research. Sinbad Limestone Member, Moenkopi Formation: The Nammalian Sinbad Limestone Member of the Moenkopi Formation, located in south-central Utah (Figure 12), represents the easternmost extension of shallow marine carbonate environments in the Early Triassic and is sandwiched between reddish-brown continental sediments of the Moenkopi Formation; the Sinbad Limestone Member is considered to be a tongue of the Thaynes Formation (Blakey, 1974; Dean 1981). The Sinbad Limestone Member, exposed in the San Rafael Swell, Teasdale Uplift, Circle Cliffs Uplift, and northern Monument Upwarp, is thinnest in the southeast (Monument Upwarp, ~ 1 m) and thickest in the northwest (San Rafael Swell and Teasdale Uplift, ~15-30 m). In the exposures of the Sinbad Limestone in the San Rafael Swell, Blakey (1974) recognized three lithofacies representing deposition in a range of marine environments: 1) skeletal calcarenite facies, open marine subtidal; 2) silty peloidal calcilutite, lagoonal subtidal; and 3) dolomitized calcarenite, intertidal to supratidal. In the Teasdale Uplift, Dean (1981) recognized six lithofacies: 1) lithofacies A, supratidal and intertidal; 2) lithofacies B, lagoonal subtidal; 3) lithofacies C, supratidal; 4) lithofacies D, open marine subtidal; 5) lithofacies E, ooid shoals; and 6) lithofacies F, prodelta. The different Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 20 Utah Salt Lake li-TsI F t o I G eorge B River 11-701 k M o a b Hanksville Torrey Hite 50 kilometers Figure 12: Maps of localities of the Sinbad Limestone Member, Moenkopi Formation examined in Utah, U.S.A. A) Localities examined in shaded area. B) Outlined areas represent outcropping of the Sinbad Limestone Memer. Five localities examined in the San Rafael Swell: 1) Black Box; 2) AMNH locality 3026; 3) Jackass Benches; 4) Black Box; 5) I-70 Roadcut. Two localities in the Teasdale Uplift:6) Fish Creek; 7) Miners Mountain. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 21 lithofacies of the Sinbad Limestone Member record minor transgressive and regressive phases of the Sinbad Sea (Blakey, 1974; Dean, 1981). The lithofacies described by Blakey (1974) and Dean (1981) were confirmed in the field. Many of the packstone and grainstone lithologies outcrop as shell beds (Bottjer and Droser, 1998; Boyer et al., 2002) and Sinbad Limestone Member paleocommunities are dominated by bivalves and gastropods (Blakey, 1974; Dean, 1981). The most fossiliferous facies are Blakey’s (1974) skeletal calcarenite and Dean’s (1981) lithofacies A, B, and D; these lithofacies were the most intensely examined for the purposes of this study (Figure 13). Virgin Limestone Member, Moenkopi Formation: The Virgin Limestone Member is a marine unit in the predominantly nonmarine Moenkopi Formation, recording the third major transgressive event during the Early Triassic (Kummel, 1954; Pauli et al., 1989). The Virgin Limestone Member consists of a mixed carbonate-siliciclastic succession deposited in supratidal to middle shelf marine paleoenvironments (Poborski, 1954). Fossiliferous packstones and grainstones comprised of bivalves, gastropods, echinoid spines, rhynchonelliform brachiopods, and crinoid ossicles are common and were sampled for the purposes of this study. Hummocky cross-stratification is preserved in siliciclastic beds. Several localities in Nevada and Utah of the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. sS S sq sgsggi © i42££24 f / / S A ' / s . 5«««< {< < < < < < < £< < < < < < ' {< < < < < < < £ < < < < < < * ? £ < < < < < « £ < < < < < < < S S fiS S S v { k k k 1 < < < < < < < ■ • » » » ? {< < < < /< « ?«{ { «< & 4 2 4 C 4 4 {£ £ < < < < « iiin o to o its □ ootonucme with crypiatgai bedding ootrt*-p*to*d ptetuton* akateiai packshyt»/waci>.esuyt« V < > 1 W«Ck*tOO« [y .\'v jootom«U I»d l»C>*» ootn*-fTx>liu*k packatone paKHdai muctttone/wackMton* dotom rtatd pramatone toariajaod-flttti 0 0 mud intraciastt 0 bfv«>v« Ooo mtcropastropod* Od cO m a M nw cfoptttropM ltovtiv* auambtage « ecaphopod* • ammonoWa fty ^ horizontal tree* taeaita y vortical trace toaarts 1 iTBcrooaatropoo-dorrvnatad interval 2 b»vatv*-oommat*d tntarvaJ 3 mixad rmcrogaatropodtoivaiv* m m b U Q * w M W M tiM i Q O C Figure 13: Representative stratigraphic column of the Sinbad Limestone Member, MoenkopiFormation. (modifed from Fraiser, 2000) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 23 western U.S.A. representing deposition in very shallow subtidal to more offshore paleoenvironments were examined (Figures 14, 15). Western Paleotethys: Present-day Northern Italy Werfen Formation The Werfen Formation exposed in the southern Alps represents latest Permian through Early Triassic deposition in the westernmost region of the Paleotethyan Ocean (Wignall and Hallam, 1992). The Werfen is comprised of nine lithostratigraphic units of siliciclastic and carbonate strata representing supratidal to subtidal marine environments deposited on a shallow shelf (Broglio Loriga et al., 1990; Broglio Loriga and Cassinis, 1992; Twitchett and Wignall, 1996). Though the nine members are delineated by lithologic characteristics (Broglio Loriga et al., 1990), they grade into one another and no facies uniquely belongs to any member, making the delineation of the members somewhat difficult. The Werfen ranges in thickness from 150 m for the westernmost exposures to 600-700 m for the easternmost exposures in the Dolomites (Broglio Loriga and Cassinis, 1992). The Werfen is underlain by the Upper Permian Val Gardena Sandstone and the Upper Permian Bellerophon Formation, and is overlain conformably by the latest Scythian (Early Triassic) to early Middle Triassic (Anisian) in age Lower Serla Dolomite in western exposures and unconformably by the Upper Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 24 A Nevada Utah 'George fe ga* 15 km © Las Vegas 20 km Figure 14: Maps of localities of the Virgin Limestone Mem ber of the Moenkopi Formation examined in Nevada and Utah,U.S.A. A) Localities examined in shaded areas. B) Three localities in Nevada: 1) Lost Cabin Springs;2) Muddy Mountains; 3) U te.Q T w o localities in Utah:4) White Hills; 5) Hurricane. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 25 NEVADA UTAH F R E N C H M A N M T S LOST CABIN V IR G IN , U T A H BLU E D IA M O N D UPPER RED MEMBER SHNABKAIB MEMBER m VIRGIN MIDDLE RED MEMBER MEMBER LOWER RED MEMBER C o a te d g ra in * >.i» £ 7 ] CD E l S a ndstone k 'b s i m Fossil de bris C rtn o id d e b ris S ills to n e S h ale G ypsum C o n g lo m e ra te Figure 15: Correlation of the Moenkopi Formation across southern Nevada and western Utah. Sections were measured at the Lost Cabin and Virgin, Utah localities, among others. Modified from Skyllingstad, 1977. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 26 Anisian Richtofen Conglomerat in eastern exposures (Broglio Loriga et al., 1990; Twitchett and Wignall, 1996). The Tesero Oolite Horizon is a laterally extensive oolite representing latest Permian deposition in the Werfen Formation; the Permian/Triassic boundary is within the Mazzin Member (Twitchett and Wignall, 1996). Five members of the Werfen Formation comprising Griesbachian- Smithian aged strata were examined in the field at three exposures in the Dolomites. Four members, the Mazzin, Siusi, Gastropod Oolite, and Campil, are fossiliferous and are the focus of the Lower Triassic sections from western Paleotethys in this study (Figures 16, 17). Mazzin Member. The Mazzin Member consists of laminated to thinly bedded micrite and marly siltstone commonly exhibiting stylonodular fabrics (Wignall and Hallam, 1992). Centimeter-thick bivalve- and microgastropod-dominated packstones and grainstones occur throughout the Mazzin Member but are most common in the top few meters of the member; ostracode grainstones are also common (Wignall and Hallam, 1992). Bivalve-dominated wackestones ranging from a few dm to more that 2 m in thickness also occur throughout the Mazzin Member and are interpreted to have resulted from micrite-rich debris flows (Twitchett and Wignall, 1996). The absence of a burrowing fauna, common pyrite framboids, and low Th/U values indicate Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 27 ED B Bolzano/ Bozen S 48 Falcade S34J Moena S 12 S 50 Predazzo S48 ;ero 10 km Figure 16: Maps of Werfen Formation localities in northern Italy. A) Exposures of Werfen Formation examined within the shaded area. B) Proximity of Lower Triassic localities to major roads: 1) Punta Rolle; 2) Tesero; 3) Uomo. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 28 ^ 5 3 1 Distal tempestites B f f l Proximal tempestite © Oolites Tepees tf* Microgastropods Figure 17: Stratigraphic column representative of the Werfen Formation. P: Permian; TOH:Tesero Oolite Horizon; A: Andraz Horizon; GOM: Gastropod Oolite member, (modified from Twitchett and Wignall, 1996). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 29 that dysaerobic-anaerobic conditions characterized deposition of the Mazzin Member (Wignall and Hallam, 1992; Wignall and Twitchett, 1996). The Mazzin Member was deposited in inner to middle shelf settings. Siusi Member. The Siusi Member represents deposition from inner ramp to distal ramp marine settings (Broglio-Loriga etal., 1990; Twitchett and Wignall, 1996). The Siusi Member consists of cm- to dm-thick oolitic- bioclastic grainstones and packstones, many known as the “Gastropodenoolith” or the “oolite a gasteropodi” because of their abundance of microgastropods (c.f. Broglio-Loriga etal., 1990; Fraiser and Bottjer, 2004). Microgastropods and bivalves are the most abundant fossils in the Siusi Member. The upper half of the Siusi Member exhibits hummocky cross stratification, wave ripples, and more terrigenous input than the lower half and was deposited in shallower conditions. Gastropod Oolite Member. The Gastropod Oolite Member consists of two facies: the upper facies deposited in nearshor to middle shelf marine environments (Broglio-Loriga et al., 1990) and the lower facies deposited in supratidal conditions. The lower facies was not sampled for this study. Ooid- and microgastropod-dominated grainstones and packstones comprise the distinctive lithology of the Gastropod Oolite Member (“Gastropodenoolith” Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 30 or the “oolite a gasteropodi”), though this lithology occurs throughout the Werfen Formation (Broglio Loriga etal., 1990). Hummocky cross stratification and wave ripples are found in thin siltstone beds in the upper portion of the Gastropod Oolite Member. Campil Member. The Campil Member is composed predominantly of reddish siltstones and sandstones deposited in an inner ramp environment (Broliga Loriga et al., 1990). Hummocky cross stratification and load structures are found throughout the Campil Member and thin bivalve- dominated packstones and grainstones are uncommon. Western Panthalassa: Present-day Honshu, Japan Hiraiso Formation: The Smithian Hiraiso Formation, the oldest formation of the Triassic (Scythian-Anisian) Inai Group (Kamada, 1979), outcrops in northeast Japan (Honshu) in the coastal area of Miyagi Prefecture (Kimura et al., 1991). The Hiraiso Formation consists of autochthonous marine strata that unconformably overlie the Upper Permian Toyoma Group (Kamada, 1979,1983; Kimura et al., 1991) and merge into the Smithian-Spathian Osawa Formation (Kamada, 1979; Kimura et al., 1991). The lower Hiraiso Formation consists of medium to thick storm beds of calcareous, well-sorted sandstones alternating with thin to thick bivalve- Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 31 dominated lags deposited in inner shelf to outer shelf depositional environments. The majority of the sandstone storm beds exhibit hummocky cross-stratification and tabular cross-bedding. The upper Hiraiso Formation consists of thin to medium calcareous sandstone and siltstone storm beds, bivalve-rich lags, and evidence of soft-sediment deformation. The upper Hiraiso is muddier than the lower Hiraiso and was deposited farther offshore; the upper Hiraiso may grade into the Smithian-Spathian Osawa Formation that consists of laminated alternating shales and sandstones, slump overfolds, and dislocated blocks that indicate a submarine slide (Kamada, 1979; 1983). Three coastal exposures of the Hiraiso Formation several hundreds of meters apart were measured and sampled (Figures 18, 19). Sections of the Hiraiso vary laterally because of the nature of its storm-dominated deposition. Bivalves are the most common fossil; microgastropods and crinoid ossicles are rare. Open-ocean Panthalassa: Present-day Kyushu, Japan Kamura Formation: In the Takachiho area of Kyushu, Japan, a fault- bounded slab of Permian-Triassic carbonates consisting of the Changhsingian Mitai Formation and the disconformably overlying Triassic Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 32 *Kesennuma Figure 18: Maps of localities of the Hiraiso Formation examined in Miyagi Prefecture, Honshu Island, Japan. A) Localities examined in shaded area. B) Three localities on Hiraiso: 1) Kesennuma A; 2) Kesennuma B; 3) Kesennuma C. Map B modified from Kashiyama and Oji (2004). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 33 B * Crinoid Ossicles iz-rj-z Fossiliferous Lag m i l ? 30 20 I O 30 20 Figure 19: Stratigraphic columns of the Hiraiso Formation. A), B),and C): Sections at HF-A,HF-B,and HF-C respectively. Modified from Kashiyama and Oji (2004). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 34 Kamura Formation is exposed (Watanabe etal., 1979; Sano and Nakashima, 1997) (Figure 20). The Mitai and Kamura Formations represent accumulation on the top of a seamount in open-ocean Panthalassa (Sano and Nakashima, 1997). The Kamura Formation is divided into the basal, lower, middle and upper members; the basal member is Griesbachian in age and the lower member is Dienerian-Spathian in age (Figure 21). In the basal member of the Kamura Formation, microgastropod-dominated shell beds (few mm to cm in thickness), peloids, and microbial crusts form triplets that repeat upsection. The lower member consists of a very thickly-bedded (up to 10 m) bivalve coquinite (Sano and Nakashima, 1997). Two localities on the Kamura Formation near Takachiho in northern Kyushu were examined. Due to the environment of deposition, poor exposure, and tectonic history of Japan, it is difficult to determine the distance between these localities during deposition. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 35 33°N — Shioi'nouso Chichibu terrane Takachiho area 32'45'N Kyushu Island 50 km Figure 20: Maps of localities of th e Kamura Form ation exam ined in Shikoku Prefecture, Kyushu Island, Japan. A) Localities exam ined in shaded area.B) Examined localities near the city o f Takachiho. C) Localities A and B. M aps B and C m odified from Sano and Nakashima, 1997. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 36 c o ’ + - > £ < ✓ > r o o LL . 1 — 0 3 i — D u . f U L U £ 0 3 lower basal 10-> • • • > • • 4 • .4 ^ 11'l H T 1 ' • • ► • • ■ n»" «i i lllillll lllil l ll *< 5 1 . <D < 3 ' 0 < 2 ? , mudstone t-Z -3 wackestone lllillll grainstone |» » «| packstone ■ ■ ■ micritic frame &rind | »»| peloids | <g>| oncoids micritic covers 1 « • *» | cyanobacteria [ [ I QP 1 gastropods I ( A th in-shelled bivalves larger bivalves Figure 21: Composite stratigraphic column of the basal and lower members of the Kamura Formation. Modified from Sano and Nakashima, 1997. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 37 CHAPTER 3: FOSSIL PRESERVATION DURING THE AFTERMATH OF THE END- PERMIAN MASS EXTINCTION: TAPHONOMIC PROCESSES AND PALEOECOLOGICAL SIGNALS The potential Early Triassic preservation bias The end-Permian mass extinction played a pivotal role in shaping the broad-scale pattern of taxonomic diversity through the later Phanerozoic. Two mass extinctions near and at the end of the Permian eliminated 71% and 80% of marine invertebrate species, comprising the largest decreases in Phanerozoic marine biodiversity (Stanley and Yang; 1994). Mounting research indicates that the aftermath of the end-Permian mass extinction was as crucial as the mass extinction itself in shaping the evolutionary history of life on Earth. Sedimentologic (Woods et al., 1999; Pruss et al., 2004) and isotopic (e.g., Marenco et al., 2003; Payne et al., 2004) evidence indicates that the physiologically stressful environmental conditions likely related to the cause of the end-Permian mass extinction persisted through the Early Triassic, for possibly 5-6 million years (Martin et al., 2001; Mundil et al., 2004). Because of these global environmental perturbations, biotic recovery was suppressed in Early Triassic oceans: global taxonomic diversity remained very low (Ciriacks, 1963; Schubert and Bottjer, 1995; Erwin and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 38 Pan, 1996) and opportunistic organisms proliferated (Rodland and Bottjer, 2001; Fraiser and Bottjer, 2004). In addition to the phyletic switch from the Paleozoic Fauna to the Modern Fauna, the prolonged deleterious environmental conditions during the Early Triassic facilitated a host of temporary and permanent structural changes in benthic level-bottom marine paleocommunities (Fraiser and Bottjer, 2005) (see Chapter 6). Thus, the vast majority of studies focusing on the end-Permian mass extinction and its Early Triassic aftermath indicate that, during this geologically brief interval in Earth’s history, broad-scale evolutionary patterns were drastically and permanently altered. However, a variety of literature on the mode of preservation of Early Triassic skeletonized invertebrate marine fossils and on Early Triassic taxonomic patterns questions the quality of the Lower Triassic fossil record and, therefore, the notion that the Early Triassic was as significant to the course of evolution as previously determined. The Lower Triassic fossil record has been described as a “fossilization low” (Twitchett, 2001) because a large portion of Early Triassic taxa are Lazarus taxa (Batten, 1973; Erwin and Pan, 1996; Twitchett, 2001), taxa that temporarily disappear from the fossil record but reappear later unchanged (Flessa and Jablonski, 1983). Aftermaths of mass extinctions are typified by high numbers of Lazarus taxa from several phyla; these taxon outages may be the result of migration of taxa to refugia, population sizes below the level Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 39 of detection, lack of sampling, or taphonomic bias (Jablonski, 1986a,b; Erwin and Pan, 1996; Kauffman and Harries, 1996; Wignall and Benton, 1999; Twitchett, 2001). Nevertheless, the more Lazarus taxa present in a particular interval, the less complete the fossil record is considered to be (e.g., Twitchett, 2001). The high number of Early Triassic Lazarus taxa recently has been attributed to a taphonomic bias rather than any ecological cause because of an alleged dearth of silicified Early Triassic invertebrate marine faunas. The Early Triassic is also considered to represent a long “chert gap” when very little biogenic chert was produced and/or preserved (Racki, 1999; Beauchamp and Baud, 2002) because of latest Permian global warming and subsequent shutdown of thermohaline circulation that eliminated conditions favourable to the production, accumulation and preservation of biogenic silica (Beauchamp and Baud, 2002). Erwin (1996) and Erwin and Pan (1996) propose that poor preservation makes many gastropod taxa only appear to be absent during the Early Triassic because several genera are known almost exclusively from silicified material, others are difficult to identify without silicification, and many had robust, easily preserved shells. It was thus postulated that many Early Triassic Lazarus taxa may have actually been present in large numbers but were not preserved because of a lack of extensive early silicification of Early Triassic fossils; the Lazarus taxa Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. represent organisms whose calcareous body fossils were simply dissolved away, leaving no record of their existence (Erwin, 1996; Erwin and Pan, 1996). More recent studies revealing that silicified faunas have a higher fidelity of fossil preservation than non-silicified faunas (Cherns and Wright, 2000; Wright et al., 2003) lend credence to these interpretations about the Early Triassic fossil record. It is contended that a lack of fossil silicification may bias our understanding of recovery events (Schubert et al., 1997) and skew palaeoecological interpretations (Cherns and Wright, 2000; Erwin and Kidder, 2000). Certainly, a lack of silicified fossils may indicate that a preservation bias threatens previous perceptions of the taxonomic patterns during the aftermath of the end-Permian mass extinction. Taxonomic studies require excellent fossil preservation, such as that provided by early silicification. Increasingly, however, taxonomic approaches, like counting the number of Lazarus taxa, are considered to be one-dimensional and insufficient for elucidating a complete picture of evolution if used alone. Paleoecological approaches, in which organisms and their interactions with each other and the environment are evaluated, are required to fully understand evolutionary patterns and processes, including aftermaths and biotic recoveries from mass extinctions (e.g., Bottjer, 2001). Excellent fossil preservation such as silicification is not a requirement in paleoecological studies because Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 41 interpretations can be made using a wide range of data available from the rock record (e.g., Bottjer, 2001) [although taphonomic analyses are vital to paleoecological studies to ensure that paleoecological patterns are not artifacts of preservation processes (e.g., Parsons-Hubbard et al., 1999; Marquez-Aliaga and Ros, 2002)]. Furthermore, a recent study on partially silicified Early Triassic gastropods revealed only one Lazarus genus despite the fauna’s presumed increased preservation potential, suggesting other controls on the abundance of Lazarus taxa (Wheeley and Twitchett, 2005). Doubts about the quality of the Lower Triassic fossil record must be addressed in regards to paleoecologic as well as taxonomic data not only because the end-Permian mass extinction and its aftermath are considered to be a defining interval in evolutionary history, but because taxonomic and ecologic patterns during the aftermaths of mass extinctions can be decoupled and differ in severity, and the most significant result of a mass extinction can be the new ecological patterns that arise during its aftermath (Droser et al., 1997, 2000). Very few studies have addressed the Early Triassic Lazarus phenomenon (q.v. Wignall and Benton, 1999) or have examined early diagenetic processes that potentially affected Early Triassic faunas. The purpose of this pilot study was to test the hypothesis that the Early Triassic fossil record is not taphonomically biased and that it actually records primary Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 42 paleoecologic signals during the aftermath of the end-Permian mass extinction. Until the usefulness of the Lower Triassic fossil record is determined, all taxonomic and paleoecologic studies of the aftermath of the end-Permian mass extinction will be precluded by the possibility of preservation bias (sensu Erwin and Pan, 1996). Presented here is: an assessment of Lower Triassic fossil preservation; a discussion of environmental and ecological effects upon Early Triassic early diagenetic processes; and proposed future tests of the usefulness of the Lower Triassic fossil record for paleoecologic and taxonomic studies. Methods Several studies have focused on preservation of select Lower Triassic invertebrate marine fossils of particular regions (e.g., Assereto and Rizzini, 1975; Boyd and Newell, 1976; Nice, 1985; Boyd et al., 1999; Moffat and Bottjer, 1999), but the general nature of global Early Triassic fossil preservation has not been synthesized or evaluated. To gain a basic understanding of Early Triassic fossil preservation around the world for the purposes of this study, fossiliferous Lower Triassic strata deposited in level- bottom marine environments in western Paleotethys, eastern Panthalassa, and open-ocean Panthalassa were examined in the field where they are exposed today in the western United States, northern Italy, and Japan Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 43 (Figure 22). The members and formations examined range from approximately 10 m (e.g., Kamura Formation, Kyushu, Japan) to nearly 700 m (e.g., Werfen Formation) in thickness, and numerous localities tens to hundreds of kilometers apart were selected for each member and formation. The examined strata span the entire Early Triassic and represent shallow marine subtidal to slope deposition and continuous accumulation on open- ocean seamounts. The field observations were supplemented with an evaluation of literature-based observations and data. Preservation of Early Triassic skeletonized invertebrate benthic marine fossils Silicified and partially silicified faunas were found in several beds deposited in present-day western U.S.A. (Figures 22, 23): Smithian lower member, Union Wash Formation; Spathian upper member, Thaynes Formation; and the Spathian Virgin Limestone Member, Moenkopi Formation. Partially silicified faunas were discovered in Lower Triassic sections of northern Italy; no silicified faunas were found in Japan. A review of the literature supports the field-based observations and reveals that despite being patchy, silicified faunas are moderately common in Lower Triassic strata (Figures 22, 23) and are not non-existent as previously Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 247 m ya , 252.6*0.2 m ya ■ c C < 0 < 0 O l sz c * o u VI w u V ) V ) < 0 m t — > c 0 3 < 0 3 LJ ■ o C Spathian Smithian Dlenerian Griesbachian eastern Panthalssa western United States E California Union Wash Formation upper member middle member lower member SE Nevada SE central Utah Moenkopi Formation Virgin Limestone Member Sinbad Limestone Member N central Utah, ID, MT, WY upper member Dinwoody Formation western Paleotethys N Italy Dolomites Werfen Formation Campil Member Gastropod Oolite Member Siusi Member Andraz Horizon Mazzin Member open-ocean Panthalssa Japan Kyushu Kamura Formation lower member basal member Honshu Hiraiso Formation Neotethys Oman Wadi Wasit Wasit Block Figure 22- Generalized stratigraphy of fossiliferous Lower Triassic sections containing silicified and partially silicified faunas as indicated by shading. The Union Wash, Moenkopi,Thaynes, Dinwoody, Werfen, Kamura, and Hiraiso Formations were examined in the field (modified from Kimura et al., 1991; Stone et al., 1991; Schubert and Bottjer, 1995;Twitchett and Wignall, 1996; Sano and Nakashima, 1997; Martin et al., 2001; F . Corsetti, pers. comm., 2003; Mundil et al., 2004); Oman data from Krystyn et al. (2003). owner. Further reproduction prohibited without permission. Paleotethys Panthalassa Figure 23- Early Triassic paleogeographic map modified from Scotese (1994) indicating where silicified and partially silicified faunas occur: 1) upper member,Thaynes Formation, western USA; 2) Virgin Limestone Member, Moenkopi Formation, western USA; 3) lower member, Union Wash Formation, western USA;4) Siusi,Gastropod Oolite,and Campil Members, Werfen Formation, northern Italy; 5) Wasit Block, Wadi Wasit, Oman. - t* . O l 46 maintained (Erwin, 1996). Silicified and partially-silicified faunas have been discovered and documented from Panthalassan, Paleotehthyan, and Neotethyan sections (Boyd and Newell, 1997, 2002; Newell and Boyd, 1995, 1999; Krystyn et al., 2003; Wheeley and Twitchett, 2005). Nevertheless, Early Triassic bivalves and microgastropods around the world were most commonly preserved as internal and external molds (Figure 24) or were recrystallized. In the Spathian Virgin Limestone Member of Nevada, bivalve shell voids were commonly filled by sparry calcite or were left open. Less commonly, in the Spathian upper member of the Thaynes Formation in Utah, voids created by dissolution of bivalve shells were filled by unlithified clastic material piped in from conduits (Boyd et al., 1999) and, in the lower Dinwoody Formation in northeastern Nevada, fossils of the bivalve Claraia cf. stachei were thickened diagenetically by uniform addition of calcite over the shell exterior before dissolution of aragonitic inner layers (Boyd and Newell, 1976). Microgastropods from the Werfen Formation are commonly coated with iron-oxide, giving them a reddish-pink color in outcrop (Assereto and Rizzini, 1975). The linguliform brachiopod Lingula is most commonly represented by original shell material in Griesbachian strata around the world (Xu and Grant, 1992; Rodland and Bottjer, 2001). Rhynchonelliform brachiopods, echinoid spines, and crinoids in Lower Triassic strata around the world were most commonly recrystallized. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 47 Figure 24- Preservation of Early Triassic fossils. (A) Internal molds of bivalves {Unionites),S\us\ Member, Werfen Formation.(B) Internal molds of microgastropods, Campil Member, Werfen Formation. (C) Silicified Promyalina, upper member,Thaynes Formation. Scale in mm. (D) Silicified microgastropods, Virgin Limestone Member, Moenkopi Formation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 48 Preservation often precludes identification of fossils to the species level (e.g., Fraiser and Bottjer, 2004), but the modes of life of most Early Triassic benthic marine invertebrate organisms have been identified easily as epifaunal and shallow infaunal (Schubert and Bottjer, 1995). Though molds and recrystallized shells are not the ideal modes of preservation for taxonomic studies, they can be used to determine relative abundances of higher groups of taxa, number of guilds, and tiering, and are therefore sufficient for paleoecological studies. Environmental and ecological effects upon Early Triassic early diagenetic processes Silicified faunas have been considered to be vital, perhaps even essential, for paleontologic studies (e.g., Schubert et al., 1997) and numerous well-known taxonomic studies have been based on silicified faunas (e.g., Cooper and Grant, 1972). Silicification preserves intricate details of calcareous invertebrate shells and makes them relatively easy to extract from the rock matrix in the laboratory. Major differences can exist between coeval silicified and non-silicified faunas when aragonitic shells are not preserved by early silicification, resulting in non-silicified faunas comprised only of originally calcitic shells (Cherns and Wright, 2000; Wright Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 49 et al., 2003). According to Schubert et al. (1997), good preservation of calcareous fossils does not compensate for the lack of silicified faunas. While it has been shown here that silicified fossils are actually moderately common in Lower Triassic strata, many Early Triassic faunas are preserved as molds and recrystallized calcareous shells and a taphonomic bias still may be credible for describing the condition of the Lower Triassic fossil record in some regions. Under actualistic conditions, originally aragonitic shells typically dissolve and are replaced as a result of meteoric or burial diagenetic processes during early diagenesis because aragonite is less stable than calcite at surface temperatures and pressures, even during times of “aragonite seas” (e.g., Tucker and Wright, 1990). Microbially mediated reactions associated with the decay of organic matter (e.g., Walter and Burton, 1990) and high levels of atmospheric and hence ocean concentrations of C 02 (Berner and Kothavala, 2001; Sabine et al., 2004) are processes that increase the acidity of seawater and can contribute to dissolution of calcareous shells (Hautmann, 2004). However, an evaluation of the non-actualistic environmental and ecological characteristics of Early Triassic oceans indicates that the Lower Triassic fossil record does not suffer from a taphonomic “megabias” (sensu Schubert et al., 1997) and that useful, unbiased paleontologic data were in fact preserved. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 50 Rapid dissolution of biogenic carbonate is pronounced in the upper part of the sediment column under actualistic conditions. Biogenic reworking of sediments increases oxygen levels in the mixed layer and increases oxidative decay of organic matter, thereby increasing acidity near the sediment-water interface and causing pore waters to become undersaturated with respect to both aragonite and calcite and enhancing the dissolution of calcareous shells (Aller, 1981; Walter and Burton, 1990). Shell dissolution is therefore greatest in areas with well-developed infaunal benthic communities, and maximum shell preservation occurs in regions with low bioturbation (Aller, 1981). Under actualistic conditions, epifaunal, shallow infaunal, and small organisms are expected to be preferentially dissolved while calcareous shells of deeper-burrowing and larger organisms should be less prone to dissolution (e.g., Wright et al., 2003). Sediment reworking by infaunal organisms also disrupts mold space left after shells dissolve (Cherns and Wright, 2000). However, the majority of Early Triassic fossils were originally aragonite (e.g., Schubert and Bottjer, 1995) and are from organisms that had epifaunal or shallow infaunal modes of life; they would have therefore been predicted to have been preferentially dissolved. Bioturbation during the Early Triassic resembled the Late Cambrian/Early Ordovician (Bottjer et al., 1996): bioturbation was primarily horizontal (Twitchett, 1999; Pruss and Bottjer, 2004b), depth of infaunal trace fossils never exceeded 10 cm (Schubert and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Bottjer, 1995; Twitchett, 1999; Pruss and Bottjer, 2004b), and bioturbation intensity was low (Schubert and Bottjer, 1995; Twitchett, 1999). The anachronistic characteristics of bioturbation during the Early Triassic prevented destruction and dissolution of calcareous shells and may have actually aided calcareous fossil preservation. Even if after death benthic marine invertebrate calcareous shells were dissolved on the seafloor in some regions due to decreased saturation state of seawater (Berner and Kothavala, 1999; Sabine et al., 2004), the low levels of bioturbation would have ensured that molds were not disturbed and may have even countered these effects because of high alkalinity at the sediment-water interface. The preservation of Early Triassic fossil molds also may be an indication that skeletal aragonite survived shallow burial and that dissolution took place during deeper burial (sensu Wright et al., 2003). Furthermore, the decrease in ichnogeneric diversity and in depth and extent of bioturbation during the Early Triassic are excellent proxies for ecological degradation during the aftermath of the end-Permian mass extinction independent of fossilization processes and falsify the hypothesis that taxonomic and ecologic patterns during the Early Triassic are more apparent than real (sensu Erwin, 1996; Erwin and Pan, 1996). In addition to the lack of extensive bioturbation, evidence in the form of large d3 4 S excursions (Marenco et al., 2003), submarine carbonate fans Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 52 (Woods et al., 1999; Baud and Richoz, 2004), and subtidal stromatolites (Pruss and Bottjer, 2004a) indicate that alkalinity periodically built up in Early Triassic oceans due to bacterial sulfate reduction. Though this phenomenon varied regionally and temporally throughout the Early Triassic, increased oceanic alkalinity would have aided carbonate fossil preservation in some regions during the Early Triassic. The prevalence of molds and recrystallized fossils of originally aragonitic organisms only millimeters to 2-3 centimeters in size (Fraiser and Bottjer, 2004) is another indication of the fidelity of the Lower Triassic fossil record and supports the hypothesis that the Lower Triassic fossil record reflects a primary ecological signal. Small aragonitic shells would be expected to dissolve before larger ones (e.g., Wright et al., 2003). The commonness of small originally phosphatic shells (e.g., Lingula) (Price-Lloyd and Twitchett, 2002) lends further support to the hypothesis proposed herein. The idea that incompletely silicified larger fossils may result in micromorphic faunas (Erwin and Kidder, 2000) does not apply to the Early Triassic fossil record. Even though various aspects of the Early Triassic biotic crisis were manifest at different times at different places around the world, paleocommunities in the Panthalassa, Paleotethys, Neothethys, and Boreal Oceans are remarkably similar in terms of biodiversity and paleoecology (c.f. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 53 Fraiser and Bottjer, 2005). That silicified and non-silicified benthic skeletonized invertebrate marine faunas in various oceans and latitudes around the world share taxonomic and paleoecologic characteristics (i.e., low biodiversity, low levels of tiering, numerical dominance by the same genera) is another line of evidence that refutes the hypothesis of an extensive Early Triassic taphonomic bias. Thus, based on these lines of evidence, the Early Triassic “fossilization low” appears actually to be a paleoecological indicator of the severity of the physio-chemically harsh environmental conditions that persisted long after the end-Permian mass extinction {sensu Wignall and Benton, 1999) rather than merely poor preservation. Furthermore, the fossil record of Early Triassic ammonoids is considered suitable for determining their taxonomic and morphologic recovery patterns after the end-Permian mass extinction (McGowan, 2004a,b), even though their originally aragonitic shells, once settled on the seafloor after death of the animal, would have been subjected to the same early diagenetic processes as originally aragonitic skeletonized benthic organisms. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54 Testing the quality and utility of the Lower Triassic fossil record of skeletonized invertebrate benthic marine fossils This preliminary examination of the preservation of Early Triassic skeletonized benthic invertebrate marine fossils has revealed that: 1) silicified faunas are moderately common in Lower Triassic strata, and 2) molds and recrystallized body fossils of Early Triassic skeletonized benthic invertebrate marine organisms are adequate at least for paleoecologic studies because environmental characteristics unique to the Early Triassic prevented originally calcareous shells of benthic marine invertebrate organisms and their molds from being preferentially dissolved or destroyed. Although these preliminary observations indicate that reservations about the quality of the Lower Triassic fossil record are not completely valid, future testing is required to more accurately determine the quality and utility of the non-silicified Lower Triassic fossil record for taxonomic and paleoecologic purposes because the majority of Early Triassic fossils are non-silicified (Figure 24) and paleoecologic analyses of the aftermath of the end-Permian mass extinction have focused on non-silicified faunas (e.g., Rodland and Bottjer, 2001; Fraiser and Bottjer, 2003; 2004). Three tests of the quality and utility of the Lower Triassic fossil record, one literature-based and two field-based, are proposed here. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 55 Determining how the number and extent of Early Triassic silicified faunas compares with the number and extent of silicified faunas from the Permian, Middle and Late Triassic will further test the assumption that silicified faunas are rare in Lower Triassic strata deposited during the aftermath of the end-Permian mass extinction (sensu Erwin, 1996). Preliminary evidence presented here indicates that Early Triassic silicified faunas are actually moderately common in Lower Triassic strata, and the number of late Early Triassic silicified faunas may even be larger than that of the Middle Triassic (C. McRoberts, pers. comm., 2004). Secondly, to test the Early Triassic taphonomic model proposed herein, the biodiversity, relative abundances, sizes, and extent of secondary tiering (epibiont cover) of Early Triassic silicified faunas should be compared to the biodiversity, relative abundances, sizes, and extent of secondary tiering of coeval non-silicified faunas; similar methods have been used previously (Cherns and Wright, 2000). Comparisons of the biodiversities and relative abundances of the two groups will determine if non-silicified Early Triassic faunas are significantly biased because originally aragonitic shells were preferentially dissolved (sensu Cherns and Wright, 2000; Wright et al., 2003) and test the model proposed here that the Lower Triassic fossil record is adequate for discerning paleoecology. Comparisons of ranges in fossil Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 56 size and in extent of epibiont cover will assess the extent of any shell dissolution. Taxonomic and paleoecologic characteristics of different Early Triassic marine environments must also be compared and contrasted. Early dissolution of aragonite can be a major process in offshore settings regardless of the depths of the aragonite or calcite compensation depths where a source of organic matter is available upon which microbial processes can act and increase acidity (Wright et al., 2003). Shell dissolution and preservation therefore can be dependent on facies-controlled factors. Conclusions The high number of Lazarus taxa during the aftermath of the end- Permian mass extinction has been previously attributed to an alleged dearth of silicified faunas that also has been used previously as an indication that the entire Early Triassic fossil record is afflicted by a taphonomic bias (Erwin; 1996; Erwin and Pan, 1996; Twitchett, 2001). However, silicified faunas are moderately common in Lower Triassic strata and preservation of calcareous benthic skeletonized invertebrate marine shells during the Early Triassic was possibly aided by environmental, ecological, and geochemical characteristics in the early diagenetic environment unique to the aftermath of the end- Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 57 Permian mass extinction. Early Triassic fossil molds and recrystallized shells reflect primary ecologic signals, if not taxonomic ones. Early silicification of calcareous organisms may be important for determining taxonomic patterns, but it is not required for determining paleoecological patterns. Furthermore, the well-entrenched Early Triassic “chert gap” is more likely an Early Triassic “chert eclipse” and its causes and global patterns deserve reexamination. This preliminary examination indicates that the Early Triassic “fossilization low” is largely due to ecological and environmental factors that persisted during the aftermath of the end-Permian mass extinction (sensu Wignall and Benton, 1999), not because of a preservation bias as previously posited (Erwin, 1996; Erwin and Pan, 1996). Consideration of all aspects of the fossil record for critical time intervals in the history of life is thus a crucial task necessary for evaluating the preservation and hence utility of particular fossil faunas to providing answers to large-scale evolutionary and paleoecological questions. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 58 CHAPTER 4: THE EARLY TRIASSIC GLOBAL BIVALVE ECOLOGICAL “TAKEOVER” The “Brachiopod-Bivalve Question” Large-scale evolutionary patterns are recognized throughout the fossil record in taxonomic and paleoenvironmental contexts (e.g., Sepkoski, 1981; Bottjer and Jablonski, 1988). One renowned pattern identifies large-scale variations in taxonomic dominance throughout the Phanerozoic marine record and is comprised of three “great evolutionary faunas” (Sepkoski, 1981). Each evolutionary fauna is composed of higher taxonomic groups that share similar histories of diversification which dominate the marine biota for an extended interval of geologic time (Figure 25). The expansion of each evolutionary fauna is associated with the decline of the previously dominant evolutionary fauna. Thus, the rise and fall of the three great evolutionary faunas signifies temporal changes in global taxonomic biodiversity through the Phanerozoic. The faunal changes associated with the abrupt decline of the Paleozoic Fauna and the subsequent ascent of the Modern Fauna comprise an extraordinary phyletic turnover. Rhynchonelliform brachiopods were the major benthic constituents of the Paleozoic Fauna from the Ordovician to the Permian (Gould and Calloway, 1980; Sepkoski, 1984; Sepkoski and Hulver, Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 900 600 300 Modern Fauna Paleozoic Fauna Cambrian Fau T r 200 600 CAMBRIAN FAUNA M onoplacophora Inarliculaia ■200 £ Hyolitha T rilobila PALAEOZOIC FAUNA Anthozoa C ephalopoda Stenolaemata Stelleroida O in o id e a O stracoda MODERN FAUNA 600 C hondnchthyes G astropoda Demo&pongia R hizopodea Echinoidea 200 200 600 400 0 G eological tim e (10*’ yrs) Figure 25: A) The histories of familial diversity in each of the three great evolutionary faunas of the marine fossil record. B) Representative members of each evolutionary fauna. Modified from Sepkoski, 1981,1984). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 60 1985). However, since the Permian/Triassic boundary, bivalves have surpassed rhynchonelliform brachiopods with respect to diversity and are the major benthic constituents of the Modern Fauna (Gould and Calloway, 1980; Sepkoski and Hulver, 1985) that has dominated metazoan biodiversity in the world’s oceans for the past 250 million years (Sepkoski, 1981). The precipitous post-Paleozoic bivalve phyletic “takeover” in level-bottom benthic marine environments, dubbed the “brachiopod-bivalve question” (Stanley, 1972), has been contemplated for at least 150 years (Gould and Calloway, 1980) because rhynchonelliform brachiopods and bivalves have similar modes of life and resource requirements (e.g., Steele-Petrovic, 1979). The Modern Fauna attained appreciable diversity during the Ordovician because of increasing bivalve diversity. Generic diversity of bivalves increased throughout the Paleozoic and experienced a “hyperexponential burst” in diversification following the end-Permian mass extinction when many other groups of organisms became extinct, becoming the most diverse class in the world’s oceans (Sepkoski, 1981; Miller and Sepkoski; 1988). Rhynchonelliform brachiopod and bivalve diversity patterns through the Phanerozoic indicate an abrupt transposition in diversity at the Permian/Triassic boundary (Gould and Calloway, 1980; Sepkoski, 1981) (Figure 25) and therefore the reversal in diversity between rhynchonelliform brachiopods and bivalves is the result of a single incident: the end-Permian Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 61 mass extinction (Gould and Calloway, 1980; Sepkoski, 1981). Mass extinctions can change the course of evolution because a group’s success during “background” times does not guarantee survivorship during global devastation when successful incumbents are commonly eliminated (Erwin, 2001; Jablonski, 2001). Since it is evident that the end-Permian mass extinction played a pivotal role in the reversal of taxonomic dominance between rhynchonelliform brachiopods and bivalves (Gould and Calloway, 1980; Sepkoski, 1981), a variety of explanations have been offered to explain the switch. Most of the hypotheses regarding the “brachiopod-bivalve question” have focused on physiological differences between rhynchonelliform brachiopods and bivalves as a means to determine which group would have been “superior” in competitive interactions. Steele-Petrovic (1979) concluded that bivalves, compared to rhynchonelliform brachiopods have a greater net energy gain in feeding; are able to exploit a larger number of habits; and are better able to cope with more environmental factors, giving them a competitive advantage over rhynchonelliform brachiopods. Steele-Petrovic (1979) further hypothesized that because of these physiological advantages, bivalves were able to invade vacant environments earlier and faster than rhynchonelliforms after the end-Permian mass extinction and that competition prevented rhynchonellifoms from reoccupying many Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 62 environments. Thayer (1986) provides evidence that rhynchonelliform brachiopods are energetically efficient and that they may have a competitive advantage over bivalves when oxygen or food is limiting. However, Rhodes and Thompson (1993) show that rhynchonelliform brachiopods do not feed as effectively as bivalves at high algal concentrations. Thayer (1985), based on a series of laboratory experiments with Recent rhynchonelliform brachiopods and mussels, hypothesized that the mobility of bivalves made them better competitors for food and space than sessile rhynchonelliform brachiopods, leading to the post-Paleozoic decline of rhynchonelliform diversity. Law and Thayer (1991) showed that rhynchonelliforms produce fewer offspring than bivalves and hypothesized that this gave bivalves a competitive advantage over rhynchonelliform brachiopods. Valentine and Jablonski (1986) suggested that planktotrophs such as rhynchonelliform brachiopods were preferentially selected against during the end-Permian mass extinction with long-lasting effects. Gould and Calloway (1980) advocate that there was no interaction between rhynchnelliforms and bivalves through the Phanerozoic and that the two groups are like “ships that pass in the night” during the end-Permian mass extinction. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 63 Purpose Much research has focused on the taxonomic patterns at the Permian/Triassic boundary, determining which and how many taxa became extinct during the end-Permian mass extinction (e.g., Sepkoski, 1981; Stanley and Yang, 1994). More recently, research has focused on the paleoecology of certain groups that thrived during the aftermath of the end- Permian mass extinction (Rodland and Bottjer, 2001; Fraiser and Bottjer, 2004). Despite this recent attention, the ecological context of the end- Permian mass extinction and its aftermath has hardly been examined and is still crudely understood. In fact, the most significant results of mass extinctions may actually be new ecological patterns that arise during their aftermaths (Droser et al., 1997). The purpose of this research is two-fold. One purpose of this research was to test the hypothesis that new, significant ecological patterns arose during the Early Triassic aftermath of the end-Permian mass extinction. Specifically, was there an ecologic switch in shallow level-bottom benthic marine communities that resulted from the end-Permian mass extinction, in addition to the phyletic switch? Previous studies of taxonomic diversity have led to the conclusion that bivalves replaced rhynchonelliform brachiopods as ecological dominants in shallow level-bottom marine environments after the end-Permian mass extinction (Sepkoski, 1981), but no Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 64 paleoecological data have been presented to support or refute this assumption, although it has been repeated widely in the literature (e.g., Vermeij and Herbert, 2004). Secondly, this research has endeavored to illuminate the role of the end-Permian mass extinction and its aftermath on the “brachiopod-bivalve question” and if this involved paleoecological changes. Now that ample evidence indicates that global environmental perturbations persisted from the Middle Permian through the Early Triassic (e.g., Isozaki, 1997; Woods etai, 1999; Payne etal., 2004), the “brachiopod-bivalve question" deserves another examination within a paleoecological context. Results show that though the post-Paleozoic importance of bivalves in benthic marine communities had roots in the Paleozoic (Miller, 1988), environmental perturbations such as global warming, a reduced pole to equator temperature gradient, sluggish ocean circulation, massive release of CH4 , global marine anoxia, hypercapnia, and H2 S poisoning (see references in Chapter 1) that caused the end-Permian mass extinction and its prolonged biotic recovery played pivotal roles in shaping broad-scale taxonomic and ecologic patterns. Broad Scale Patterns of Post-Cambrian Ecological Dominance The first requirement for this research was to determine the large- scale pattern of ecological dominance in benthic marine communities for the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 65 post-Cambrian Phanerozoic, the interval of geologic time when the Paleozoic and Modern Faunas dominated. The three great evolutionary faunas comprise a renowned taxonomic pattern that identifies large-scale variations in taxonomic dominance throughout the Phanerozoic marine record (Sepkoski, 1981). However, taxonomic richness data alone, even when examined in a paleoenvironmental context (e.g., Bottjer and Jablonski, 1988), does not sufficiently reflect ecological processes (McKinney et al., 1998; Kidwell, 2001; Novack-Gottshall and Miller, 2003). Commonly used methods of paleoecological analysis include biomass estimations (e.g., Powell and Stanton, 1985); tiering (e.g., Bottjer and Ausich, 1986); and differentiation of guilds (e.g., Bambach, 1983). Abundance data are also crucial for understanding ecology and broad ecological processes because abundant species, or ecological dominants, play a major role in controlling the rates and directions of many community and ecosystem processes (Power et al., 1996). The importance of abundance data for understanding ecological processes has been demonstrated on fine and regional scales (e.g., Novack-Gottshall and Miller, 2003), but large-scale patterns of ecological dominance through the Phanerozoic have not yet been systematically discerned (Clapham et al., 2003). Data available in the primary literature on fossil accumulations were used as a proxy for ecological dominance during the Ordovician through the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 66 Permian and during the post-Early Triassic. Accumulations of skeletonized fossils can adequately represent the relative abundances of once-living organisms (Kidwell, 2001; 2002) and so can be used to determine a group’s dominance in the Phanerozoic. The formation of and trends in marine skeletal accumulations through the Phanerozoic have been analyzed and documented by Kidwell (1991) and Kidwell and Brenchley (1994,1996), but fossil accumulations have rarely been used as a proxy for ecological dominance (see Li and Droser, 1997, 1999). Since shell beds can be used as a proxy for determining a group’s dominance in the Phanerozoic, Kidwell’s (1991) compilation of examples of different types of shell beds (event, composite, or hiatal concentrations) for the Phanerozoic from the literature was analyzed because it is the only published compilation of shell beds throughout the Phanerozoic. Kidwell’s (1991) appendices are unbiased sources for the purposes of this study because: 1) a wide range of environments was examined (shallow subtidal to deep basin); and 2) the purpose of the compilation was to list examples of shell concentrations with different stratigraphic features (the emphasis was not on what fossils were present); this compilation is therefore ideal for determining the broad pattern of ecological dominance through the Phanerozoic. Each post-Cambrian example listed in the appendices of Kidwell (1991) was directly examined (no Lower Triassic examples were listed) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 67 (Appendix B). Numerical dominants were determined for each shell bed example using relative abundance tables, information in the text, or photos. All types of shell beds were included because, even though Vermeij and Herbert (2004) advocate that event beds are the only types of fossil assemblages not subject to sampling bias, the purpose of this broad analysis was to determine ecological dominants per period, not per community. Each numerically dominant group was counted only once per member or formation, regardless of shell bed type. Thus, each member or formation could consist of one or more shell bed types or numerically dominant groups. Only shell bed examples listed in the appendices were included and only level-bottom marine examples were tallied [accumulations of pelagic fossils and meiofauna, reefs, bioherms, and brackish faunas were excluded]. These methods yielded conservative estimates of ecological dominants through the Phanerozoic because each numerically dominant group received the same score of “1” whether it dominated one shell bed or many shell beds per stratigraphic unit. Pelmatazoan abundance may be underestimated because regional encrinites (sensu Ausich, 1997) were not included in Kidwell’s (1991) study. However, a regional encrinite would have received the same “score” as small encrinites that were included in Kidwell (1991). During the Ordovician to the Permian, the majority of fossil accumulations were dominated by rhynchonelliform brachiopods (Figure Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 68 26A); bivalve-dominated shell beds, though present, were rare. During the post-Early Triassic, the majority of fossil accumulations were dominated by bivalves (Figure 8B). The Modern Fauna is dominated by bivalve and gastropod taxa (Sepkoski, 1981), but gastropods do not comprise a significant portion of the fossil accumulations during the post-Early Triassic (Figure 26B). The general pattern of ecological dominance through the Phanerozoic is that rhynchonelliform brachiopods were the most abundant skeletonized group in shallow level-bottom benthic marine communities during the Ordovician through the Permian, and bivalves were the most abundant skeletonized group in these communities during the post-Early Triassic. This broad-scale pattern of ecological dominance corresponds with previously published fine-scale analyses from Kidwell and Brenchley (1994, 1996) and with anecdotal evidence (Rudwick, 1970). This analysis thus serves as the necessary broad framework for the more specific examination of Lower Triassic fossil accumulations presented in this paper. Early Triassic Patterns of Ecological Dominance The more specific focus of this study is an analysis of 678 fossil accumulations exposed in northern Italy, Japan, and the western U.S., deposited in a wide variety of shallow level-bottom marine environments in different oceans during various stages and substages of the Early Triassic Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. Ecological Dominants in Post-Lower Triassic Fossil Accumulations Ecological Dominants in Ordovician- Permian Fossil Accumulations 50 'e 3 o N=75 N=109 C O v > o 20 c 2 0 c w in V) in in co in in in in in in •o a> f f a > •s as -j =e 5 » to f l > Figure 26- Post-Cambrian Phanerozoic ecological dominants showing (A) rhynchonelliform brachiopods ecologically dominate Ordovician-Permian fossil accumulations, and (B) bivalves ecologically dominate post-Lower Triassic fossil accumulations; N equals the total number of fossil accumulations included in the analysis. Data from Kidwell (1991) (see text). 0 5 c o 70 (Figure 27). Detailed stratigraphic sections were measured at 2-7 localities of each member and formation to ensure sampling of a transect of marine environments. In the field, the number of fossil accumulations was noted (including fossiliferous grainstones, packstones, and wackestones, shell beds, and shell pavements), and the abundance of fossil groups in the fossil accumulations was determined semi-quantitatively by visual estimates (see Appendix B). For example, in a fossil accumulation labeled as bivalve- dominated, bivalves comprise 60% or more of the fossil constituents (60% was chosen rather than 50% to ensure that a group was indeed numerically dominant). Seventy-five random bulk samples of Lower Triassic fossil accumulations (Italy and Japan: 5,440 cm3 each; western U.S.: 27,200 cm3 each) were collected and disaggregated mechanically in the laboratory; fossils were tallied and identified to genus level (preservation precluded identification to species level). A bulk sample was considered to be dominated by one bivalve genus if one bivalve genus comprised 50% or more of the individuals in that bulk sample (the number of bivalve valves was divided by 2 in order to obtain the number of bivalve individuals). The scope of the Lower Triassic field-based portion of this project is fine-scale in order to determine the ecological context of the Paleozoic and Modern Faunas during the Early Triassic aftermath of the end-Permian mass extinction; methods similar to these have been used in previous studies of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 71 N Italy Japan western United States N central Utah SE central Utah S E Nevada ID, MT, WY Dolomites Kyushu Honshu Kamura Formation Stages and Substages Werfen Formation Thaynes Formation Moenkopl Formation 247 m ya Virgin Limestone Member upper member Spathlan Campil Member lower member Slnbad Limestone Member Hlraiso Formation S m ith ia n Gastropod Oolite Member D ie n e ria n Siusl Member Andraz Member Mazzin Member basal member Dlnwoody Formation G riesbachian 25 2 .0 i0 .6 m ya Paleotethys Panthalassa Figure 27- Stratigraphy (A) and paleogeography (B) (modified from Erwin; 1993) of Lower Triassic sections examined. Shading in (A) indicates members and formations that were examined in the field and from where bulk samples were collected; numbers in (B) indicate general paleogeographic locations of sites examined. Lower Triassic strata deposited in the western United States (1) and in northern Italy (2) represent shallow subtidal to outer shelf marine deposition of mixed carbonates and siliciclastics in eastern Panthalassa and in northern Paleotethys respectively (Larson, 1966; Blakey, 1974; Newman, 1974; Pauli et al., 1989; Twitchett and Wignall, 1996; F . Corsetti, pers. comm., 2003). The Kamura Formation, exposed in southern Japan (3), represents seamount carbonate deposition in open-ocean Panthalassa (Sano and Nakashima, 1997), and the Hiraiso Formation, exposed in northern Japan (4), represents siliciclastic deposition in a storm-dominated nearshore marine environment in western Panthalassa (Kimura et al., 1991). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 72 fossil accumulations through time (Kidwell and Brenchley, 1994). The stratigraphic characteristics of Lower Triassic shell beds in the western United States have been determined by Boyer et al. (2004). The results of this field-based assessment reveal that bivalves were the ecological dominants during the aftermath of the end-Permian mass extinction. In the Lower Triassic of the western U.S.A., northern Italy, and Japan, bivalves always dominate at least 50% of fossil accumulations of any stage or substage (Figure 28). Bivalves are commonly the sole components of shell beds, shell pavements, and up to 6 m of accumulations on a seamount (Figure 29). Overall, bivalves dominate 70% of Lower Triassic fossil accumulations; they are unequivocally the most abundant Early Triassic fossil individuals. Conversely, the presence of rhynchonelliform brachiopods in Lower Triassic strata is meager: rhynchonelliform brachiopods were found in Lower Triassic strata only in the western United States and dominate only 4% of the Lower Triassic fossil accumulations examined in this study (Figures 28, 30). Only 30% of the Lower Triassic shell beds examined are not dominated by bivalves; microgastropods and the inarticulated brachiopod Lingula also numerically dominate Lower Triassic shell beds (Rodland and Bottjer, 2001; Fraiser and Bottjer, 2004). Early Triassic bivalve ecologic dominance is not restricted to one environment, ocean, stage or substage (Figures 31, 32). Though the study areas Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 73 western USA (A 0 ) C T ) O 2 « 8 {§ 3 ■5(0 H TJ > £ ■ = T O (A Ui V O ) (O ' C O Spathian Nammalian Griesbachian F — i N=283 10 20 30 40 50 60 70 80 percentage of fossil accumulations 90 100 ■ bivalve-dom inated O rh ynchonelliform -dom inated northern Italy < / > a > D ) 5 5 j§ !8 = •5(0 I - - D > £ — ™ (0 (A U i a > u > ( 0 + - I ( O Smithian Nammalian Induan Griesbachian N=211 10 20 30 40 50 60 70 80 90 100 percentage of fossil accumulations H b ivalve-dom inated O rhynchonelliform -dom inated northern Japan O (A £t 3 •£(0 I- ■ o > > £ re (A ui a > O ) re ( O Smithian N=184 0 50 100 percentage of fossil accumulations ■ b ivalve-dom inated O rh yn chonelliform -dom inated Figure 28- Percentage of Lower Triassic fossil accumulations at study sites dominated by bivalves and rhynchonelliform brachiopods. Data for Japan just includes the Hiraiso Formation because the Kamura Formation accumulations were not "scorable" Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 74 Figure 29- Examples of Lower Triassic fossil accumulations dominated by bivalves. (A) Bivalve-dominated shellbed from the upper member,Thaynes Formation, western U.S.A. (B) Bivalve-dominated shell pavement from the Gastropod Oolite Member, Werfen Formation, northern Italy. (C) Bivalve- dominated lag from the Hiraiso Formation, northern Japan. (D) Bivalve- dominated seamount accumulation from the Kamura Formation, southern Japan. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. % bivalve-dominated fossil accumulations % rhynchonelliform-dominated fossil accumulations post- Lower Triassc [based on Kidwell (1991)] 57% 12% Lower Triassic [this study] 70% 4% Ordovician- Permian [based on Kidwell (1991)] 5% 40% Figure 30-Percentage of bivalve- and rhynchonelliform brachiopod- dominated fossil accumulations in the Ordovician-Permian,the Lower Triassic, and the post-Lower Triassic. ''4 O n 76 Dinwoodv Formation total # fossil accum ulations 51 # dom inated bv bivalves 32 # dom inated bv rhynchonelliform brachiopods 10 # dom inated by Lingula ■ 4 mixed bivalves & Lingula 5 Sinbad Limestone Member, Moenkopi Fm. total # fossil accum ulations 82 # dom inated bv bivalves 55 # dom inated bv microaastroDods 17 mixed bivalves & m icrogastropods 10 upper member. Thavnes Fm. total # fossil accum ulations 75 w estern # dom inated by bivalves 41 United States # dom inated by rhynchonelliform brachiopods 18 # dom inated bv crinoids 11 m ixed bivalves & rhvnchonelliform brachiopods 3 mixed bivalves & m icroqastropods 1 # dom inated by m icrogastropods 1 Virain Limestone Member, Moenkopi Fm. total # fossil accum ulations 75 # dom inated bv bivalves 34 # dom inated bv crinoids 6 # dom inated bv m icroaastrooods 9 mixed bivalves & m icroaastrooods 13 m ixed bivalves & m icroaastrooods & crinoids 3 m ixed bivalves & m icroaastrooods & echinoids 1 m ixed bivalves & microaastrooods & crinoids & echinoids 1 mixed dom inated bv crinoids & echinoids 6 m ixed bivalves & rhvnchonelliform brachiopods 1 m ixed bivalves & rhynchonelliform brachiopods & crinoids 1 Mazzin Member. Werfen Fm. total # fossil accum ulations 29 # dom inated bv bivalves 17 mixed bivalves & m icrogastropods 12 Siusi Member, Werfen Fm. total # fossil accum ulations 77 northern # dom inated by bivalves 47 Italy # dom inated by m icrogastropods 14 mixed bivalves & m icrogastropods 16 Gastropod Oolite Member, Werfen Fm. total # fossil accum ulations 57 # dom inated bv bivalves 30 # dom inated by m icrogastropods 27 Camoil Member, Werfen Fm. total # fossil accum ulations 48 # dom inated bv bivalves 34 # dom inated bv m icroaastrooods 12 mixed bivalves & microgastropods 2 Hiraiso Fm. Japan total # fossil accum ulations 184 # dom inated by bivalves 184 Figure 31: Results of the field analysis of ecological dominants in Lower Triassic fossil accumulations. See text for explanation of methods. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 77 total # accumulations 678 # dominated bv bivalves 474 # dominated bv crinoids 17 # dominated bv microaastrooods 80 # dominated bv rhvnchonelliform brachiooods 28 mixed bivalves & microaastrooods 54 mixed rhvnchonelliform brachiooods 28 TOTALS # dominated by Lingula 4 mixed bivalves & Lingula 5 mixed bivalves & microaastrooods & crinoids 3 mixed bivalves & microaastrooods & echinoids 1 mixed bivalves & microaastrooods & crinoids & echinoids 1 mixed crinoids & echinoids 6 mixed bivalves & rhvnchonelliform brachiooods 4 mixed bivalves & rhynchonelliform brachiopods & crinoids 1 Figure 32:Total results of the field analysis of ecological dominants in Lower Triassic fossil accumulations. See text for explanation of methods. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 78 examined represent deposition at low paleolatitudes, Lower Triassic strata deposited in high paleolatitudes contain similar faunas and similar proportions of bivalves and brachiopods (Twitchett et al., 2001; Krystyn et al., 2003). Early Triassic bivalve hegemony primarily is due to only a few widespread and numerically abundant bivalve genera. Eumorphotis, Promyalina, and Unionites are the most widespread Early Triassic bivalve genera; they are found throughout the Lower Triassic in the western United States, Italy, and Japan and are found in 57%, 57%, and 71% respectively of all 75 bulk samples analyzed in the laboratory (Figure 33). Nearly a quarter (23%) of the analyzed bulk samples are numerically dominated by Unionites; 9% and 7% of the analyzed bulk samples are numerically dominated by Eumorphotis and Promyalina, respectively. Surprisingly, the biostratigraphically important bivalve Claraia is widespread and abundant, but never numerically dominant. The phenomena reported in this study are not the result of a taphonomic bias. Silicified Early Triassic faunas from the western United States contain the same taxa and proportions of taxa as non-silicified faunas (which were examined in this study) (e.g., Newell and Boyd, 1995), and silicified Griesbachian faunas containing the same taxa and proportions of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Claraia Eumorphotis Unionites 2 cm Prom yalina Figure 33: Sketches of Eum orphotis, Unionites, and Prom yalina, th e three most common bivalve genera in Lower Triassic strata, and Claraia, a biostratigrtaphically im portant Early Triassic bivalve genus, (modified from Wignall and Hallam, 1997) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 80 taxa as those examined in this study have been reported from Oman (Krystyn et al., 2003). (See Chapter 4) Discussion Large-scale evolutionary patterns, in which taxonomic changes are framed in temporal and paleoenvironmental contexts, have been recognized throughout the Phanerozoic fossil record (e.g., Sepkoski, 1981; Bottjer and Jablonski, 1988). However, this study is the first to document large-scale patterns of ecological dominance through the Phanerozoic and to demonstrate with quantitative data that the end-Permian biotic crisis was ecologically as well as taxonomically significant in shallow level-bottom marine environments. This research indicates that mass extinctions not only have the ability to alter taxonomic patterns on large- and fine-scales as previously determined (e.g., Sepkoski, 1981), but also that they can completely restructure ecosystems around the world (e.g., Droser etal., 1997). A switch in ecological dominance occurred abruptly during the transition from the Paleozoic to the post-Paleozoic and has persisted for the subsequent 250 million years: bivalves became the abundant benthic suspension feeders in level-bottom marine environments during the Early Triassic where rhynchonelliform brachiopods had been the previously most abundant Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 81 benthic suspension feeders (Figure 12). Bivalves and rhynchonelliform brachiopods have been called “ships that pass in the night” as an analogy to explain their seemingly passive, inevitable phyletic switch at the Permian/Triassic boundary (Gould and Calloway, 1980). However, the simultaneous abrupt, sweeping ecologic switch is more appropriately referred to as a “takeover”. Certainly, bivalves were abundant and even ecologically dominant in certain marine environments during the Paleozoic (Miller, 1989; Simoes et al., 2000) and perhaps an ecologic switch from rhynchonelliform brachiopods to bivalves in shallow level-bottom marine environments was inevitable. However, as evidenced by the data collected in this study, it was not until the aftermath of the end-Permian mass extinction that bivalves ecologically dominated a variety of marine siliciclastic and carbonate environments around the world, indicating that, at the very least, the end- Permian mass extinction and its aftermath accelerated the ecologic switch from brachiopod-dominated to bivalve-dominated shallow level-bottom marine environments. Additionally, rhynchonelliform brachiopods were certainly abundant in certain Mesozoic marine environments (Tchoumatchenco, 1972; Sandy, 1995), but this short-lived episode is anomolous compared to the remainder of the bivalve-dominated Mesozoic and Cenozoic. Previous authors have attempted to answer the “bivalve- brachiopod question” (Stanley, 1972; Steele-Petrovic, 1979; Thayer, 1986; Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 82 Rhodes and Thompson, 1993), but this study presents the first data demonstrating that bivalves actually replaced brachiopods ecologically during the Early Triassic. The characteristics of the bivalves responsible for the Early Triassic ecologic takeover are significant and surprising. The ecologically dominant Early Triassic bivalves (Eumorphotis, Promyalina, and Unionites) have overall shell morphologies that are indistinct from those common to many Permian bivalves (for example, Astartella, Aviculopecten, and Myalina; Ciriacks, 1963). Thus, the modes of life that characterize Early Triassic bivalves did not evolve in response to the end-Permian mass extinction but had already evolved during the Paleozoic. Therefore, the profound morphological innovations that fueled the post-Paleozoic bivalve radiation (Stanley, 1968; 1972) were not responsible for the Early Triassic bivalve ecologic takeover. Much sedimentologic and isotopic evidence indicates that the aftermath of the end-Permian mass extinction was characterized by repeated periods of environmental stress caused by anoxic and/or C 02 -rich waters that emanated from deeper ocean environments, suppressing biotic recovery for 5-6 million years (Martin et al., 2001; Mundil et al., 2004). The Early Triassic bivalve ecologic takeover likely resulted from physiological advantages that certain bivalves already possessed which enabled them to thrive in the deleterious environmental conditions that characterized much of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 83 the Early Triassic. Whereas the stressful environmental conditions associated with the end-Permian mass extinction and its prolonged Early Triassic aftermath decimated rhynchonelliforms taxonomically and ecologically, these Early Triassic bivalves behaved opportunistically, proliferating into ecospace vacated as a result of the mass extinction. Though these 3 genera are not the precursors to the Mesozoic bivalve radiation (Ciriacks, 1963), they secured the future of ecological hegemony for bivalves, thus creating the longest-lasting, significant legacy of the end- Permian mass extinction. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 84 CHAPTER 5: PROLIFERATION OF EARLY TRIASSIC WRINKLE STRUCTURES Introduction Wrinkle structures are microbially mediated sedimentary structures preserved on bedding plane surfaces in siliciclastic strata that are characterized by their irregularly pustulose, contorted surface morphologies (Hagadorn and Bottjer, 1997) (Figure 34). Wrinkle structures were initially interpreted as sedimentary structures produced by physical current waning, wind-induced shear, and sediment loading (e.g., Allen, 1985; Dzulynski and Simpson, 1966), but the formation of wrinkle structures ultimately has been attributed to the stabilization of the substrate by microbial mats (Hagadorn and Bottjer, 1997, 1999; Noffke, 2000; Noffke et al., 2002, 2003; Noffke and Krumbein, 1999). Wrinkle structures were determined to be the preserved remnants of an irregular surface of a microbial mat community (Hagadorn and Bottjer, 1997) or are formed and preserved when overlying sediment is deposited on a microbial mat forming load molds and casts (Noffke et al., 2002). The presence of a microbial mat is inherent to the widely accepted models of wrinkle-structure formation. Microbial mats in siliciclastic environments do not form stromatolites because little to no mineral formation occurs within these communities (Noffke et al., 2003). The mats form cohesive fabrics that resist the dynamic processes of water motion in subtidal Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 85 A B Intercrest Distance (cross-section) Crest Shape Surface Patterns (plan view (cross-section) Crest & Trough W idth Figure 34: Wrinkle structures and their characteristics. A) Wrinkle structures from the Cambrian Poleta Formation. B) Schematic representation of morphologic characteristics used to describe wrinkle structures; from Hagadorn and Bottjer (1999). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 86 environments. Biofilms (an initial phase of cyanobacterial colonization) have been found to contribute little to the stabilization of sediment whereas mats (mature colonization stages) provide much stabilization to siliciclastic sediment (Noffke, 1998). Wrinkle structures are common sedimentary structures in Proterozoic-Cambrian strata (e.g., Hagadorn and Bottjer, 1997,1999), and their record has been found to extend back to the Mesoarchean (Noffke et al., 2003). In the Proterozoic-Cambrian, wrinkle structures are preserved in intertidal to deep-sea marine settings (Hagadorn and Bottjer, 1999). Post- Cambrian, wrinkle structures have been restricted to supratidal, intertidal, and deep-sea environments because of the increase in levels of bioturbation and consequent mixed-layer development during the Ordovician (Hagadorn and Bottjer, 1999). As a result of the end-Permian mass extinction and the lingering physio-chemically harsh environmental characteristics, the depth and intensity of bioturbation was decreased through the Early Triassic. Since low depth and intensity of bioturbation was crucial for microbial mat formation and wrinkle structure preservation during the Proterozoic-Cambrian, I predicted that wrinkle structures should be preserved in Lower Triassic strata deposited in subtidal marine environments during the aftermath of the end- Permian mass extinction. Indeed, wrinkle structures are found in Lower Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 87 Triassic strata representing subtidal deposition in northern Italy and the western U.S.A. Furthermore, though microbialites have been recorded globally from Lower Triassic carbonate rocks (e.g., Baud et al., 1996, 2002; Lehrmann, 1999; Schubert and Bottjer, 1992), this study is the first to record coeval siliciclastic microbial structures in Lower Triassic strata. Study Locations and Methods Early Triassic wrinkle structures are preserved in three formations exposed in northern Italy and the western United States (Figures 35, 36, 37). In northern Italy, wrinkle structures are preserved in the Smithian Campil Member of the Werfen Formation, which was deposited along the western margin of the Paleotethys. The Campil Member (150 m) is composed of red siltstones and sandstones deposited in an inner-ramp environment (Broglio Loriga et al., 1990; Twitchett and Wignall, 1996). In the western United States, wrinkle structures are preserved in the Spathian Virgin Limestone Member of the Moenkopi Formation and the Spathian upper member of the Thaynes Formation, which were deposited along the eastern margin of Panthalassa. The Virgin Limestone Member (~150-200 m thick) consists of a mixed carbonate-siliciclastic succession deposited primarily in a subtidal paleoenvironment. Because many of the siliciclastic beds in the Virgin Limestone Member are covered, bedding-plane exposures of wrinkle Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 88 rea/i han Paleotethys Panthalassa Figure 35 -- Late Permian-Early Triassic paleogeographic map (modified from Erwin, 1993) showing global distribution of Early Triassic wrinkle- structure-bearing strata. Numbers indicate approximate locations where Early Triassic wrinkle structures were formed and preserved: (1) western United States, Spathian Virgin Limestone Member, Moenkopi Formation; (2) western United States, Spathian upper member,Thaynes Formation; (3) northern Italy, Smithian Campil Member, Werfen Formation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. SE Nevada, U.S.A. N- central Utah, U.S.A Dolomites, N Italy substages Moenkopi Formation Thaynes Formation Werfen Formation Lower Triassic (Scythian) Spathian Virgin Limestone upper member San Lucano Lower Red Cencenighe ■ Timpoweap Val Badia Smithian Dienerian Griesbachian Campil Gastropod Oolite Siusi Andraz Mazzin Figure 36 - Generalized Lower Triassic stratigraphy of western United States and northern Italy (modified from Harland et al., 1990; Larson, 1966; Newman, 1974; Schubert and Bottjer, 1995). Shading indicates members in which wrinkle structures have been found. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 90 Figure 37 - Photographs of Cambrian and Early Triassic wrinkle structures for comparison. (A) Lower Cambrian Poleta Formation, Westgard Pass, central California, United States (37°17_30_N, 118°08_00_W ). (B) Smithian Campil Member, Werfen Formation, Punta Rolla locality, northern Italy (Broglio Loriga et al., 1990). (C) Spathian upper member,Thaynes Formation, Cascade Springs locality, northern Utah, United States (Newman, 1974). (D) Spathian Virgin Limestone Member, Moenkopi Formation, Muddy Mountains Overton locality, United States (Shorb, 1983); there are many wrinkle structures (examples indicated by arrows) and six large unidirectional scour marks (examples indicated by stars) in center as well as parts of several unidirectional scour marks at margins of photograph. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 91 structures are limited. The upper member (~125 m thick) of the Thaynes Formation, exposed in northeastern Utah, United States, consists of interbedded carbonate and siliciclastic rocks deposited in a low-energy, open-marine environment below fair-weather wave base (Newman, 1974). Bedding plane surfaces containing wrinkle structures were described and samples were collected. To further constrain the paleoenvironments in which the wrinkle structures formed, detailed observations were made on other sedimentary structures and trace and body fossils of the wrinkle structure-encompassing strata. Because the wrinkle structures exhibited a variety of geometries, crest heights and distances between crests were measured for comparison (Hagadorn and Bottjer, 1999). Samples of wrinkle structures were slabbed in cross section to study changes in grain size, and thin sections were prepared to search for evidence of the former presence of microbial mats. Results Wrinkle structures are a dominant sedimentary feature of the Campil Member. At the Uomo and Punta Rolle localities (Broglio Loriga et al., 1990), wrinkle structures exhibiting a variety of surface geometries are exposed on numerous sandstone bedding planes and are ubiquitous in sandstone and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 92 siltstone talus (Figure 37B). The Campil reaches >150 m in thickness, and wrinkle structures at both localities were preserved on all visible bedding planes (numbering >50) and at the top of centimeter-scale hummocky cross-stratified sandstone beds that occur throughout the Campil. The geometries of the Campil Member wrinkle structures range from small and closely packed (crests 1 mm in height and 1-2 mm between crests) to larger and widely spaced (crests of 7 mm in height and 3-5 mm between crests). Mica is concentrated in the troughs between the crests of the wrinkle structures. The trace fossils Asteriacites, Cochlichnus, Diplocraterion, Palaeophycus, and Planolites are found in the Campil Member but are confined to a few bedding planes (Twitchett, 1999). In the Virgin Limestone Member, wrinkle structures are preserved at two localities. At the Lost Cabin Springs locality (Schubert and Bottjer, 1992), wrinkle structures have been found in siltstone talus. The crests of the wrinkle structures range in height from 1 to 5 mm, and the distances between crests are 2-3 mm. Hummocky cross-stratification is preserved in beds that exhibit wrinkle structures at their tops. Mica is concentrated in the troughs of the wrinkle structures. At the Muddy Mountains Overton locality (Shorb, 1983), wrinkle structures are found in more than one horizon though only one bedding plane, on the top of an 11.6-m-thick calcareous siltstone unit, is fully exposed (Figure 37D) (Pruss et al., 2004). Wrinkle structures on this bedding Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 93 plane cover much of the exposed area (~ 1 m 2 ), with the exception of several conspicuous unidirectional scour marks (Figure 37D). These wrinkle structures have smaller crest heights (1-2 mm) and smaller distances between crests (1-2 mm) than those reported from the Lost Cabin Springs locality. Ripple marks, cross-bedding, and abundant trace fossils, including Rhizocorallium, Arenicolites, Planolites, Gyrochorte, and Asteriacites, occur in close proximity to the wrinkle structures. In the upper member of the Thaynes Formation exposed near Provo, Utah (Newman, 1974), wrinkle structures are well preserved on a bedding plane of a 1.5-m-thick laminated siltstone occurring between two decimeter-scale bivalve/crinoid shell beds (Figure 37C). The wrinkle structures are only exposed on a 50 cm2 section of the bedding plane and have crest heights of 3-4 mm and between-crest distances of 4 mm. Rhizocorallium is present in close proximity. Samples from the Campil Member of the Werfen Formation and from the Virgin Limestone Member of the Moenkopi Formation were thin-sectioned to search for evidence of the former presence of microbial mats. In thin section, dark clay-rich bands that represent possible mat fabrics similar to those reported by Noffke et al. (2002) are evident. Additionally, aligned grains of mica were visible, also indicating the former presence of a microbial mat (Schieber, 1999). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 94 Depositional and Taphonomic Conditions The Lower Triassic wrinkle structures not only represent the former presence of microbial mats in subtidal marine environments, but also the existence of biological and environmental conditions conducive to their preservation (e.g., Hagadorn and Bottjer, 1997, 1999; Noffke et al., 2002). In addition to the presence of microbial mats, a certain set of characteristics constituting a taphonomic window must exist to allow these wrinkle structures to be preserved in the rock record(Hagadorn and Bottjer, 1997; Noffke et al., 2002). Wrinkle structures in the late Neoproterozoic Nama Group (Namibia) formed in storm-dominated siliciclastic settings where hydrodynamic flow was strong enough to sweep away mud yet not erode microbial mat surfaces (Noffke et al., 2002). Microbial mats colonized surfaces and trapped and bound quartz grains during periods of reduced water agitation and the preservation of wrinkle structures took place when burial occurred without erosional destruction. In the Lower Triassic siliciclastic sedimentary rocks in which wrinkle structures are preserved, evidence suggests that depositional conditions similar to those described by Noffke et al. (2002) were present. The presence of hummocky cross-stratification in the siliciclastic sedimentary rocks provides evidence for storm-dominated paleoenvironments (sensu Hamblin, et al., 1979). The fine grain size noted in the samples was optimal for Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 95 colonization by cyanobacteria that ultimately formed mats (Noffke and Krumbein, 1999). The enrichment of mica on wrinkle-structure-bearing bedding planes points to the trapping and binding activity of microbial mats (Hagadorn and Bottjer, 1997; Schieber, 1999). The preservation of wrinkle structures then occurred when storm-influenced sediments were deposited on top of microbially bound sediment, not causing complete erosional disruption (Noffke et al., 2002) (Figure 37D). The wrinkle structures at all localities exhibit a variety of geometries, and this finding is also consistent with descriptions of Proterozoic-Cambrian wrinkle structures (Figures 34, 37A) (Hagadorn and Bottjer, 1997). The suite of trace fossils in association with the sedimentological evidence suggests the wrinkle structures found in Lower Triassic strata were preserved in shallow subtidal environments below normal wave base but above storm wave base. The trace fossil Asteriacites, an ophiuroid resting trace commonly found in Lower Triassic siliciclastic strata interpreted to represent subtidal paleoenvironments (Broglio Loriga et al., 1990; Twitchett and Wignall, 1996), is found at all localities where wrinkle structures are preserved (Broglio Loriga et al., 1990; Twitchett and Wignall, 1996). Other traces found with the wrinkle structures, including Rhizocorallium, Asteriacites, and Gyrochorte, also commonly occur in subtidal marine paleoenvironments (e.g., Bromley, 1996, and references therein). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 96 A vast reduction in the depth and extent of bioturbation occurred after the end-Permian mass extinction (e.g. Ausich and Bottjer, 2002; Twitchett, 1999; Twitchett and Wignall, 1996). In the late Early Triassic, traces such as Rhizocorallium reappeared (Twitchett, 1999; Twitchett and Wignall, 1996), but it was not until the Middle Triassic that many features of bioturbation returned to pre-extinction levels (e. g., Ausich and Bottjer, 2002; Zonneveld et al., 2001, 2002). Despite the presence of traces in Lower Triassic strata with vertical components, the ability to significantly disturb the sediment must have been reduced so that a taphonomic window was opened to the extent that global preservation potential for wrinkle structures increased. The presence of this type of taphonomic window means that Early Triassic siliciclastic seafloors were typically characterized by a Proterozoic-style soft substrate with minimal bioturbation (e.g., Bottjer et al., 2000; Hagadorn et al., 1999). This substrate would have differed notably from the soft- substrates of most of the Phanerozoic, which have been characterized by significant mixed layers produced by infaunal bioturbators (e.g., Bottjer et al., 2000; Hagadorn et al., 1999). Wrinkle structures in Lower Triassic strata can be described as components of anachronistic facies (Sepkoski et al., 1991): a facies consisting of rocks having sedimentary structures that were more common during earlier times but that have since become rare. Wrinkle structures Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 97 formed in many Proterozoic-Cambrian marine paleoenvironments, but thereafter have been restricted to marginal-marine and deep-sea settings (Hagadorn and Bottjer, 1999). Thus, as for other evidence of post-Cambrian microbial mats in shallow subtidal settings (Buatois et al., 2002), the abundance of wrinkle structures in Early Triassic subtidal paleoenvironments is anachronistic. This occurrence suggests that the Early Triassic is unusual when compared to the rest of the Phanerozoic, and the conditions that allowed for the proliferation of wrinkle structures persisted for millions of years after the end-Permian mass extinction. Conclusions The occurrence of wrinkle structures in Lower Triassic shallow subtidal siliciclastic strata is anomalous for the Phanerozoic. Whereas wrinkle structures were extremely common in subtidal paleoenvironments of the Proterozoic-Cambrian, thereafter they became restricted to deep-sea or stressed environments (Hagadorn and Bottjer, 1999). This restriction is attributed to an increase in infaunalization after the Cambrian (e.g., Bottjer and Ausich, 1986; Crimes et al., 1992; Droser and Bottjer, 1988). The anachronistic resurgence of wrinkle structures in the Early Triassic is thus indicative of a return to Proterozoic-style soft substrates (e.g., Bottjer et al., 2000; Hagadorn et al., 1999). Unlike the Proterozoic-Cambrian, the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 98 reduction of vertical bioturbation in the Early Triassic (Ausich and Bottjer, 2002; Twitchett, 1999; Twitchett and Wignall, 1996) did not occur because vertical bioturbators had not yet evolved, but because infaunal behavior was suppressed for several million years after the end-Permian mass extinction. The proliferation of microbialites in Lower Triassic carbonates has been well documented (e.g., Baud et al., 1996, 2002; Lehrmann, 1999; Schubert and Bottjer, 1992), and these occurrences have been linked to stressful oceanic conditions following the end-Permian mass extinction. The prevalence of Early Triassic subtidal wrinkle structures has great significance because it illustrates that siliciclastic depocenters also were under environmental stress. The fact that the wrinkle structures reported here occurred in the Smithian-Spathian time interval, millions of years after the end-Permian mass extinction, means that Phanerozoic levels of bioturbation had still not recovered by this time (Ausich and Bottjer, 2002). This delayed recovery, in addition to the widespread occurrences of carbonate and siliciclastic microbialites in normal-marine environments, is likely related to environmental stress such as anoxia (e. g., Isozaki, 1997) or hypercapnia (e.g., Woods et al., 1999) that persisted for millions of years after the end- Permian mass extinction event (e.g., Hallam, 1991; Lehrmann, 1999; Woods et al., 1999). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 99 CHAPTER 6: RESTRUCTURING IN BENTHIC LEVEL-BOTTOM SHALLOW MARINE COMMUNITIES DUE TO PROLONGED ENVIRONMENTAL STRESS FOLLOWING THE END-PERMIAN MASS EXTINCTION Introduction The end-Permian mass extinction signifies the largest decrease in global biodiversity in the Phanerozoic (Raup, 1979); several causes for this biotic crisis have been proposed, including hypercapnia (C02 poisoning) (Knoll et al., 1996), global marine anoxia (Wignall and Twitchett, 1996; Isozaki, 1997), H2 S poisoning (Grice et al, 2005; Kump et al., 2005), extraterrestrial impacts (Becker et al., 2004), and intense volcanism (e.g., Renne et al., 1995). Physiological and chemical stresses likely linked to the end-Permian mass extinction pulsed throughout its aftermath during the Early Triassic (Scythian), as evidenced by isotopic (Baud et al., 1989; Marenco et al., 2003; Payne et al., 2004 and sedimentologic (Woods et al., 1999) data; hypercapnia and marine anoxia are the most widely cited mechanisms for the prolonged environmental stress (e.g., Wignall and Hallam, 1992). A taxonomic pattern, the extinction of a significant proportion of the world’s biota in a geologically insignificant period of time (Hallam and Wignall, 1997), was the first signal that a major change in paleocommunities Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 100 occurred approximately 250 million years ago. Thus, numerous studies subsequently have focused on taxonomic changes and patterns at the Permian/Triassic boundary to determine the timing of the extinction (Sepkoski, 1981; Stanley and Yang, 1994), and throughout the Early Triassic aftermath, to determine the nature of taxonomic recovery (Erwin and Pan, 1996; Nutzel, 2005; Groves and Altiner, 2005; Twitchett and Oji, 2005). However, taxonomic data alone are insufficient for discerning ecological patterns and processes (Droser et al., 1997; Novack-Gottshall and Miller, 2003). Furthermore, the most significant results of mass extinctions actually may be the establishment of the new ecological patterns that arise during the aftermath (Droser et al., 1997; 2001). Bottjer et al. (1996) determined that the entire Early Triassic aftermath of the end-Permian mass extinction experienced severe ecological degradation; ecospace utilization had been reset to the level of the Late Cambrian/Early Ordovician because of prolonged environmental stresses. The short- and long-term consequences of the latest Permian/earliest Mesozoic environmental perturbations on paleocommunity structure are still being deciphered, but mounting research indicates that the aftermath of the end-Permian mass extinction was as crucial as the mass extinction in shaping the evolutionary history of life on Earth. A current synthesis of the short-term and long-term structural changes in benthic level-bottom shallow marine paleocommunities that occurred Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 101 during the Early Triassic, as well as evidence that these structural changes resulted from the environmental stresses during the Paleozoic-Mesozoic transition, is presented here. Proxies for Assessing Structural Changes in Benthic Level-Bottom Shallow Marine Paleocommunities Structural changes within benthic level-bottom shallow marine paleocommunities during the aftermath of the end-Permian mass extinction are indicated by various types of paleoecological data. Included in this synopsis are data on alpha diversity, taxonomic dominance, relative abundance, tiering, Bambachian megaguilds, and biosedimentary fabrics (ichnofabrics, shell beds, and wrinkle structures). Except in the discussions of Early Triassic tiering and Bambachian megaguilds, body fossils and trace fossils are treated separately because trace fossils represent behavior of organisms; tiering and Bambachian megaguilds are paleoecological gauges that evaluate the combined epifaunal and infaunal characteristics of paleocommunities to assess broad-scale changes in adaptive strategies. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 102 Taxonomic patterns Biodiversity and taxonomic dominance among the Early Triassic skeletonized invertebrate fauna Taxonomic patterns, such as alpha diversity (species richness) and taxonomic evenness/dominance, are useful as the initial indicators of change in community structure (Bambach, 1977; Sepkoski, 1981; Peters, 2004). In Early Triassic benthic level-bottom marine communities around the world, alpha, beta, and gamma diversity were very low. Molluscs, brachiopods, and echinoderms are the only higher taxa with known macroscopic benthic fossil representatives (Schubert and Bottjer, 1995), even in regions interpreted to have experienced rapid recovery (Twitchett et al., 2004). Compared to the Late Permian and the Late Triassic, taxonomic diversity among these skeletonized groups remained low throughout much of the Early Triassic around the world (Ciriacks, 1963; Schubert and Bottjer, 1995; Erwin and Pan, 1996). Alpha diversity of Early Triassic macroinvertebrate paleocommunities was low (average=13) (Schubert and Bottjer, 1995) and more closely resembled that of lower Paleozoic paleocommunities than typical upper Paleozoic or other Mesozoic paleocommunities (Bottjer et al., 1996). Global pre-extinction taxonomic diversities did not appear until the Middle Triassic (Anisian) (Erwin and Pan, 1996). Low alpha, beta, and gamma diversity among the skeletonized macroscopic biota during the Early Triassic Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 103 represents a short-term structural change in benthic level-bottom shallow marine communities. A shift among the taxonomic dominants in benthic level-bottom marine paleocommunities was also facilitated by the end-Permian mass extinction and the Early Triassic aftermath, and represents a long-term structural change in paleocommunities that persisted for the remainder of the Phanerozoic. Rhynchonelliform brachiopods were taxonomically dominant during the Ordovician to the Permian and dominated the Paleozoic Evolutionary Fauna for nearly 500 million years, but the Mesozoic and Cenozoic are dominated by gastropod and bivalve taxa, the major constituents of the Modern Evolutionary Fauna (Sepkoski, 1981). Despite this Evolutionary Fauna pattern, bivalves and rhynchonelliform brachiopods were taxonomically dominant in certain marine environments during the Paleozoic (Miller, 1988) and Mesozoic (Sandy, 1995), respectively. However, the end-Permian mass extinction precipitated the global abrupt phyletic switch from the Paleozoic Fauna to the Modern Fauna (Gould and Calloway, 1980; Sepkoski, 1981). Ichnogeneric diversity Changes in ichnofossil taxonomic patterns after the end-Permian mass extinction are not long-term and last only during the Early Triassic. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 104 Early Triassic ichnogeneric diversity in low paleolatitudes is low compared to uppermost Permian strata but increases through the Early Triassic (Twitchett, 1999; Pruss and Bottjer, 2004; Twitchett and Barras, 2004). While ichnogeneric diversity remained high in high paleolatitudes (see references in Pruss and Bottjer, 2004), in oldest Lower Triassic (Griesbachian) strata deposited at low paleolatitudes in western Paleotethys, the horizontal trace fossil Planolites is commonly the only ichnofossil present (Twitchett, 1999). The reappearance of Diplocraterion in the late Griesbachian/early Dienerian and of Rhizocorallium in the Smithian/Spathian may be somewhat synchronous around the world in low paleolatitudes (Twitchett, 1999; Twitchett and Barras, 2004). Thalassinoides, which has been used as an indication of a return of “normal” marine conditions, reappears in latest Griesbachian-Dienerian age strata deposited in high paleolatitudes (Wignall et al., 1998; Twitchett and Barras, 2004) and in upper Lower Triassic (Spathian) strata deposited in low latitudes (Pruss and Bottjer, 2004), indicating that recovery was not uniform around the world (Pruss and Bottjer, 2004; Twitchett and Barras, 2004). Planolites, Arenicolites, and Diplocraterion are the most common ichnogenera in Lower Triassic strata around the world (Schubert and Bottjer, 1995; Twitchett, 1999). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 105 Paleoecologic patterns Relative abundance of Early Triassic skeletonized invertebrates The most abundant members of a community, ecological dominants, may be more important than species richness in governing energy flow, trophic structure, and species composition of communities (Droser et al., 1997; Grime, 1997; Symstad et al., 1998). Therefore, determination of the most abundant organisms in Early Triassic paleocommunities provides a more complete understanding of short-term and long-term changes in community structure after the end-Permian mass extinction. Ecological dominance among the skeletonized biota in benthic level- bottom marine paleocommunities can be assessed from the fossil record using distinctive biofacies, shell bed composition, and relative abundance data (Clapham et al., 2003). Relative abundance data and shell bed surveys indicate that Early Triassic paleocommunities from a wide range of level- bottom benthic marine environments around the world were numerically dominated by very few taxa. Worldwide during the Griesbachian, many paleocommunities in nearshore to middle shelf marine environments were numerically dominated by the inarticulate brachiopod Lingula (Rodland and Bottjer, 2001). Intermittently throughout the Griesbachian, Dienerian, and Smithian, paleocommunities from low paleolatitudes around the world are dominated by large numbers of three species of microgastropods Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 106 (gastropods < 1 cm in height) (Fraiser and Bottjer, 2004) that commonly form a microgastropod biofacies unique to the Lower Triassic (Fraiser et al., in press). Bivalves, however, are the most numerically dominant group in Early Triassic benthic level-bottom shallow marine paleocommunities and primarily only three genera (Eumorphotis, Promyalina, Unionites) are responsible for the group’s numerical dominance (Chapter 3). Abundant crinoids and echinoids are only found at some intervals in the late Early Triassic (Schubert and Bottjer, 1995). Comparisons to Modern communities and paleocommunities throughout the Phanerozoic indicate that, in terms of ecological dominance, Early Triassic paleocommunities around the world are non-actualistic and anomalous (Fraiser and Bottjer, 2004). The numerical dominance of Lingula, microgastropods and bivalves in Early Triassic paleocommunities has been attributed to opportunistic behavior of these organisms; opportunistic behavior subsided by the latest Early Triassic (Rodland and Bottjer, 2001; Fraiser and Bottjer, 2004; Fraiser et al., in press). A long-term, permanent change among the ecological dominants in level-bottom benthic marine paleocommunities also occurred at the Permian/Triassic boundary. An ecologic switch in benthic level-bottom marine environments between rhynchonelliform brachiopods, which numerically dominated Paleozoic paleocommunities, and bivalves, which Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 107 dominated post-Paleozoic paleocommunities, was triggered by the end- Permian mass extinction and facilitated by conditions during the Early Triassic aftermath (e.g., Gould and Calloway, 1980; Chapter 3). Though bivalves and rhynchonelliform brachiopods are present in large numbers (and even dominant) in certain environments during the Paleozoic (Miller, 1989) and the Mesozoic (Sandy, 1995) respectively, the Early Triassic marks the first time in Earth’s history that bivalves are numerically dominant globally in nearly all marine environments (Chapter 3). Extent of bioturbation (ichnofabric indices) Though not directly correlative to determining the relative abundance of body fossils, determining the cumulative amount or extent of bioturbation in Lower Triassic strata using ichnofabric indices (Droser and Bottjer, 1986) provides an indication of the amount of infaunal activity during the aftermath of the end-Permian mass extinction. Very little data on extent of bioturbation is available from Permian and Middle Triassic strata, but general patterns that resulted from the end-Permian mass extinction are discernible from the present literature. The extent of bioturbation decreases from ii5-6 in the Upper Permian (Twitchett, 1999; Twitchett and Barras, 2004) to ii2 in the immediate aftermath of the end-Permian mass extinction in eastern Panthalassa (Schubert and Bottjer, 1995), western Paleotethys (Twitchett, Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 108 1999(, and the Boreal ocean (Wignall et al., 1998). Like ichnodiversity, the decrease in extent of bioturbation was short-term and the extent of bioturbation increased throughout the Early Triassic so that beds with ii 5 and ii6 are characteristic of the Spathian (Pruss and Bottjer, 2004; Twitchett and Barras, 2004). Tiering Tiering, the vertical subdivision of space by organisms above and below the benthic boundary layer, is useful for evaluating paleocommunity structure because it reflects resource and space partitioning by organisms (Ausich and Bottjer, 2001). Epifaunal and infaunal tiering were reduced as a result of the end-Permian mass extinction, and reestablishment of the highest and deepest tiers varied throughout the Early Triassic. During the earliest Early Triassic (Griesbachian, Nammalian), epifaunal tiering, primarily by bivalves, microgastropods, and the inarticulate brachiopod Lingula, was confined to the 0 to +5 cm tier in low paleolatitudes around the world (Bottjer et al., 1996). The reappearance of crinoids during the Smithian in Japan (Kashiyama and Oji, 2005) added the +5 to +20 cm tier back in some paleocommunities, but this tier was not characteristic of benthic level-bottom shallow marine paleocommunities until the late Early Triassic (Spathian), at least in low paleolatitudes (with the reappearance of abundant crinoids) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. (Schubert et al., 1992; Hagdorn and Baumiller, 1998). Infaunal tiering in pre extinction strata, indicated by trace fossils, occupied the 0 to -6 cm, the -6 to -12 cm, and the -12 to -100 cm tiers (e.g., Twitchett and Barras, 2004). Infaunal burrowers, including the Arenicolites and Diplocraterion tracemakers, only occupied the 0 to -6 cm tier during the Griesbachian in eastern Panthalassa and western Paleotethys (Rodland, 1999; Twitchett, 1999; Pruss et al., 2004); by the Dienerian in western Paleotethys and by the Smithian in eastern Panthalassa, Arenicolites and Diplocraterion tracemakers occupied the -6 to -12 cm tier (Schubert and Bottjer, 1995; Twitchett, 1999; Twitchett and Barras, 2004). The reappearance of higher tiers (due to the reappearance of crinoids) in Neotethys during the Griesbachian has been used as an indication of rapid recovery in this region (Twitchett et al., 2004). Early Triassic reductions in epifaunal and infaunal tiering were short-term structural changes in benthic level-bottom shallow marine communities. Benthic Bambachian megaguilds In addition to tiering, another method of evaluating the short- and long-term changes in ecospace utilization during the Early Triassic is by determining which combinations of mode of life and feeding type, or Bambachian megaguilds (c.f., Droser et al., 2000), were present and/or Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 110 absent. Of 17 possible benthic Bambachian megaguilds [BBMs], only four were occupied during the Early Triassic (Bottjer et al., 1996): bivalves and rhynchonelliform brachiopods occupied the epifaunal-attached-low- suspension-feeding megaguild; crinoids occupied the epifaunal-attached- erect-suspension-feeding megaguild; echinoids and gastropods occupied the epifaunal-mobile-herbivore megaguild; and bivalves and inarticulate brachiopods occupied the infaunal-shallow-passive-suspension-feeding megaguild. The attached-erect-suspension-feeding megaguild, occupied by crinoids, reappeared during the Smithian in western Panthalassa (Kashiyama and Oji, 2005), during the Spathian in eastern Panthalassa and western Paleotethys (Schubert et al., 1992), and during the Griesbachian in Neotethys (Twitchett et al., 2004), indicating that ecospace refilled at different times around the world. Ecospace remained fairly empty only for the Early Triassic; 8 BBMs were occupied during the Middle Triassic (Schubert and Bottjer, 1995). However, more BBMs were occupied during the Mesozoic and Cenozoicthan during the Paleozoic (Bambach, 1983), suggesting that conditions during the Paleozoic/Mesozoic boundary also had a long-term effect on ecospace utilization. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 111 Biosedimentary Structures Shell beds Shell beds, densely packed accumulations of biologic hardparts (Kidwell, 1991), accurately record broad-scale ecological changes and therefore serve as proxies for structural changes in marine communities, particularly in patterns of dominance and abundance through geologic time (Kidwell, 1991; Kidwell and Brenchley, 1994). Shell beds are abundant throughout Lower Triassic strata around the world (Boyer et al., 2004; Fraiser and Bottjer, 2004; Fraiser and Bottjer, in press) and therefore depict the restructuring that occurred in benthic level-bottom shallow marine communities during the aftermath of the end-Permian mass extinction. The majority of Lower Triassic shell beds range from mm-scale pavements to 20 cm-thick beds; amalgamated shell beds can reach up to 2 m in thickness. The majority of Lower Triassic shell beds are numerically and taxonomically dominated by members of the Modern Evolutionary Fauna (see Chaper 3). Lower Triassic shell beds are more similar to shell beds from the Paleozoic, though, in thickness and geometry (Boyer et al., 2004). Therefore, Lower Triassic shell beds represent a transition from archaic-style shell beds characteristic of the Paleozoic to modern-style shell beds characteristic of the post-Jurassic (Boyer et al., 2004). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 112 Wrinkle structures Wrinkle structures have been found in shallow subtidal siliciclastic paleoenvironments in Lower Triassic strata in the western United States and in northern Italy (Pruss et al., 2004). Wrinkle structures are a type of microbially-mediated sedimentary structure found commonly in Proterozoic-Cambrian siliciclastic strata deposited in intertidal to deep-sea marine environments, the formation of which has been attributed to the stabilization of the substrate by microbial mats (Hagadorn and Bottjer, 1997; 1999; Noffke et al., 1999; 2002). In the post-Cambrian, wrinkle structures have been restricted to supratidal, intertidal and deep-sea siliciclastic environments because of the increase in levels of bioturbation and consequent mixed-layer development during the Ordovician (Hagadorn and Bottjer, 1997). Therefore, subtidally-deposited Lower Triassic wrinkle structures likely formed because of decreased bioturbation during the aftermath of the end-Permian mass extinction (Pruss et al., 2004). The proliferation of subtidal microbial mats was limited to the Early Triassic and represents another short-term structural change in benthic level-bottom shallow marine communities. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 113 Restructuring in Benthic Level-Bottom Shallow Marine Communities due to Prolonged Environmental Stress Following the End-Permian Mass Extinction Data from a variety of paleoecological approaches presented here indicate that benthic level-bottom shallow marine communities were restructured during the Early Triassic (Figure 38). Using the system of four paleoecological levels which Droser et al. (1997) developed as a comparative approach to assess major ecological changes in Phanerozoic life, Bottjer et al. (2001) showed that the structural changes in Early Triassic paleocommunities can be classified as level 2 (major structural changes within an ecosystem), level 3 (community-type level changes within an ecosystem), and level 4 (community-level changes) changes. Some aspects of the community restructuring (i.e., decrease in biodiversity and the numerical dominance of few taxa) produced a non-actualistic ecology that lasted only during the Early Triassic, while other aspects of benthic level- bottom shallow marine communities were permanently altered (i.e., switch in taxonomic and ecologic dominants). This synopsis also reveals that taxonomic and ecologic recovery from the end-Permian mass extinction was decoupled and was geographically and temporally varied. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. benthic skeletonized invertebrate m arine fauna soft-bodied marine ichnofauna biosedim entary structures alpha diversity taxonomic dom inants ecologic dominants extent of bioturbation epifaunal tiering infaunal tiering benthic Bambachian megaguilds shell beds w rinkle structures post-Early Triassic 35 bivalves and gastropods bivalves ii 4-5 all tiers all tiers 17 m odern style supratidal and intertidal | Early Triassic (S cythian) | e * £ £ < 0 z | Oleneklan | S p a th ia n 13 bivalves bivalves ii 3-6 0 - +5 cm +5 - +20 err 0 -- -6 cm - 6 - -12 cm 4 characteristics of archaic and modern styles supratidal, intertidal, and subtidal S m ith ia n gastropods and bivalves ii 3 0 - +5 cm c « 9 •a e D ie n e ria n G rie sb a ch ia n Lingula and bivalves ii 2 0 - -6 cm Upper Paleozoic 23 rh y n c h o n e llifo rm bra ch io p o d s rh y n c h o n e llifo rm b ra ch io p o d s ii 4-5 all tiers all tiers 12 archaic style supratidal and intertidal Figure 38: Generalized short-term and long-term structural changes among skeletonized invertebrates and infauna in benthic level-bottom shallow marine paleocommunities before, during, and after the Early Triassic aftermath of the end-Permian mass extinction. In this figure: 1) alpha diversity indicates mean number of species in paleocommunities from variable nearshore and from open marine environments ; 2) data on taxonomic and ecologic dominants refers to the general pattern; 3) ichnofabric indices for the Upper Paleozoic and post-Early Triassic represent best estimates; ichnofabric indices for the Early Triassic represent characteristic bioturbation of each stage/substage; data from low paleolatitudes only; 4) epifaunal and infaunal tiering refers only to characteristic tiering; and 5) benthic Bambachian megaguilds refers to number of megaguilds occupied. Ichnogeneric diversity was omitted because it varies greatly with latitude and because more comparative studies need to be done. Date of 252.6±0.2 mya represents the age of the end-Permian mass extinction (Mundil et al., 2004) and 247 mya is the most recent age for the Early-Middle Triassic boundary (Martin et al., 2001). 115 What facilitated the temporary and permanent structural changes in benthic level-bottom shallow marine paleocommunities during the Paleozoic/Mesozoic transition? The short-term ecological restructuring during the Early Triassic has been underscored in the literature because it indicates that recovery from the end-Permian mass extinction and the return to “normal” marine communities did not occur until 5-6 million years after the extinction (Martin et al., 2001; Mundil et al., 2004). Three mechanisms to explain Early Triassic non-actualistic paleoecology and the apparent delayed biotic recovery have been hypothesized (c.f., Erwin and Pan, 1996): 1) physiologically harsh environmental conditions persisted long after the end- Permian mass extinction, inhibiting “normal” community development; 2) Earth’s biota needed an exceptionally long time to rewrite community assembly rules after marine ecosystems were profoundly disrupted by the end-Permian mass extinction; and 3) a preservation and sampling bias indicates that Early Triassic non-actualistic paleoecology is more apparent than real and makes the biotic recovery following the end-Permian mass extinction only appear to be delayed. Several lines of data support the hypothesis that physiologically harsh environmental conditions persisted long after the end-Permian mass extinction. Though no proposed mechanism is widely accepted as its Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 116 definitive cause, ever-increasing sedimentological (Woods et al., 1999; Pruss et al., 2004) and isotopic (Marenco et al., 2003; Payne et al., 2004) data from around the world indicate that deleterious environmental conditions affected marine ecosystems for 5-6 million years after the end-Permian mass extinction. This prolonged environmental stress is likely linked to the end- Permian mass extinction and facilitated the ecological degradation and short term restructuring observed in benthic level-bottom shallow marine Early Triassic paleocommunities (Schubert and Bottjer, 1995; Twitchett, 1999; Rodland and Bottjer, 1999; Fraiser and Bottjer, 2004). The long-term, permanent changes in paleocommunities (i.e., phyletic and ecologic switches) also were facilitated by the harsh environmental conditions that prevailed during the earliest Mesozoic. The hypothesis that the magnitude of the extinction so disrupted normal communities that the biotic recovery from the end-Permian mass extinction was delayed (Erwin and Pan; 1996) is not completely unsupported. According to Erwin and Pan (1996), if ecospace restructuring caused the delayed recovery, then the length of time it took for the recovery would be controlled by the extent of community collapse. However, the severe ecological degradation (Bottjer et al., 1996) and restructuring of paleocommunities during the Early Triassic were largely controlled by the deleterious environmental conditions of the time. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 117 The hypothesis that the entire Early Triassic is afflicted by a preservation gap (Erwin, 1996; Twitchett, 2001) is not well-supported. Indeed, most Early Triassic faunas consist mainly of molds and casts (see Chapter 3). However, a recent evaluation of Early Triassic environmental and ecological characteristics indicates that fossil preservation likely was not significantly decreased during the Early Triassic (Fraiser and Bottjer, in press). The widespread occurrence of assemblages dominated by small fossils [microgastropod biofacies (Fraiser et al. 2004)], the lack of extensive bioturbation, and periodic increases in alkalinity that built up in Early Triassic oceans due to bacterial sulfate reduction indicate that shells typically may not have been preferentially dissolved and molds may not have been destroyed in the early diagenetic environment (Fraiser and Bottjer, in press). Therefore, though silicification is not extensive in Lower Triassic strata, the body fossils and molds that are present are useful and valuable at least for paleoecologic studies, if not for detailed taxonomic studies. The decrease in ichnogeneric diversity and in the depth and extent of bioturbation during the Early Triassic are also excellent proxies for ecological degradation independent of the fossilization process and falsify the hypothesis that the taxonomic and ecologic patterns during the Early Triassic are more apparent than real. Furthermore, the taxonomic and ecologic patterns that characterize the Early Triassic herald the taxonomic and ecologic patterns that characterize the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 118 remainder of the Phanerozoic; these long-term changes would not have persisted if Early Triassic patterns were merely the result of a preservation bias. Short-term structural changes in Early Triassic paleocommunities are not merely artifacts of taphonomic bias as previously suggested (Erwin and Pan, 1996; Twitchett, 2001), but are primary signals of non-actualistic paleoecology during the aftermath of the end-Permian mass extinction. The end-Permian mass extinction and its aftermath are ecologically, as well as taxonomically, significant events in the history of life. The end- Permian mass extinction was only one result of deleterious environmental conditions affecting the late Paleozoic/early Mesozoic. Rather than concentrate solely on the end-Permian mass extinction, future studies, such as paleocommunity and onshore/offshore pattern analyses, should focus on pre- and post-extinction ecologic patterns to gain a more complete view of the consequences of this environmental stress on evolutionary history. Examining ecologic as well as taxonomic parameters will also aid in constraining the cause of the end-Permian mass extinction and will reveal what aspects of paleocommunities are resilient to severe environmental stress. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 119 CHAPTER 7: THE MID-PHANEROZOIC BIOCALCIFICATION CRISIS: THE PAST IS THE KEY TO THE FUTURE Introduction For 70-80 million years during the latest Paleozoic and early Mesozoic, Earth’s marine biota suffered multiple prolonged crises, including two of the “big 5” Phanerozoic mass extinctions (Raup and Sepkoski, 1982). The configuration of Pangea and continental flood basalt volcanism led to a cascade of global detrimental environmental consequences, including increased atmospheric C 02 levels, global warming, reduced pole to equator temperature gradient, and sluggish ocean circulation, that facilitated massive release of CH4 , marine anoxia, hypercapnia, and H2 S poisoning. Extensive recent deliberation on the potential impacts of increasing atmosphere/ocean C 02 concentrations due to anthropogenic input (Feely et al., 2004; Sabine et al., 2004) alludes that one mechanism is conspicuously missing from models for this mid-Phanerozoic interval of marine biotic degradation: a biocalcification crisis. Here we demonstrate through a synthesis of modern and ancient data that marine biocalcification crises induced by increased atmosphere/ocean C 02 were major contributors to the protracted biotic crises of the mid-Phanerozoic. These ancient biocalcification crises are an Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 120 analogue for the fate of Earth’s marine biota if anthropogenic input of atmosphere/ocean C 02 continues to rise. Response of Skeletonized Marine Biota to Increases in Atmospheric C02 The current amount of atmospheric C 02 on Earth is higher than it has been for the past 420,000 years and perhaps for tens of millions of years (Prentice et al., 2001). Due to anthropogenic input, the atmospheric C 02 concentration has risen continuously since the Industrial Era, from 280 ± 10 ppm to 380 ppm observed today and is projected to reach 540-970 ppm by the end of this century (Prentice et al., 2001). This excess anthropogenic atmospheric C 02 is diffusing into the oceans and experiments and observations on modern marine organisms predict devastating circumstances for Earth’s marine biota caused by these increasing concentrations of C 02 (Feely et al., 2004). In particular, passive diffusion of atmospheric C 02 into the ocean causes [C03 '2 ] concentration and the CaC03 saturation state of seawater to decrease, causing a biocalcification crisis for many organisms (Feely et al., 2004; Sabine et al., 2004). The degree and rate of calcification among corals and coral reef communities (e.g., Kleypas et al., 1999), coccolithophores (Riebesell et al., 2000), and foraminiferans (Barker and Elderfield, 2002) decreases as the CaC03 saturation state of Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 121 seawater decreases. Because metastable forms of CaC03 are most susceptible to dissolution, it is predicted that organisms with aragonitic and high-magnesium calcite skeletons may experience greater dissolution than calcite producers under increased atmospheric C 02 conditions (Feeley et al., 2004). The predicted physiological and biomineralogical effects of increases in ocean C 02 concentration may alter the species composition and succession of phytoplankton and corals (Kleypas et al., 1999). Increased C 02 may result in narrowing of inhabitable water for some biogenic carbonate producers and, as the ocean becomes increasingly undersaturated over time, the aragonite and calcite saturation depths will likely shoal and dissolution of CaC03 particles will increase (Feely et al., 2004; Sabine et al., 2004). Late Paleozoic and Early Mesozoic Increased atmospheric C02 , Mass Extinctions, and Prolonged Ecological Degradation Perhaps the best way to predict changes in the world’s oceans due to increased anthropogenic C 02 is to understand what happened in the past when atmospheric C02 levels were very high. During the last 300 million years, some of the highest atmospheric C 02 levels have been recorded from the mid-Phanerozoic between 260 and 183 m.y.a., as evidenced by paleobiological data, carbon cycle models, and simulations (Berner and Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 122 Kothavala, 2001; Retallack, 2001) (Figure 39A). Sustained levels of atmospheric C 02 several times greater than the pre-industrial levels of 280 p.p.m. during the mid-Phanerozoic correlate well with continental flood basalt province (CFBP) volcanism (Figure 39A,B): the Emeishan flood basalts at the Guadalupian/Lopingian boundary, the Siberian Traps at the Permian/Triassic boundary, the Central Atlantic Magmatic Province (CAMP) at the Triassic/Jurassic boundary, and the Karoo Traps and Ferrar Traps in the early Toarcian (Wignall, 2001; Courtillot and Renne, 2003; Bottjer, 2004). These CFBPs and increases in atmospheric C 02 also correlate very well with the end-Guadalupian, end-Permian, end-Triassic, and early Jurassic (Toarcian) mass extinctions (Wignall, 2001; Courtillot and Renne, 2003; Bottjer, 2004) (Figure 40A). C 02 injected into the atmosphere by successive large volcanic eruptions and voluminous non-explosive eruptions of flood basalt from CFBP fissures was likely climatically significant because of the long residence time of C 02 (Wignall, 2001) (Figure 39A). Increases in atmospheric C 02 would have facilitated the development of a vertically stratified, sluggish ocean with reduced upwelling and marine anoxia; sedimentologic, paleontologic, and isotopic evidence of these conditions are observed in the latest Permian and Early Triassic and in the Early Jurassic (Wignall, 2001). Warming of the oceans would have contributed to the release of methane in methane hydrates and there is sedimentologic, Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 123 15 — rs CC 10 — 5 — 300 145 3 — i 145 300 Figure 39: Mid-Phanerozoic environmental and atmospheric changes. A) Atmospheric C 02 300-145 Ma. RC02 is the ratio of reconstructed C02 concentration to a preindustrial level of 300 ppm (modified from Berner and Kothavala,2001). B) Original volume of mid-Phanerozoic flood basalts: Emeishan flood basalts at the Guadalupian/Lopingian boundary (259±3 Ma), Siberian Traps at the Permian/Triassic boundary (252±1.6 Ma),the Central Atlantic Magmatic Province (CAMP) at the Triassic/Jurassic boundary (200±4 Ma),and the Karoo Traps and Ferrar Traps in the early Toarcian (183±2 Ma); data from Wignall (2001), Courtillot and Renne (2003); Bottjer (2004). Light grey =Permian, medium grey=Triassic, dark grey=Jurassic. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. 2 0 - i <D 1 5 - 4 - » 1 J C O c O " + - > u B io— X < U "ftJ 4— ' O 5 - 140n Q J 120 C D 100 microbid reefs Uthiotis reefs _C C T » aj 10 Figure 40: Mid-Phanerozoic biotic changes. A) Statistically significant mass extinctions during the mid-Phanerozoic depicted as number of extinctions of families per million years (modified from Raup and Sepkoski, 1982). Subsequent analyses demonstrate that the indicated Late Triassic extinction peak is at the end-Triassic; the early Toarcian mass extinction was regional in scope and is not shown (Hallam, 1996; Palfy and Smith, 2000; Palfy et al., 2001). B) Number of reef sites for the Permian through Jurassic (Kiessling, 2002); a reef site lumps data of an area of about 315 km2. Microbial reefs from Pruss and Bottjer (2004); "Lithiotis" reefs from Fraser and Bottjer (2004). C) Maximum height of gastropods from Late Permian (12-15 cm) to Early Triassic (Scythian) (1.88 cm) to Middle Triassic (Anisian) (20 cm) (data from Fraiser and Bottjer, 2004), and maximum height of megalodontoid bivalves from Late Triassic (Rhaetian) (42 cm) to Early Jurassic (Lias) (6 cm) (data from Hautmann, 2004). Light grey =Permian, medium grey=Triassic, dark grey=Jurassic. 125 paleontologic, and isotopic evidence of global warming and methane hydrate destabilization during the early Mesozoic (e.g., Wignall, 2001; Courtillot and Renne, 2003; Bottjer, 2004). The mid-Phanerozoic marine extinctions are hypothesized to have been caused by a host of environmental and physiological stresses triggered by the emission of large amounts of volcanic C 02 from their correlative CFBPs during the early breakup of Pangea (Wignall, 2001; Benton and Twitchett, 2003; Bottjer, 2004) (Figure 39A,B). In particular, hypercapnia, or poisoning by excess C 02 , is supported as a major cause for the mid- Phanerozoic mass extinctions in the marine realm (Knoll et al., 1996) because metabolically slow organisms (rhynchonelliform brachiopods and bryozoans) experienced large extinctions during the end-Permian, end- Triassic, and early Toarcian extinctions (Taylor and Larwood, 1988; Knoll et al., 1996; Hallam, 1996). Marine anoxia is an extinction mechanism well- supported by decreases in ichnogeneric diversity and in the extent of bioturbation (Wignall and Twitchett, 1996), and the concomitant drop in atmospheric 0 2 due to lower global burial rate of organic matter and oxidation of methane (Berner, 2002) is linked with the destruction of reefs during the end-Permian biotic crisis (Weidlich et al., 2003). Several lines of evidence indicate that the mid-Phanerozoic did not experience only brief intervals of environmental stress culminating in mass Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 126 extinctions—the biotic crises were prolonged for millions of years. Data on d1 3 C isotopes indicates that there were large perturbations of the carbon cycle during the Late Permian through the Early Triassic (Payne et al., 2004), at the Triassic/Jurassic boundary (Palfy et al., 2001), and during the Toarcian (Palfy and Smith, 2000). Current models for the early Mesozoic biotic crises cannot account for all aspects of the biota during this time or for their protracted nature. For example, paleontologic evidence for biotic crisis occurs in regions where there is no sedimentologic or isotopic evidence for anoxic seawater (Weidlich et al., 2003; Fraiser and Bottjer, 2004). Furthermore, benthic invertebrate species that formed massive carbonate skeletons, aragonite- and high-magnesium calcite-secreting organisms, and all major groups of reef organisms (Kiessling, 2002; Hautmann, 2004) (Figure 40B) also suffered preferentially during the end-Permian, end- Triassic, and Early Toarcian mass extinctions. However, as predicted from modern observations, late Paleozoic/early Mesozoic increases in atmospheric C02 (Figure 39A) would have led to increased ocean C 02 levels and decreased CaC03 saturation of seawater, causing a long-term biocalcification crisis in skeletonized invertebrate benthic marine organisms. Such a biocalcification crisis readily explains extinction patterns of a variety of organisms as well as the protracted absence of colonial metazoan reefs and reef organisms during much of this time (Figure 40B). Organisms that Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 127 behaved opportunistically during the early Mesozoic, such as Early Triassic microgastropods and inarticulate brachiopods (Fraiser and Bottjer, 2004) (Figure 40B), as well as Early Jurassic “Lithiotis" bivalves (Fraser and Bottjer, 2004), likely were able to do so because they possessed a unique ability to secrete a shell in conditions of low CaC03 saturation. The decrease in size of some benthic marine organisms during the Early Triassic and Early Jurassic was likely an adaptation to the increased energetic costs for carbonate secretion (Fraiser and Bottjer, 2004; Hautmann, 2004) (Figure 40C). Metazoan reef-builders (Kiesling, 2002) and larger shells reappear when atmospheric C 02 levels decrease (Figure 40B,C). This particular effect of increased ocean C02 concentration, in addition to the associated effects of hypercapnia and marine anoxia, was a major contributor to this protracted interval of mid-Phanerozoic biotic crises. Furthermore, a drop in atmospheric 0 2 (Berner, 2002) likely compounded the biocalcification crisis for physiological reasons (Rhoads and Morse, 1971). The biocalcification crisis proposed here represents one significant interlocking piece of the causes that led to these mid-Phanerozoic biotic crises (Figure 40B). Discussion The complex interplay of perturbations to the global atmosphere and ocean triggered by CFBP volcanism and the breakup of Pangea was Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 128 manifested in different ways in various parts of the globe, as demonstrated by spatially and temporally varied biotic crises. For example, while numerous lines of evidence outlined here indicate that surface waters in much of the world’s oceans were undersaturated with respect to CaC03 during the mid-Phanerozoic, other lines of evidence, including submarine carbonate fans (Woods et al., 1999) and microbial reefs (Pruss and Bottjer, 2004) (Figure 40B), indicate that due to deep-water stagnation and anoxia, parts of the world’s oceans experienced CaC03 supersaturation during this time. These varied regional and temporal patterns likely resulted from new upwelling patterns and sea level fluctuations related to impingement of superplumes and CFBP volcanism (Hallam and Wignall, 1999), for which the precise relationships still must be deciphered. Deep-water anoxia (e.g., Wignall and Twitchett, 1996; Isozaki, 1997), significant buildup of deep-water H2 S (e.g., Kump et al., 2005), and photic zone euxina (Grice et al., 2005) were likely the mechanisms responsible for the end-Permian mass extinction, while increased atmospheric C 02 was an important mechanism responsible for the protracted nature of this biotic crisis. The mid-Phanerozoic benthic skeletonized marine biota and that predicted for the future have much in common for the same proximal cause: increased atmospheric C 02 . Though the ocean is potentially a large sink for increasing amounts of atmospheric anthropogenic C 02 (Sabine et al., 2004), Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 129 this synthesis demonstrates that the duration and scope of the biotic effects resulting from the input of anthropogenic atmospheric C 02 into the oceans will be very large; we must remember the past as we anticipate the future. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 130 CHAPTER 8: CONCLUSIONS Despite the attention the end-Permian mass extinction has received recently, the ecological context of the end-Permian mass extinction and its aftermath has hardly been examined and is still crudely understood. This research focused on evaluating marine paleoecology during the aftermath of the end-Permian mass extinction and represents a novel approach to understanding how global environmental changes and perturbations affect the Earth’s biota on the short- and long-term. Chapter 3 evaluates the alleged Early Triassic taphonomic bias (c.f. Erwin, 1996; Twitchett, 2001). A high number of Lazarus taxa and an alleged rarity of silicified faunas during the Early Triassic have been interpreted previously as indications that the fossil record following the end- Permian mass extinction is poor and unreliable for palaeontologic studies. However, an examination of Early Triassic fossil preservation reveals that silicified faunas are actually moderately common in Lower Triassic strata. Furthermore, an evaluation of environmental and ecological characteristics of the aftermath of the end-Permian mass extinction indicates that the numerous Early Triassic molds and recrystallized calcareous fossils are at least suitable for palaeoecologic studies. Within this context future tests with Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 131 the aim of continuing to examine the potential Early Triassic preservation bias are proposed. In Chapter 4, the taxonomic versus ecologic significance of the end- Permian mass extinction and its aftermath was addressed. Studies of taxonomic diversity trends have led to the conclusion that bivalves replaced brachiopods as ecological dominants in shallow level-bottom marine environments after the end-Permian mass extinction. However, until now no systematic paleoecological data have been presented to support this conclusion. I report here on new paleoecological data from study of shell beds which confirms that bivalves indeed replaced brachiopods as ecological dominants in the Early Triassic. Of particular note is the rate and scale of this ecological takeover, with primary bivalve ecological dominance beginning in the earliest Early Triassic. Of great interest is that this bivalve ecological takeover was done by three genera, none of which has any particular morphological features to distinguish it from many typical Paleozoic bivalve genera. Thus, the ecological success of these Early Triassic bivalves is not due to any of the well-known morphological evolutionary innovations of post-Paleozoic bivalves, but most likely due to physiological characteristics which separated them from most Paleozoic brachiopods. Most likely these physiological features were ones that enabled Early Triassic bivalves to thrive during periods of repeated environmental stress, in particular flooding Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 132 of the shelves with anoxic and/or C 02 rich waters that emanated from deeper ocean environments. Microbial-metazoan interactions following the end-Permian mass extinction were examined in Chapter 5. Lower Triassic strata in the western United States and in northern Italy have yielded the first reported occurrence of microbially mediated wrinkle structures in shallow subtidal siliciclastic paleoenvironments since the Cambrian. These wrinkle structures occur in siliciclastic sedimentary rocks in association with hummocky cross stratification and trace fossils that indicate a subtidal paleoenvironment. Wrinkle structures commonly formed in a variety of subtidal paleoenvironments during the Proterozoic-Cambrian, but thereafter became restricted to intertidal-supratidal and deep-sea environments. This restriction has been attributed to the increase in infaunalization of metazoans following the Cambrian radiation. The proliferation of wrinkle structures in subtidal settings during the Early Triassic suggests that infaunal bioturbation was reduced after the end-Permian mass extinction and that this reduction lasted for millions of years. Because the end-Permian mass extinction was the largest mass extinction since the Cambrian, numerous studies have focused on taxonomic changes and patterns immediately before and after the Permian/Triassic boundary. Chapter 6 is a synthesis of paleoecological data demonstrating Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 133 that the end-Permian mass extinction and the Early Triassic aftermath were ecologically, as well as taxonomically, significant events in the history of life. A variety of short-term and long-term structural changes in ecosystems and paleocommunities were facilitated by deleterious environmental conditions that persisted through the Early Triassic. This paleoecological analysis of the Early Triassic aftermath of the end-Permian mass extinction has led to a hypothesis about a new mechanism as one of the causes of the Permian-Triassic marine biotic crisis, outlined in Chapter 7. Based on modern observations, latest Paleozoic/earliest Mesozoic increases in atmospheric C 02 due to Siberian Trap volcanism should have led to increased ocean C 02 levels and decreased CaC03 saturation of seawater, causing a long-term biocalcification crisis in skeletonized invertebrate benthic marine organisms. This particular effect of increased ocean C 02concentration, in addition to the associated effects of global warming, hypercapnia and marine anoxia, was a major contributor to this protracted interval of biotic crisis. Evidence indicates that undersaturation of seawater with respect to CaC03 was also a contributing factor to the end-Triassic (Hautmann, 2004) and early Toarcian mass extinctions. These ancient biocalcification crises are an analogue for the fate of Earth’s marine biota if anthropogenic input of atmosphere/ocean C 02 continues to rise. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 134 REFERENCES Allen, J.R.L., 1985, Wrinkle-marks: An intertidal sedimentary structure due to aseismic soft-sediment loading: Sedimentary Geology, v. 41, p. 75-95. Aller, R.C., 1981. Carbonate dissolution in nearshore terrigenous muds: the role of physical and biological reworking. Journal of Geology, v. 90, p. 79-95. Assereto, R.L., Rizzini, A., 1975. Reworked Ferroan Dolomite grains in the Triassic "oolite a gasteropodi" of Camoniche Alps (Italy) as indicators of early diagenesis: Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen, v. 148(2), p. 215-232. Ausich, W.I., and Bottjer, D.J., 2002, Sessile invertebrates, in: Briggs, D.E.G., and Crowther, P.R., eds., Palaeobiology II: Oxford, Blackwell Science, p. 384-386. Batten, R.L, 1973. The vicissitudes of the gastropods during the interval of Guadalupian-Ladinian time, in: Logan, A., Hills, L. V. (Eds.), The Permian and Triassic Systems and Their Mutual Boundary. Canadian Society of Petroleum Geologists Memoir 2, pp. 596-607. Bambach, R.K., 1977, Species richness in marine benthic habitats through the Phanerozoic: Paleobiology, v. 3, p. 152-167. Bambach, R.K., 1983, Ecospace utilization and guilds in marine communities through the Phanerozoic, in: Tevesz, M.J.S, and McCall, P.L., eds., Biotic interactions in Recent and fossil benthic communities: Plenum Press, New York, p. 719-746. Barker, S. & Elderfield, H., 1999, Foraminiferal calcification response to glacial-interglacial changes in atmosperic C 02: Science, v. 297, p. 833-836. Baud, A., Margaritz,M., and Holser, W.T., 1989, Permian-Triassic of the Tethys; Carbon isotope studies: Geolog. Rundschau v. 78, p. 649- 677. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 135 Baud, A., Cirilli, S., and Marcoux, J., 1996, Biotic response to mass extinction: The lowermost Triassic microbialites, in: Reitner, J., et al., eds., Biosedimentology of microbial build-ups: IGCP Project No. 380: Facies, v. 36, p. 238-242. Baud, A., Richoz, S., Cirilli, S., and Marcoux, J., 2002, Basal Triassic carbonate of the Tethys: A microbialite world, in: Proceedings, 16th International Sedimentological Congress: Rand Afrikaans University, Johannesburg, South Africa, p. 24-25. Baud, A., Richoz, S., 2004. Anachronistic facies after mass extinctions: Tethyan basal Triassic calcimicrobial cap rocks. GSA Abstracts with Programs, 35: 336. Beauchamp, B., Baud, A., 2002, Growth and demise of Permian biogenic chert along northwest Pangea: evidence for end-Permian collapse of thermohaline circulation: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 184, p. 37-63. Becker, L., Poreda, R.J., Basu, A.R., Pope, K.O., Harrison, T.M., Nicholson, C. and lasky, R., 2004, Bedout: A possible end-Permian impact crater offshore northwestern Australia: Science, v. 304, p. 1469-1476. Benton, M.J., and Twitchett, R.J., 2003, Howto kill (almost) all life: the end- Permian extinction event: TRENDS in Ecology and Evolution, v. 18, p. 358-365. Berner, R.A., 2002, Examination of hypotheses for the Permo-Triassic boundary extinction by carbon cycle modeling: PNAS, v. 99, p. 4172- 4177. Berner, R.A., Kothavala, Z., 2001. GEOCARB III: A revised model of atmospheric C02 over Phanerozoic time: American Journal of Science, v. 301, p. 182-204. Blakey, R.C., 1974, Stratigraphic and depositional analysis of the Moenkopi Formation, southeastern Utah: Utah Geological and Mineral Survey Bulletin, v. 104, 81 p. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 136 Bottjer, D.J., 2001. Biotic recovery from mass extinctions, in: Briggs, D.E.G., Crowther, P.R. (Eds.), Palaeobiology II. Blackwell Science, Oxford, pp. 202-206. Bottjer, D.J., 2004, The beginning of the Mesozoic: 70 million years of environmental stress and extinction, in: Taylor, P.D., ed., Extinctions in the History of Life, Cambridge University Press, p. 99-118. Bottjer, D.J., and Ausich, W.I., 1986, Phanerozoic development of tiering in soft substrate suspension-feeding communities: Paleobiology, v. 12, p. 400-420. Bottjer, D.J., and Droser, M.L., 1998, Tracking mass extinction recoveries with shell beds: the Lower Triassic of the western United States: Geological Society of America Abstracts with Programs, v. 30, p. 312. Bottjer, D.J., Droser, M.L., Sheehan, P.M., and McGhee, G.R. Jr., 2001, The ecological architecture of major events in the Phanerozoic history of marine invertebrate life, in: W.D. Allmon, D.J. Bottjer (Eds.), Evolutionary Paleoecology: The ecological context of macroevolutionary change, Columbia University Press, pp. 35-61. Bottjer, D.J., Hagadorn, J.W., and Dornbos, S.Q., 2000, The Cambrian substrate revolution: GSA Today, v. 10, no. 9, p. 1-7. Bottjer, D.J. and Jablonski, D., 1988, Paleoenvironmental patterns in the evolution of post-Paleozoic benthic marine invertebrates: Palaios, v. 3, p. 540-560. Bottjer, D.J., Schubert, J.K., Droser, M.L., 1996. Comparative evolutionary palaeoecology: assessing the changing ecology of the past, in: Hart, M. B. (Ed.), Biotic Recovery from Mass Extinction Events. Geological Society Special Publication No. 102, pp. 1-13. Boyd, D.W., Newell, N.D., 1976, Diagenetic image reversal in a Triassic pelecypod: University of Wyoming Contributions to Geology, v. 14, p. 65-68. Boyd, D.W., Newell, N.D., 1997, A reappraisal of Trigoniacean families (Bivalvia) and a description of two new Early Triassic species: American Museum Novitates, Number 3216,14 p. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 137 Boyd, D.W., Newell, N.D., 2002, A unique pterioid bivalve from the Early Triassic of Utah: American Museum Novitates, Number 3375, 9 p. Boyd, D.W., Nice, D.E., Newell, N.D., 1999, Silt injection as a mode of fossilization: A Triassic example: Palaios, v. 14, p. 545-554. Boyer, D.L., Bottjer, D.J., and Droser, M.L., 2004, Ecological signature of Lower Triassic shell beds of the western United States: Palaios, v. 19, p. 372-380. Broglio Loriga, C., Goczan, F., Haas, J., Lenner, K., Neri, C., Oravecz Scheffer, A., Posenato, R., Szabo, I., and Makk, A., 1990, The Lower Triassic sequences of the Dolomites (Italy) and Transdanubian mid mountains (Hungary) and their correlation: Memorie di Scienze Geologiche, v. 42, p. 41-103. Broglio Loriga, C., and Cassinis, G., 1992, The Permo-Triassic boundary in the southern Alps (Italy) and in adjacent Peradriatic regions: in Sweet, W.C. et al., eds., Permo-Triassic events in the eastern Tethys: stratigraphy, classification, and relations with the western Tethys: International Geological Correlation Programme, Project 203: Permo- Triassic events of the east Tethys region and their intercontinental correlation, Cambridge University Press, New York, p. 78-97. Bromley, R.G., 1996, Trace fossils: Biology, taphonomy and applications: London, Chapman and Hall, 361 p. Buatois, L. A., Netto, R. G., and Mangano, M. G., 2002, Estructuras vinducladas a tapetes microbiales en despositos siliciclasticos post- vendianos: Evidencias de ecosistemas extremos en el Paleozoic superior gondwanico: Actas del XV Congreso Geologico Argentino, El Calafate, v. 3, p. 140-141. Cherns, L., Wright, V.P., 2000, Missing molluscs as evidence of large-scale, early skeletal aragonite dissolution in a Silurian sea: Geology, v. 28(9), p. 791-794. Ciriacks, K.W., 1963, Permian and Eotriassic bivalves of the Middle Rockies: Bulletin of the American Museum of Natural History, v. 125, p. 1-100. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 138 Clapham, M.E., Bottjer, D.J., Pruss, S.B., Marenco, P.J., Jamet, C.M., Fraiser, M.L., Dornbos, S.Q., and Bonuso, N., 2003, Phanerozoic trends in ecological dominance: Geological Society of America, Abstracts with Programs, v. 35, (6), p. 589. Cooper, G.A., Grant, R.E., 1972, Permian brachiopods of west Texas, I: Smithsonian Contributions to Paleobiology, 231 p. Courtillot, V.E., and Renne, P.R., 2003, On the ages of flood basalt events: Comptes Rendus Geoscience, v. 335, p. 113-140. Crimes, T.P., Garcia Hidalgo, J.F., and Poire, D.G., 1992, Trace fossils from Arenig flysch sediments of Eire and their bearing on the early colonisation of the deep seas: Ichnos, v. 2, p. 61-77. Dean, J.S., 1981, Carbonate petrology and depositional environments of the Sinbad Limestone Member of the Moenkopi Formation in the Teasdale Dome area, Wayne and Garfield Counties, Utah: Brigham Young University Geology Series, v. 28, p. 19-51. Downing, A.L., and Leibold, M.A., 2002, Ecosystem consequences of species richness and composition in pond food webs: Nature v. 416, p. 837-841. Droser, M.L., and Bottjer, D.J., 1986, A semiquantitative field classification of ichnofabric: Journal of Sedimentary Petrology, v. 56, p. 558-559. Droser, M.L., and Bottjer, D.J., 1988, Trends in depth and extent of bioturbation in Cambrian carbonate marine environments, western United States: Geology, v. 16, p. 233-236. Droser, M.L., Bottjer, D.J., and Sheehan, P.M., 1997, Evaluating the ecological architecture of major events in the Phanerozoic history of marine invertebrate life: Geology, v. 25 (2), p.167-170. Droser, M.L., Bottjer, D.J., Sheehan, P.M., and McGhee, G. Jr., 2000, Decoupling of taxonomic and ecologic severity of Phanerozoic marine mass extinctions: Geology, v. 28, p. 675-678. Dzulynski, S., and Simpson, F., 1966, Experiments of interfacial current markings: Geologica Romana, v. 5, p. 197-214. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 139 Erwin, D.H., 1993, The great Paleozoic crisis: Columbia University Press, New York, 327 p. Erwin, D.H., 1994, The Permo-Triassic extinction: Nature, v. 367, p. 231-236. Erwin, D.H., 1996, Understanding biotic recoveries: extinction, survival, and preservation during the end-Permian mass extinction, in: Jablonski, D., Erwin, D.H., Lipps, J. (Eds.), Evolutionary Paleobiology. The University of Chicago Press, Chicago, p. 398-418. Erwin, D.H., Kidder, D.L., 2000, Depositional controls on selective silicification of Permian fossils, southwestern United States, in: Wardlaw, B.R., Grant, R.E., Rohr, D.M. (Eds.), The Guadalupian Symposium. Smithsonian Contributions to the Earth Sciences, Number 32, pp. 407-415. Erwin, D.H., and Pan, H., 1996, Recoveries and radiations: gastropods after the Permo-Triassic mass extinction, in: Hart, M. B. (Ed.), Biotic Recovery from Mass Extinction Events. Geological Society Special Publication No. 102, pp. 223-229. Erwin, D.H., 2001, Lessons from the past: biotic recoveries from mass extinctions: Proceedings of the National Academy of Sciences, v. 98(10), p. 5399-5403. Feely, R.A., Sabine, C.L., Lee, K., Berelson, W., Kleypas, J., Fabry, V.J., & Millero, F.J., 2004, Impact of anthropogenic C 02 on the CaC03 System in the oceans: Science, 305, 362-366. Flessa, K.W., Jablonski, D., 1983, Extinction is here to stay: Paleobiology, v. 9, p. 315-321. Fraiser, M.L., Bottjer, D.J., 2003, Paleoecology of bivalves during their initial rise to dominance: Geological Society of America Annual Meeting Abstracts with Programs, v. 35 (6), p. 417. Fraiser, M.L., and Bottjer, D.J., 2004, The Non-Actualistic Early Triassic Gastropod Fauna: A case study of the Lower Triassic Sinbad Limestone Member: Palaios v. 19, p. 259-275. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 140 Fraiser, M.L., Bottjer, D.J., 2005, Restructuring in Benthic Level-Bottom Shallow Marine Communities due to Prolonged Environmental Stress Following the End-Permian Mass Extinction: Comptes Rendus Palevol, v. 3, in press. Fraiser, M.L., and Bottjer, D.J., in press, Fossil Preservation During the Aftermath of the End-Permian Mass Extinction: Taphonomic Processes and Palaeoecological Signals, in: J. Morrow, D.J. Over, P.B. Wignall (Eds.), Understanding Late Devonian and Permian- Triassic Biotic and Climatic Events: Towards an Integrated Approach. Fraiser, M.L., Twitchett, R.J., and Bottjer, D.J., in press, Unique microgastropod biofacies in the Early Triassic: Indicator of long-term biotic stress and the pattern of biotic recovery after the end-Permian mass extinction, Comptes Rendus PALVEOL. Fraser, N.M, and Bottjer, D.J., 2004, Dissecting “Lithiotis” bivalves: implications for the Early Jurassic reef eclipse: Paiaios, v. 19, p. 51- 67. Gould, S.J., and Calloway, C.B, 1980, Clams and brachiopods-ships that pass in the night: Paleobiology, v. 6(4), p. 383-396. J.G.Gradstein, A.G. Ogg, Smith et al., 2004, A Geologic Time Scale, Cambridge Univeristy Press. Grice, K., Cao, C., Love, G.D., Bottcher, M.E., Twitchett, R.J., Grosjean, E., Summons, R.E., Turgeon, S.E., Dunning, W., and Jin, Y., 2005, Photic Zone Euxinia During the Permian-Triassic Superanoxic Event; Science. Hagadorn, J.W., and Bottjer, D.J., 1997, Wrinkle structures: Microbially mediated sedimentary structures common in subtidal siliciclastic settings at the Proterozoic-Phanerozoic transition: Geology, v. 25, p. 1047-1050. Hagadorn, J.W., and Bottjer, D.J., 1999, Restriction of a late Neoproterozoic biotope: Suspect-microbial structures and trace fossils at the Vendian- Cambrian transition: Paiaios, v. 14, p. 73-85. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 141 Hagadorn, J.W., Pflueger, F., and Bottjer, D.J., 1999, Unexplored microbial worlds: Paiaios, v. 14, p. 73-85. Hallam, A., 1991, Why was there a delayed radiation after the end-Paleozoic extinctions?, /n:Brasier, M., ed., Innovations and revolution in the biosphere, Volume 5: London, Harwood Academic Publishers, p. 257-262. Hallam, A., 1996, Recovery of the marine fauna in Europe after the end- Triassic and early Toarcian mass extinctions, in: Hart, M.B., ed., Biotic Recovery from Mass Extinction Events, Geological Society Special Publication No. 102, p. 231-236. Hallam, A. and Wignall, P.B., 1997, Mass extinctions and their aftermath: Oxford University Press, New York, 320 p. Hallam, A., and Wignall, P.B., 1999, Mass extinctions and sea-level changes: Earth- Science Reviews, v. 48, p. 217-250. Hamblin, A.P., Duke, W.L., and Walker, R.G., 1979, Hummocky cross stratification: Indicator of storm-dominated shallow-marine environments: American Association of Petroleum Geologists Bulletin, v. 63, p. 460-1. Harland, W.B., Armstrong, R.L., Cox, A.L., Craig, L.E., Smith, A.G., and Smith, D.G., 1990, A geologic time scale 1989: New York, Cambridge University Press, p. 263. Hautmann, M., 2004, Effect of end-Triassic C 02 maximum on carbonate sedimentation and marine mass extinction: Facies, v. 50, p. 257-261. Isozaki, Y., 1997, Permo-Triassic boundary superanoxia and stratified superocean: Records from lost deep sea: Science, v. 276, p. 235-238. Jablonski, D., 1986a, Background and mass extinctions: the alternation of macroevolutionary regimes: Science, v. 231, p. 129-133. Jablonski, D., 1986b, Causes and consequences of mass extinctions: a comparative approach, in: Elliot, D.K. (Ed.), Dynamics of extinction. Wiley, New York, pp. 183-230. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 142 Jablonski, D., 2001, Lessons from the past: evolutionary impacts of mass extinctions: PNAS, v. 98(10), p. 5393-5398. Kamada, K., 1979, The Triassic Inai Group in the Karakuwa area, southern Kitakami Mountains, Japan (Part I): Kamada, K., 1983, Triassic Inai group in the Toyoma area in the southern Kitakami Mountains, Japan: The Journal of the Association for the Geological Collaboration in Japan (Chikyu Kagaku), v. 37, p. 147-161. Kashiyama, Y. and Oji, T., 2005, Low diversity, shallow marine benthic fauna from the Smithian of northeast Japan: paleoecologic and paleobiogeographic implications, Palaeontological Research in press. Kauffman, E.G., Harries, P.J., 1996, The importance of crisis progenitors in recovery from mass extinction, in: Hart, M. B. (Ed.), Biotic Recovery from Mass Extinction Events. Geological Society Special Publication No. 102, pp. 15-39. Kidwell, S.M., 1991, The stratigraphy of shell concentrations, /r?:Allison, P.A., and Briggs, D.E.G., eds., Taphonomy: Releasing the data locked in the fossil record: Plenum Press, New York, p. 211-290. Kidwell, S.M., 2001, Preservation of species abundance in marine death assemblages: Science, v. 294, p. 1091-1094. Kidwell, S.M., 2002, Time-averaged molluscan death assemblages: Palimpsets of richness, snapshots of abundance: Geology, v. 30, p. 803-806. Kidwell, S.M., and Brenchley, P.J., 1994, Patterns in bioclastic accumulation through the Phanerozoic: changes in input or in destruction?: Geology, v. 22, p. 1139-1143. Kidwell, S.M., and Brenchley, P.J., 1996, Evolution of the fossil record: Thickness trends in marine skeletal accumulations and their implications, in:Jablonski, D., Erwin, D.H., and Lipps, J., eds., Evolutionary Paleobiology: The University of Chicago Press, Chicago, p. 290-336. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 143 Kiessling, W., 2002, Secular variations in the Phanerozoic reef ecosystem, in: Phanerozoic Reef Patterns, SEPM Special Publication No. 72, p. 625-690. Kimura, T., Hayami, I., and Yoshida, S., 1991, Geology of Japan: University of Tokyo Press, Tokyo, 287 p. Kleypas, J.A., Buddemeier, R.W., Archer, D., Gattuso, J.-P., Langdon, C., and Opdyke, B.N., 1999, Geochemical consequences of increased atmospheric carbon dioxide on coral reefs: Science, v. 284, p. 118- 120. Knoll, A.H., Bambach, R.K., Canfield, D.E., and Grotzinger, J.P., 1996, Comparative earth history and Late Permian mass extinction: Science, v. 273, p. 452-457. Krull, E.S., Lehrmann, D., Kessel, B.Y.Y., and Li, R., 2004, Stable carbon isotope stratigraphy across the Permian-Triassic boundary in shallow marine carbonate platforms, Napajiang Basin, South China, Palaeogeography, Palaeoclimatology, Palaeoecology, v. 204, p. 297- 315. Krystyn, L., Richoz, S., Baud, A., and Twitchett, R., 2003, A unique Permian- Triassic boundary section from the Neotethyan Hawasina Basin, central Oman Mountains: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 191 (3-4), p. 329-344. Kummel, B., 1954, Triassic stratigraphy of southeastern Idaho and adjacent areas: U.S. Geological Survey Professional Paper 254-H, 194 p. Kump, L.R., Pavlov, A., and Arthur, M.A., 2005, Massive release of hydrogen sulfide to the surface ocean and atmpsphere during intervals of oceanic anoxia: Geology, v. 33, p. 397-400. Larson, A.R., 1966, Stratigraphy and paleontology of the Moenkopi Formation of southern Nevada: Ph.D. dissertation, University of California (Los Angeles), 267 p., 8 pis. Law, R.H., and Thayer, C.W., 1991, Articulate fecundity in the Phanerzoic: Steady state or what?, in\ Mackinnon, D.I., Lee, D.E., and Campbell, J.D., eds., Brachiopods through time, A.A. Balkema, Rotterdam. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 144 Lehrmann, D.J., 1999, Early Triassic calcimicrobial mounds and biostromes of the Nanpanjiang Basin, South China: Geology, v. 27, p. 359-362. Li, X., and Droser, M.L., 1997, Nature and distribution of Cambrian shell concentrations: evidence from the Basin and Range Province of the western United States (California, Nevada, and Utah): Paiaios, v. 12, p. 111-126. Li, X., and Droser, M.L., 1999, Lower and Middle Ordovician shell beds from the Basin and Range province of the western United States (California, Nevada, and Utah): Paiaios v. 14, p. 215-233. Marenco, P.J., Corsetti. F.A., Bottjer, D.J., and Kaufman, A.J., 2003. Killer oceans of the Early Triassic. Geological Society of America Annual Meeting Abstracts with Programs, v. 35 (6), p. 386. Marquez-Aliaga, A., and Ros, S., 2002. Taphonomy richness of the scarce Spanish bivalves Triassic record: some examples to be discussed, in: De Renzi, M., Alonso, M.V.P., Belinchon, M., Penalver, E., Montoya, P., Marquez-Aliaga, A. (Eds.), Current Topics on Taphonomy and Fossilization, International Conference Taphos 2002. 3r d Meeting on Taphonomy and Fossilization, pp. 199- 206. Martin, M.W., Lehrmann, D.J., Bowring, S.A., Enos, P., Ramezani, J., Wei, J., Zhang, J. 2001 .Timing of the Lower Triassic carbonate bank buildup and biotic recovery following the end-Permian mass extinction across the Nanpanjiang Basin, south China, Geological Society of America Abstracts with Programs, v. 33 (6), p. 201. McGowan, A.J., 2004a. Ammonoid taxonomic and morphologic recovery patterns after the Permian-Triassic: Geology, v. 32, p.665-668. McGowan, A.J., 2004b. The effect of the Permo-Triassic bottleneck on Triassic ammonoid morphological evolution: Paleobiology, v. 30, p. 369-395. Moffat, H.A., Bottjer, D.J., 1999, Echinoid concentration beds: two examples from the stratigraphic spectrum: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 149, p. 329-348. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 145 Moritz, C.A., 1951, Triassic and Jurassic stratigraphy of southwestern Montana: American Association of Petroleum Geologists Bulletin, v. 35, p. 1781-1814. McKinney, F.K., Lidgard, S., Sepkoski, J.J., Jr., and Taylor, P.D., 1998, Decoupled temporal patterns of evolution and ecology in two post- Paleozoic clades: Science, v. 281, p. 807-809. Miller, A.I., 1988, Spatio-temporal transitions in Paleozoic Bivalvia: An analysis of North American fossil assemblages: Historical Biology, v. 1, p. 251-273. Miller, A.I., 1989, Spatio-temporal transitions in Paleozoic Bivalvia: A field comparison of Upper Ordovician and Upper Paleozoic bivalve- dominated fossil assemblages: Historical Biology, v. 2, p. 227-260. Miller, A.I. and Sepkoski, J.J, Jr., 1988, Modeling bivalve diversification: the effect of interaction on a macroevolutionary system: Paleobiology, v. 14(4), p. 364-369. Mundil, R., Ludwig, K. R., Metcalfe, I., and Renne, P. R., 2004, Age and Timing of the Permian Mass Extinctions: U/Pb Dating of Closed- System Zircons: Science, v. 305, p. 1760-1763. Newman, D.H., 1974, Paleoenvironments of the Lower Triassic Thaynes Formation near Cascade Springs, Wasatch County, Utah: Brigham Young University Geology Studies, v. 21, p. 63-96. Newell, N.D., and Boyd, D.W., 1995, Pectinoid bivalves of the Permian- Triassic crisis: Bulletin of the American Museum of Natural History, Number 227, 95 p. Newell, N.D., Boyd, D.W., 1999. A new Lower Triassic Permophorus from the Central Rocky Mountains. American Museum Novitates, Number 3263: 1-5. Newell, N.D., and Kummel, B., 1942, Lower Eo-Triassic stratigraphy, western Wyoming and southeast Idaho: Geological Society of American Bulletin, v. 53, p. 937-996. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 146 Nice, D.E., 1985, The role of skeletal diagenesis in carbonate fabric development, Thaynes Formation (Lower Triassic), northeast Utah and southeast Idaho. M.S. thesis, University of Wyoming, Laramie. Noffke, N., 1998, Multidirected ripple marks rising from biological and sedimentological processes in modern lower supratidal deposits (Mellum Island, southern North Sea): Geology, v. 26, p. 879-882. Noffke, N., 2000, Extensive microbial mats and their influences on the erosional and depositional dynamics of a siliciclastic cold water environment (lower Arenigian, Montagne Noire, France): Sedimentary Geology, v. 136, p. 207-215. Noffke, N., Gerdes, G., Klenke, Th., and Krumbein, W. E., 2001, Microbially induced sedimentary structures - a new category within the classification of primary sedimentary structures: Journal of Sedimentary Research, v. 71, p. 649-656. Noffke, N., and Krumbein, W.E., 1999, A quantitative approach to sedimentary surface structures contoured by the interplay of microbial colonization and physical dynamics: Sedimentology, v. 46, p. 417-426. Noffke, N., Knoll, A.H., and Grotzinger, J.P., 2002, Sedimentary controls on the formation and preservation of microbial mats in siliciclastic deposits: A case study from the Upper Neoproterozoic Nama Group, Namibia: Paiaios, v. 17, p. 533-544. Noffke, N., Hazen, R., and Nhleko, N., 2003, Earth’s earliest microbial mats in a siliciclastic marine environment (2.9 Ga Mozaan Group, South Africa): Geology, v. 31, p. 673-676. Novack-Gottshall, P.M., and Miller, A.I., 2003, Comparative taxonomic richness and abundance of Late Ordovician gastropods and bivalves in mollusc-rich strata of the Cincinnati Arch: Paiaios, v. 18, p. 559-571. Palfy, J., and Smith, P., 2000, Synchrony between Early Jurassic extinction, oceanic anoxic event, and the Karoo-Ferrar flood basalt volcanism: Geology, v. 28, p. 747-750. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 147 Palfy, J. et al., 2001, Carbon isotope anomaly and other geochemical changes at the Triassic-Jurassic boundary from a marine section in Hungary: Geology, v. 29, p. 1047-1050. Parsons-Hubbard, K.M., Callender, W.R., Powell, E.N., Brett, C.E., Walker, S.E., Raymond, A.L., Staff, G.M., 1999. Rates of burial and disturbance of experimentally-deployed molluscs: implications for preservation potential: Paiaios, v. 14(4), p. 337-351. Pauli, R.K., and Pauli, R.A., 1994, Shallow marine sedimentary facies in the Earliest Triassic (Griesbachian) Cordilleran miogeocline, U.S.A.: Sedimentary Geology, v. 93, p. 181-191. Pauli, R.A., Pauli, R.K., and Kraemer, B.R., 1989, Depositional history of Lower Triassic rocks in southwestern Montana and adjacent parts of Wyoming and Idaho: in French, D.E., and Gabb, R.F., eds., Montana Centennial Edition: Montana Geological Society Field Conference Guidebook, p. 69-90. Payne, J.L., Lehrmann, D.J., Wei, J., Orchard, M.J., Schrag, D.P., and Knoll, A.H., 2004, Large perturbations of the carbon cycle during recovery from the end-Permian extinction: Science v. 305, p. 506-509. Peters, S.E., 2004, Eveness of Cambrian-Ordovician benthic marine communities in North America: Paleobiology, v. 30, p. 325-346. Poborski, S.J., 1954, Virgin Formation (Triassic) of the St.Georga, Utah, Area: Bulletin of the Geological Society of American, v. 65, p. 971- 1006. Powell, E.N., and Stanton, R.J., Jr., 1985, Estimating biomass and energy flow of molluscs in paleo-communities: Palaeontology, v. 28, p. 1-34. Power, M.E., Tilman, D., Estes, J.A ., Menge, B.A., Bond, W.J., Mills, L.S., Daily, G., Castilla, J.C., Lubchenco, J., and Paine, R.T., 1996, Challenges in the quest for keystones: BioScience, v. 46, p. 609-620. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 148 Prentice, I.C. et al., 2001, The carbon cycle and atmospheric carbon dioxide, in: Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change; J. Houghton et al. (eds.), Cambridge University Press, New York, p. 183-237. Price-Lloyd, N., Twitchett, R.J., 2002, The Lilliput Effect in the aftermath of the end-Permian mass extinction event: Geological Society of American Annual Meeting Abstracts with Programs, v. 34 (6), p. 355. Pruss, S.B., Bottjer, D.J., 2004a, Late Early Triassic microbial reefs of the western United States: a description and model for their deposition in the aftermath of the end-Permian mass extinction: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 211, p. 127- 137. Pruss, S.B., Bottjer, D.J., 2004b, Early Triassic trace fossils of the western United States and their implications for prolonged environmental stress from the end-Permian mass extinction: Paiaios, v. 19, p. 551- 564. Pruss, S.B., Fraiser, M.L., Bottjer, D.J., 2004, The proliferation of Early Triassic wrinkle structures: Implications for environmental stress following the end-Permian mass extinction: Geology, v. 32, p. 461- 464. Racki, G., 1999, Silica-secreting biota and mass extinctions: survival patterns and processes: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 154, p. 107-132. Raup, D.M., 1979, Size of the Permo-Triassic bottleneck and its evolutionary implications: Science, v. 206, p. 217-218. Raup, D.M, and Sepkoski, J.J., 1982, Mass extinctions in the marine fossil record: Science, v. 215, p. 1501-1503. Renne, P.R., Zhang, Z., Richardson, M.A., Black, M.T., Basu, A.R., 1995, Synchrony and causal relations between Permo-Triassic boundary crises and Siberian flood volcanism: Science, v. 269, p. 1413-1416. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 149 Retallack, G.J., 2001, A 300-million-year record of atmospheric carbon dioxide from fossil plant cuticles: Nature, v. 411, p. 287-290. Rhoads, D.C., and Morse, J.W., 1971, Evolutionary and ecologic significance of oxygen-deficient marine basins: Lethaia, v. 4, p. 413-428. Rhodes, M.C., and Thompson, R.J., 1993, Comparative physiology of suspension-feeding in living brachiopods and bivalves: evolutionary implications: Paleobiology, v. 19(3), p. 322-334. Riebesell, U., Zondervan, I., Rost, B., Tortell, P.D., Zeebe, R.E., and Morel, F.M.M., 2000, Reduced calcification of marine plankton in response to increased atmospheric C 02: Science 407, 364-367. Rodland, D.L., 1999, Paleoenvironments and paleoecology of the disaster taxon Lingula in the aftermath of the end-Permian mass extinction: Evidence from the Dinwoody Formation (Griesbachian) of southwestern Montana and western Wyoming: unpublished M.S. thesis, University of Southern California, Los Angeles, 113 p. Rodland, D.L., and Bottjer, D.J., 2001, Biotic Recovery from the end-Permian mass extinction: behavior of the inarticulate brachiopod Lingula as a disaster taxon: Paiaios v. 16, p. 95-101. Rudwick, M.J.S., 1970, Living and fossil brachiopods: Hutchinson University Library, London, 199 p. Sabine, C.L. et al., 2004. The ocean sink for anthropogenic C 02 : Science, v. 305, p. 367-371. Sandy, M.R., 1995, Early Mesozoic (Late Triassic-early Jurassic) Tethyan brachiopod biofacies: possible evolutionary intra-niche replacement within the Brachiopoda: Paleobiology: v. 21 (4), p. 479-495. Sano, H., Nakashima, K., 1997, Lowermost Triassic (Griesbachian) microbial bindstone-cementstone facies, southwest Japan: v. Facies, 36, p. 1- 24. Schieber, J., 1999, Microbial mats in terrigenous elastics: The challenge of identification in the rock record: Unexplored microbial worlds, v. 14, p. 3-12. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 150 Schock, W.W., Maughan, F.K., and Warlaw, B.R., 1981, Permian-Triassic boundary in southwestern Montana and western Wyoming: in Tucker, T.F., ed., Montana Geological Society Field Conference and Symposium Guidebook to Southwest Montana, p. 59-69. Schubert, J.K., and Bottjer, D.J., 1992, Early Triassic stromatolites as post-mass extinction disaster forms: Geology, v. 20, p. 883-886. Schubert, J.K., and Bottjer, D.J., 1995, Aftermath of the Permian-Triassic mass extinction event: Paleoecology of Lower Triassic carbonates in the western USA: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 116, p. 1-39. Schubert, J.K., Kidder, D.L., Erwin, D.H., 1997. Silica-replaced fossils through the Phanerozoic. Geology, 25 (11): 1031 -1034. Scotese, C.R., 1994, Early Triassic paleogeographic map, in: G.D.Klein, (Ed.), Pangea: Paleoclimate, Tectonics, and Sedimentation During Accretion, Zenith, and Breakup of a Supercontinent, Geological Society of America Special Paper 288, Boulder, Colorado. Sepkoski, J.J., Jr., 1981, A factor analytic description of the Phanerozoic marine fossil record: Paleobiology, v. 7, p. 36-53. Sepkoski, J.J., Jr, 1984, A kinetic model of Phanerozoic taxonomic diversity. III. Post-Paleozoic families and mass extinctions: Paleobiology, v. 10(2), p. 246-267. Sepkoski, J.J, Jr. and Hulver, M.L., 1985, An atlas of Phanerozoic clade diversity diagrams: in Valentine, J.W., ed.: Phanerozoic Diversity Patterns, Profiles in Macroevolution: Princeton University Press, Princeton, New Jersey, p. 11-41. Sepkoski, J.J., Bambach, R.K., and Droser, M.L., 1991, Secular changes in Phanerozoic event bedding and the biological imprint, in Einsele, G., et al, A., ed., Cycles and events in stratigraphy: Berlin, Springer- Verlag, p. 298-312. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 151 Shorb, W.M., 1983, Stratigraphy, facies analysis and depositional environments of the Moenkopi Formation (Lower Triassic), Washington County, Utah, and Clark and Lincoln counties, Nevada [Master’s thesis]: Durham, North Carolina, Duke University, 205 p. Simoes, M.G., Kowalewski, M., Torello, F.F., Ghilardi, R.P., and Mello, L.H.C., 2000, Early onset of Modern-style shell beds in the Permian sequences of the Parana Basin: Implications for the Phanerozoic trend in bioclastic accumulations: Revista Brasileira de Geociencias, v. 30 (3), p. 485-499. Smith, A.G., and Briden, J.C., 1977, Mesozoic and Cenozoic Paleocontinental Maps: Cambridge University Press, Cambridge, 63 P - Stanley, S.M., 1968, Post-Paleozoic adaptive radiation of infaunal bivalve mollusks-A consequence of mantle fusion and siphon formation: Journal of Paleontology, v. 42, p. 214-229. Stanley, S.M., 1972, Functional morphology and evolution of byssally attached bivalve mollusks: Journal of Paleontology, v. 46, p. 165-212. Stanley, S.M. & Yang, X. A double mass extinction at the end of the Paleozoic era, Science 266,1340-1344 (1994). Steele-Petrovic, H.M., 1979, The physiological differences between articulate brachiopods and filter-feeding bivalves as a factor in the evolution of marine level-bottom communities: Paleontology, v. 22, p. 101-134. Stone, P., Stevens, C.H., Orchard, M.J., 1991. Stratigraphy of the Lower and Middle (?) Triassic Union Wash Formation, East-Central California. U.S.G.S. Bulletin, 1928:1-26. Symstad, A.J., Tilman, D., Willson, J., Knops, J.M.H., 1998, Species loss and ecosystem functioning: effects of species identity and community composition: Oikos, v. 81, p. 389-397. Taylor, P.D., and Larwood, G.P., 1988, Mass extinctions and the pattern of bryozoan evolution, in: Larwood, G.P., ed., Extinction and survival in the fossil record, Clarendon Press, Oxford, p. 99-119. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 152 Tchoumatchenco, P., 1972, Thanatocoenoses and biotopes of Lower Jurassic brachiopods in central and western Bulgaria: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 12, p. 227- 242. Thayer, C.W., 1985, Brachiopods versus mussels: competition, predation, and palatability: Science, 228, p. 1527-1528. Thayer, C.W., 1986, Are brachiopods better than bivalves? Mechanisms of turbidity tolerance and their interaction with feeding in articulates: Paleobiology, v. 12(2), p. 161-174. Tucker, M.E., Wright, V.P., 1990. Diagenetic processes, products and environments. In: Carbonate Sedimentology: Blackwell Science, pp. 314-364. Twitchett, R.J., Barras, C.G., 2004, Trace fossils in the aftermath of mass extinction events, in: D. Mcllroy (Ed.), The Application of Ichnology to Palaeoenvironmental and Stratigraphic Analysis: Geological Society, London, Special Publications 228, p. 397-418. Twitchett, R.J., and Wignall, P.B., 1996, Trace fossils and the aftermath of the Permo-Triassic mass extinction: evidence from northern Italy: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 124, 137- 151. Twitchett, R.J. 1999. Palaeoenvironments and faunal recovery after the end- Permian mass extinction. Palaeogeography, Palaeoclimatology and Palaeoecology, 154: 27-37. Twitchett, R.J., 2001. Incompleteness of the Permian-Triassic fossil record: a consequence of productivity decline? Geological Journal, 36: 341-353. Twitchett, R.J., Krystyn, L., Baud, A., Wheeley, J.R., Richoz, S., 2004, Rapid marine recovery after the end-Permian mass-extinction event in the absence of marine anoxia: Geology, v. 32, p. 805-808. Twitchett, R.J., Looy, C.V., Morante, R., Visscher, H., and Wignall, P., 2001, Rapid and synchronous collapse of marine and terrestrial ecosystems during the end-Permian mass extinction event: Geology, v. 29 (4), p. 351-354. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 153 Valentine, J.W., and Jablonski, D., 1986, Mass extinctions: Sensitivity of marine larval types: Proceedings of the National Academy of Sciences, v. 83, p. 6912-6914. Vermeij, G.J., and Herbert, G.S., 2004, Matter of the Record: Measuring relative abundance in fossil and living assemblages: Paleobiology, v. 30, p. 1-4. Walter, L.M., Burton, E.A., 1990, Dissolution on platform carbonate sediments in marine pore fluids: American Journal of Science, v. 290 p. 601-643. Watanabe, K., Nakashima, K., and Kanmera, K., 1979, Conodont biostratigraphy in the Kamura Limestone (Triassic), Takachiho-cho, Nishiusuki-gun, Miyazaki Prefecture, in: Biostratigraphy of Permian and Triassic conodonts and holothurian sclerites in Japan, p. 127-137. Weidlich, O., Kiessling, W., and Flugel, E., 2003, Permian-Triassic boundary interval as a model for forcing marine ecosystem collapse by long term atmospheric oxygen drop: Geology, v. 31, p. 961-964. Wheeley, J.R., and Twitchett, R.J., 2005. Palaeoecological significance of a new Griesbachian (Early Triassic) gastropod assemblage from Oman. Lethaia, 38:1-9. Wignall, P.B., 2001, Large igneous provinces and mass extinctions: Earth- Science Reviews, 53, 1-33. Wignall, P.B., Benton, M.J., 1999, Lazarus taxa and fossil abundance at times of biotic crisis: Journal of the Geological Society, London, 156: 453-456. Wignall, P.B., and Hallam, A., 1992, Anoxia as a cause of the Permian/Triassic mass extinction: facies evidence from northern Italy and the western United States: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 93, p. 21-46. Wignall, P.B. & Twitchett, R.J., 1996, Oceanic anoxia and the end Permian mass extinction. Science v. 272, p. 1155-1158. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 154 Wignall, P.B., Morante, R., Newton, R., 1998, The Permo-Triassic transition in Spitsbergen: d1 3 Co rg chemostratigraphy, Fe and S geochemistry, facies, fauna and trace fossils: Geological Magazine, v. 135, p. 47-62. Wilson, E.O., 2002, The Future of Life: Vintage Books, New York, 229 p. Woods, A.D., Bottjer, D.J., 2000: Distribution of ammonoids in the Lower Triassic Union Wash Formation (eastern California): Evidence for paleoceanographic conditions during recovery from the end-Permian mass extinction: Paiaios, v. 15, p. 535-545. Woods, A.D., Bottjer, D.J., Mutti, M., Morrison, J., 1999, Lower Triassic large seafloor carbonate cements: their origin and a mechanism for the prolonged biotic recovery from the end-Permian mass extinction: Geology, v. 27, p. 645-648. Wright, P., Cherns, L., and Hodges, P., 2003, Missing mollusks: field testing taphonomic loss in the Mesozoic through early large-scale aragonite dissolution: Geology, v. 31(3), p. 211-214. Xu, G., and Grant, R.E., 1992, Permo-Triassic brachiopod successions and events in South China, in: Sweet, W.C., Zunyi, Y., Dickens, J.M., Hongtu, Y. (Eds.), Permo-Triassic Events in the Easterh Tethys. Cambridge University Press, Cambringe, p. 98-108. Zonneveld, J-P., Gingras, M. K., and Pemberton, S. G., 2001, Trace fossil assemblages in a Middle Triassic mixed siliciclastic-carbonate marginal marine depositional system, British Columbia: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 166, p. 249- 276. Zonneveld, J-P., Pemberton, S. G., Saunders, T. D. A., and Pickerill, R. K., 2002, Large, robust Cruziana from the Middle Triassic of Northeastern British Columbia: Ethologic, biostratigraphic and paleobiologic significance: Paiaios, v. 17, p. 435-448. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 155 APPENDIX A: LOWER TRIASSIC LOCALITIES STUDIED Western U.S.A. Dinwoody Formation (Griesbachian) Montana Blacktail Creek (DF-BC1: section: 26 L_12S R: 6W latitude and longitude: 44°45’08.9”N; 112°17’52.2”W From 1-15 N, take exit 62 to Dillon. Turn right on Atlantic Street, then right onto old Highway 915. Turn left onto Blacktail Deer Creek Road and go 38.9 miles; outcrop is on the left side of the road. Hidden Pasture (DF-HP1: Lima, MT topographic map section: 26 I : 13S R: 10W latitude and longitude: 44°40,37.7" N, 112°47'25.3" W From 1-15 N, take the Dell exit and go left under the interstate. Take a left onto the Frontage Road and turn right onto Big Sheep Creek Road. Go 5.3 miles to Hidden Pasture Trail on the right. Turn right and park in the parking area. Hike Hidden Pasture Trail for approximately 1 1/2 to 2 hours until an opening between the mountains. The sedimentary rocks outcropping 200 yards directly ahead is the Dinwoody Formation. Wyoming Gros Ventre (DF-GV1: Jackson Lake, WY tophographic map section: 5 & 6 Tj_42N R: 114W latitude and longitude: 43°38,08.3" N, 1 lO ^ m e " W From 1-15 N, take Highway 26 E to Highway 89 N. Go 1.9 miles into Grand Teton National Park and turn right at Gros Ventre Junction. Go 7.8 miles and turn right at Gros Ventre Road. Go 3.1 miles and the outcrop is on the left (north) side of the road. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 156 Thaynes Formation (Spathian) Upper member Idaho Fall Creek (TF-FC1: Palisades, ID topographic map section: 17 I : 1N R: 43E From 1-15N, take Highway 26 E. Turn immediately right before crossing the Snake River onto Snake River Road. Go 1 mile and turn right onto Falls Creek Road. Go 3.7 miles and the outcrop of the Thaynes Formation is on the right (west) side of the road. Utah Cascade Springs (TF-CS1: Provo, UT topographic map section: 17 I : 4S El 4E latitude and longitude: 40o28,02.0,, N, 111 °31 '51.7" W From 1-15 N, take Highway 189 E to Highway 113 N. Go 2.1 miles and turn left onto Tate Lane. Go 0.5 miles and turn right onto Stringtown Road. Go 0.2 miles and turn left onto Cascade Springs Dive. Go 2.6 miles and the upper member of the Thaynes Formation is exposed on the right. (Just follow signs for Cascade Springs.) University (TF-U): Salt Lake City, UT topographic map section: 34 I I 1W B l 1E From 1-15 N, take 1-215 E to I-80 W. Take Highway 186 W (Foothill Blvd.) and turn right onto Wasatch Drive. Then, turn right onto Hempstead Drive (South Campus Drive). Turn left onto Chase Street, then right onto Potter Street, then right onto Fort Douglas Blvd, then left onto Pollock Road, then left onto Connor Road, then right onto Stover Road. Go towards Red Butte 0.3 miles and turn left onto an unnamed road behind dormitories and in front of a parking lot. Go 0.2 miles and turn right and park in Lot #66 (part A). The Thaynes Formation is exposed on the hillside. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 157 Sinbad Limestone Member, Moenkopi Formation (Nammalian) Utah Batten and Stokes (SL-BS): section: 10 I : 21S R: 11E latitude and longitude: 39°, 00’ N, 110°40’30”W From 1-15 N, take I-70 E. Take exit 129 (Ranch Exit), go under the interstate, and turn right onto Frontage Road. Drive past large gravel piles and the Hyde Draw Sign, staying to the left. Drive past the Jackass Benches/Sinkhole Flat sign and go 6.8 miles. The Sinbad Limestone Member is exposed near the road. Black Box (SL-BB1: section: 32 I : 20S R: 12E latitude and longitude: 39°2’30” N, 110°38’00” W From 1-15 N, take I-70 E. Take exit 129 (Ranch Exit), go under the interstate, and turn right onto Frontage Road. Stay on this road until the San Rafael River. Turn right onto Mexican Mountain Road and stay to the left at the forks. At a the first crossroads, turn right and drive down the wash until the Sinbad Limestone Member is exposed. Fish Creek (SL-FC1: section: 20 I : 29S E l 5E latitude and longitude: 38°16’00” N, 111°, 22’33” W From 1-15 N, take Highway 24 E to Torrey, Utah. Take Highway 12 S for 1.9 miles. The Sinbad Limestone Member is exposed on the left side of the road. Jackass Benches (SL-JB1: section: 1 I : 22S R: 12 E latitude and longitude: 38°56’00” N, 110°32’30” W Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 158 From 1-15 N, take I-70 E. Take exit 129 (Ranch Exit), go under the interstate, and turn right onto Frontage Road. At the Sinkhole Flat/ Jackass Benches sign, turn right and go 3.4 miles, taking left forks. The Sinbad Limestone Member is exposed in the benches to the left. Junction (SL-J): section: 4 I : 22S Bi 12E latitude and longitude: 38°55’30”N, 110°38’00” W From 1-15 N, take I-70 E. Take exit 129 (Ranch Exit), go under the interstate, and turn right onto Frontage Road. Go 5.8 miles to the Sinkhole Flat/Jackass Benches Sign. The Sinbad Limestone Member is exposed on the right and left. Miners Mountain (SL-MM): section: 21 I I 30S E l 6E latitude and longitude: 38°11 ’00” N, 111 °16’00” W From 1-15 N, take Highway 24 E to Torrey, Utah. Take Highway 12 S for 7.0 miles and turn left on a dirt road. After 2.4 miles, stay to the left at a fork. Then, turn right after an additional 1.4 miles. The Sinbad Limestone Member is exposed on the left after a total of 6.3 miles. Roadcut (SL-RC1: section: 3 I I 22 S El 13E latitude and longitude: 38°55’ N, 110°28’ W From 1-15 N, take I-70 E. Go 11.7 miles past Exit 129 to a view area. The Sinbad Limestone Member is exposed on the right as a roadcut. Virgin Limestone Member, Moenkopi Formation (Spathian) Nevada Lost Cabin Springs (VL-LCS1: latitude and longitude: 36°05.012' N, 115°39.253’ W From 1-15 N, take exit 33 (Highway 160 W, or the Blue Diamond Highway). Go 28.4 miles, past a radio tower, just past a silver guardrail. Turn right onto a BLM road and stay on the main road. At the fork at 1.9 miles, stay left. At Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 159 the fork at 5.7 miles, stay left. At the fork at 6.6 miles, stay right. Park after 6.7 miles. The Virgin Limestone Member is exposed in the hillside straight ahead. Muddv Mountains (VL-MM): From 1-15 N, take exit 91 (Glendale/Moapa). Take the first left and drive to the railroad tracks. Turn left and drive parallel to the railroad tracks for 0.5 miles. Cross the railroad tracks on the right and go approximately 0.3 miles. At the prominent Fishing Sign, turn right and go 0.1 miles until an ATV course. Turn right after 0.1 miles around the ATV course. Go 9.2 miles as you drive through Weiser Valley. Turn right onto the paved road. Go 1.3 miles until a break in the California Ridge. This is the bottom of the Virgin Limestone Member. (Travel a total of 11.5 miles since exit 91.) Ute (VL-UL From 1-15 N, take Exit 80 (Ute) until you reach the break in the California Ridge. The base of the Virgin Limestone Member is on the west side of the outcrop, above the Kaibab Formation. Utah Hurricane (VL-HL _From 1-15 N, take Highway 9 E to Hurricane (exit 16). In Hurricane, take Highway 59 E and go 3.4 miles to a BLM dirt road. Turn right and go 3.1 miles. At the fork, bear right and go 2.9 miles. The Virgin Limestone Member is exposed in a cliff along the right. White Hills (VL-WH1: latitude and longitude: 37°3.610' N, 113°41.852'W From 1-15 N, take the Bluff Street exit in St. George, Utah. Turn left onto Bluff Street and go 0.3 miles to Hilton Drive. Turn left and go 1 mile until Hilton Drive turns into Tonaquint Road. Go another 1.8 miles until Bloomington Drive. Turn left and go 1.1 miles. Turn left onto Navajo Drive and go 0.5 miles. Take the dirt road at the end of Navajo Drive. At the fork, stay right. Go a total of 1.8 miles until the Virgin Limestone Member is exposed on the right. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 160 Northern Italy Werfen Formation Mazzin Member Tesero (WF-TV. latitude and longitude: N46°17’14.7”, E11°31’40.7” The Mazzin Member is exposed on the north side of SS 48 in Tesero. The roadcut is covered with chainlink fencing. Uomo (WF-U1: latitude and longitude: N46°23’45.8”, E11 °47’56.1 ” From SS 48, take SS 346 east and go 11.8 km, turing left in Passo San Pellegrino. Go 0.9 km towards the mountains and park at Rif. Cima Uomo. Lower Triassic strata is exposed on a steep mountainside by an approximately 1 1/2-2 hour hike. Siusi Member Uomo (WF-U): latitude and longitude: 46°23’45.8”, E11 °47’56.1 ” From SS 48, take SS 346 east and go 11.8 km, turing left in Passo San Pellegrino. Go 0.9 km towards the mountains and park at Rif. Cima Uomo. Lower Triassic strata is exposed on a steep mountainside by an approximately 1 1/2-2 hour hike. Gastropod Oolite Member Punta Rolle (WF-PR1: latitude and longitude: N46°17’56.1”. E11°48’16.6” From SS 48 in Predazzo, take SS 50 east towards Passo Rolle; go 21.1 km. Once in Passo Rolle (designated by a road sign), go 0.8 kilometers and then turn left onto a gravel road. Go 2.9 km on this gravel road to a hotel and park. Looking towards the mountains, take the middle trail to Punta Rolle. The GOM is exposed on Punta Rolle. Uomo (WF-U): latitude and longitude: 46°23’45.8”. E11°47’56.1” From SS 48, take SS 346 east and go 11.8 km, turing left in Passo San Pellegrino. Go 0.9 km towards the mountains and park at Rif. Cima Uomo. Lower Triassic strata is exposed on a steep mountainside by an approximately 1 1/2-2 hour hike. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 161 Canrmil Member Punta Rolle (WF-PR1: latitude and longitude: N46°17’56.1”. E11°48’16.6” From SS 48 in Predazzo, take SS 50 east towards Passo Rolle; go 21.1 km. Once in Passo Rolle (designated by a road sign), go 0.8 kilometers and then turn left onto a gravel road. Go 2.9 km on this gravel road to a hotel and park. Looking towards the mountains, take the middle trail to Punta Rolle. The Campil Member is exposed on Punta Rolle. Uomo (WF-UL latitude and longitude: 46°23’45.8”. E11°47’56.1” From SS 48, take SS 346 east and go 11.8 km, turing left in Passo San Pellegrino. Go 0.9 km towards the mountains and park at Rif. Cima Uomo. Lower Triassic strata is exposed on a steep mountainside accessible after an approximately 1 1/2-2 hour hike. Northern Japan (Honshu) Hiraiso Formation The Hiraiso Formation outcrops along the coast near Kesennuma, Honshu Island, Japan. Dr. Tatsuo Oji (University of Tokyo) aided with field work on the Hiraiso Formation. Southern Japan (Kyushul Kamura Formation The Kamura Formation outcrops in the hills near Takachiho, Kyushu Island, Japan. Dr. Hiroyoshi Sano (Kyushu University) aided with field work on the Kamura Formation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. APPENDIX B: Ecological Dom inants in post-C am brian Fossil Accum ulations [d ata from Kidwell (1 9 9 1 )] Each entry spans 3 pages and should be read the following way: page 1) reference and description; page 2 ) data for bivalves, rhynchonelliform brachiopods, lingulid brachiopods, trilobites, bryozoans, corals, pelmatozoans, scaphopods, gastropods, and echinoids; page 3 ) data for barnacles, starfish, sponges, serpulids, benthic forams, and benthic ammonites. Because of the nature of the study, some pages will contain a grid with no data. Every 3 pages should be examined together. ORDOVICIAN-PERMIAN reference Description ORDOVICIAN Webby and Percival. 1983 stratiqraphic unit Fossil Hill Limestone Member and Bourimbla Limestone Member description monotypic linqulid brachiopod shell beds & a coral facies environment shallow lagoon Brezinski, 1986 stratiqraphic unit equivalent to Scales Formation. Maquoketa Group description one Ampryxina (trilobite) bed about 2 0 cm thick environment restricted shallow marine Laudon, 1939 stratiqraphic unit upper dense member. Bromide Formation description one Isotelus (trilobite) bed environment subtidal Walker and Alberstadt, 197 5 stratiqraphic unit "unit 3" of Chickamauqa Group description short-term succesions: rhvnchonelliform brachiopods: branching & encrusting bryozoans environment shallow subtidal open marine Hurst. 