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Community paleoecology and global diversity patterns during the end-Guadalupian extinction (middle-late Permian) and the transition from the Paleozoic to modern evolutionary faunas
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Community paleoecology and global diversity patterns during the end-Guadalupian extinction (middle-late Permian) and the transition from the Paleozoic to modern evolutionary faunas
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COMMUNITY PALEOECOLOGY AND GLOBAL DIVERSITY PATTERNS DURING THE END-GUADALUPIAN EXTINCTION (MIDDLE-LATE PERMIAN) AND THE TRANSITION FROM THE PALEOZOIC TO MODERN EVOLUTIONARY FAUNAS by Matthew Eric Clapham A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfullment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (EARTH SCIENCES) December 2006 Copyright 2006 Matthew Eric Clapham ii TABLE OF CONTENTS LIST OF TABLES ......................................................................................................iv LIST OF FIGURES .....................................................................................................v ABSTRACT..............................................................................................................viii CHAPTER I: INTRODUCTION................................................................................1 Brachiopod-Bivalve Ecological Replacement .........................................................1 Late Paleozoic Environmental Change ....................................................................6 Permian-Triassic Extinction...................................................................................13 Timing and Severity...........................................................................................14 Causes ................................................................................................................17 Brachiopod and Bivalve Physiology......................................................................26 Objectives...............................................................................................................31 CHAPTER II: PERMIAN ECOLOGICAL CHANGES ..........................................33 Previous Work........................................................................................................34 Methods..................................................................................................................38 Permian Community Paleoecology........................................................................46 Early Permian.....................................................................................................46 Middle Permian..................................................................................................56 Late Permian ......................................................................................................65 Quantifying Paleocommunity Change ...................................................................77 Implications for the Paleozoic Fauna-Modern Fauna Transition...........................82 CHAPTER III: END-GUADALUPIAN DIVERSITY CHANGES.........................86 Previous Work: Timing, Severity, and Causes ......................................................86 Methods..................................................................................................................94 Taxonomic Severity and Selectivity ......................................................................98 Paleogeographic Extinction Patterns....................................................................104 Summary ..............................................................................................................117 CHAPTER IV: END-GUADALUPIAN ECOLOGICAL REPLACEMENT.........119 Taphonomic Biases ..............................................................................................119 Mass Extinction....................................................................................................121 Adaptive Radiation...............................................................................................123 Environmental Change.........................................................................................124 CHAPTER V: SUMMARY....................................................................................127 BIBLIOGRAPHY....................................................................................................131 APPENDIX 1: MEASURED STRATIGRAPHIC SECTIONS ..............................148 iii APPENDIX 2: QUANTITATIVE ASSEMBLAGE DATA ..................................166 APPENDIX 3: DIVERSITY AND PALEOBIOGEOGRAPHY............................191 iv LIST OF TABLES Table 3.1. Middle and Late Permian diversity and extinctions...............................100 Table 3.2. Diversity and extinction among rhynchonelliform brachiopod orders ..103 Table 4.1. End-Guadalupian and end-Permian extinction rates..............................122 v LIST OF FIGURES Figure 1.1. Global diversity of the Phanerozoic Evolutionary Faunas .......................2 Figure 1.2. Global diversity of rhynchonelliform brachiopods and bivalves.............4 Figure 1.3. Late Paleozoic ecosystem stability ...........................................................7 Figure 1.4. Trends in brachiopod substrate attachment and bioturbation...................9 Figure 1.5. Modeled oxygen concentrations during the Phanerozoic.......................12 Figure 1.6. End-Permian extinction patterns.............................................................16 Figure 1.7. Hypercapnia model for the end-Permian extinction...............................20 Figure 1.8. Evidence for anoxia during the end-Permian extinction ........................23 Figure 1.9. Anatomy of brachiopod lophophore and bivalve gill .............................28 Figure 2.1. Ecological changes during the Permian-Triassic transition....................36 Figure 2.2. Location map of sampled fossil assemblages.........................................39 Figure 2.3. Formations and age of bulk samples ......................................................40 Figure 2.4. Criteria for onshore-offshore distribution...............................................42 Figure 2.5. Abundance patterns in Early Permian onshore assemblages..................48 Figure 2.6. Typical Early Permian onshore fossils ...................................................50 Figure 2.7. Early Permian onshore size histograms..................................................52 Figure 2.8. Abundance patterns in Early Permian offshore assemblages .................53 Figure 2.9. Typical Early Permian offshore fossils...................................................55 Figure 2.10. Early Permian environmental trends in mean abundance.....................57 Figure 2.11. Abundance patterns in Capitanian Gerster Formation assemblages.....59 Figure 2.12. Abundance patterns in Wordian Word Formation assemblages...........60 vi Figure 2.13. Typical Gerster Formation fossils ........................................................62 Figure 2.14. Typical Word Formation fossils ...........................................................63 Figure 2.15. Abundance patterns in Late Permian samples from Hydra ..................67 Figure 2.16. Abundance patterns in Late Permian samples from Heshan ................68 Figure 2.17. Typical Episkopi Formation fossils ......................................................70 Figure 2.18. Typical Heshan Formation fossils ........................................................71 Figure 2.19. Gastropod size-frequency distributions ...............................................73 Figure 2.20. Size histograms of Middle-Late Permian brachiopods and bivalves....74 Figure 2.21. Brachiopod and bivalve size distributions in Late Permian samples....76 Figure 2.22. Temporal trends in mean abundance in offshore assemblages.............78 Figure 2.23. Abundance and identity of late Guadalupian bioclasts, Penglaitan......81 Figure 3.1. End-Guadalupian diversity changes ......................................................87 Figure 3.2. End-Guadalupian environmental changes ..............................................89 Figure 3.3. Severity and selectivity of the end-Guadalupian extinction ...................91 Figure 3.4. Paleogeographic variation in end-Guadalupian extinction intensity ......93 Figure 3.5. Middle and Late Permian fossil localities for diversity analysis............96 Figure 3.6. Paleogeographic distribution of diversity sample localities ...................97 Figure 3.7. Middle and Late Permian diversity patterns...........................................99 Figure 3.8. Distribution and age of brachiopod diversity stations ..........................106 Figure 3.9. Survival and extinction at Capitanian stations......................................107 Figure 3.10. Geographic variations in Wordian and Wuchiapingian extinctions ...109 Figure 3.11. Geographic variations in Capitanian extinction severity....................110 vii Figure 3.12. Brachiopod extinction rates at well-sampled stations.........................112 Figure 3.13. Bivalve extinction rates at well-sampled stations...............................113 Figure 3.14. Effect of geographic distribution on extinction and survival .............115 viii ABSTRACT The replacement of Paleozoic brachiopod-dominated marine benthic communities by post-Paleozoic assemblages dominated by molluscs was one of the most significant ecological transitions in the Phanerozoic, completely restructuring benthic ecosystems and paving the way for modern marine communities. The timing of the abrupt diversity switch has been tightly constrained to the catastrophic mass extinction at the Permian-Triassic boundary. In contrast, the shift in ecological dominance, as measured by relative abundance in marine communities, has only been assumed to be synchronous with the taxonomic change. This assumption ignores environmental changes throughout the Permian as well as potential effects of the earlier end-Guadalupian extinction (at the end of the Middle Permian). In order to test whether the ecological transition was contemporaneous with the end-Permian taxonomic shift, I quantified Permian community change based on fossil assemblages collected from the western United States (Early and Middle Permian, 15 samples), Greece (Late Permian, 6 samples), and China (Late Permian, 6 samples). All assemblages were derived from offshore carbonate deposits formed in tropical environments. During the Early Permian, paleoenvironmental trends in community composition parallel those documented from biodiversity studies. Molluscs were extremely abundant in nearshore assemblages (comprising close to 100% of the assemblage), while inner shelf settings contained a mosaic of communities with co- dominant brachiopods and molluscs. However, Early and Middle Permian offshore ix fossil communities were overwhelmingly dominated by rhynchonelliform brachiopods, with a mean abundance of 98.9%. Brachiopods were approximately evenly split between pedically-attached and reclining forms, with cementing genera rare in most samples. Bivalves only accounted for 0.7% and were strongly dominated by epibyssate suspension-feeding forms (>90% of the bivalve population). In contrast, Late Permian offshore assemblages contained a mixture of brachiopods and molluscs. Brachiopods only comprised 34.6%, with bivalves accounting for 17.9% and gastropods the most abundant group at 47.5%. Bivalve life habits were also more evenly distributed between epifaunal suspension feeders (52%) and infaunal suspension feeders (42%). In addition, bivalves were comparable in size to co-existing brachiopods. These results demonstrate that a substantial portion of the ecological transition from brachiopods to bivalves – in terms of relative abundance, ecological dominance of infaunal forms, and size distributions – had occurred prior to the end-Permian biotic crisis and was apparently synchronous with the end-Guadalupian extinction. Despite this large ecological change, a re-evaluation of the severity and selectivity of the end-Guadalupian extinction reveals that it was only a minor event, with an overall extinction rate of 33.8%. Some groups, such as corals and bryozoans, suffered more than others, but the selectivity between rhynchonelliform brachiopods (33.8%) and bivalves (32.7%) was minimal. Paleobiogeographic patterns of extinction show that elevated extinction intensities only occurred in x western North America (among brachiopods) and eastern Australia (among bivalves). Both of those regions had a strongly endemic fauna during the Capitanian Stage and lacked marine deposition during the Late Permian because of tectonic activity. Extinction rates throughout most of the Tethyan region were low and not significantly different from either preceding or succeeding stages, implying that this tectonically-induced loss of biotic provincialism was the primary cause of the apparent extinction. The minimal selectivity and severity in all regions except for North America and eastern Australia (and to some extent, south China) therefore suggests that the ecological change was not triggered by severe taxonomic effects, as has been inferred for the end-Permian crisis. It is not clear what may have triggered the substantial decoupling of global diversity (minor biotic crisis) and local community ecology (major shift in relative abundance). Given the minimal severity of the end- Guadalupian crisis, potential causes of this dramatic increase in the relative abundance of molluscs include: (1) acquisition of evolutionary innovations that conferred a competitive advantage to molluscs; or (2) a change in environmental conditions that favored molluscs over rhynchonelliform brachiopods. As nearly all of the abundant bivalve and gastropod genera in Late Permian assemblages were also present during the Middle Permian, it does not seem likely that a new evolutionary innovation was responsible for their increased Late Permian abundance. Instead, the increase in molluscan abundance may have resulted from environmental changes, xi possibly precursors to the end-Permian mass extinction, during the Guadalupian- Lopingian interval. 1 CHAPTER I: INTRODUCTION Brachiopod-Bivalve Ecological Replacement The composition of Phanerozoic marine ecosystems has undergone several major shifts during which previously diverse higher-level taxonomic groups were replaced by new clades that radiated to become the most diverse components of benthic communities (Sepkoski, 1981). These significant and relatively rapid diversity changes have been documented and tightly constrained, both temporally and environmentally, through a wide range of biodiversity studies (Sepkoski, 1981; Sepkoski and Miller, 1985; Westrop et al., 1995). Two such ecosystem shifts include the Ordovician Radiation, where diverse trilobites declined at the expense of groups such as rhynchonelliform brachiopods (Droser and Finnegan, 2003) and the Permo- Triassic transition, during which bivalves abruptly replaced brachiopods as the most diverse skeletonized marine organisms (Gould and Calloway, 1980; Erwin, 1993). Sepkoski (1981) recognized these fundamental diversity changes and used them to group marine clades into “evolutionary faunas” (Fig. 1.1) containing taxa with similar temporal trends in biodiversity. For example, the Cambrian Evolutionary Fauna includes clades such as trilobites and linguliform brachiopods that were most diverse during the Cambrian Period, whereas the Paleozoic Evolutionary Fauna (including rhynchonelliform brachiopods, crinoids, stenolaemate bryozoans) was most diverse from the Ordovician to Permian (Sepkoski, 1981). The Modern Evolutionary Fauna includes those clades (primarily bivalves and gastropods) that are diverse in the 2 Figure 1.1. Family-level global diversity trends and characteristic groups of the Cambrian, Paleozoic, and Modern Evolutionary Faunas. Geologic timescale is C = Cambrian, O = Ordovician, S = Silurian, D = Devonian, C = Carboniferous, P = Permian, Tr = Triassic, J = Jurassic, K = Cretaceous, T = Tertiary. Modified from Sepkoski (1981). 3 modern ocean and have been the most diverse components of marine communities since the Triassic (Sepkoski, 1981). These diversity shifts during the Ordovician Radiation and Permo-Triassic crisis were also associated with fundamental paleoecological changes in marine communities. However, it is often only assumed that changes in ecological dominance, as indicated by relative abundance, were synchronous with the observed diversity trends. In some cases the two are contemporaneous: for example, diversity changes during the Ordovician Radiation were accompanied by significant parallel changes in the relative abundance structure of benthic marine communities as brachiopods and echinoderms increased in abundance at the expense of trilobites during the Early and Middle Ordovician (Li and Droser, 1997, 1999). However, decoupled patterns of diversity and ecological dominance have been recognized within certain clades at other times, such as the taxonomic and ecological change of bryozoans following the end-Cretaceous mass extinction (McKinney et al., 1998). The transition between the brachiopod-rich Paleozoic Fauna and the molluscan Modern Fauna has attracted a great deal of study because of its apparently close temporal association with the end-Permian mass extinction and its importance in creating marine ecosystems that have persisted to the present day. The well- documented diversity switch between rhynchonelliform brachiopods and bivalves was abrupt and coincident with the end-Permian extinction (Fig. 1.2) (Gould and Calloway, 1980; Knoll et al., 1996; Sepkoski, 1996). In contrast, the timing of the ecological shift has only loosely been constrained, mostly by anecdotal observations. 4 Figure 1.2. Global generic diversity for rhynchonelliform brachiopods and bivalves. Timescale is same as Figure 1.1, except Pal = Paleogene, N = Neogene. Modified from Sepkoski (1996). 5 Quantitative data indicates that the transition occurred some time between the Middle Permian, when rhynchonelliform brachiopods were still highly abundant (Sepkoski and Miller, 1985; Waterhouse, 1987), and the Early Triassic, when bivalves were extremely dominant (Fraiser and Bottjer, 2005b). This shift in dominance has traditionally been attributed to the catastrophic effects of the end-Permian mass extinction (Gould and Calloway, 1980), although other studies have proposed that either competitive interactions (Sepkoski, 1996) or physiological differences between the two clades (Steele-Petrovic, 1979; Thayer, 1985, 1986a; Rhodes and Thompson, 1993) were driving causes of a more gradual replacement. The tacit assumption that the ecological dominance shift was synchronous with the end-Permian mass extinction, based almost entirely on diversity data (e.g., Gould and Calloway, 1980), may also be overly simplistic given the variety of other environmental trends during the Late Permian. Although the end-Permian extinction was clearly the most significant event during the Permian-Triassic transition, there may also have been long-term background environmental changes throughout the late Paleozoic (e.g., Thayer, 1979; Martin, 1996; Weidlich et al., 2003). In addition, a smaller extinction at the end of the Middle Permian, the end-Guadalupian extinction (Stanley and Yang, 1994), may have further influenced the ecological transition between the Paleozoic and Modern Evolutionary Faunas. A complete understanding of the Permian-Triassic ecological shift will require analysis of late Paleozoic background environmental conditions and fluctuations, the causes and consequences 6 of the end-Permian mass extinction, and the implications of the smaller end- Guadalupian crisis. Late Paleozoic Environmental Change Previous studies have concluded that the marine ecosystem was largely unchanging during the Carboniferous and Permian (Sheehan, 1996). Total global diversity did not vary significantly during the middle and late Paleozoic and the relative diversity of the evolutionary faunas was largely unchanged except for a small increase in the Modern Fauna during the Late Devonian (Fig. 1.3A). The onshore- offshore distribution of the evolutionary faunas also displays a similar pattern, with relatively static environmental preferences during the Silurian-Devonian and Carboniferous-Permian, separated by a Late Devonian expansion of the Modern Fauna (Fig. 1.3B). This presumed stasis, especially apparent during the Carboniferous-Permian interval, has reinforced the assumption that the ecological switch between brachiopods and bivalves occurred entirely at the end-Permian extinction (Gould and Calloway, 1980), and downplayed potential effects of long- term environmental changes during the late Paleozoic. Such environmental trends as a change in bioturbation depth and degree of substrate consistency (Thayer, 1979; Bottjer and Ausich, 1986), increase in marine nutrient levels (Bambach, 1993; Martin, 1996, 2003), fluctuation in atmospheric oxygen and carbon dioxide concentrations (Weidlich et al., 2003; Berner, 2005), and climate change (Isbell et al., 2003) may have contributed to or mediated the ecological transition. 7 Figure 1.3. Late Paleozoic ecosystem stability. A. Global diversity trends showing stable diversity during the middle and late Paleozoic and succession of “Ecological Evolutionary Units” (EEU) representing relatively stable community composition. Modified from Sheehan (1996). B. Onshore-offshore diversity patterns of the Paleozoic and Modern Faunas. Shaded areas delineate environments and times where each fauna was diverse, as indicated by factor analysis, and black dots indicate Permian sample locations. Modified from Sepkoski and Miller (1985). 8 The nature of the substrate exerts a fundamental influence on benthic marine organisms (e.g., Rhoads and Young, 1970; Thayer, 1975), and geologically rapid changes in substrate consistency can have significant evolutionary implications, even causing extinction among clades that are unable to adapt to new substrate regimes (Bottjer et al., 2000). One of the primary controls on substrate consistency is the degree of infaunal activity, which promotes softer, more fluid substrates by thoroughly bioturbating the sediment into a thick mixed layer with high water content (Rhoads and Young, 1970; Bottjer et al., 2000). Typical bioturbation depth increased significantly in the late Paleozoic (Fig. 1.4) with the evolution of deep-burrowing bivalves and their radiation into infaunal habitats up to 1 m below the sediment-water interface (Bottjer and Ausich, 1986; Ausich and Bottjer, 2001). If this gradual late Paleozoic increase in bioturbation depth also indicated a corresponding increase in bioturbation intensity, it may have negatively affected epifaunal organisms, especially immobile free-living genera like many Permian rhynchonelliform brachiopods, potentially contributing to the decline of such groups in the late Paleozoic and into the Triassic (Fig. 1.4) (Thayer, 1979). However, the implications of the proposed substrate changes and resultant diversity trends on the ecological replacement of brachiopods by bivalves have not yet been assessed in a rigorous or quantitative manner. Nutrient levels are one of the primary controls on the diversity, structure, and composition of many modern animal communities (Worm et al., 2002; van Ruijven and Berendse, 2005) and can be expected to have had similar effects in the fossil 9 Figure 1.4. Relative diversity of reclining (free-resting), pedically attached, and cementing rhynchonelliform brachiopods (top panel) and Phanerozoic trends in maximum typical burrow depth (lower panel). Top panel modified from Thayer (1979); bottom panel modified from Ausich & Bottjer (2001). 10 record. Although there is no method for directly measuring nutrient concentrations, a variety of indirect proxies imply that marine productivity increased during the late Paleozoic. Changes in the physiological requirements and biomass of abundant fossil groups suggest that productivity and energetics have increased in the marine biosphere through the Phanerozoic (Bambach, 1993). The spread of terrestrial plant biomass during the Carboniferous may have resulted in increased nutrient run-off into shallow water environments, promoting greater food availability in marine ecosystems (Bambach, 1993). Secular trends in strontium, sulfur, and carbon isotopes, as well as sedimentological evidence from phosphorites – indicative of intensified phosphorus recycling and oceanic eutrophication – also imply that the late Paleozoic was a time of increasing marine nutrient levels (Martin, 1996). Early and mid-Paleozoic oceans are thought to have been “super-oligotrophic,” with extremely low dissolved nutrient levels, whereas nutrients may have increased to more mesotrophic conditions during the Carboniferous-Permian interval (Martin, 1996). However, the extent and timing of the proposed late Paleozoic productivity increase are unclear because of the indirect evidence used to document nutrient levels. Nevertheless, gradual or stepwise increases in nutrients, combined with different nutrient requirements of major clades such as brachiopods and bivalves (described below), may have influenced the relative abundance of those two groups (Bambach, 1993; Rhodes and Thompson, 1993). Geochemical modeling suggests that, in addition to these potential substrate and nutrient changes, atmospheric oxygen levels underwent a drastic drop from 11 nearly 30% at the beginning of the Middle Permian (270 Ma) to as low as 15% by the end of the Early Triassic (245 Ma) (present atmospheric levels are 21%) (Berner, 2005). This decrease, apparently gradual at first but increasing in severity in the Late Permian and especially in the Early Triassic (Fig. 1.5), would have resulted in lower dissolved oxygen concentrations in shallow water and likely contributed to anoxic conditions in the Late Permian and Early Triassic (Berner, 2005). Decreased oxygen concentrations were accompanied by a concomitant increase in atmospheric carbon dioxide levels (Berner, 2005). Although lowered oxygen levels have been proposed as a cause of the end-Permian mass extinction (e.g.,Weidlich et al., 2003, and see below), its potential long-term effects on the marine biota during the Middle and Late Permian have not been addressed, especially given the differing oxygen tolerances of brachiopods and bivalves outlined below (Thayer, 1986a; Curry et al., 1989). The late Paleozoic was also a time of extensive glaciation, ending in the Early Permian with the transition from an icehouse climate to greenhouse conditions (Isbell et al., 2003). The late Paleozoic ice age had significant effects on marine diversity and latitudinal biotic gradients (Stanley and Powell, 2003; Powell, 2005) and could potentially have affected benthic ecology. However, deglaciation occurred during the Sakmarian (mid-Early Permian) in most regions (dos Santos et al., 1996; Eyles et al., 2003; Jones and Fielding, 2004), with cool-water deposition persisting until only the Kungurian (late Early Permian) in regions like eastern Australia (Isbell et al., 2003). The timing of deglaciation and climate amelioration therefore seems to have been too 12 Figure 1.5. Modeled oxygen concentrations during the Phanerozoic. Inset shows an expanded view of modeled oxygen levels during the Middle Permian-Middle Triassic time interval. Modified from Berner (2005). 13 early to have affected the Paleozoic Fauna-Modern Fauna transition, which apparently took place some time after the Guadalupian (Middle Permian). Although the timing and extent of these long-term environmental changes remain obscure, it remains possible that they may have influenced late Paleozoic benthic marine ecology. The relatively constant diversity patterns through the Carboniferous-Permian interval confirm that substrate or nutrient changes did not affect marine biodiversity but it is plausible that ecological changes may have been decoupled from static marine diversity. Regardless of the ecological significance of late Paleozoic environmental change, it is clear that there was substantial ecological change by the Early Triassic (Fraiser and Bottjer, 2005b), implying that, as previously assumed, the end-Permian mass extinction was likely a contributor, and possibly a major contributor, to the Paleozoic-Modern Fauna switch. Therefore review of the end-Permian mass extinction, especially its timing and causes, will be of critical importance for assessing the Paleozoic-Modern Fauna ecological transition. Permian-Triassic Extinction The mass extinction at the Permian-Triassic boundary was the most severe biotic crisis of the Phanerozoic (Jin et al., 2000). The environmental catastrophe had wide-ranging geological and biological consequences, including intense soil erosion and abrupt change in fluvial style (Sephton et al., 2005), UV-related environmental mutagenesis (Visscher et al., 2004), anomalous oceanic and biotic conditions during 14 the entire Early Triassic (Fraiser and Bottjer, 2005b; Pruss et al., 2005), and potentially a fundamental ecological restructuring of marine communities (McGhee et al., 2004). However, nearly all studies have concentrated on taxonomic measures of severity (e.g., Raup, 1979; e.g., Knoll et al., 1996) or proposed causes for the crisis (Renne et al., 1995; Wignall and Twitchett, 1996; Isozaki, 1997; Weidlich et al., 2003; Grice et al., 2005; Kump et al., 2005). Several studies have described the ecological recovery from the end-Permian crisis (Fraiser and Bottjer, 2004; Fraiser and Bottjer, 2005b; Payne et al., 2006), but the detailed ecological history of extinction interval itself has not been investigated. In addition, the potential similarities, both in their causes and effects, between the end-Permian extinction and the earlier end-Guadalupian event are not known. Therefore, an examination of the effects and potential causes of the end-Permian crisis will constrain how it may have influenced ecological change and whether the end-Guadalupian extinction may have had similar effects. Timing and Severity Uranium-lead radiometric dating of volcanic ash layers from south China has constrained the timing of the Permo-Triassic biotic crisis to 252.6 ± 0.2 Ma (Mundil et al., 2004; Ovtcharova et al., 2006). A variety of studies have implied that the extinction was rapid, occurring in less than 500 kyr (Bowring et al., 1998) and possibly even less than 200 kyr (Mundil et al., 2004). Despite the extremely short duration of the extinction interval, it appears that the amount of taxonomic turnover 15 was exceedingly high, with initial estimates suggesting an extinction rate of between 88% and 96% at the species level (Raup, 1979). However, these extinction intensities included pooled diversity data from the final three stages of the Permian and subsequent refined estimates based only on the terminal Permian suggested slightly lower, but still catastrophic, global species loss of 76% to 84% (Stanley and Yang, 1994). A detailed compilation of the stratigraphic range of 333 species from the Meishan section in China documented a local extinction rate of 94% in bed 25 (Fig. 1.6A), the main extinction pulse at that locality (Jin et al., 2000). In addition to its extraordinary magnitude, the end-Permian mass extinction displayed significant taxonomic selectivity (Fig. 1.6B), with members of the Paleozoic Fauna suffering much greater extinction intensities than taxonomic groups belonging to the Modern Fauna (Sepkoski, 1981). The Paleozoic Fauna includes marine groups that typically have low metabolic rates and weak internal circulation, such as rhynchonelliform brachiopods (93% genus-level extinction), stenolaemate bryozoans (28% extinction), crinoids (100% extinction, although at least one genus must have survived to initiate the Mesozoic radiation (Twitchett and Oji, 2005)), and tabulate and rugose corals (100% extinction) (Knoll et al., 1996). In contrast, groups with active internal circulation and higher metabolic rates belonging to the Modern fauna had significantly lower extinction rates: only 37% of bivalve genera and 13% of gastropod genera became extinct according to data from the Sepkoski global diversity compilation (Knoll et al., 1996). This marked taxonomic selectivity is one 16 Figure 1.6. End-Permian extinction patterns. A. Stratigraphic ranges of species at the Meishan section (Zhejiang Province, China), showing abrupt extinction of 94% of species at Bed 25. Modified from Jin et al. (2000). B. Genus-level extinction rates in the final four stages of the Permian (Wordian, Capitanian, Wuchiapingian, Changhsingian) for rhynchonelliform brachiopods, bivalves, and gastropods. Based on data from Knoll et al. (1996). 17 of the primary lines of evidence used to support the assumption that the end-Permian extinction caused the ecological replacement of brachiopods by molluscs (Gould and Calloway, 1980). Selectivity patterns have also been used as supporting evidence for a variety of proposed extinction mechanisms (e.g., Knoll et al., 1996). Causes There are two primary classes of hypothesized causal mechanisms for the end-Permian mass extinction: a set of theories arguing for terrestrial (primarily climatic and/or oceanographic) causes and a group attributing the biotic and environmental catastrophe to an extraterrestrial impact. Evidence for an impact was initially based on the presence of shocked quartz grains and a small iridium anomaly in terrestrial Permian-Triassic boundary sections in Antartica and Australia (Retallack et al., 1998). However, the iridum concentration and number and size of shocked quartz crystals were an order of magnitude smaller than in undisputed impact beds at the Cretaceous-Paleogene boundary, and the peak iridium value was located approximately 1 meter below the paleobotanically defined Permian-Triassic boundary (Retallack et al., 1998). A similar small iridum spike, along with anomalous high nickel concentrations, was reported from a deep marine P-T boundary section in Guangxi Province, south China (Wang et al., 1997). Putative impact-metamorphosed grains have also been identified at the Permian-Triassic boundary in China, where they co-occur with a pronounced sulfur and strontium isotope excursion interpreted to result from mantle sulfur release during an impact 18 event (Kaiho et al., 2001). Finally, sediments from the extinction horizon in Hungary and Japan have been reported to contain fullerenes (complex organic molecules) that trapped helium and argon gas with isotopic signatures typical of carbonaceous chondrite meteorites (Becker et al., 2001). Arguably the strongest evidence in support of a bolide impact is the interpretation of the Bedout structure, on the northwestern Australian shelf, as a preserved Permian-Triassic boundary crater (Becker et al., 2004). This determination is based on the presence of supposed maskelynite glass typical of impact melts, shocked plagioclase crystals, argon-argon isotopic dating indicating an age of 250.1 ± 4.5 Ma, the significant (9 km) faulted relief of the putative central uplift, and the broadly circular shape of the structure in geophysical gravity surveys (Becker et al., 2004). However, nearly all aspects of this study are controversial; notably, it has been argued that the maskelynite glass does not resemble impact melt and there are no definitive planar deformation features (Glikson, 2004); and that the gravity data are not consistent with the preserved central uplift of a large crater and the argon- argon plateau age is not valid (Renne et al., 2004). There is also no evidence in nearby marine Permian-Triassic boundary sections, such as those in Western Australia only 1000 km from the Bedout structure, for an ejecta layer or tsunami deposit, in contrast to the widespread distribution of those features in Cretaceous- Paleogene sections similar distances from Chicxulub (Wignall et al., 2004). In addition, many of these geochemical results, namely the extraterrestrial helium isotopes, have not been repeatable (Koeberl et al., 2004) or were poorly 19 biostratigraphically constrained. Finally, the shocked quartz crystals originally described by Retallack et al. (1998) have been reexamined and do not possess distinctive impact-related deformation features (Langenhorst et al., 2005). Although it is not possible to definitively rule out extraterrestrial causes, there is little conclusive supporting evidence for a bolide impact at the Permian-Triassic boundary. Most data instead are consistent with intrinsic climatic and/or oceanographic causes, related to the Siberian flood basalt province (Renne et al., 1995; Grard et al., 2005) and/or the development of oceanic stratification and upwelling of toxic waters containing carbon dioxide (Knoll et al., 1996), methane (Ryskin, 2003), hydrogen sulfide (Grice et al., 2005; Kump et al., 2005; Marenco et al., 2005), and/or reduced oxygen levels (Wignall and Twitchett, 1996), into shallow marine environments. Knoll et al. (1996) hypothesized that hypercapnia (toxic effects of excess CO 2 ) could account for the taxonomic selectivity of the extinction, in which metabolically active organisms, primarily bivalves and gastropods, suffered less than those with low metabolic rates such as corals or brachiopods. The model requires the development of a stratified ocean so that carbon dioxide can be sequestered in an isolated reservoir of deep water where it may build up to fatal levels (Fig. 1.7). The carbon fraction in this deep oceanic reservoir would also have become enriched in the light isotope ( 12 C) derived from remineralized sinking organic matter. Oceanic overturn and upwelling of the CO 2 -rich deep water at the Permo-Triassic boundary would have flooded the continental shelves with toxic water, decimating both benthic 20 Figure 1.7. Model for generation of hypercapnia during the end-Permian mass extinction. Sulfate reduction in the deep ocean during the Late Permian resulted in elevated carbon dioxide and hydrogen sulfide concentrations. Upwelling of this deep water mass at the end of the Permian would have flooded shallow marine shelves with hypercapnic and sulfidic waters. Modified from Knoll et al. (1996). 21 and planktonic organisms and producing the large negative carbon isotope excursion at the boundary (Knoll et al., 1996). However, although climate modeling implies that the Late Permian ocean may have had sluggish circulation and high primary productivity favoring stratification (Hotinski et al., 2001; Kiehl and Shields, 2005), ocean chemistry may not have suitable for accumulation of the high dissolved CO 2 concentration required to cause the observed extinction rate (Hotinski et al., 2001; Berner, 2002). Catstrophic methane release has also been proposed as an end-Permian kill mechanism (Heydari and Hassanzadeh, 2003; Ryskin, 2003), in particular to account for the pronounced negative carbon isotopic excursion at Permo-Triassic boundary sections worldwide (e.g., Berner, 2002; Dolenec et al., 2004; e.g., Krull et al., 2004). The methane eruption hypothesis predicts buildup of 10 18 to 10 19 g of dissolved methane in a stratified deep ocean reservoir that can catastrophically exsolve and erupt into shallow water and the atmosphere (Ryskin, 2003). Methane released may combust in the atmosphere, instantaneously decimating the terrestrial biosphere, with remaining concentrations potentially causing global warming immediately following the oceanic eruption (Ryskin, 2003). Although methane release from clathrates may cause negative carbon isotope excursions, the end-Permian negative shift can be accommodated without invoking methane input (Knoll et al., 1996; Grard et al., 2005), especially considering that no known sections contain the highly negative δ 13 C values typically associated with methane. In addition, the mass of methane required is extremely large, at least several times higher than that invoked at the Paleocene- 22 Eocene boundary (Berner, 2002), implying that, as with the hypercapnia model, the geochemical conditions required for methane eruptions may not be feasible. In contrast to the hypercapnia and methane eruption models, both of which may be physically unfeasible and do not have strong independent supporting evidence, there are abundant signs of anoxic and even euxinic conditions in both shallow and deep water during the Late Permian (Fig. 1.8). Chert lithofacies in deep- sea sections from Panthalassa, exposed in Japan and British Columbia (Isozaki, 1997), as well as pyrite framboid size distributions from basinal deposits in Greenland (Nielsen and Shen, 2004) suggest that much of the deep ocean was anoxia or even sulfidic during the Late Permian. Similar pyrite framboid evidence from Kashmir (Wignall et al., 2005), a negative cerium anomaly in Iran (Kakuwa and Matsumoto, 2005), sulfate isotope excursions in Italy and Turkey, interpreted to result from bacterial oxidation of hydrogen sulfide (Newton et al., 2004; Marenco et al., 2005), and sedimentological evidence from Spitsbergen, Italy, and Slovenia (Wignall and Twitchett, 1996) are all indicative of anoxia in shallow water Permian- Triassic boundary sections. Furthermore, the presence of molecular biomarkers such as isorenieratane in Western Australia and south China indicate the presence of green sulfur bacteria, which require both light and hydrogen sulfide, implying that euxinic waters extended into the photic zone at both localities (Grice et al., 2005). 23 Figure 1.8. Lithological and geochemical evidence for anoxia and/or euxinia during the end-Permian extinction. 24 Climate modeling confirms the feasibility of development and maintenance of oceanic stratification and anoxia during the Late Permian (Hotinski et al., 2001; Kiehl and Shields, 2005; Winguth and Maier-Reimer, 2005). Reduced latitudinal temperature gradients due to polar warming slowed oceanic circulation, and elevated temperatures decreased the solubility of oxygen dissolved during deep water formation (Kiehl and Shields, 2005). A long-term decrease in atmospheric oxygen levels, to the lowest values of the Phanerozoic, would also have significantly reduced the quantity of dissolved oxygen in the oceans (Weidlich et al., 2003). Increased nutrient utilization also would have contributed to anoxia; however, a larger marine nutrient inventory is required to form the quantities of hydrogen sulfide thought necessary to cause the mass extinction (Hotinski et al., 2001). Once sulfide concentrations reached a threshold value, the chemocline would have abruptly risen to the surface, killing marine life and emitting a huge flux of H 2 S to the atmosphere that would decimate a large proportion of terrestrial life, destroy the ozone layer, and contribute to elevated methane levels (Kump et al., 2005). Development of marine anoxia may have been exacerbated by global warming due to massive CO 2 release from the Siberian traps (Marenco et al., 2005), possibly triggering formation of oxygen-poor saline bottom waters in tropical latitudes (Kidder and Worsley, 2004). The Siberian Traps large igneous province was one of the most voluminous of the Phanerozoic, with an estimated volume of at least 3-4 million km 3 (Reichow et al., 2002) or significantly more if lavas in other nearby basins were continuations of the province (Racki and Wignall, 2005). Ar-Ar 25 isotopic dating of the Siberian Traps has demonstrated that they were synchronous with the end-Permian extinction, with the bulk of the volume erupting around 251 Ma (Renne et al., 1995; Racki and Wignall, 2005). The immense volcanic eruptions would have had extensive climatic effects, including both short-term cooling due to sulfate aerosols and significant long-term global warming from substantial CO 2 release (Renne et al., 1995). The large volume of depleted CO 2 released from the mantle by the Siberian volcanism may also have contributed to the major negative carbon isotope excursion at the boundary (Grard et al., 2005) and increased ocean acidity, creating a “biocalcification crisis” that may have negatively affected skeletonized marine organisms (Fraiser and Bottjer, 2005a). These studies have yielded a general picture of the end-Permian mass extinction, in which decreasing atmospheric oxygen and gradual climate warming contributed to ocean stratification and deep-water euxinia through the Late Permian, ultimately culminating in photic zone euxinia during the extinction interval. This environmental crisis was compounded by eruption of the Siberian Traps igneous province, which contributed immense amounts of carbon dioxide to the atmosphere, causing global warming, increased ocean acidity, and potentially releasing methane from clathrates. In that respect, no single cause (either solely hypercapnia or hydrogen sulfide) is sufficient to explain the extinction severity and length of recovery; rather, the combined environmental deterioration in ocean and atmosphere systems was responsible for the extraordinary magnitude of the extinction event. Many of the causes also appear broadly similar to those of the end-Guadalupian 26 extinction (discussed in more detail below), also implying that the two crises may have had similar biotic effects. Brachiopod and Bivalve Physiology Although the Permian-Triassic extinction was clearly responsible for the taxonomic shift between the Paleozoic and Modern Faunas, many workers have also considered the physiological tolerances of bivalves and rhynchonelliform brachiopods as a means of explaining the Permian-Triassic transition between the two groups. Both groups have superficial similarities in their bivalved anatomy where the soft tissues are contained within two shells articulated by a hinge and ligament structure. However, there are considerable differences in the soft tissue anatomy of these two clades that have important implications for their physiology and environmental tolerances. It was hypothesized that these physiological differences may have resulted in differing feeding efficiency and food requirements, turbidity tolerance, respiration mechanism, predation susceptibility, and/or substrate adaptations and may have accounted for the contrasting trajectories of bivalves and brachiopods during the Permian-Triassic interval, especially if bivalves were superior competitors. One of the most important anatomical differences is found in the organs used for feeding and respiration in these two groups. Rhynchonelliform brachiopods feed and respire using a complex, cilia-bearing lophophore whereas bivalves have an elaborate gill for the same purposes (Fig. 1.9). The open, ciliate structure of the 27 lophophore, compared to the closed, lamellar structure of many bivalve gills, allows rhynchonelliform brachiopods to be better adapted for feeding and respiration in high-turbidity environments (Steele-Petrovic, 1975; Thayer, 1986a). Although brachiopods and bivalves feed on similar suspended material (Suchanek and Levinton, 1974), such as bacteria, colloids, algae, and even dissolved organic material (Steele-Petrovic, 1976), brachiopods have a lower metabolic rate and, as a result, they are able to thrive at lower food concentrations than bivalves (Rhodes and Thompson, 1993) and have significantly lower oxygen requirements than similarly- sized bivalves (Thayer, 1986b; Rhodes and Thayer, 1991). In addition, the filtering ability of modern brachiopods seems to be hindered when food density was elevated, whereas bivalves suffered no decrease in filtering efficiency (Rhodes and Thompson, 1993). The ability of brachiopods to survive at low food concentrations is not necessarily a benefit under high nutrient levels, which are able to support the “wasteful” metabolism of bivalves and potentially also hinder the feeding of brachiopods (Thayer, 1986a). The Permo-Carboniferous increase in nutrient levels, to more mesotrophic conditions from Cambrian-Devonian “super-oligotrophy” (Martin, 1996), may therefore have helped favor bivalves over the more austere brachiopods and driven a moderate expansion of Modern Fauna organisms before the end-Permian extinction. Brachiopods tend to have lower biomass than the comparatively fleshy bivalves because of their lower metabolic rates; as a result, modern brachiopods are 28 Figure 1.9. Anatomy of example rhynchonelliform brachiopod lophophore and bivalve gill. Brachiopod illustration from Grant (1995). 29 generally unappealing prey items (Thayer, 1985). Modern rhynchonelliform brachiopods also have chemical defenses that make them repellent to most predators, although it is not clear that Paleozoic genera necessarily had similar defenses (Thayer, 1985). Although overall rates of drilling predation were still lower than values reported from late Mesozoic and Cenozoic fossil assemblages, surveys of drilled Permian shells confirm that bivalves (7.4% drilled) were attacked much more frequently than rhynchonelliform brachiopods (1.1% drilled) (Hoffmeister et al., 2004). Another fundamental difference between rhynchonelliform brachiopods and bivalves is their method of attaching to the substrate. Many late Paleozoic brachiopods and some bivalves were adapted for living freely (reclining) or semi- infaunally on soft substrates and others were able to cement to hard substrates; however, the primary method of hard substrate attachment among rhynchonelliform brachiopods was with a fleshy pedicle while most epifaunal bivalves utilized a network of byssal threads. Experimental trials have shown that modern pedically- attached brachiopods are routinely displaced by byssally-attached bivalves in competition for space and attachment sites because bivalves are able to detach and reattach their byssal threads whereas brachiopods are unable to reattach once dislodged (Thayer, 1985). The significant increase in infaunal tiering depth during the Carboniferous and Permian (Bottjer and Ausich, 1986), possibly indicating an increase in biogenic reworking rates, may also have adversely affected the rhynchonelliform brachiopods before the end-Permian mass extinction. Many of the 30 most widespread and abundant Permian brachiopods were specialized for sessile life on soft substrates (exemplified by many productids); however, the diversification of mobile infauna could have disrupted this strategy by extensively reworking and disturbing the sediment (Thayer, 1979). The reduction of soft-substrate lifestyles would have increased competition between pedically-attached brachiopods and byssally-attached bivalves for limited hard substrata, favoring the bivalves which tended to be superior competitors for attachment space (Thayer, 1979, 1985). The resulting pressure on soft-substrate specialists may ultimately have caused their decline, with bivalves, especially the infaunal groups that were largely responsible for the increases in bioturbation, expanding to occupy a more prominent role in Late Permian communities. These physiological traits seem to suggest that brachiopods, which are metabolically efficient organisms that can survive lower oxygen and food levels than bivalves, should be superior competitors. Most discussion has concentrated on why the taxonomic selectivity during the Permian-Triassic interval, which significantly favored bivalves over brachiopods, should contradict these expected trends (Steele- Petrovic, 1979; Thayer, 1985, 1986a; Knoll et al., 1996), neglecting the potential consequences that physiological differences might have during non-extinction time. As taxonomic selectivity during extinction is not necessarily linked to the traits that confer a competitive advantage in non-extinction time (Jablonski, 1989), the interaction of brachiopod and bivalve physical characteristics with secular 31 environmental trends described above (nutrient levels, substrate consistency) may have affected the competitive balance between the two groups. Objectives The primary goal of this project is to assess Permian benthic paleoecology in order to determine if the ecological transition between the Paleozoic and Modern Faunas was synchronous with the Permian-Triassic extinction and taxonomic switch. If the bulk of ecological and taxonomic changes were indeed synchronous, this work will test if there were precursor signs to the Permian-Triassic abrupt shift between the brachiopod-dominated Paleozoic Fauna and mollusc-dominated Modern Fauna. Initial stages of the ecological replacement may have been favored by long-term environmental trends in the late Paleozoic or triggered by the effects of the end- Guadalupian extinction. However, no studies have examined Late Permian paleoecology; as a result, it is not known what ecological impact the end- Guadalupian extinction had or whether there were any ecological changes prior to the end-Permian extinction. This project addresses Late Permian ecological change and the potential importance of the end-Guadalupian based on two lines of evidence. First, quantitative counts of relative abundance in benthic marine fossil assemblages will be used to document paleoecological changes during the Permian, and especially the Late Permian. This study will provide the first quantitative fossil assemblage data from the Late Permian and supplement the sparse Middle Permian data reported in 32 the literature. Initial stages of the paleoecological transition from brachiopods to bivalves, if occurring before the end-Permian extinction, will be demonstrated by changes in the relative abundance, size distributions, or life habits of those groups. Second, the taxonomic severity, selectivity, and geographic distribution of the end- Guadalupian extinction will be assessed using a new diversity compilation of Middle and Late Permian marine invertebrates. Estimates of paleogeographic variations in extinction intensity will help constrain the causes of the end-Guadalupian crisis for comparison with the better understood end-Permian extinction. A revised estimate of extinction severity and selectivity will allow comparison of the timing and magnitude of the ecological change with the taxonomic changes at the end-Guadalupian extinction, with possible implications for the decoupling of taxonomic and ecological responses. Finally, the taxonomic and ecological data will be integrated to assess the relative impact of gradual late Paleozoic environmental change, the end-Guadalupian crisis, and the end-Permian mass extinction, on the initial stages of the ecological transition from the Paleozoic to Modern Evolutionary Faunas. 33 CHAPTER II: PERMIAN ECOLOGICAL CHANGES The transition from benthic marine communities with diverse rhynchonelliform brachiopods to mollusc-rich assemblages was one of the two fundamental shifts in taxonomic composition during the Phanerozoic, recognized by Sepkoski (1981) as the switch from the Paleozoic Evolutionary Fauna to the Modern Evolutionary Fauna. The timing and magnitude of the shift in diversity has been tightly constrained by global biodiversity compilations (e.g., Gould and Calloway, 1980; Sepkoski, 1981; Sepkoski, 1996). Rhynchonelliform brachiopods were significantly more diverse than bivalves until the latest Permian but, beginning in the earliest Triassic immediately after the end-Permian mass extinction, bivalves became the most diverse group (Sepkoski, 1996). The abrupt timing and extreme magnitude of the taxonomic shift resulted in the assumption that the diversity data could be directly equated with changes in ecological structure, despite later recognition in other groups that taxonomic and ecological responses may be decoupled (e.g., McKinney et al., 1998). Investigation of changes in relative abundance during the Permian will be able to assess shifts the ecological structure and test whether the ecological and taxonomic transitions were in fact synchronous. In addition, a better understanding of Late Permian ecology will help elucidate the details of the Paleozoic Fauna-Modern Fauna replacement and differentiate between hypotheses arguing for competitive causes (Sepkoski, 1996) or extinction-driven causes (Gould and Calloway, 1980) for this fundamental change in marine paleoecology. 34 Previous Work Most studies have quantified the taxonomic switch between the Paleozoic and Modern Faunas and assumed that the ecological transition was synchronous (e.g., Gould and Calloway, 1980). There is sparse paleoecological data, primarily from the Early Triassic but also from the Early and Middle Permian, that constrains the timing of the ecological transition. Several paleoecological studies have shown that marine communities during the Early Triassic aftermath of the end-Permian mass extinction were strongly dominated by bivalves and gastropods (Schubert and Bottjer, 1995; Boyer et al., 2004; Fraiser and Bottjer, 2004; Fraiser and Bottjer, 2005b). The Early Triassic recovery interval, lasting about 5 million years from the end-Permian extinction (252.6 Ma) to the Middle Triassic (247.5 Ma), was a protracted interval of severe ecological deterioration (Fig. 2.1). The degree of bioturbation intensity was significantly reduced, especially during the Griesbachian and Dienerian, and the epifaunal and infaunal tiering structure was essentially eliminated during the extinction. Although benthic communities began to recovery in the latter half of the Early Triassic (Spathian), it was not until the Anisian (Middle Triassic) that bioturbation and tiering fully recovered. Griesbachian paleocommunities were dominated by the linguliform brachiopod Lingularia and bivalves such as Eumorphotis (Rodland and Bottjer, 2001; Boyer et al., 2004; Fraiser and Bottjer, 2005b); rhynchonelliform brachiopods were locally present but usually rare in the Griesbachian, primarily representing Permian survivor genera such as Orbicoelia and Prelissorhynchia, and Mesozoic progenitors 35 such as Meishanorhynchia (Chen et al., 2002; Twitchett et al., 2004; Chen et al., 2005c, 2005b). The average abundance of rhynchonelliform brachiopods in nine Griesbachian samples (each with at least 100 specimens) collected by Fraiser and Bottjer (2005b) from the western United States was 9.5% (Fig. 2.1). In one of those samples, three genera (Orbicoelia, a terebratulid, and a spiriferinid) comprised 84% of the assemblage. Tiny microgastropods and bivalves were also numerically dominant, typically comprising 90-100% of many fossil assemblages, through the Dienerian-Smithian interval (Boyer et al., 2004; Fraiser and Bottjer, 2004). Groups such as rhynchonelliform brachiopods and crinoids (not including survivor taxa) only became more abundant and widespread by the later Early Triassic (Spathian) (Schubert and Bottjer, 1995; Fraiser and Bottjer, 2005b). Rhynchonelliform brachiopods were recorded in five of 18 bulk samples from the Spathian Virgin Limestone and Thaynes Formation in the western United States (Schubert and Bottjer, 1995), but only had an average abundance of 3% in eight of those samples containing at least 100 specimens. Rhynchonelliform brachiopods had fully recovered by the Middle and Late Triassic, comprising about 33% of the average fossil assemblage (Fig. 2.1). In contrast, Permian benthic paleoecology, and especially Late Permian community ecology, has received much less study. Sepkoski and Miller (1985) reconstructed onshore-offshore community trends during the Paleozoic based on North American fossil assemblages, but used taxonomic proxies instead of abundance data. Some of the data used for their onshore-offshore compilation was derived from 36 Figure 2.1. Ecological changes during the Permian-Triassic transition, emphasizing the Early Triassic recovery interval. Alpha diversity, the identity of the most diverse groups, relative abundance data derived from literature sources, bioturbation intensity, and epifaunal and infaunal tiering structures are shown for the Guadalupian (Middle Permian) to Middle Triassic. The question mark indicates that no quantitative ecological data has been collected from the Late Permian. Modified from Fraiser and Bottjer (2005b). 37 quantitative community studies but only three collections (with presence-absence data only) were Late Permian in age, and were derived from nearshore environments (Walter, 1953). There are some quantitative community data for Early Permian assemblages from western North America, also primarily derived from nearshore and inner shelf environments (Mayou, 1967; Yancey and Stevens, 1981), as well as a few semi-quantitative studies (Terrell, 1972; Mills and Langenheim, 1987). Molluscs were moderately abundant in the more onshore settings represented by the quantitative studies, as expected based on previously documented onshore-offshore trends (Sepkoski and Miller, 1985), but the community structure of offshore carbonates is poorly known. The only Middle Permian quantitative data are derived from Wordian and Capitanian assemblages from siliciclastic sediments in the Bowen Basin, Australia (Waterhouse, 1987). Seven of the fossil collections made by Waterhouse (1987) contain at least 100 specimens, and are numerically dominated by rhynchonelliform brachiopods (average abundance of 79.5%) with subordinate bivalves (16.9%) and gastropods (3.6%). However, the bulk of the relative abundance data reported from the Middle or Late Permian consists of brachiopod-only faunal lists, excluding all other taxa or reporting only their presence/absence (e.g., Waterhouse and Piyasin, 1970; Grant, 1976; Waterhouse, 1978; Chen et al., 2005a). Semi-quantitative data from west Texas are consistent with the patterns documented in Australia and imply that brachiopods remained extremely dominant in most environments, and particularly in offshore carbonate settings, through the Middle Permian (Cooper and 38 Grant, 1977). However, the lack of numerical data from Late Permian assemblages only allows the timing of the ecological change to be constrained between the Middle Permian (Capitanian) and Early Triassic (Griesbachian). Methods I collected quantitative community data from Permian fossil assemblages, focusing on the Middle and Late Permian in both Tethys and Panthalassa (Fig. 2.2), in order to constrain the timing of the ecological transition from Paleozoic Fauna dominance to Modern Fauna dominance. Fossil assemblages were collected only from tropical, level-bottom carbonate platform or ramp environments in order to minimize potential confounding effects from lithological differences or latitudinal variations in community structure. Early and Middle Permian samples (Fig. 2.3) were collected from the Sakmarian-Artinskian Bird Spring Formation in southern Nevada (Rich, 1961; Langenheim et al., 1962; Heath et al., 1967; Langenheim et al., 1977), the Artinskian-Kungurian Pequop and Loray Formations (Bissell, 1962, 1964), and the Capitanian Gerster Formation in northeastern Nevada (Wardlaw, 1977; Wardlaw and Collinson, 1978, 1979; Henderson and Mei, 2000). Additional Early and Middle Permian samples from the Artinskian Taylor Ranch Member of the Hess Formation and the Wordian upper Word Formation in west Texas (Cooper and Grant, 1972; Rogers, 1972; Rathjen et al., 2000), were studied at the Smithsonian Museum. Late Permian samples (Fig. 2.3) were collected from the Wuchiapingian- Changhsingian Heshan Formation at Heshan, Guangxi Province, south China 39 Figure 2.2. Location map showing the paleogeographic position of sampling localities. Inset maps show present-day geographic locations of bulk samples. 40 Figure 2.3. Stratigraphic age distribution of the formations from which bulk fossil samples were collected. 41 (Jin and Li, 1987; Zhang and Shao, 1990; Mei et al., 1999; Shao et al., 2003) and from the late Wuchiapingian or Changhsingian Episkopi Formation on the island of Hydra, Greece (Grant et al., 1991; Jenny et al., 2004). The environmental context of the sampled fossil assemblages was assessed from measured stratigraphic sections and thin section analysis, using lithology, bedding style (such as nodular or massive limestones), the presence of allochems like ooids or intraclasts, sedimentary fabrics (e.g., bioclast fragmentation and packing), sedimentary structures such as cross-stratification, and diagnostic stratal boundaries such as karst surfaces. Samples were placed in nearshore (peritidal, lagoonal, or shoreface settings), inner shelf (above fair weather wave base), middle shelf (below fair weather wave base), and outer shelf (below storm wave base) environments based on these criteria (Fig. 2.4). Bulk samples were collected from taphonomically screened shell beds (Fürsich, 1978; Kidwell, 1985; Kidwell et al., 1986; Kidwell and Holland, 1991; Fürsich, 1995) in order to minimize and control the effects of time averaging and spatial mixing. All samples were collected in situ from the outcrop, except sample LE(float), from the Lehusis section (Hydra). Sample LE(float) was a single isolated block collected from loose material, but can be constrained to the narrow stratigraphic interval containing silicified fossils at that locality (Grant et al., 1991), with relatively unchanging paleoenvironmental conditions (Jenny et al., 2004). Only thin (<20 cm) wackestone (or floatstone) beds were used for sampling. Thicker beds 42 Figure 2.4. Physical sedimentological guidelines used to subdivide the shelf into nearshore, inner shelf, middle shelf, and outer shelf domains. FWWB = Fair Weather Wave Base; SWB = Storm Wave Base; Lith. = Lithology. 43 may represent amalgamations of several successive storm deposits and denser skeletal fabrics (such as packstones and especially grainstones) may have suffered from winnowing or size-sorting. Beds that contained lenticular shell accumulations or discontinuous pods, or displayed conspicuous size-sorting or grading may also have suffered from greater taphonomic overprint and were not sampled. Only those shell accumulations containing sparsely packed and mostly unbroken fossils representing a wide range of size classes and evenly distributed both laterally and vertically within the bed were sampled for this study. In some cases only a single, large bulk sample was obtained but several replicate samples were ideally collected as the outcrop and fossil distribution allowed (Bennington, 2003). Fossil assemblages were collected entirely from beds with completely silicified skeletal material. Silica-replaced fossils were etched from the limestone matrix using hydrochloric acid (3 M concentration). The size of etched blocks varied from approximately 1 kg to 15 kg depending on the size and density of bioclasts. Silicification has several benefits, most notably that silicified fossils are easily extracted from the limestone matrix and are often preserved with great fidelity. In addition, early diagenetic replacement by silica appears to result in better preservation of originally aragonitic components of the biota, such as gastropods and some bivalves (Cherns and Wright, 2000). Differential silicification due to variations in shell mineralogy and microstructure, depositional environment, and other factors may bias fossil abundance in the preserved fossil assemblage (Boyd and Newell, 1972; Erwin and Kidder, 2000), but the taphonomic bias with respect to brachiopod 44 and mollusc abundance will likely be less significant than in non-silicified assemblages (Cherns and Wright, 2000) and, most importantly, should have largely similar effects in all of the offshore carbonate assemblages studied. All fossils appear to be well-silicified, based on examination of thin sections prepared from each sampled bed. No unsilicified fossils were present in any of the thin sections, implying that preservation of brachiopods, bivalves, and gastropods was similar in assemblages from the Early, Middle, and Late Permian (although bryozoan silicification varied considerably). In addition, preservation quality was exceptionally good in most of the samples, and especially in Middle Permian samples from Nevada, where microscopic details such as echinoderm stereom and brachiopod punctae were preserved with great fidelity. All complete fossils, as well as brachiopod and bivalve fragments containing the umbo region and gastropod fragments containing the apex, were picked from the residue. Sample size in the field collections varied from 125 to 1059 individuals, with most samples containing 250-400 individuals. Smithsonian collections examined contained between 202 and 25947 individuals. Specimens were identified to genus level where possible, except for crinoids and bryozoans. Specimens were counted, using the “minimum number of individuals” (MNI) method (Gilinsky and Bennington, 1994) for bivalved organisms, which estimates the number of individuals represented in collection based on the total number of articulated specimens plus the most abundant unique valve (left or right for bivalves; dorsal or ventral for rhynchonelliform brachiopods). The number of individual trilobites can 45 similarly be estimated from the maximum number of unique fragments (cephalon, thorax, or pygidium) – although no sample contained more than one trilobite fragment. Polyplacophorans, although uncommon, were counted from the maximum number of head, intermediate, or tail plates. Each sponge, coral, cephalopod, bryozoan fragment (where possible), and echinoid spine or plate was counted as a single individual. It was not possible to count bryozoans in many of the Middle Permian samples because silicification was incomplete and the specimens disintegrated into silica needles during dissolution. Crinoid ossicles were counted using an estimate of 50 ossicles per individual (e.g., Watkins, 1973). The dimensions of complete fossils and large fragments were measured to estimate the relative size of each genus. The height of gastropods was measured from apex to aperture and the diameter measured at the last whorl. Three dimensions (height, length, and width) were measured for rhynchonelliform brachiopods and bivalves. Maximum length and diameter were measured for sponges, rugose corals, nautiloids, and bryozoans. The life habit of each brachiopod, bivalve, and gastropod genus was interpreted based on functional morphology and previously published studies. Rhynchonelliform brachiopods were divided into three categories: pedically- attached epifaunal suspension feeders, reclining epifaunal suspension feeders (e.g., Grant, 1968), and cementing epifaunal suspension feeders. Bivalve functional morphology (e.g., Stanley, 1970) was used to group taxa as byssate epifaunal suspension feeders, cemented epifaunal suspension feeders, infaunal suspension feeders, and infaunal deposit feeders. Modern gastropods exhibit a variety of life 46 habits, including epifaunal and infaunal lifestyles, as well as carnivory, detritus- feeding, and herbivory; however, there are few definitive links between shell form and life habits in fossil taxa (Linsley, 1977, 1978b, 1978a; Signor, 1982; Savazzi, 1989, 1994). As a result, most gastropod taxa are here assumed to be mobile epifaunal detritvores/herbivores, with the exception of a few specialized groups that likely were immobile, reclining suspension-feeders (Linsley et al., 1978). The mean abundance of taxonomic clades (e.g. rhynchonelliform brachiopods or bivalves) and ecological groupings (e.g., pedically-attached suspension feeders or infaunal deposit feeders) was calculated for each time interval (Early, Middle, and Late Permian). Abundances of rhynchonelliform brachiopods, bivalves, and gastropods were normalized to include only those three groups because of taphonomic bias and difficulties in counting taxa such as bryozoans or crinoids. The mean and maximum size of each genus was also calculated from the dimensions of complete specimens. The statistical significance of temporal changes in the mean abundance of marine clades, ecological groups, and mean specimen size was assessed with either a t-test or its nonparametric equivalent the Mann-Whitney U-test. Permian Community Paleoecology Early Permian Nine fossil assemblages were examined from Early Permian carbonates, including five field samples from Nevada and four Smithsonian museum collections, originally from west Texas. Three samples of probable Sakmarian-Artinskian age 47 were collected from the Bird Spring Formation in the Spring Mountains (NSM), Las Vegas Range (WSN), and Arrow Canyon Range (SACR) of southern Nevada (Fig. 2.2). One sample was collected from the Artinskian Pequop Formation in the Egan Range (CO) and one from the Kungurian Loray Formation in the Butte Mountains of eastern Nevada (BM). The four west Texas samples were collected from the Artinskian Taylor Ranch Member of the Hess Formation in the Glass Mountains (collection numbers USNM702e, 702m, 716n, 716o; Fig. 2.2). The samples span an environmental range from nearshore peritidal (BM), inner shelf (NSM, SACR, CO), to outer shelf (WSN) (see measured stratigraphic sections in Appendix 1). Smithsonian samples from the Taylor Ranch Member likely formed in middle shelf environments (Rogers, 1972), although the depositional setting is more difficult to evaluate from published information. Assemblage BM, collected from peritidal deposits in the Butte Mountains, was overwhelmingly dominated by molluscs (Fig. 2.5 and Appendix 2), as was typical of nearshore communities during much of the Paleozoic (Sepkoski and Miller, 1985). The infaunal deposit-feeding bivalve Nuculavus was the most abundant genus, comprising 63.2% of the census (Fig. 2.6). Abundant gastropods included the euomphalid Amphiscapha (22.7%) and the bellerophontid Euphemites (8.5%). The infaunal suspension-feeding bivalve Schizodus was uncommon (3.8%) and other gastropods (Worthenia, Naticopsis, Orthonema, Meekospira) comprised less than 1% of the assemblage. No brachiopods were found in the sample and a single putative scaphopod (Plagioglypta?) was identified. 48 Figure 2.5. Normalized relative abundance of rhynchonelliform brachiopods, bivalves, and gastropods in onshore (nearshore and inner shelf) assemblages. The relative abundance of the three most abundant brachiopods and bivalves are shown along with the relative proportion of life habits in each group. 49 Inner shelf environments, represented by fossil assemblages CO, NSM, and SACR, contain a mosaic of communities with abundant brachiopods and molluscs. Molluscs are abundant: assemblage CO contains 55.6% gastropods and 6.5% bivalves while assemblage NSM contains 14.8% gastropods and 37.9% bivalves (Fig. 2.5). Assemblage SACR is strongly dominated by gastropods, with 16 genera (dominated by Glyptospira and Anomphalus) comprising 96.9% of the assemblage (Appendix 2). The most abundant gastropods in sample NSM were Amaurotoma and Amphiscapha, while Orthonema, Naticopsis, and Anomphalus were most abundant in sample CO. Extremely large specimens of Omphalotrochus (reaching diameters of 60 mm) were present in assemblage CO. Most brachiopods were pedically-attached (abundant genera include the terebratulid Dielasma, athyridids Composita and Hustedia (Fig. 2.6), and the spiriferid Crurithyris). Bivalves from NSM were mostly epifaunal byssally-attached forms such as the pectinoid Heteropecten (44.6% of bivalves) and the myalinid Septimyalina (39.1% of bivalves) (Fig. 2.6). In contrast, bivalves were dominated by infaunal forms in sample CO, where 90% of the bivalves were infaunal suspension feeders such as Schizodus, Wilkingia?, and Astartella. Bivalves are significantly larger than co-existing brachiopods in both samples CO and NSM (Fig. 2.7). The mean size of bivalves in sample NSM is 14.8 mm, significantly larger (p<0.001) than the 8.6 mm mean size of rhynchonelliform brachiopods. The most abundant bivalves from sample NSM (Heteropecten, maximum 23.7 mm; and Septimyalina, 53.1 mm) also have significantly larger 50 Figure 2.6. Typical fossils from onshore Early Permian fossil assemblages. 51 maximum sizes than the most abundant brachiopods (Dielasma, maximum 12.8 mm; Composita, 18.2 mm; and Hustedia, 11.8 mm). In fact, 50% of the Septimyalina specimens (18 of 36) are larger than the largest brachiopod from that sample. Brachiopods (mean size 4.8 mm) are also significantly smaller (p<0.001) than bivalves (mean size 8.1 mm) in assemblage CO (Fig. 2.7), although the maximum size of brachiopods (Dielasma, 11.3 mm; Crurithyris, 9.6 mm; Martinia, 9.3 mm, Pontisia, 7.3 mm; Schuchertella, 6.7 mm) is only slightly less than that of bivalves (Schizodus, 13.9 mm; Permophorus?, 12.2 mm, Astartella, 5 mm; Aviculopecten, 6.7 mm). Offshore samples, including the outer shelf WSN sample and the middle shelf west Texas samples 702e, 716n, and 716o, are extremely strongly dominated by rhynchonelliform brachiopods (Fig. 2.8). Sample 702m only contains 64 individuals (95.3% brachiopods) so will not be discussed further because of the small sample size, although its composition is similar to the other, better-sampled assemblages. Rhynchonelliform brachiopods have an average abundance of 98.3% (range 96.9%- 99%) in the four offshore samples. Pedically-attached forms such as Rhipidomella or Crurithyris (Fig. 2.9) were more abundant (60.8%) than reclining genera (36.7%) such as Oncosarina, but the difference is not significant (p=0.34) due to the small sample size and high variance. Some assemblages were strongly dominated by pedically-attached brachiopods (89% of WSN and 702e), whereas sample 716n 52 Figure 2.7. Size-frequency histograms for Early Permian onshore rhynchonelliform brachiopods, bivalves, and gastropods 53 Figure 2.8. Relative abundance, life habits, list of abundant genera, and fossil size for Early Permian offshore (middle and outer shelf) assemblages. 54 contained a mixture of pedically-attached and reclining genera (45.5% and 52.8%) and assemblage 716o contained mostly reclining forms (72.7%). Cementing genera (orthotetids and some productids) were generally rare, comprising 0-7.2% (mean 2.5%) of the brachiopod assemblage, significantly less than either pedunculate or reclining forms (p=0.03). Bivalves (1%) and gastropods (0.7%) were both exceedingly rare on average (Fig. 2.8), significantly less abundant than rhynchonelliform brachiopods (p<0.001). There was no significant difference in the abundance of bivalves and gastropods (p=0.49). Assemblage 702e contains 23 bivalves (0.49% of the total), dominated by epifaunal forms (which comprise 82.6% of all bivalves) such as Elversella (47.8%) (Fig. 2.9) and Eocamptonectes (30.4%). In contrast, all three bivalves recorded from 716n were infaunal suspension feeders (Schizodus and Wilkingia?), as were all three from sample WSN (Astartella and an unidentifiable form) (Appendix 2). It appears that byssally-attached epifaunal forms were strongly dominant; however, the small sample size and rarity of bivalves preclude statistical testing of this hypothesis. Common gastropods (see Appendix 2) included Anomphalus (WSN), Tapinotomaria, Apachella, and Euconospira (702e), Omphalotrochus (716n), and Discotropis (716n and 716o). Large sessile genera (Linsley et al., 1978), such as Omphalotrochus and Discotropis (Fig. 2.9) were moderately abundant and common. It is difficult to assess the relative sizes of rhynchonelliform brachiopods and bivalves because of the rarity of bivalves in sample WSN and the lack of quantitative size information in the west Texas samples. The mean brachiopod size in sample 55 Figure 2.9. Typical fossils from offshore Early Permian assemblages. 56 WSN was 6.7 mm, slightly higher than the mean size of 6.0 mm for bivalves from that sample. However, only two bivalves are present in the sample, precluding statistical comparison of the two populations. In summary, Early Permian fossil assemblages displayed the predicted onshore-offshore trend in community composition, from exclusively molluscan nearshore assemblages, through a mosaic of inner shelf assemblages in which molluscs and brachiopods co-dominated, to extremely brachiopod-rich offshore communities (Fig. 2.10). Middle and outer shelf assemblages were composed of 98% rhynchonelliform brachiopods, with bivalves and gastropods each contributing 1% of the total community abundance. Pedically-attached brachiopods were more dominant in inner shelf settings, with offshore environments containing a mixture of reclining and pedunculate groups. In most settings, except nearshore environments, byssally- attached epifaunal suspension feeding bivalves were the most abundant bivalve functional group in these carbonate environments, although some assemblages contained abundant infaunal suspension feeders. Bivalves were much larger than co- existing rhynchonelliform brachiopods in inner shelf environments but were similar in size or may have been smaller in offshore settings. Middle Permian Eleven Middle Permian fossil assemblages were sampled – eight from the Capitanian Gerster Formation of northeastern Nevada (Cherry Creek Range, 57 Figure 2.10. Environmental trends in the mean abundance of rhynchonelliform brachiopods, bivalves, and gastropods in the Early Permian. 58 Medicine Range, and Palomino Ridge; Fig. 2.2) and three from a carbonate lens between the Willis Ranch and Appel Ranch members of the Word Formation, west Texas, of earliest Wordian age (USNM706b, 732c, 737w; Fig. 2.2). All 11 samples are from offshore carbonate environments, primarily represented by middle shelf settings in northeastern Nevada (see measured sections in Appendix 1). The three Word Formation samples were also likely derived from middle shelf settings, or possibly from more distal parts of the inner shelf (Rathjen et al., 2000). Early Permian samples from nearshore and inner shelf assemblages confirmed the molluscan dominance in those settings and the correlation between onshore-offshore diversity and abundance patterns, so no further effort was expended in collecting from those environments in the Middle or Late Permian. In addition, sampling was focused on offshore settings in order to capture biotic changes occurring near the interface of the onshore-offshore transition from the Modern to Paleozoic Evolutionary Faunas (Sepkoski and Miller, 1985). Middle Permian assemblages from offshore carbonate settings had nearly identical community composition to their Early Permian counterparts (Figs. 2.11, 2.12). Rhynchonelliform brachiopods were extremely dominant (mean of 99.2%, range of 97.9%-100%), with bivalves (0.57%) and gastropods (0.21%) remaining rare. Large branching bryozoans were qualitatively abundant in nearly all Middle Permian samples from northeastern Nevada but could not be counted because of poor silicification. Five sponge individuals were recorded in sample PR5, and crinoid 59 Figure 2.11. Relative abundance, life habits, dominant genera, and fossil size for Middle Permian offshore assemblages from the Gerster Formation, Nevada. 60 Figure 2.12. Relative abundance, life habits, and dominant genera for Middle Permian offshore assemblages from the Word Formation, Texas. 61 ossicles were abundant in MR2. Bryozoans, especially fenestrate bryozoans, and crinoids were common in all west Texas assemblages and rugose corals were occasionally present. Dominant brachiopod genera from northeastern Nevada include the productids Yakovlevia, Dyoros, and Echinauris, the spiriferinid Xestotrema, the athyridid Composita, and the terebratulid Hemiptychina (Fig. 2.13; faunal lists in Appendix 2). Dyoros and Echinauris were also abundant in west Texas samples, as was the spiriferid Spiriferella, the athyridid Hustedia, and the productids Heteralosia, Cyclacantharia, Paucispinifera, and Rhamnaria (Fig. 2.14). Pedically- attached forms tended to be more abundant in northeastern Nevada, often comprising 80-90% of the brachiopod populations (although only 33.2% at CCR, 39.6% at MR1, and 56.5% at PR5). Reclining productids were more common in west Texas samples, accounting for 69.9% of 737w and 73.5% of 732c. Cementing forms such as the productids Heteralosia, Cyclacantharia, and Collemataria as well as orthotetids were common, comprising 9.5% to 29.5% of the brachiopod population. Bivalve populations in these offshore carbonate communities were strongly dominated by byssally-attached epifaunal pectinoids (Figs. 2.11, 2.12). Most samples from northwest Nevada contain no more than a single bivalve individual, almost always Aviculopecten (Fig. 2.13); Streblopteria is also present in sample CCR and Streblochondria? is also found in sample PR6. Pectinoids are also the dominant bivalve group in west Texas samples. Sample 732c contains Guizhoupecten (8 individuals) and Cyrtorostra (1 individual) (Fig. 2.14). Cyrtorostra is also abundant 62 Figure 2.13. Typical fossils from Middle Permian assemblages from the Gerster Formation, Nevada. 63 Figure 2.14. Typical fossils from Middle Permian assemblages from the Word Formation, Texas 64 in sample 706b, accounting for 35% of the 77 bivalve individuals; other abundant genera include Leptodesma (9.1%) and Procostatoria (7.8%) (see Appendix 2). The epifaunal cementing genus Prospondylus is also common, comprising 6.5% of the bivalve population. The most abundant infaunal suspension-feeding bivalves in 706b are Astartella (5.2%), Schizodus (3.8%), and Permophorus (3.8%). Only a single infaunal deposit-feeding individual of Nuculavus (1.3% of the bivalve population) was found in the assemblage. No gastropods were found among the 3000 individuals counted in this study from northeastern Nevada localities and from sample 732c. Similarly, no gastropods were reported by Wardlaw (1977) from 201 fossil collections from the GersterFormation in northeastern Nevada and northwestern Utah. Sample 737w contains only a single specimen (0.5% of the sample) of the large sessile genus Babylonites (Fig. 2.14). More gastropods occur in sample 706b, which contains 483 individuals (1.9% of the total assemblage), of which 72% were Platyceras, which has been interpreted to have a parasitic lifestyle on crinoids (Rollins and Brezinski, 1988). Babylonites and the motile genera Peruvispira, Tapinotomaria?, and Apachella were also moderately common gastropods in sample 706b (faunal lists in Appendix 2). Estimation of the relative sizes of rhynchonelliform brachiopods and bivalves is hindered by the small number of bivalves in samples from northeastern Nevada (never more than two individuals). In addition, bivalve specimens are frequently fragmented, making estimation of their full size difficult. However, in most samples 65 from northeastern Nevada the rhynchonelliform brachiopods appear to be approximately the same size as, or possibly slightly larger than, co-existing bivalves. In summary, Middle Permian offshore carbonate communities, like their Early Permian counterparts, were extremely strongly dominated by rhynchonelliform brachiopods. Pedically-attached and reclining brachiopods were approximately equally common, with some assemblages strongly dominated by pedunculate forms and others by recliners. Cementing brachiopods were rare (mean abundance of only 6.4%). Infaunal suspension-feeding bivalves appear to have been rare, not occurring in any northeastern Nevada sample and only comprising 21% of the well-sampled bivalve population from sample 706b. Although the data are sparse, rhynchonelliform brachiopods may have been slightly larger than bivalves from the same communities. Late Permian Twelve Late Permian fossil assemblages were collected from offshore carbonates in south China and Greece, including six samples from the late Wuchiapingian-Changhsingian Episkopi Formation (Nestell and Wardlaw, 1987), exposed on the island of Hydra, Greece (Fig. 2.2), and six samples from the mid- Wuchiapingian to early Changhsingian Heshan Formation (Mei et al., 1999) in Heshan, Guangxi Province, south China (Fig. 2.2). Sedimentological evidence implies deposition in middle to outer shelf environments, with the samples from Hydra formed in slightly shallower settings on average (see Appendix 1). Two of the 66 samples (EP and MA2) were collected from more reefal settings; sample EP (Hydra) was derived from a small bioherm constructed by siliceous demosponges, whereas sample MA2 (Heshan) was collected from an algal-hydrozoan thicket or biostrome. The Late Permian samples from offshore carbonate environments in both Heshan and Hydra contain a mixed assemblage of rhynchonelliform brachiopods, bivalves, and gastropods (Figs. 2.15, 2.16). Gastropods are the most abundant clade, comprising 47.5% of an average assemblage. Rhynchonelliform brachiopod abundance is only 34.6% and bivalves comprise 17.9% of the typical sample. Brachiopods range in abundance from 1.2% (sample LE3) to 84.1% in the biohermal sample EP. Assemblage EP contains the fewest gastropods (only 2.7%) whereas gastropod abundance is 88.6% in sample LE4. Bivalves comprise as much as 34.7% (ET-B) and as little as 0.6% in the algal-hydrozoan thicket in sample MA2. Among other clades, bryozoans are extremely rare – represented only by a few tiny individuals in some samples. Orthocone nautiloids occur frequently and sponges, crinoids (especially at Heshan), and echinoid spines (at Heshan) are common accessory groups (see Appendix 2 for complete faunal lists). “Spirorbis” was the most abundant genus in sample LE(float), which also contained common rugose corals. Abundant rhynchonelliform brachiopod genera from the Heshan samples include Spinomarginifera, Streptorhynchus, Araxathyris, and Crurithyris in level- bottom settings (Fig. 2.17) and Notothyris, Crenispirifer, and Dielasma in sample 67 Figure 2.15. Relative abundance, life habits, and dominant genera in Late Permian samples from Hydra, Greece. 68 Figure 2.16. Relative abundance, life habits, and dominant genera in Late Permian samples from Heshan, China. 69 MA2. Non-reefal samples from Hydra contain a different set of dominant brachiopods, including Transennatia, Waagenites, Orthotichia, and Crurithyris (Fig. 2.18). Sample EP, derived from a small sponge bioherm, contains an extremely diverse brachiopod population with abundant Crurithyris, Crenispirifer, Schuchertella, “Tautosia,” Uncinunellina, Martinia, and Transcaucasathyris. Pedically-attached and reclining genera have approximately equivalent average abundance (43.6% and 36.7%, respectively) (Figs. 2.15, 2.16). Cementing genera (primarily orthotetids such as Streptorhynchus, Perigeyerella, Derbyia, and Schuchertella), account for 15.9% of the average brachiopod assemblage. Cementing forms are more common in samples from China, accounting for a maximum of 33% in assemblage MA3 and 27.8% in MA1 and MA3a. Byssally-attached epifaunal taxa are the most abundant group of bivalves in the Late Permian samples, accounting for 52.4% of the bivalve assemblage, with infaunal suspension-feeding bivalves comprising 42.9% of an average sample. Infaunal deposit-feeding (3.2%) and cementing (1.5%) bivalves are both rare. The most abundant bivalve in samples from Hydra is the shallow infaunal suspension- feeder Astartella, with epifaunal pterioid Leptodesma and arcoid Grammatodon also abundant (Fig. 2.17). Byssally-attached epifaunal Ensipteria and Promytilus, and infaunal Stutchburia and Gujocardita, were the dominant bivalve genera in samples 70 Figure 2.17. Typical fossils from the Episkopi Formation, Hydra. 71 Figure 2.18. Typical fossils from the Heshan Formation, Heshan. 72 from Heshan (Fig. 2.18). Infaunal deposit-feeding genera such as Phestia, Palaeoneilo, and Nuculopsis are abundant only in sample LE(float) whereas cementing genera (Pegmavalvula and “Lopha”) are uncommon in sample EP and rare in ET-B. Gastropods are extremely diverse and abundant in samples from both Hydra and Heshan. At least 39 genera were recovered from silicified residues from Hydra and Heshan (see Appendix 2). Some of the more abundant and widespread gastropod genera are Ananias, Palaeostylus, Manzanospira, Donaldina, Orthonema, and bellerophontids such as Bellerophon or Retispira (Figs. 2.17, 2.18). Nearly all gastropods are interpreted as motile detritivores based on their shell morphology (mostly moderate- to high-spired cones along with planispiral bellerophontids). Sessile genera that were common in the Early and Middle Permian, such as Amphiscapha, Discotropis, Babylonites, or Omphalotrochus (Linsley et al., 1978), are very rare in the Late Permian samples, with only Porcellia represented in sample MA2. A large proportion of the gastropod individuals (97%) and genera (66.7%) recovered are microgastropods (less than 1 cm height, cf. Fraiser and Bottjer, 2004); the mean gastropod size (of those specimens 2.5 mm or larger) is a tiny 4.6 mm (Fig. 2.19). The largest gastropod (of 1318 individuals) in the samples is 23.4 mm in height. Size measurements from the Late Permian fossil assemblages show that rhynchonelliform brachiopods are slightly, but significantly larger, than bivalves (mean size 10.44 mm vs. 9.58 mm; p=0.003) (Fig. 2.20), and that both groups are 73 Figure 2.19. Size-frequency distributions of gastropods in Early Permian, Late Permian, and Early Triassic assemblages. Early Triassic data is from Fraiser & Bottjer (2004). 74 Figure 2.20. Size-frequency distributions of rhynchonelliform brachiopods and bivalves in Middle and Late Permian fossil assemblages. 75 much larger than gastropods. Late Permian brachiopods were also significantly larger than their Middle Permian counterparts (Fig. 2.20). Four samples did not have sufficient numbers of either brachiopods or bivalves for size comparison, but the other samples (Fig. 2.21) were evenly divided between those in which brachiopods were significantly larger than bivalves (three samples), those in which bivalves were significantly larger (three samples), and those where there was no significant difference (two samples). In sample EP, the mean size of bivalves was 19.2 mm, significantly larger than brachiopods (12.2 mm, p=0.04). Bivalves were also larger than brachiopods in sample MA1 (15.5 mm vs. 10.2 mm; p=0.003) and MA3 (12.2 mm vs. 9.2 mm; p=0.03). Rhynchonelliform brachiopods were larger in sample LE1 (9.5 mm vs. 5.2 mm; p=0.001), the LE(float) assemblage (7.1 mm vs. 5.7 mm; p<0.001), and sample ET-B (14.7 mm vs. 10.4 mm; p<0.001). There was no statistical size difference in samples MA3a and ET-C. To summarize, Late Permian communities contain both abundant rhynchonelliform brachiopods and molluscs. Gastropods are the most abundant group in the samples but are extremely small. Brachiopods are evenly divided between pedunculate and reclining forms, with moderately abundant cementing taxa. Bysally-attached epifaunal bivalves are slightly more abundant than infaunal suspension-feeding forms, but both together comprise 95.3% of all bivalves. Rhynchonelliform brachiopods are, on average, only 9% larger than bivalves during the Late Permian. However, individual assemblages are evenly divided between those where brachiopods were larger and those where bivalves were larger. 76 Figure 2.21. Size-frequency distributions for rhynchonelliform brachiopods and bivalves in Late Permian samples. Mean size of each group is shown for each assemblage and statistical significance indicated when sample size is sufficient. 77 Quantifying Paleocommunity Change Changes in the ecological structure of Permian communities include (1) changes in the relative abundance of higher taxa such as rhynchonelliform brachiopods and bivalves, (2) shifts in the proportion of life habits represented, and (3) changes in the average size of fossil groups. Comparison of relative abundance and the abundance of brachiopod life habits imply that there were no significant ecological changes between the Early and Middle Permian in the offshore carbonate samples (Fig. 2.22). Rhynchonelliform brachiopod relative abundance increased slightly from 98.3% to 99.2% (not significant, p=0.053), bivalves decreased in abundance from 1.0% to 0.6% (not significant, p=0.22), and gastropods declined from 0.7% to 0.2% (not significant, p=0.11). There was also no change in the relative frequency of brachiopod life habits. Pedically-attached forms decreased from 60.8% to 56.4% (p=0.80) while reclining genera were essentially unchanged (36.7% to 37.1%; p=0.98). Cementing genera increased slightly, but not significantly, from 2.5% to 6.4% (p=0.42). In contrast, there were highly significant changes in relative abundance, life habits, and size distributions between the Middle Permian samples and Late Permian assemblages (Fig. 2.22). Rhynchonelliform brachiopods were considerably less abundant (34.6% vs. 99.2%; p<0.001), while bivalves (17.9% vs. 0.6%; p<0.001) and gastropods (47.5% vs. 0.2%; p<0.001) were significantly more abundant in the Late Permian. There was also a significant change in the abundance of brachiopod life habits, with cemented groups increasing from 6.4% in the Middle Permian to 15.9% 78 Figure 2.22. Summary showing the mean relative abundance and life habits in Early, Middle, and Late Permian assemblages. 79 of brachiopods in the Late Permian (p=0.03). This increase was offset by a slight, but not significant, decline in the abundance of pedunculate taxa (56.4% to 47.4%; p=0.55). There was no change in the abundance of reclining forms (37.1% to 36.7%; p=0.97). Bivalves underwent a major shift in the proportion of life habits represented in offshore carbonate communities in addition to their 30-fold increase in relative abundance. Infaunal suspension-feeding forms greatly increased in abundance from 2.3% of the bivalve population to 42.9% in the Late Permian (p=0.002) at the expense of byssally-attached epifaunal genera, which declined from 96.2% to 52.4% (p<0.001). There was no significant change in the abundance of infaunal deposit feeders (0.1% to 3.2%; p=0.49). Late Permian brachiopods were significantly larger than their Middle Permian counterparts (10.4 mm average size vs. 9.1 mm; p<0.001) and were larger on average than Late Permian bivalves (10.4 mm vs. 9.6 mm; p=0.003) (Fig. 2.20). Brachiopods were significantly larger than co-existing bivalves in three Late Permian assemblages, but bivalves were the larger group in three other samples, suggesting that the size difference between the two clades was not great in the Late Permian. However, it is not clear whether the size disparity between rhynchonelliform brachiopods and bivalves changed from the Middle Permian to the Late Permian. Changes in relative abundance and life habits were documented from Late Permian localities in both China (eastern Tethys) and Greece (western Tethys), suggesting that they likely represent a global ecological transition. However, as all Guadalupian data were collected from localities in North America (eastern 80 Panthalassa; Fig 2.2) it is possible, although unlikely, that the apparent Guadalupian- Lopingian change instead reflects biogeographic differences in community structure. However, presence/absence data and qualitative assessments of abundance from Guadalupian collections in Tethys and Lopingian assemblages from North America imply that the ecological shift is primarily a true secular change in dominance. Silicified Wordian assemblages from Thailand (possibly derived from inner shelf, not offshore, environments) contain mostly brachiopods, with other groups qualititatively reported to be present in smaller numbers (Grant, 1976). In contrast, Changhsingian assemblages from the Rustler Formation, west Texas (also from inner shelf settings), contain relatively abundant molluscs in addition to brachiopods (Walter, 1953). Quantitative point counts of fossil abundance across the Guadalupian-Lopingian boundary interval at Penglaitan, Guangxi Province, also demonstrate that latest Guadalupian fossil assemblages were overwhelmingly dominated by sponges, crinoids, bryozoans, and brachiopods, with no molluscs found, whereas all early Lopingian bioclasts are gastropods (Fig. 2.23) (Kaiho et al., 2005). These results, although not based on quantitative whole-assemblage counts from offshore environments, strongly imply that at least some component of the ecological change recorded in this study represents a true change in dominance. 81 Figure 2.23. Abundance and taxonomic identity of skeletal fragments in thin sections from the Penglaitan section (Guangxi Province, China). Modified from Kaiho et al. (2005). 82 Implications for the Paleozoic Fauna-Modern Fauna Transition These results document substantial ecological change between the Middle and Late Permian, in the form of an extraordinary increase in the relative abundance of molluscan groups and a significant shift towards dominance of infaunal suspension- feeding bivalves. Molluscs were more abundant than rhynchonelliform brachiopods in offshore carbonate environments during the Late Permian – before the Permian- Triassic mass extinction that was previously assumed to have triggered the ecological replacement (Gould and Calloway, 1980). In addition, infaunal suspension-feeding bivalve groups increased to become as abundant as epifaunal forms in the Late Permian, earlier than has been inferred based on taxonomic measures and prior to the radiation of diverse infaunal siphonate genera (Stanley, 1968). This implies that the ecological transition from the Paleozoic Fauna to the Modern Fauna was not a simple switch at the Permian-Triassic boundary, and that Late Permian communities may have occupied an intermediate stage between the extremely brachiopod-dominated assemblages of the Paleozoic (to the Middle Permian) and post-Paleozoic mollusc- dominated assemblages. All Middle and Late Permian samples were collected from broadly similar environments (middle and outer shelf carbonates) as assessed by field sedimentological criteria (Fig. 2.4), so it is unlikely that the observed change in dominance resulted from lithological or environmental sampling bias towards more mollusc-dominated assemblages in the Late Permian. Lithofacies assessment from thin sections of each fossil sample confirms that Middle and Late Permian samples 83 are all wackestones to packstones, with large fossil fragments in a fine-grained matrix, and all contain approximately similar proportions of terrigenous detritus (mud, silt, or sand). Middle Permian samples tend to contain more skeletal material, both in terms of large fossil fragments and small matrix fragments, than Late Permian assemblages. The matrix is more often a dense wackestone or packstone in the Middle Permian and a mudstone or sparse wackestone in the Late Permian. This may indicate that Late Permian samples were derived from quieter water settings, possibly more distal on the shelf, or may imply that skeletal input was lower in the Late Permian. Kaiho et al. (2005) document a huge decrease in the abundance of skeletal fragments in the immediate aftermath of the end-Guadalupian extinction (Fig. 2.23), but it is also not clear whether the decrease results from changing depositional environment or biotic change. Even if the slight difference in skeletal fragment abundance in Late Permian samples does indicate sampling from different depositional environments, it seems highly unlikely that the environmental variation can explain the substantial observed ecological change, especially as Late Permian samples may have come from somewhat more offshore settings than Middle Permian assemblages. Late Permian fossil assemblages are more similar in many respects to those from the early Mesozoic than they are to Middle Permian samples. The mean relative abundance of rhynchonelliform brachiopods in the Middle and Late Triassic (based on data from Kochanova and Pevny, 1982; Kochanova and Michalik, 1986; Golebiowski, 1989; Hogler, 1992; Kaim, 1997) is 32.1% (Fig. 2.1), nearly 84 indistinguishable from the 34.6% documented here in the Late Permian (p=0.37). Rhynchonelliform brachiopods were actually slightly more abundant in Early Jurassic communities (based on unpublished Paleobiology Database data from F.T. Fürsich and data from Aberhan, 1992; Gahr, 2002), although not significantly different from the Late Permian, with a mean relative abundance of 47.1% (p=0.39). In addition, the relative abundance of microgastropods during the Late Permian (3.0%) is the same as the microgastropod abundance in the >2.5 mm size fraction from the Early Triassic Sinbad Limestone Member (2.7%) (p=0.86) (Fraiser and Bottjer, 2004). These similarities in rhynchonelliform brachiopod relative abundance between Late Permian and early Mesozoic assemblages suggest that the ecological transition from the brachiopod-dominated Paleozoic Fauna to the molluscan Modern Fauna was a protracted interval extending through much of the Triassic and into the Jurassic. With the exception of the unusual Early Triassic recovery interval, which was caused by extremely significant but transient ecological change resulting from the Permo-Triassic extinction (Fraiser and Bottjer, 2005b), benthic communities from the Late Permian through at least the Early Jurassic contained a mixed fauna with abundant bivalves and rhynchonelliform brachiopods. This shows that the ecological transition occurred in two phases, not a single abrupt shift during the end-Permian extinction as implied from diversity data. While the second transition appears to have occurred more gradually during the Jurassic, the first and largest shift in the relative abundance of brachiopods and molluscs was during the Guadalupian- Lopingian boundary interval. 85 Quantitative data from Middle and Late Permian assemblages constrains the timing of ecological change between the mid-Capitanian (Gerster Formation samples) and middle Wuchiapingian (lower Heshan Formation samples), coincident with the end-Guadalupian extinction (Stanley and Yang, 1994). However, as described above, there were also environmental changes during the late Paleozoic and those secular trends may also have had a substantial influence on ecological changes during that interval. The relative impacts of either long-term environmental change or the end- Guadalupian extinction will depend both on the timing and magnitude of environmental change, but more importantly on the severity and causes of the end- Guadalupian crisis itself. Mass extinctions are commonly invoked as drivers of ecological change (McGhee et al., 2004) so it is plausible, given the timing of the ecological change, that the end-Guadalupian extinction was an important trigger. Therefore, investigation of the severity, selectivity, and causes of the end- Guadalupian crisis will provide crucial constraints on the nature of the ecological transition from the Paleozoic to Modern Evolutionary Faunas. 86 CHAPTER III: END-GUADALUPIAN DIVERSITY CHANGES Nearly all studies of the ecological transition between the Paleozoic and Modern Faunas have recognized that extinction rates were also elevated at the end of the Capitanian Stage of the Guadalupian Series (Middle Permian) (Fig. 3.1A) but most considered the diversity changes from the Middle Permian to the Early Triassic as a single, protracted biotic crisis (Raup and Sepkoski, 1982; Sepkoski, 1989). However, subsequent studies demonstrated that the end-Guadalupian event was in fact an independent extinction (Fig. 3.1B, C), separated from the end-Permian crisis by a recovery and brief biotic radiation during the Lopingian (Late Permian) (Stanley and Yang, 1994; Weidlich, 2002). This implies that the ecological consequences of the end-Guadalupian extinction, if any, would be distinct from those documented at the end-Permian event (e.g., Fraiser and Bottjer, 2005b). Therefore, assessment of the severity and taxonomic selectivity of the end-Guadalupian crisis will help elucidate its potential effects on the transition from Paleozoic brachiopods to Mesozoic mollusc-dominated communities. Previous Work: Timing, Severity, and Causes The causes of the end-Guadalupian extinction have received less investigation than those of the larger and better-known end-Permian event; however, there seem to be broad similarities between the two events. The end-Guadalupian crisis appears to have been extremely rapid in south China, where fossil abundance plummeted and most typical Guadalupian clades disappeared in an 18 cm thick interval (Fig. 3.2) 87 Figure 3.1. Diversity changes during the end-Guadalupian interval. A. Global extinction rate indicating strongly elevated extinction at the end of the Guadalupian Series. Modified from Raup and Sepkoski (1982). B. Brachiopod generic diversity in south China, displaying a pronounced diversity drop at the end of the Capitanian Stage. Modified from Shen and Shi (1996). C. Schematic illustration of changes in abundance and diversity of reef assemblages from the late Early Permian (Kungurian) to the end of the Permian. Modified from Weidlich (2002). 88 in the earliest Lopingian at Penglaitan, Guangxi province (Kaiho et al., 2005). There was moderate flood basalt volcanism in south China during the Guadalupian- Lopingian boundary interval in the form of the Emeishan large igneous province (Fig. 3.2), with an estimated volume of only 300,000-500,000 km 3 (Ali et al., 2005) – much smaller than the immense end-Permian Siberian Traps. Biostratigraphic, magnetostratigraphic, and radiometric dating indicate that main flows slightly predated the boundary but that the final explosive volcanic phase at 259 ± 3 Ma was largely synchronous with the end-Guadalupian extinction (Ali et al., 2002; Zhou et al., 2002; He et al., 2006). There is lithological evidence suggesting the development of deep oceanic anoxia around the Guadalupian-Lopingian boundary (Isozaki, 1997) but no geochemical signals exist for low oxygen levels in shallow marine waters. The mass extinction was also immediately followed by a small negative carbon isotope excursion of around 1‰ in both carbonate and organic carbon at the Penglaitan section in south China (Fig. 3.2), similar to but smaller than the end- Permian excursion (Kaiho et al., 2005). The primary difference between the end- Guadalupian and end-Permian extinctions was the correlation of the end-Guadalupian crisis to a major sea-level lowstand (Fig. 3.2), compared to the marked transgression at the Permo-Triassic boundary (Hallam and Wignall, 1999). Sea level during the Guadalupian-Lopingian interval was at its lowest point of the Phanerozoic (Racki and Wignall, 2005), resulting in a worldwide regression exposing much of the continental shelf area and possibly contributing to extinction through loss of habitat space (Shen and Shi, 2002). Despite this, the general similarities to the end-Permian event 89 Figure 3.2. Environmental changes during the Guadalupian-Lopingian interval. Lithofacies change and stratified oceans from Isozaki (1997), sea-level changes and flood basalt distribution from Racki and Wignall (2005), and bioclast change and carbon isotope profile from Kaiho et al. (2005). 90 (negative carbon isotope excursions and correlation with flood basalts and possibly anoxia), all imply that the end-Guadalupian crisis may also have had similar ecological consequences to the end-Permian mass extinction. The magnitude of ecological change may depend on the taxonomic severity and degree of selectivity during the end-Guadalupian extinction. Analyses of global diversity compilations for the Permian suggest that the end-Guadalupian extinction may have been severe (Fig. 3.3), possibly one of the largest of the Phanerozoic. Raup and Sepkoski (1982) proposed that, at the family level, the extinction rate per million years for the Guadalupian was only exceeded by the end-Ordovician, end-Cretaceous, and end-Permian intervals. At the genus level, overall extinction intensities may have been as high as 58-60% for skeletonized marine taxa (Stanley and Yang, 1994; Knoll et al., 1996) based on data from the Sepkoski (2002) compendium. The end-Guadalupian crisis also displayed minor taxonomic selectivity (Fig. 3.3), with members of the Paleozoic Fauna slightly more likely to suffer extinction than molluscs of the Modern Fauna (Knoll et al., 1996), further suggesting parallels between the end-Guadalupian and end-Permian events. For example, extinction rates among rhynchonelliform brachiopods may have been as high as 58% in the Capitanian, whereas bivalves only suffered a 47% genus-level extinction (Knoll et al., 1996). At the substage level, rhynchonelliform brachiopod diversity declined from 82 genera in the late Maokouan (Capitanian) to only 29 genera in the early Wuchiapingian in south China, but rebounded to pre-extinction levels, including many Middle Permian genera not found in the early Wuchiapingian, 91 Figure 3.3. Severity and selectivity of the end-Guadalupian crisis. A. Estimated genus-level extinction rates for selected members of the Modern and Paleozoic Faunas, and fusulinids, for the Guadalupian Series. Modified from Stanley and Yang (1994). B. Estimated genus-level extinction rates for selected members of the Modern and Paleozoic Faunas for the Capitanian Stage. Modified from Knoll et al. (1996). 92 by the late Wuchiapingian (Fig. 3.1) (Shen and Shi, 1996). Similar high extinction rates were measured for corals, with a 78% genus-level extinction (Wang and Sugiyama, 2000), and fusulinid foraminifera (85% extinction), both in China (Yang et al., 2004). However, the timing and intensity of the end-Guadalupian extinction differed in other biogeographic realms (Fig. 3.4), at least among brachiopods. It was severe but more gradual in the Gondwanan realm, occurring throughout the Guadalupian, whereas the extinction was barely noticeable in the Paleoequatorial Realm due to rapid radiation and immigration in the Wuchiapingian (Shen and Shi, 2002). However, most of these recent end-Guadalupian extinction studies either considered only single taxonomic groups (e.g, Shen and Shi, 2002), or a single geographic region (e.g., Wang and Sugiyama, 2000; Yang et al., 2004), whereas global biodiversity analyses (Stanley and Yang, 1994; Knoll et al., 1996) tend to undersample the Late Permian because many English-language taxonomic studies have been published in the last decade and much of the older literature was published in foreign, especially Chinese, journals. In addition, Permian chronostratigraphic subdivisions have only recently been formalized (Jin et al., 1997) and previous studies (e.g., Stanley and Yang, 1994) often used outdated and poorly controlled regional stage names such as “Leonardian” or “Tatarian.” Recent developments in Permian biostratigraphy and global correlation, especially using conodonts (Henderson and Mei, 2000; Mei and Henderson, 2001; Mei et al., 2002), has helped 93 Figure 3.4. Paleogeographic variations in end-Guadalupian extinction severity among rhynchonelliform brachiopods. Genus-level extinction rates are shown for Permian time intervals in three Tethyan and west Panthlassan paleobiogeographic realms (the eastern Panthalassa province was not included), including the Guadalupian-Lopingian boundary (indicated by large circle). Modified from Shen and Shi (2002). 94 to constrain the ages of many fossil localities and refine estimates of diversity changes during the Middle and Late Permian. Methods I created a new compilation of Permian fossil occurrences, independent of previous work such as the Sepkoski compendium, in order to quantify the extinction severity and selectivity of the end-Guadalupian crisis. This new compilation takes advantage of the many Late Permian fossil studies published in the past decade as well as recent advances in Permian biostratigraphic correlation. I recorded the presence of marine invertebrate genera at the stage level and their geographic distribution, based on information from primary literature sources as well as the Paleobiology Database (www.pbdb.org). For some groups I utilized recently published diversity compilations, such as the ammonoid database of Leonova (2002), bryozoan data from Gilmour and Morozova (1999), crinoid occurrences (based on calyx identifications only) from Webster (2002), and trilobite ranges from Owens (2003), all supplemented with additional occurrences from more recent literature. The crinoid data is sparse and strongly governed by monographic bias and preservation quality; for example, no genera are reported from the Capitanian, whereas 25 are present in the Wordian. The stratigraphic positions of the fossil collections were assigned to stage level using conodont biostratigraphy where possible, or less precise fusulinid or ammonoid data when conodont information was not available. In some cases, especially in cool-water localities in Australia and New 95 Zealand that often lack conodonts and fusulinids, published correlations using a combination of more tentative brachiopod zonations, palynomorph data, and radiometric and magnetostratigraphic ages were used to constrain the age of the fossils. The resulting database includes 1315 genera from 34 countries on all continents except Antarctica (Fig. 3.5, Appendix 3). Only localities that can be reliably constrained to a single stage are included; as a result some diverse and classic Permian localities, such as those from Timor that lack stratigraphic control (Charlton et al., 2002), are excluded from the compilation. Diversity patterns, extinction intensity, and origination rates are estimated from ranged-through diversity, the simplest diversity metric where total diversity is the sum of all genera known to occur in a stage and those that range through a stage but are not reported from that time. All genera, even those confined to a single stage (“singletons”), were used in the analysis. Potential biases affecting diversity compilations are related to latitudinal diversity gradients (Allison and Briggs, 1993) and the amount of exposed sedimentary rock (Crampton et al., 2003). Latitudinal diversity gradients are not likely to have a signficant effect on Middle-Late Permian data because of the relatively consistent geographic and paleolatitudinal sampling coverage throughout all time intervals (Fig. 3.6). There is a decrease in preserved rock volume from the Middle to Late Permian, but it results from an actual decrease in continental shelf area related to tectonic activity in western North America, eastern Australia, and northern China (Shen and Shi, 2002). 96 Figure 3.5. Location of Middle and Late Permian fossil collections included in the diversity database. Many points represent multiple collections from a single geographic region. 97 Figure 3.6. Paleogeographic distribution of diversity samples for each stage in the Middle and Late Permian. 98 Taxonomic Severity and Selectivity Middle-Late Permian diversity reached its maximum during the Wordian Stage, when 927 marine invertebrate genera are recorded (either occurring or ranging through the stage), and declined steadily through the remainder of the Permian to a low of 492 genera before the end-Permian extinction (Fig. 3.7). Late Permian (Wuchiapingian and Changhsingian) diversity is more completely represented in this database than in previous studies – the 492 Changhsingian genera are more than double the number contained in the Sepkoski database (Fig. 3.7) (Knoll et al., 1996). As a result of this enhanced sampling of Late Permian diversity, the extinction rate at the end of the Capitanian Stage (the end of the Guadalupian Series) was only 33.9% at the genus level (Table 3.1), significantly lower than the previous estimates of 58- 60% (Stanley and Yang, 1994; Knoll et al., 1996). In addition, extinction rates were not particularly elevated during the Capitanian relative to the preceding Wordian Stage (27.6%) and were essentially identical to those in the succeeding Wuchiapingian Stage (32.1%) (Table 3.1). All of these stages had greater extinction intensity compared to the preceding Roadian Stage (12.7% extinction rate) and earlier stages, although the Roadian was very short (1.4 Myr) and not well represented in stratigraphic sections worldwide. The slight increase in extinction rates during the Wordian through Wuchiapingian does not necessarily reflect a long-term biotic crisis; rather, different groups suffered intensified extinction during different stages. Bivalves display a doubling of extinction intensity during the Capitanian, to 32.7%, typical of a classic 99 Figure 3.7. Middle and Late Permian diversity of major invertebrate groups. The traditional end-Guadalupian extinction occurred between the Capitanian and Wuchiapingian. The dashed line and grey circles indicate the total global diversity data reported in the Sepkoski compilation presented by Knoll et al. (1996). 100 Table 3.1. Generic diversity, number of extinctions at the genus level, and percent extinction rate for skeletonized marine clades during the Middle and Late Permian. No crinoids are known from calyx remains in the Changhsingian, but they were present as ossicles. 101 end-Guadalupian extinction (Table 3.1). Gastropods (26.0%) and trilobites (50%) had elevated extinction rates in the Capitanian, as well as in the Wordian (Table 3.1), whereas brachiopods (33.8%) and bryozoans (46.4%) suffered more in both the Capitanian and Wuchiapingian (Table 3.1). Reef-dwelling groups such as sponges had an extinction peak during the Wordian, due to the loss of diverse reefs in Tunisia (Newell et al., 1976), Oman (Weidlich and Senowbari-Daryan, 1996), Sicily (Aleotti et al., 1986), and south China (Rigby et al., 1994), and decreased extinction in the Capitanian and Wuchiapingian (Table 3.1). Extinction intensity among corals and ammonoids was consistently elevated from the Wordian through Wuchiapingian, ranging from 53-80% (Table 3.1). In contrast, nautiloids suffered essentially no genus-level extinctions (0-17.1%) until the end-Permian crisis (Table 3.1). Despite the apparent diachronous timing of peak extinction intensities among Permian marine invertebrates, the broad end-Guadalupian crisis had distinct taxonomic selectivity – but not in the straightforward manner seen at the end-Permian crisis. Gastropods only suffered a minimal extinction, with end-Capitanian genus- level extinction rates of 26.0%. In contrast, extinction rates among bivalves, also part of the Modern Fauna (32.7%) and Paleozoic Fauna rhynchonelliform brachiopods (33.8%) were slightly higher, but still moderate. Extinction among sessile colonial taxa (bryozoans and corals) was more severe, with extinction rates of 41-46%. Ammonoids and nautiloids, two closely related pelagic cepalopod groups, had extraordinarily different extinction patterns through the end-Guadalupian crisis. Ammonoids displayed extreme taxonomic turnover, with extinction rates of 55% 102 during the Capitanian, compared to the conservatism of nautiloids (all 21 nautiloid genera survived the Capitanian). The end-Guadalupian extinction also had marked selectivity at lower taxonomic levels, for example, among the eight common Permian brachiopod orders (Table 3.2). Members of the orders Orthida and Orthotetida suffered essentially no extinctions during the end-Guadalupian crisis; only one of nine orthid genera and one of 17 orthotetid genera had last appearances in the Capitanian. In contrast, athyridids and rhynchonellids suffered 50% genus-level extinctions, as five athyridid and 16 rhynchonellid were eliminated. Spiriferinids also had a high extinction rate (47.1%), while spiriferids had slightly fewer extinctions than average (29.6%). The most diverse order, the productids (159 Capitanian genera), had an average extinction rate of 34.0%, similar to the 35.7% of terebratulids that became extinct. The four rhynchonelliform genera that survived into the Mesozoic (Athyridida, Rhynchonellida, Spiriferinida, and Terebratulida) had the highest extinction rates in the end-Guadalupian crisis, and the athyridids, rhynchonellids, and spiriferinids were significantly elevated compared to groups such as orthids, orthotetids, and productids that did not survive past the end-Permian crisis (Table 3.2). It is more difficult to evaluate extinction selectivity among bivalves orders as most are only represented by a few genera (two arcoid genera, four limoids, two mytiloids, two pinnoids, one solemyoid, five trigonioids, one unionoid, and five veneroids in the Capitanian). However, among the four more diverse orders (nuculoids, pectinoids, pholadomyoids, and pterioids), the infaunal deposit-feeding 103 Table 3.2. Generic diversity (N) and extinction rate (E) among rhynchonelliform brachiopod orders during the Middle and Late Permian. Four orders (Athyridida, Rhynchonellida, Spiriferinida, Terebratulida) marked with stars in the Changhsingian represent Mesozoic brachiopod orders. 104 nuculoids (41.7%) and infaunal suspension-feeding pholadomyoids (40%) suffered the greatest extinction. Epifaunal pterioids were not significantly affected (18.8%) but epifaunal pectinoids underwent a moderate extinction (32.1%). These patterns of selectivity were complicated and did not display any consistent trends related to physiology or life habit at either the class or order level. Similar extinction rates were observed among both epifaunal and infaunal bivalves, and among clades with active metabolism (such as bivalves) as well as those with lower metabolic rates (such as rhynchonelliform brachiopods). Overall, these diversity changes show that the end-Guadalupian extinction, as measured by extinction rates at the end of the Capitanian Stage, had complex temporal patterns and taxonomic effects but was only a minor excursion relative to preceeding and following stages – not a massive crisis as was previously estimated (Raup and Sepkoski, 1982; Stanley and Yang, 1994). Paleogeographic Extinction Patterns The end-Guadalupian extinction has been attributed to effects of the Emeishan flood basalts (Racki, 2003; Ali et al., 2005) or to major sea level regression at the Middle-Late Permian boundary (Hallam and Wignall, 1999). Each mechanism will have different taxonomic and ecological consequences, and should manifest itself in paleogeographic variations in extinction intensity. If the Emeishan igneous province, located in Yunnan and Sichuan provinces of south China, was the primary driver of the end-Guadalupian biotic crisis, extinction severity should be greatest in 105 nearby regions of south China, because of intense proximal impacts from volcanism and mantle plume uplift. Far-field effects from CO 2 release and oceanographic changes (Racki and Wignall, 2005) should be small due to the relatively minor extent of the Emeishan province but more or less consistent worldwide. In contrast, extinction triggered by sea level fall and loss of provincialism should have similar effects on all passive margins and epicontinental seaways but a much higher impact in regions where tectonic activity resulted in a Late Permian hiatus, in which case many endemic taxa would become extinct. Paleogeographic patterns of extinction for brachiopods, the most abundant and commonly reported group, were compiled from 38 stations worldwide (Fig. 3.8, Appendix 3), including 17 where Capitanian brachiopods have been recorded. Bivalve extinctions were also assessed, in some cases from the same regions where brachiopods have been reported. Most of those 17 Capitanian regions include relatively unbroken deposition across the Guadalupian-Lopingian boundary, such as those throughout the ancient Tethys ocean (e.g., south China, Japan, Malaysia, Xizang, Kashmir, Pakistan, and Iran). In contrast, tectonically active regions such as the western United States (Collinson et al., 1976; Trexler Jr. et al., 2004), eastern Australia (Collins, 1991), and Mongolia and northern China (Li, 2006) record an extensive hiatus or nonmarine deposition spanning the Late Permian. Figure 3.9 shows the number of brachiopod and bivalve genera at each Capitanian station that survived (i.e., are found anywhere worldwide in the Late Permian) and those that become extinct during the end-Guadalupian crisis. In addition, the number of 106 Figure 3.8. Permian continental reconstruction showing the location of sampling stations used to analyze brachiopod paleobiogeographical extinction patterns. Numbered stations and their age(s) are shown on the right. 107 Figure 3.9. Number of surviving (S) and disappearing (D) brachiopod and bivalve genera at the end of the Capitanian Stage. Data for all genera found at a station as well as only those genera endemic to that region are shown. Western US is the combined total of genera found in the Phosphoria basin and Texas. 108 endemic genera surviving and disappearing at the Guadalupian-Lopingian boundary are reported for each station. Paleobiogeographic patterns of brachiopod extinction were broadly similar during both the Wordian (preceding the end-Guadalupian extinction) and Wuchiapingian (following the extinction) (Fig. 3.10). During the Wordian, brachiopod extinctions were less than 20% at most stations throughout Tethys, except for the southwestern margin of the ocean where extinction was greater than 30% in Oman, Sicily, and the Balkans. Wordian extinction rates were also less than 20% in most eastern Panthlassan sites, although slightly higher in Venezuela. Essentially no extinctions occurred during the Wordian in eastern Australia or New Zealand. Patterns of extinction were broadly similar during the Wuchiapingian (although there was essentially no marine deposition in western North America or eastern Australia). Wuchiapingian extinctions in Tethys were again very low in the central portions of the ocean and highest (>20%) on the southern and southwestern margins (in Hydra, Xizang, and Western Australia). The highest extinctions were observed in the isolated Zechstein sea, exposed in Greenland, England, and the Baltics, where as many as 30-40% of brachiopod genera disappeared. In contrast, the end-Capitanian extinction distribution exhibits a strikingly different pattern (Fig. 3.11). In Tethys, extinction rates were lowest around the margins of the sea (<10% in Iran, the Salt Range (Pakistan), Kashmir, and Western Australia) and highest in the inner area centered around south China (24%). However, the bulk of the end-Guadalupian extinction appears to have been caused 109 Figure 3.10. Paleobiogeographic variations in rhynchonelliform brachiopod extinction rates during the Wordian and Wuchiapingian Stages. 110 Figure 3.11. Paleobiogeographic variations in rhynchonelliform brachiopod extinction rates during the Capitanian Stage. 111 by significantly elevated extinction rates in regions with no Late Permian marine sedimentation, especially west Texas (52.9% extinction) and the Phosphoria basin of Wyoming and northeastern Nevada (48.6%) extinction. In fact, 43 of the 107 Capitanian genera that became extinct were endemic to the western United States. Extinction rates were also slightly elevated in eastern Australia (20.8%) relative to the Wordian (8.7%) (Fig. 3.12). Most Tethyan regions, such as Japan, China, or Iran, do not show an elevation of brachiopod extinction rates during the Capitanian (Fig. 3.12). These patterns of extinction support the theory that loss of habitat space and biotic provincialism, especially the disappearance of the highly isolated Grandian Faunal Province of western North America (Shen and Shi, 2004), resulting from tectonic activity was a primary driver of the end-Guadalupian extinction. The peak of extinction severity within Tethys was broadly centered in south China, the location of the Emeishan igneous province, implying that volcanism may also have had moderate regional effects in central parts of the Tethys ocean. The extinction pattern for bivalves, although less well defined than that for brachiopods, shows a broadly similar trend. End-Capitanian extinction rates in Tethys (Japan or south China) were no different than the Roadian, Wordian, or Wuchiapingian (Fig. 3.13). Extinction rates were slightly elevated in western North America (and significantly elevated among endemic genera), but overall extinction was not particularly high because many of the North American genera also lived in tropical regions of Tethys. The most significant bivalve extinctions occurred in cool- water Gondwanan localities (primarily eastern Australia, Fig. 3.13), which contained 112 Figure 3.12. Extinction rates for all rhynchonelliform brachiopod genera and endemic genera at Middle and Late Permian stations with relatively continuous fossil records. The total number of genera and endemic genera is indicated below the graph for each time interval at each station. 113 Figure 3.13. Extinction rates for all bivalve genera and endemic genera at Middle and Late Permian stations with relatively continuous fossil records. The total number of genera and endemic genera is indicated below the graph for each time interval at each station. 114 a diverse assemblage of endemic taxa. Most of the end-Guadalupian bivalve extinction can be accounted for by loss of those endemic cool-water genera from eastern Australia and New Zealand. Similar high extinction rates have been reported during the Capitanian for cool-water bivalve taxa in the Boreal Realm of northeastern Asia (Biakov, 2006). Permian marine sedimentation persists in much of polar northeastern Asia during the Lopingian, so it is not clear how much of the bivalve extinction can be attributed to loss of provincialism in Gondwana or if some effect from temperature changes (perhaps global warming from the Emeishan flood basalts) was also important. Endemic brachiopod genera were much more likely to suffer during the end- Guadalupian crisis, as 78.6% of those becoming extinct only occurred at a single station (Fig. 3.14). In contrast, 90% of survivors occurred at three or more stations. Preferential extinction of endemic genera would be expected if regression and habitat fragmentation were responsible for the extinction, although groups with a small geographic range may also be more likely to suffer extinction during times of stress because of small population size, limited dispersal ability, or other factors (e.g., Jablonski and Raup, 1995). However, endemic genera do not display uniformly enhanced end-Guadalupian extinction rates, as predicted if limited population size caused their preferential extinction. Localities from the south China block contained 31 endemic genera, only 14 of which became extinct (45.2%). Only 18% of endemic genera from Tibet and 25% from the Salt Range failed to survive the extinction. In striking contrast, 72.3% of Texas endemics and 88.9% of genera only found in the 115 Figure 3.14. Number of extinct and surviving brachiopod and bivalve genera in the Wordian-Wuchiapingian interval as a function of their distribution (the number of stations where the genus is reported). 116 Phosphoria basin became extinct, strongly implying that much of the increased brachiopod extinction resulted from loss of the western North American biotic province (the Grandian Province of Shen and Shi, 2004). It is possible that apparent high extinction of taxa endemic to western North America reflects an over-representation of endemic taxa due to the enormous number of specimens collected from west Texas (Cooper and Grant, 1977). West Texas does contain the highest proportion of endemic genera, with 54% of the 87 Capitanian genera reported from west Texas only known from that region (likely reflecting the geographic isolation of tropical western North America in the Permian). However, brachiopod genera from south China have also been extensively studied and the proportion of endemic genera is only slightly lower than that in west Texas: 41% of the 78 Capitanian genera have only been reported from that region. Likewise, overall extinction rates and extinction of endemic genera were low in western North America during the Roadian and Wordian (Fig. 3.12) even though the sampling effort and proportion of endemic taxa were equivalent to the Capitanian. It seems unlikely, therefore, that the high degree of extinction in west Texas (more than twice that recorded in south China) stems from a sampling bias, as Texas does not contain significantly more endemic genera than other well-studied regions such as south China and extinction of genera endemic to Texas during the Wordian was not elevated. Instead, it is more plausible that endemic genera in Tethyan regions such as south China were more likely to survive the end-Guadalupian extinction because they could more easily migrate short distances to other Tethyan microcontinents such as 117 the Japanese terranes, Pakistan, or Iran. The importance of immigration is shown in the diversity pattern recorded across the Guadalupian-Lopingian boundary in China (e.g., Shen and Shi, 1996). Diversity decreased from 82 genera in the Capitanian to only 29 in the early Wuchiapingian, as a result of sea-level regression and potentially the local effects of the Emeishan eruptions; however, many of those Capitanian genera survived elsewhere and recolonized the south China block by the late Wuchiapingian or Changhsingian. In contrast, genera endemic to tropical western North America (such as west Texas) were much more geographically isolated so would have had less chance to migrate to other suitable tropical habitats during the extinction interval. Summary A new diversity compilation indicates that the end-Guadalupian extinction was only a minor biotic crisis with an overall genus-level extinction rate of 33.9%. Extinction selectivity at the class level was moderate, with members of the Paleozoic Fauna, such as rhynchonelliform brachiopods (33.8%) and stenolaemate bryozoans (46.4%), suffering more than bivalves (32.7%) or gastropods (26.0%). Selectivity was also extreme at lower taxonomic levels – extinction rates among brachiopod orders varied from 0% to 50%. Both the magnitude of taxonomic selectivity (in particular between brachiopods and bivalves) and overall severity were much lower than previously estimated (Stanley and Yang, 1994; Knoll et al., 1996). The end- Guadalupian extinction was coincident with a pronounced marine regression and 118 eruption of the Emeishan flood basalt province. Paleobiogeographic estimates of extinction severity, based on rhynchonelliform brachiopods and bivalves, show that most of the generic loss at the end-Guadalupian crisis was concentrated in regions such as western North America and eastern Australia where tectonic activity resulted in non-marine deposition during the Late Permian. Endemic taxa in those regions, especially those only found in the geographically isolated Grandian Province of western North America, suffered particularly high extinction rates, largely contributing to the end-Guadalupian crisis. Extinction rates were not particularly elevated in those localities where marine conditions persisted into the Late Permian, such as in Tethys, implying that loss of provincialism played a fundamental role in the biotic crisis. The Emeishan igneous province may also have contributed to slightly elevated extinction rates in the central Tethys ocean. 119 CHAPTER IV: END-GUADALUPIAN ECOLOGICAL REPLACEMENT Changes in relative abundance in offshore carbonate environments from the Middle Permian to the Late Permian document a substantial ecological shift broadly coincident with the end-Guadalupian extinction; however, the new taxonomic compilation reveals that the end-Guadalupian extinction was only a minor crisis and that extinction rates were even unchanged in many regions. This implies that local ecological changes were decoupled from global biodiversity patterns. Such decoupling of taxonomic and ecological responses has been documented in other cases (McKinney et al., 1998; Strömberg, 2005) but the end-Guadalupian crisis appears to be the most severe instance of large-scale decoupling yet recognized. The dramatic ecological shift from offshore Middle to Late Permian fossil assemblages may have resulted from either (1) taphonomic variations resulting in differential preservation of molluscs, (2) preferential extinction of rhynchonelliform brachiopods to produce vacant ecospace for molluscs, (3) acquisition of new evolutionary innovations by molluscs that allowed them to radiate in the Late Permian, or (4) environmental changes that favored molluscs over rhynchonelliform brachiopods. Taphonomic Biases It is possible that the observed change from rhynchonelliform brachiopod- dominated Middle Permian assemblages to mixed mollusc-brachiopod Late Permian assemblages reflects variations in taphonomic biases between the two time intervals rather than a real ecological phenomenon. For example, it is possible that there were 120 differences in the preservation of aragonitic shells in the silicified Middle or Late Permian assemblages, given the potentially selective effects of skeletal mineralogy on silicification (Boyd and Newell, 1972; Erwin and Kidder, 2000). However, thin section analysis does not reveal the presence of unsilicified aragonitic fossils, implying that silicification was complete (at least in terms of brachiopods, bivalves, and gastropods). In addition, silicification occurred during early diagenesis before sediment compaction, suggesting that dissolution of aragonitic fossils before their replacement by silica would be unlikely, especially in the exceptionally well- preserved Middle Permian assemblages from Nevada. Unsilicified, originally aragonitic, gastropods were also abundant in other beds of the Late Permian Episkopi Formation on Hydra, indicating that their abundance in silicified beds during the Late Permian likely records a true increase in abundance and not an artifact of the silicification process. In addition, calcite-shelled bivalves were also extremely rare in the Middle Permian and increased substantially in the Late Permian, further indicating that the observed ecological changes are unlikely to represent a taphonomic bias against aragonitic components in Middle Permian assemblages. The dramatic increase in molluscan relative abundance from Middle to Late Permian offshore carbonate assemblages therefore most likely represents a real global ecological change. 121 Mass Extinction In the marine realm, ecological replacement has often been attributed to the taxonomic severity and selectivity of mass extinctions, such as the end-Permian crisis (Gould and Calloway, 1980). It therefore seems reasonable to conclude, at least in a general sense, that the earlier end-Guadalupian crisis may also have contributed to the observed ecological change in a similar manner as inferred for the end-Permian extinction (but see McKinney et al., 1998). For example, a biotic crisis may have preferentially eliminated rhynchonelliform brachiopods, opening up the habitat niches previously occupied by those taxa and allowing molluscs, and bivalves in particular, to colonize the vacated ecospace. However, the taxonomic impact of the end-Guadalupian extinction was surprisingly small in comparison to the large magnitude of ecological change in tropical carbonate environments, implying that the taxonomic extinction itself was not solely responsible for the ecological change. Only 33.9% of Capitanian genera failed to survive into the Late Permian, compared with a total extinction rate of 77.6% in the end-Permian catastrophe. Likewise, extinction intensity for all major invertebrate clades (except stenolaemate bryozoans) was two to three times greater during the end-Permian crisis than the end- Guadalupian extinction (Table 4.1). It is possible that the selectivity of the end- Guadalupian crisis may have triggered an ecological switch where molluscs became more abundant than brachiopods in the Late Permian. However, there was essentially no difference in extinction between rhynchonelliform brachiopods and bivalves – the brachiopod extinction intensity was only 3% greater than the bivalve extinction rate. 122 Table 4.1. Comparison of genus-level extinction rates during the end-Guadalupian extinction (end of the Capitanian Stage) and the end-Permian extinction (end of the Changhsingian Stage). 123 In contrast, end-Permian extinction selectivity was significantly more pronounced – the brachiopod extinction rate (95.5%) was 50% greater than that for bivalves (63.8%) (Table 4.1). In addition, it is not clear why the ecological change should be confined to the Guadalupian-Lopingian boundary interval when extinction rates and selectivity were similar in the preceding Wordian Stage and subsequent Wuchiapingian. Given the low extinction rates during the Capitanian stage and lack of selectivity among brachiopods, bivalves, and gastropods, there does not appear to be a causal link between the end-Guadalupian extinction and the ecological change documented here. The pronounced increase in molluscan abundance in the Late Permian was not related to newly-vacated ecospace and must therefore have been caused either by intrinsic biotic or extrinsic environmental factors. Adaptive Radiation The acquisition of key evolutionary innovations can alter competitive interactions between clades and open previously inaccessible ecospace, resulting in substantial adaptive radiations and increases in both diversity and abundance (Stanley, 1968). It is possible that the striking increase in the relative abundance of bivalves and gastropods in the Late Permian may have resulted from such an evolutionary innovation that gave them a competitive advantage over the previously superior rhynchonelliform brachiopods. However, this scenario is highly implausible because it would require the synchronous development of key adaptations in a wide variety of both bivalve and gastropod clades. The increased molluscan abundance in 124 Late Permian assemblages did not result from the adaptive radiation of a specific group, but rather was generated by an increase in epifaunal bivalves, infaunal bivalves, as well as gastropods. In addition, nearly all of the bivalve and gastropod genera that are abundant in the Late Permian samples were also present in earlier assemblages, demonstrating that Late Permian molluscan dominance was not triggered by an adaptive radiation of new genera with new evolutionary adaptations. Environmental Change Given that the Guadalupian-Lopingian shift towards mixed brachiopod- mollusc ecological dominance did not result from taxonomic effects of the end- Guadalupian extinction or from an adaptive radiation of molluscan taxa, a change in environmental conditions may have helped favor molluscs over brachiopods in the Late Permian. Molluscs and brachiopods have a wide variety of environmental preferences and have different competitive advantages under different regimes. Turbulence, salinity, food supplies, and substrate conditions all may have influenced the competitive interactions between the two groups (Steele-Petrovic, 1979). A potential increase in productivity during the late Paleozoic (Martin, 2003) may have favored molluscs over brachiopods, given the food requirements of the two groups (Steele-Petrovic, 1979; Rhodes and Thompson, 1993). However, the timing of the inferred late Paleozoic productivity increase is not well constrained and nutrient-driven changes in community composition should have been substantially diachronous because of the wide range in nutrient levels on 125 continental shelves, varying with proximity to upwelling zones or river mouths, for example. Other workers have proposed that an increase in bioturbation intensity during the late Paleozoic contributed to the ecological replacement of brachiopods (Thayer, 1979). However, this effect was not likely important in the Middle and Late Permian for several reasons. First, there is no evidence that the increase in bioturbation depth (Ausich and Bottjer, 2001) corresponded to a similar increase in bioturbation intensity or that it had any effect on substrate conditions. Second, sessile reclining brachiopods, the group that should have been affected most significantly by changes in substrate consistency, remained globally diverse and were still abundant components of the brachiopod population in the Late Permian samples. Both bivalves and gastropods are better-adapted than rhynchonelliform brachiopods to withstand fluctuating and stressful environmental conditions (Steele- Petrovic, 1979). This eurytopic habit is largely responsible for their diversity and abundance in environmentally variable nearshore and inner shelf settings through much of the Paleozoic, while the more stenotopic rhynchonelliform brachiopods dominated more stable offshore settings (Steele-Petrovic, 1979). The increased abundance of molluscs in Late Permian offshore settings may reflect more variable or stressful environmental conditions that would have given then a competitive advantage over rhynchonelliform brachiopods. A different set of environmental fluctuations are required to explain molluscan abundance in these offshore settings, as physical disturbances such as turbulence would not operate and there is no geochemical evidence for significant variations in salinity at a global scale. It is 126 possible that Late Permian offshore habitats were more stressful due to initial stages of the environmental deterioration that caused the end-Permian mass extinction. The timing of the ecological change corresponds with the onset of deep-water anoxia in the latest Guadalupian and at the Guadalupian-Lopingian boundary (Isozaki, 1997). Euxinic waters were present in deeper basins during much of the Late Permian (Nielsen and Shen, 2004) and water masses with lowered oxygen and/or higher sulfide concentrations may have intermittently affected these deeper shelf communities. Although there is no geochemical evidence for severe or long-term anoxia in these shelf environments, a decrease in environmental stability and more frequent fluctuations in water mass chemistry due to proximity to the basinal euxinic waters would have favored the more eurytopic molluscs. The similarity in size- frequency distribution between Late Permian offshore gastropods and their Early Triassic counterparts from shallow water is also consistent with similar intermittent environmental stresses in the two settings, although the high diversity found in the Late Permian may indicate that the environmental perturbations operated at a much lower intensity or frequency. The coincidence of substantial ecological change with the onset of deleterious oceanographic conditions suggests a plausible link between the two and implies that the initial stages of the Paleozoic Fauna-Modern Fauna transition were driven more by competitive interactions between the groups than by mass extinctions as previously proposed. 127 CHAPTER V: SUMMARY Previous work has shown that the taxonomic transition between the Paleozoic Evolutionary Fauna, with diverse rhynchonelliform brachiopods, crinoids, and stenolaemate bryozoans, and the bivalve- and gastropod-rich Modern Evolutionary Fauna occurred abruptly during the end-Permian mass extinction. Most workers used the abruptness and severity of the taxonomic switch, in conjunction with primarily anecdotal ecological data, to argue that the transition in terms of relative abundance also occurred at the end-Permian extinction. This study is the first to document the ecological change, in terms of relative abundance and life habits, using quantitative community data from Early, Middle, and Late Permian silicified fossil assemblages. Quantitative study of Permian ecology, based on relative abundance counts from silicified faunas in offshore carbonate environments, confirms that there was indeed a Permian-Triassic ecological switch to extreme molluscan dominance (e.g., Fraiser and Bottjer, 2005b). But, more importantly, the quantitative data has documented substantial ecological change from Middle Permian assemblages to Late Permian samples. Middle Permian samples were highly dominated by rhynchonelliform brachiopods (99.2% of the brachiopod/bivalve/gastropod abundance) and stenolaemate bryozoans (volumetrically abundant but not counted). Molluscs dominated the Late Permian assemblages from similar environments and lithologies, comprising 65.4% of the assemblage. The abundance change was paralleled by a similar change in bivalve life habits, from overwhelming dominance by epifaunal 128 byssate forms (96.2% of the bivalve assemblage) to an even mixture of byssate (52.4%) and infaunal suspension-feeding (42.9%) genera. Overall, Late Permian brachiopods were slightly larger than bivalves, but individual samples were equally split between those with larger bivalves and those with larger brachiopods. These results demonstrate that a sizeable proportion of the ecological transition from the Paleozoic to Modern Fauna predated the end-Permian mass extinction, and was instead apparently synchronous with the end-Guadalupian extinction. Although the ecological change was broadly coincident with the end- Guadalupian extinction, it is not certain that the taxonomic effects of the biotic crisis actually triggered the ecological transition. The overall taxonomic severity of the end-Guadalupian crisis was low (33.9% at the genus level), much lower than the end- Permian extinction (77.6%) and not substantially elevated relative to either the preceding Wordian or succeeding Wuchiapingian stages. The crisis displayed moderate taxonomic selectivity, but essentially no difference between rhynchonelliform brachiopods (33.8%) and bivalves (32.7%). In addition, selectivity was much less pronounced than in the later end-Permian crisis. This suggests that the extinction itself may have been too insignificant to have triggered the restructuring, although both may have been driven by the same causes. Extinction rates were high only in those regions where marine deposition ceased in the Guadalupian, such as western North American or eastern Australia, implying that the extinction may have been caused primarily by a loss of provincialism and resultant extinction of endemic taxa. A switch in extinction intensity within Tethys from maximum extinction rates 129 around the margins (especially the south and southwest margin) to maximum extinction centered around south China in the Capitanian implies that the Emeishan igneous province also had moderate regional effects during the end-Guadalupian crisis. The severe ecological response to minor taxonomic change provides strong evidence for extreme decoupling between the two parameters, and indicates that large-magnitude ecological change does not require the triggering of a catastrophic extinction. Likewise, the increased Late Permian abundance of molluscs did not arise from evolutionary innovations acquired by bivalves or gastropods, as the abundant taxa in Late Permian assemblages are not new genera with key adaptations not present in earlier taxa. The ecological shift was instead likely related to environmental changes during the Late Permian. The abundance of eurytopic bivalves and gastropods and predominance of tiny microgastropods may indicate the development of more stressful or fluctuating environmental conditions. This ecological transition coincides with the onset of deep-water euxinia, suggesting a causal link between deleterious oceanic conditions and the Late Permian rise of the Modern Fauna. The primary conclusion from this study is that the Modern Evolutionary Fauna first became ecologically dominant in offshore carbonate environments during the Late Permian, earlier than previously assumed and before their abrupt taxonomic switch. The shift from abundant rhynchonelliform brachiopods to dominant bivalves and gastropods is an iconic faunal transition and has been used as evidence for the 130 causal relationship between mass extinctions and ecological change. 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Zhou, M.-F., Malpas, J., Song, X.-Y., Robinson, P.T., Sun, M., Kennedy, A.K., Lesher, C.M., and Keays, R.R., 2002, A temporal link between the Emeishan large igneous province (southwest China) and the end-Guadalupian mass extinction: Earth and Planetary Science Letters, v. 196, p. 113-122. 148 APPENDIX 1: MEASURED STRATIGRAPHIC SECTIONS 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 APPENDIX 2: QUANTITATIVE ASSEMBLAGE DATA EARLY PERMIAN Sample BM UTM 644310E UTM 4389910N Kungurian Nearshore Palaeonucula Bivalvia 669 InDep Amphiscapha Gastropoda 240 Rec Euphemites Gastropoda 90 Detr Schizodus Bivalvia 40 InSusp Orthonema Gastropoda 11 Detr Naticopsis Gastropoda 3 Detr Worthenia Gastropoda 3 Detr Meekospira Gastropoda 2 Detr Plagioglypta Scaphopoda 1 InDep Sample CO UTM 681410E UTM 4323450N Artinskian Inner Shelf Dielasma Rhynchonelliformea 51 Ped Gastropod indet. Gastropoda 15 Detr Orthonema Gastropoda 13 Detr Naticopsis Gastropoda 9 Detr Anomphalus Gastropoda 8 Detr Crurithyris Rhynchonelliformea 6 Ped Stegocoelia (Taosia) Gastropoda 5 Detr Pseudozygopleura Gastropoda 5 Detr Permophorus? Bivalvia 5 InSusp Omphalotrochus Gastropoda 5 Rec Pleurotomarian? 2 Gastropoda 4 Detr Pleurotomarian 1 Gastropoda 4 Detr Echinoidea Echinoidea 4 Detr "High-spired" Gastropoda 4 Detr Platyceras Gastropoda 3 Para Trachyspira Gastropoda 3 Detr 167 Schizodus Bivalvia 3 InSusp Meekospira Gastropoda 3 Detr Glyptospira Gastropoda 3 Detr Soleniscus Gastropoda 3 Detr Palaeostylus Gastropoda 2 Detr Mourlonia Gastropoda 2 Detr Martinia Rhynchonelliformea 2 Ped Glabrocingulum Gastropoda 2 Detr Tapinotomaria Gastropoda 1 Detr Schuchertella Rhynchonelliformea 1 Cem Scaphopod Scaphopoda 1 InDep Pontisia Rhynchonelliformea 1 Ped Platyzona Gastropoda 1 Detr Peruvispira Gastropoda 1 Detr Crinoidea Crinoidea 1 Susp