1979 stratiqraphic unit Horderley Sandstone and Alternata Limestone description rhynchonelliform brachiopods concentrated as laqs in base of beds: comrprise 9 0% of fauna environment shallow subtidal marine Webby and Percival, 1983 previously mentioned stratigraphic unit; different shell bed; not included Brenchley and Cocks, 198 2 stratiqraphic unit Lanqoyene Sandstone Formation description coguinas of rhvnchonelliform brachiopods and coral-rich beds (channel-fill fauna) environment shallow subtidal Fursich and Hurst. 1 9 8 0 stratiqraphic unit Silurian Limestone Formation, Silurian Dolomite Formation description rhvnchonelliform brachiopods dominate assemblages in both Formations environment marginal marine Tasch. 1953 stratiqraphic unit Dry Shale (Formation?) description rhvnchonelliform brachiopods are most abundant; diminutive molluscs present environment deep, low oxygen basin 163 4 9 'o c Ic V ! 0 0) 1 o a . n | pelm atozoans * J O o (N i H c o o & S t iH V 1 5 *5 H i- 1 t .2 s . .a •u "5 0 1 c (N ■ 8 0 a 0 1 c e .0 E 0 c 0 _ c c £ <N 1 — ( <N ▼ H bivalves Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 164 3 '2 1 ! 1 2 c a 1 2 o 1 c £ s ■ 8 | V V C * c o o. .e ■t V ) | barnacles Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 166 1— I i H r H • P N l cn f \l r H rsi t H tH tH tH i — ( tH ro (N r H (N Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 167 * i. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. description pavements and thin beds of rhYnchonelliform brachiopods, bivalves, bryozoans, corals environment marine ramp Barthel and Barth, 1 97 2 stratiqraohic unit Ida Valiev description rhvnchonelliform brachiopods fillinq a burrow environment shallow marine Brav. 1 97 2 stratiqraohic unit Ludlowville shales description clusters of rhynchonelliform brachiopods environment subtidal Elliot. 1961 stratiqraohic unit Lummaton Shell-Bed description bed rich in rhvnchonelliform brachiopods environment shallow shelf Racki and Ballinski. 1981 stratiqraohic unit Holv Cross Mountans and Cracow Upland. Poland description beds of rhvnchonelliform brachiopods environment shallow subtidal intershoal areas Baird and Brett. 1981 stratiqraohic unit Kashone Shale Member ("R-C" Bed). Moscow Formation description densely-packed rhynchonelliform brachiopods with pelmatazoan ossicle packstone cap environment deep w ater Baird and Brett, 1981 previously mentioned stratigraphic unit; different shell bed; not included Baird and Brett, 1983 stratiqraohic unit Bay View Coral Bed and Fall Brook Coral Bed. Windom Shale Member. Hamilton Group description tw o coral beds; shell pavements of rhvnchonelliform brachiopods and bryozoans colonized by corals environment deep foreland basin Wendt e t al.. 198 4 stratiqraohic unit Lower Famennian Tafilalt Platform description rhynchonelliform brachiopod coqunias traced for 3 0 km and crinoidal limestones up to 7 m environment deep shelf < 1 0 0 m; drowned platform Wendt, 1988 same as W endt e t al. (1 9 8 4 ); not included W endt and Aiqner, 1985 Infraqriotte (France): crinoidal limestones; shallow subtidal platform Bateas Formation (Spain): crinoidal limestones with abundant bryozoans; shallow turbulent platform Rheinisches and Harz Mountains (Belaium): crinoid wackestones; shallow subtidal Moravian Karst: not included because probably a reef and not a lot of information Holv Cross Mountaints (Poland): not included because reefal in all examples, cephalopod limestones were not included W itzke. 1 98 7 stratiaraohic unit Lime Creek Formation description rhynchonelliform brachiopod-dominated faunas environment cratonic sea 169 t . ' H r H CO T— 1 r H r H tH tH t H r H t H t— 1 tH tH Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. CARBONIFEROUS Horowitz and Waters. 197 2 stratioraphic unit Monteaale Limestone description peimatozoans and rhynchonelliform brachiopods densely packed environment cratonic carbonate Masurel, 198 7 stratiqraphic unit Middle Limestone Group description "Topzone 5" dominated by rhynchonelliform brachiopod Giqanoproductu in life position environment prodelta Kinq, 1 9 8 6 stratiqraphic unit Burlinoton Limestone description core of Waulsortian-type buildup made of crinoids and bryozoans description crinoid pack- &qrainstones comprise flank facies environment shelf foreslope, toe-of-slope, and near toe-of-slope basin Chesnut and Ettensohn. 198 8 stratiqraphic unit Sloans Valiev Member, Penninqton Formation description bryozoans on skeletal debris; rhynchonelliform brachiopod pavements; "pelmatozoan sands" environment lagoon Adams, 1984 reef, not included Wilson. 1982 stratiqraphic unit Bird Sprinq Formation description lenses of bryozoans environment shallow subtidal open marine Masurel, 1 98 7 previously mentioned stratigraphic unit, different type of shell bed, not included Cava roc and Ferm. 19 68 stratiqraphic unit Appalachian Plateau: Kanawha, Kilqore. and Zaleski Flints comprise one la te ra lly extensive spiculite description rhynchonelliform brachiopods, bivalves, linqulid brachiopods, and sponqes comprise "shell-rich limestone" environment Difficult to tell which group is most abundant, not included. PERMIAN Boyd and Newell, 1973 stratiqraphic unit Park City Formation description 1 densely-packed bivalve bed environment shallow marine Paul. 198 2 stratioraphic unit Schwellen Facies of Kupferschiefer description rhynchonelliform brachiopod shell beds environment black shale basin Draper. 1988 stratiqraphic unit Buffel and Oxtrack Formations description crinoidal arainstones up to 8 m thick environment subtidal marine thickets Bledinqer. 1988 stratiqraphic unit Ba'id area in eastern Oman Mountains description cephalopod limestone; not included environment deep basin * 172 t r H tH r H CM tH r H r H t H r H tH r H r H Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 173 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. POST-LOWER TRIASSIC reference Description TRfASSIC Bodzioch, 198 5 stratiqraphic unit Terebratula Beds (Lower Muschelkalk) description lenses of rhynchonelliform brachiopods in life position environment subtidal Passeri and Pialli, 1973 stratiqraphic unit Rhaetavicula contora Limestone description beds and clumps of fraqm ented bivalves environment restricted carbonate lagoon Passeri and Pialli, 1973 previously mentioned stratigraphic unit, different shell bed, not included A iqneret al.. 1978 stratiqraphic unit Upper Muschelkalk description rhvnchonelliform brachiopods on pavements of crinoid-bivalve debris environment subtidal ramp Fursich and W endt, 197 7 stratiqraphic unit Cassian Formation description beds comprised of transported reef-dwellinq bivalves environment slope and basin Fiirsich and Wendt, 197 7 pelagic bivalves and ammonites; not incldued Wendt. 1973 stratioraphic unit Hallstatt Limestone description rhynchonelliform brachiopd-rich fissures environment deep neritic Bodzioch, 1989 stratiqraphic unit Karchowice Beds. Lower Muschelkalk description bioherms of sponaes; not included environment lagoon-shelf barrier Haqdorn, 1982 stratiqraphic unit Upper Muschelkalk description "Bank der kleinen Terebrateln": densely-packed rhynchonelliform brachiopods and bivalves environment shallow marine Michalik. 1982 stratioraphic unit Fatra Formation description denselv-packed rhynchonelliform brachiopods and bivalves; other fossils present environment shallow marine Braqa and Lopez-Lopez, 1989 stratiqraphic unit Rio Blanco Unit description 25-m -thick accumulations of serpulids; reef-buildinq aooreqation environment deep w ater carbonate ramp Passeri and Pialli, 1 97 3 previously mentioned stratigraphic unit, different type of shell bed, not included Gibson and Hedinqer, 1989 stratiqraphic unit Ludinqton Fromation Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 176 3 5 '5 n 0 JZ t J8 e s £ ,y c J! ■8 1 V H 1 2 0 c 0 a ■ | starfish f barnacles Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. description bank of whole and fragmented bivalves (qrain/packstone) environment shelf-slope margin Lee, 1983 stratioraphic unit Jebel Azourki of Central High Atlas description densely-packed Cochiearites bivalves in life position and reworked in channels environment intertidal Lee, 1983 previously mentioned stratigraphic unit, different shell bed, not included W endt, 1973 stratioraphic unit Hallstatt Limestone description ammonite-rich; not included environment deep neritic JURASSIC Bosellini, 1 97 2 stratioraphic unit Calcari qrigi Formation description densely-packed bivalves in life position and reworked in channels environment intertidal Bosellini, 1972 previously mentioned stratigraphic unit, different shell bed, not included Eberli. 1 98 7 stratioraphic unit Allqau Formation description echinoderm pack/wackestones up to 1 m thick; not included because "echinoderm" is not specific environment slope Eberli, 1987 previously mentioned stratigraphic unit, different shell bed, not included Hollowav, 1983 stratioraphic unit Forest Marble Formation description bivalve-dominated calcirudites environment subtidal Fursich, 1981 stratiqraphic unit Santa Cruz section, Estremadura description banks o f Isoqnomon bivalves environment brackish lagoon/bay, not included Noe-Nycjaard et al.. 198 7 stratioraphic unit Jvdeqard Formation description monospecific freshwater qastropod beds environment brackish lagoon/bay, not included Noe-Nygaard and Surlyk, 198 8 brackish lagoon/bay, not included Noe-Nygaard e t al., 1 9 8 7 brackish lagoon/bay and previously mentioned stratigraphic unit; different type o f shell bed not included Brookfield, 197 3 stratioraphic unit Abbotsbury Ironstone description "nests" of rhvnchonelliform brachiopods in life position environment subtidal Brookfield, 1973 previously mentioned stratigraphic unit, different shell bed, not included Seilacher, 1982b reference used later, not here 178 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 179 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. Specht and Brenner, 1979 stratiqraphic unit Redwater Shale Member, Sundance Formation description bivalves dominant; crinoids present environment subtidal Kauffman, 1978 mass mortality of nekton; not included Kauffman, 1978 same as Seilacher, 1 98 2b below; not included Seilacher, 1982 b stratiqraphic unit Posidonia Shales description pavements of bivalves and reqular echinoids; strinqers of ammonites (ammonites not included) environment restricted marine basin Wiqnall, 1989 stratioraphic unit Kimmeridqe Clav description pavements of bivalves environment restricted marine basin Hewitt, 198 0 clusters of belemnites; not used Meyer, 1988 stratiqraphic unit Seelilienqemeinschaften description crinoidal qrain/packstone environment subtical open marine Fursich, 1981 brackish lagoon/bay, not included Fiirsich, 1 981 brackish lagoon/bay, not included Vdrbs, 1986 stratiqraphic unit Bakonv Mountains description crinoidal qrainstone tens of meters thick environment abyssal foot of slope of seamount Dauwalder and Remane. 1979 stratiqraphic unit Nerinea Bed description dense-packed qastropods in 6 0 cm-thick beds environment shallow marine Noe-Nygaard and Surlyk, 1988 brackish lagoon/bay, not included Bloos, 1982 stratiqraphic unit Lower Lias, south Germany description bioclastic marker beds, laterally variable fauna; bivalves & qastropods dominate environment marine basin Benke. 1981 stratiqraphic unit Doqqer/Malm Boundary; NW Celtiberian Chains (Spain) & adjacent areas description desne-packed "echinoderm" residue; Echinoderm Limestone Facies; not specific, not included environment deep subtidal Fursich, 1981 non-marine salinity, not included Arkell. 1933 stratioraphic unit Berkshire Oolite Series description Shell-cum-Pebble Bed comprised primarily of bivalves environment shallow subtidal Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 182 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. Wieczorek, 197 9 stratiqraDhic unit Holv Cross Mountains description Nerineacean beds environment shallow carbonate bank Voros. 1986 stratiqraphic unit Bakony Mountains description rynchonelliform brachiopod-dominated shell bed environment seamount Lanq, 1989 stratiqraphic unit Northern Frankenalb description sponqe-bioherm; not included environment shallow subtidal Bayer et al., 1 98 5 stratiqraphic unit Upper Aalenian/lowermost Bajocian description Klupfet roof-beds; bivalves dominant; crinoids and ammonoids present, too environment subtidal CRETACEOUS Evans. 1985 stratiqraphic unit unit 4, lithofacies d. Northern Kaipara Harbour, New Zealand description transported concretions: bivalves dominate most of them description rhvnchonelliform brachiopods, benthic ammonites, and qastropods present, too environment base o f slope or head of fan Waaqe, 196 4 stratiqraphic unit Trail City and Tim ber Lake Members, Fox Hills Formation description concretions of bivalves and nektonic ammonites environment subtidal Middlemiss, 1962 stratiqraphic unit Ferruqinous Sands; Lower Greensand description rhynchonelliform brachiopod clusters in life position on Exoqyra environment subtidal Middlemiss, 1962 previously mentioned stratigraphic unit, different shell bed; not included Banerjee. 1981 stratiqraphic unit Eze-Aku Formation description bivalve-dominated wackestone; qastropods, echinoids. rhynchonelliform brachiopods, coralline alqae also present environment slope and deep basin Hattin, 198 6 stratiqraphic unit Upper shale Member, Graneros Shale Formation description pavements of bivalves environment open marine epicratonic Matsumoto and Nihonai. 1979 stratiqraphic unit Hokkaido description benthic ammonoid concretions environment subtidal Banerjee, 1981 previously mentioned stratigraphic unit, different type of shell bed; not included Hattin, 1 98 6 stratigraphic unit j Lincoln Member, Greenhorn Limestone Fm; Fairport Member and Juana Lopez Member, Carlile Shale Fm 184 fi i H 1 - i—1 I- 1 tH 1-H fM i-H tH Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 185 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. stratigraphic unit Jetmore and Pfeifer Members, Greenhorn Limestone Fm stratiqraphic unit Fort Havs Limestone member. Niobrara Chalk Fm. description lenses and qrainstones of bivalves (and planktonic forams. not included) environment shallow subtidal open marine Scott, 1 9 9 0 stratiqraphic unit Edwards Formation description densely-packed rudists environment marine shoreface Masse and Philip. 1981 stratiqraphic unit Lanquedoc and Provence areas (Santonian). Pyrenees & Aauitaine reqions (Campanian and Maestrictian) description rudist bafflestones environment open marine subtidal Middlemiss, 1962 previously mentioned stratigraphic unit, different shell bed type; not included Middlemiss, 1962 previously mentioned stratigraphic unit, different shell bed type; not included Krantz, 1972 stratiqraphic unit Lower Greensand description previously mentioned stratioraphic unit; different shell bed type; not included environment subtidal marine Ryer, 197 7 cannot determine dominant group; not included Garrison et al.. 198 7 stratiqraphic unit Upper Greensand/Glauconitic Marl Junction and Exoqyra bed description ammonites and silicified. crowded bivalves environment open shelf Ruffell, 199 0 stratiqraphic unit Sulphur Band, Kent. Enqland description steinkerns of ammonites, bivalves, rhynchonelliforms description Impossible to determine numerical dominance and nodules are of K and J aoes; not included. environment marine shelf Machalski and Walaszczyk. 198 7 stratiqraphic unit Upper Greensand, Poland description phosphatized Maastrichtian; sponqes. corals, rhvnchonelliform brachiopods, and bivalves description unphosphatized Maastrichtian: bivalves, rhvnchonelliform brachiopods and sponqes description Danian: bivalves environment subtidal marine Banerjee and Kidwell, 1991 freshwater-influenced marine embayment, not included TERTIARY Hanley and Flores, 1 98 7 nonmarine; not used Kidwell. 1 98 2 stratiqraphic unit Plum Point Member o f the Calvert and Choptank Formations description pavements and thin beds of bivalves and qastropods environment inner to middle shelf 187 ' fN J rH iH 1 CM i-H fM Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 188 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. Kidwell, 1982 previously mentioned stratigraphic unit, different shell bed; not included Kidwell. 1 98 7 stratiqraphic unit Imperial Formation description clumps to small lenses of densely-packed bivalves environment marine prodelta Niitsuma et al„ 1989 stratiqraphic unit Takatoriyama Pyroclastics Member, Ikeqo Formation; Uraqo and Nojima Formations description dense clumps and pavements of bivalves environment abyssal Seyfried et al., 1987a,b brackish facies; not included Squires, 1964 coral thicket; not included Vella, 1964 stratiqraphic unit Lake Ferry Coarl Thicket description monospecific bed of bivalves and monospecific clumps of bivalves (in life position?) environment upper slope and upper bathyal Vella, 196 4 previously mentioned stratigraphic unit; different shell bed; not included Zullo and Buisinq, 1989 stratiqraphic unit Bouse Formation description laq of barnacles; low salinity, not included environment distributary channels of tide-dominated delta Colella and D'Alessandro, 1988 stratiqraphic unit Facies C, Mt Torre section description laqs, qraded beds, and sand-wave forsets of bivalves, echinoids, bryozoans environment high-energy floor of bathyal strait Colella and D'Alessandro, 1988 Facies D, Mt Torre section previously mentioned stratiqraphic unit; different shell bed barnacles, corals, bryozoans, & rhvnchonelliforms are very abundant bathyal base-of-slope Thomsen. 197 6 stratiqraphic unit near Karlby Klint, Jylland. Denmark description 6-m -thick mounds of bryozoans environment tide-dominated shallow marine shelf Thomsen, 1983 previously listed stratigraphic unit; not included Hanley and Flores, 1987 nonmarine; not included Aiqner, 1983 stratiqraphic unit Mokattam Formation description "nummulite bank”; wacke/arainstones environment shallow subtidal open marine Allen and M atter. 1982 stratiaraphic unit Upper Marine Molasse description hiqh-anqle foresets of bivalves, qastropods, and echinoids environment terrigenous-starved shallow marine seafloor 190 T — t T —1 1 T —I iH T— i 1 — t T -i T — I T— 1 r o tH T — 1 T —1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. » 191 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. Cuffev et at., 1981 stratiqraphic unit basal Monterey Formation description bryozoan coquinas environment neritic to upper bathyal slope Kidwell, 1987 previously mentioned stratigraphic unit; different type of shell bed; not included Nebelsick. 198 9 stratiqraphic unit Zoqelsdorf Formation description fossils are rare in conqlomerate fades; not included environment shallow subtidal Kidwell. 1988a stratiqraphic unit Imperial Formation description listed previously; gastropods and corals also dominant environment shallow subtidal Beckvar and Kidwell, 1988 stratiqraphic unit Punta Chueca terrace description skeletal concentrations dominanted bivalves and qastropods environment shallow subtidal Colella and D'Alessandro, 1988 same as previously listed K am pet a!., 1988 stratiqraphic unit Te Onepu Limestone, Whakapunake Limestone, and Scinde Island Formation description barnacle qrainstones environment subtidal Molenaar e t al., 1988 stratiqraphic unit Roda Sandstone Formation description benthic forams, echinoids, bivavles, qastropods present No abundance data, not included. environment inner shelf Pedlev. 1976 stratiqraphic unit Upper Coralline Limestone Formation description Mtarfa Beds Member and Coralline Alqal Bioherm Member: rhynchonelliform brachiopod-bryozoan marker bed description Ghajn Melel Member: Chlamys marker-bed environment shallow marine Seyfried et al., 1987a stratigraphic unit same as below; different type of shell bed; not included Sevfried et al.. 1 987b stratiqraphic unit Miocene, Parrita coastal embayment. Costa Rica description bivalve "thanatocoenoses" environment shelf Eyles and Laqoe, 1989 stratiqraphic unit upper Yakataqa Formation description Chlamys coquinas environment outer shelf high or bank Kidwell, 1982 previously mentioned stratigraphic unit; different type of shell bed; not included Kidwell, 1989a previously mentioned stratigraphic unit; not included Norris, 1986 stratiqraphic unit Purisima Formation * 193 T — I r H t T — 1 i-H fN fM t H t-H i—1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. » 194 • ro Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. description sand with dispersed bivalves environment outer shelf Kidwell, 1982 same asabove; not included Kidwell, 1989a previously mentioned stratigraphic unit; not included Leithold. 1989 stratiqraphic unit Rio Dell Formation description laq with rhynchonelliform brachiopods environment muddy shelf QUATERNARY Miller and Dubar, 1988 stratiqraphic unit James Citv Formation description clumps of qastropods in life position environment near-normal salinity bay Randall, 1964 stratiqraphic unit St. John. Virqin Islands description Strombus qiqas (queen conch) midden; selective accumulation by humans, not included environment subtidal Shabica, 1971 selective accumulation by gulls, not included Cohen, 1989 freshwater; not included Clifton and Hunter, 1972 stratiqraphic unit West Indian Coral reefs description corals and bivalves selected by Malacantus plumieri for burrows; not included environment subtidal Gregory et al., 197 9 stratigraphic unit selective accumulation; not included Walker, 1 99 0 not ammenable for this study Cohen, 1989 freshwater lake; not included Aiqner and Reineck, 1982 stratiqraphic unit Helqoland Biqht, North Sea description thin laqs primarily of bivalves; qastropods present environment embayed shelf van Straaten. 1952 stratiqraphic unit Dutch Wadden Sea description same as Cadee, 1 97 6; different type of shell bed; not included environment intertidal Walbran et al.. 1989 stratiqraphic unit Great Barrier Reef Province (Green Island and John Brewer Reef) description spikes in abundance in Acanthaster planci for 3 0 0 0 -7 0 0 0 years environment shallow subtidal Dorjes et al., 1986 stratiqraphic unit Sapeio and Ossabaw Islands description bivalves in backshore runnels environment marine beach Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 197 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. Richmond e t a!., 1984 same as below; included below Greensmith and Tucker, 196 6 stratiqraphic unit Sales Point, near Bradwell. Essex description bivalve-dominated shell ridqes environment intertidal estuary Greensmith and Tucker, 1969 stratiqraphic unit chenier plain from the mouth of the Thames estuary description bivalve-dominated cheniers environment chenier plain Farrow. 1974 stratiqraphic unit Island of Barra. Outer Hebrides description bivalve-dominated bodies environment intertidal estuary Wiedemann, 1972 stratiqraphic unit salt-marsh estuaries, Georqia, USA description bivalve-dominated shell deposits environment intertidal estuary Richmond et al., 1984 stratiqraphic unit Ohiwa Harbour description subsurface shell bed concentrated by faunal reworkinq: "whole and broken shells" are primarily bivalves environment intertidal flat (tidally dominanted estuarine lagoon separated from the open ocean by barrier sand spit) Cadee. 1 97 6 stratiqraphic unit tidal flats, Dutch Wadden Sea description subsurface shell bed of Hydrobia concentrated by fauna! reworkinq environment intertidal flat Cadee, 1 97 9 similar to citation above; not included Meldahl, 1987b stratiqraphic unit Cholla Bay, Gulf of California description subsurface concentrations of bivalves environment intertidal flat Serlacher, 1985 stratiqraphic unit Pentai Jerum. Malaysia description bivalve-dominated shell layer environment intertidal Dix, 1989 stratiqraphic unit Northwest Shelf, Australia description sediments dominated by skeletal fraqments: molluscs, corals, benthic forams, calcareous red alqae environment No abundance data qiven; not included. inner shelf Farrow et al., 1984 stratiqraphic unit Northeast Orkney Islands. Scotland description banks of bivalves environment open shelf Mostow and Heron, 1978 stratiqraphic unit Southern Core Banks. North Carolina description bivalve-rich laq * 199 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 200 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. environment barrier island Sanders and Kumar, 1975 stratiqraphic unit Fire Island. Lonq Island. New York description bivalve-rich laq environment barrier island Aliotta and Farinati, 1 9 9 0 stratiqraphic unit Bahia Blanca Estuary description sand-shell ridqes; bivalve-dominated; qastropods present environment tidal-influenced shelf and coast Wright, 1972 stratiqraphic unit terrace near Goleta, Santa Barbara County. California description bed of diverse bivalves and qastropods environment shallow subtidal Addicott. 1964 stratiqraphic unit Cape Blanco terrace description bivalve-dominated shell bed; qastropods are more diverse, but less abundant environment shallow subtidal Ahman and Koniqsson, 1 97 6 stratiqraphic unit near Akroken at Kalix, Sweden description laq dominated by bivavles environment shallow subtidal Saito et al., 1989 stratiqraphic unit Sendai, Northeast Japan description laq of bivalves and qastropods; no abundance data qiven; not included environment shelf and upper slope Rad. 1974 stratiqraphic unit Meteor and Josephine Seamounts description predominantly planktonic foraminifera; benthos is less common: not included environment seamount Morton and Winker, 1979 stratiqraphic unit Texas inner sheJf description sand with diverse bivalves environment inner continental shelf Cohen, 1989 freshwater; not included Morton and Winker, 1 97 9 | stratigraphic unit previously mentioned stratigraphic unit, different shell bed; not included Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. A P P E N D IX C : R A W D A T A FR O M C O LLE C TE D LO W E R TR IA S S IC S A M P LE S D inw oody Fo rm atio n DF-BC 4 DF-BC 11 DF-BC 14 DF-BC 17 DF-GV 5 DF-GV 7 DF-HP 3 DF-HP 11 OTHER Bakevellia 2 1 26 Claraia sp. 4 7 17 14 4 14 3 31 Numbers for bivalves and Eumorphotis 5 100 31 57 112 11 103 brachiopods are the number Mytilus 1 2 of valves counted, not individuals Neoschizodus 6 1 1 5 Permophorus 5 3 Epibionts (serpulids) on many Promyalina 2 1 5 7 7 13 valves Unionites 10 52 133 18 220 42 11 1 unidentified bivalves 5 14 61 111 43 222 73 43 Shells preserved as internal and rhynchnelliforms 129 4 1 external molds unidentified rhynchnelliform: 42 1 inarticulates 3 80 112 108 17 113 5 - GASTROPODS 21 1 14 165 Echinoid spines 15 3 SERPULIDS 16 7 6 2 AMMONOIDS 1 204 Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. S inb ad Lim eston e M em b er, M oenko pi F o rm atio n SL-BB 13 SL-BS 6 SL-FC 1 SL-FC 9 SL-FC 13 SL-FC 16 SL-FC 21 SL-J 4 SL-MM 9 SL-MM 21 OTHER Bakevellia 10 28 2 1 4 20 5 3 6 Numbers for bivalves and Claraia sp. 4 2 brachiopods are the number Crittendenia 8 8 of valves counted, not individuals Elegantinia 2 4 1 Entoiiodes 3 14 19 3 1 Eumorphotis 11 7 6 1 1 Leptochondria 16 39 13 55 75 27 1 330 22 133 Shells preserved as internal and Myolinella 23 15 6 3 1 7 2 2 1 external molds Mytilus 1 12 Neoschizodus 16 69 23 105 32 1 98 10 7 1 Permophorus 4 2 5 43 2 2 Pleuronectites 2 13 1 2 3 Promyalina 77 40 27 3 1 16 72 3 49 7 Unionites 28 17 3 39 15 10 1 2 unidentified bivalves 94 85 45 57 29 9 328 28 7 8 rhynchnelliforms 1 inarticulates 3 6 5 GASTROPODS 1 numerous 8 24 9 1 90 13 5 Echinoid spines 8 SERPULIDS 1 SCAPHOPODS 2 2 ro 0 0 1 Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. upper m em b er, Thaynes F o rm ation TF-CS 2 TF-CS 10 TF-CS 24 TF-CS 26 TF-CS 30 TF-FC 1 TF-FC 12 TF-FD 36 TF-FD 7 TF-FD 13 OTHER Bakevellia 3 1 1 5 23 Numbers for bivalves and Claraia sp. 6 1 brachiopods are the number Crittendenia 2 of valves counted, not individuals Elegantinia 2 _ Eumorphotis 3 1 10 27 1 - Leptochondria 1 1 115 2 1 3 9 2 1 Shells preserved as internal and Myolinella 9 1 3 3 1 external molds Neoschizodus 18 1 2 4 Permophorus 4 1 2 1 6 1 2 Promyalina 8 1 7 3 7 51 2 5 Unionites 4 3 6 1 unidentified bivalves 16 8 14 24 9 11 26 18 rhynchnelliforms ’ 1 142 4 unidentified rhynchonelliform 20 2 2 inarticulates 1 GASTROPODS 6 6 402 4 44 4 93 Crinoid ossicles numerous numerous numerous numerous Echinoid spines 1 3 SERPULIDS 30 3 ro o o > Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. V irg in Lim estone I V VL-H 3 VL-W H 4 VL-W H 10 VL-W H 12 VL-U 10 VL-U 15 VL-U 26 VL-U 46 VL-U 48 VL-U 50 OTHER Bakevellia 15 6 1 4 1 Costatona 1 Numbers for bivalves and Elegantinia 2 2 1 brachiopods are the number Entoliodes 1 1 of valves counted, Eumorphotis 1 3 1 not individuals Leptochondria 5 4 57 5 Myolinella 1 8 1 Neoschizodus 19 1 2 1 2 Shells preserved as internal Pecten 1 and external molds Permophorus 8 6 3 8 2 Pleuronectites 1 1 1 Promyalina 45 3 13 18 10 58 17 30 6 17 Unionites 18 1 2 1 2 13 1 unidentified bivalves 11 8 26 16 7 9 11 14 9 11 unidentified rhynchonelliforms 2 13 inarticulates 1 GASTROPODS 4 10 11 39 7 22 9 Crinoid ossicles numerous numerous Echinoid spines 1 SERPULIDS 58 29 1 1 em b er, M oenko pi F o rm atio n 207 Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. M azzin M em ber, W erfen Fo rm ation_ _ _ _ _ _ _ _ _ _A P P E N D IX C : C O N TIN U E D W F-T 13 (M ) W F-T 13U (M ) W F-U (M ) WF-U 3 (M) W F-U 8 (M ) OTHER Claraia sp. 1 3 4 Neoschizodus 12 Numbers for bivalves and Permophorus 2 brachiopods are the number Promyalina 2 2 of valves counted, not individuals Unionites 29 67 57 unidentified bivalves 20 19 26 Shells preserved as internal and inarticulates 7 external molds GASTROPODS 2 13 208 Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. S iu si M em b er, W erfen F o rm atio n WF-U (S)neartop WF-U (S)sb WF-U (S)up WF-U (S)ubp WF-U (S)lbp WF-U (S)tsb O T H E R Claraia sp. 2 4 6 5 5 Elegantinia 1 Numbers for bivalves and Eumorphotis 1 1 3 brachiopods are the number Neoschizodus 4 19 1 1 of valves counted, not individuals Promyalina 2 4 Unionites 37 300 133 66 45 17 Shells preserved as internal and unidentified bivalves 5 24 31 2 8 external molds inarticulates 1 2 2 1 GASTROPODS 6 22 7 3 1 209 Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. G astropod O olite M em ber, W erfen F o rm atio n W F-PR 5 (1 ) WF-PR 5 (2) WF-PR 5 (3) WF-U (GOM)sb W F-U (GOM)lsb O TH ER Claraia sp. 6 Numbers for bivalves and brachiopods are the number of valves counted, not individuals Shells preserved as internal and external molds Entolium 2 Eumorphotis 1 11 2 1 18 Neoschizodus 14 2 1 6 Permophorus 2 Pteuromya 5 4 4 2 Promyalina 3 11 1 Unionites 33 19 87 28 34 unidentified bivalves 7 inarticulates 11 1 GASTROPODS SERPULIDS 2 8 4 24 210 Reproduced w ith permission o f th e copyright owner. Further reproduction prohibited without permission. C am p il M em ber, W erfen F o rm atio n WF-PR 10 WF-PR 1 1 (1 ) WF-PR 1 1 (2 ) WF-PR 1 1 (3 ) WF-U (C ) OTHER Bakevellia 3 1 8 1 Numbers for bivalves and Claraia sp. 2 brachiopods are the number Costatoria 1 2 of valves counted, not individuals EntoHum 5 3 1 Eumorphotis 6 2 1 23 Shells preserved as internal and Neoschizodus 1 7 8 external molds Permophorus 1 Promyalina 1 Scythentolium . 3 4 Streblopteria (?) Unionites 64 10 5 13 12 unidentified bivalves 61 1 15 43 unidentified rhynchonelliforms 13 inarticulates 1 GASTROPODS 12 112 1 1 211 K am u ra F o rm ation KF-A 3A KF-A 3A (1) KF-A 3A (2) KF-A 3A (3) KF-B 3A(1) KF-B 3A(2) OTHER Bakevellia 2 Eumorphotis 1 5 3 Numbers for bivalves and Leptochondria 1 4 brachiopods are the number Pteria 2 4 9 4 of valves counted, not individuals Streblochondria 3 1 Unionites 2 4 5 4 3 Shells preserved as internal and unidentified bivalves 2 15 4 3 2 external molds GASTROPODS 3 5 1 4 2 Crinoid ossicles numerous SERPULIDS numerous AMMONOIDS 2 H iraiso Fo rm atio n HF-K A(A) HF-K A(B) HF-K A(C) HF-K A (D ) HF-K B(A) HF-K B(B) HF-K B(C) HF-K B HF-K C(C) OTHER Bakevellia 1 Eumorphotis 2 2 5 5 1 5 13 Numbers for bivalves and Leptochondria 2 brachiopods are the number Neoschizodus 1 of valves counted, Pecten 3 not individuals Promyalina 1 Unionites 2 11 Shells preserved as internal unidentified bivalves 5 3 6 6 8 1 5 49 and external molds GASTROPODS 3 1

Linked assets

University of Southern California Dissertations and Theses

Conceptually similar

PDF

Paleoecology and paleoenvironments of early Triassic mass extinction biotic recovery faunas, Sinbad Limestone Member, Moenkopi Formation, south-central Utah

PDF

Paleoenvironments and paleoecology of the disaster taxon Lingula in the aftermath of the end-Permian mass extinction: Evidence from the Dinwoody Formation (Griesbachian) of southwestern Montana...

PDF

Paleoecology and depositional paleoenvironments of Pleistocene nearshore deposits, Las Animas, Baja California Sur, Mexico

PDF

Biotic recovery from the end-Permian mass extinction: Analysis of biofabric trends in the Lower Triassic Virgin Limestone, southern Nevada

PDF

Rebound from the Permian-Triassic mass extinction event: Paleoecology of Lower Triassic carbonates in the western U.S.

PDF

Evolutionary paleoecology and taphonomy of the earliest animals: Evidence from the Neoproterozoic and Cambrian of southwest China

PDF

Numerical modeling of long period events at the Piton de la Fournaise by the use of object-oriented scientific computing

PDF

The structure and development of Middle and Late Triassic benthic assemblages

PDF

The systematics of isotopic exchange among the marine, atmospheric, and the terrestrial reservoirs of carbon: Criteria for marine-terrestrial chronostratigraphic correlations

PDF

Fractionation of nitrogen isotopes during early diagenesis

PDF

Systematic high -resolution imaging of fault zone structures

PDF

The origin of enigmatic sedimentary structures in the Neoproterozoic Noonday dolomite, Death Valley, California: A paleoenvironmental, petrographic, and geochemical investigation

PDF

The unusual sedimentary rock record of the Early Triassic: Anachronistic facies in the western United States and southern Turkey

PDF

Investigation of arc processes: Relationships among deformation, magmatism, mountain building, and the role of crustal anisotropy in the evolution of the Peninsular Ranges Batholith, Baja California

PDF

A unified methodology for seismic waveform analysis and inversion

PDF

Cyclostratigraphy and chronology of the Albian stage (Piobbico core, Italy)

PDF

Investigation into the tectonic significance of the along strike variations of the Peninsular Ranges batholith, southern and Baja California

PDF

Seismic sequence stratigraphy and structural development of the southern outer portion of the California Continental Borderland

PDF

Radium isotopes in San Pedro Bay, California: Constraint on inputs and use of nearshore distribution to compute horizontal eddy diffusion rates

PDF

Holocene sedimentation in the southern Gulf of California and its climatic implications

Asset Metadata

Creator Fraiser, Margaret Lee (author)

Core Title Marine paleoecology during the aftermath of the end-Permian mass extinction

Degree Doctor of Philosophy

Degree Program Geological Sciences

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag OAI-PMH Harvest,paleoecology

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c16-401973

Unique identifier UC11340374

Identifier 3196807.pdf (filename),usctheses-c16-401973 (legacy record id)

Legacy Identifier 3196807.pdf

Dmrecord 401973

Document Type Dissertation

Rights Fraiser, Margaret Lee

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA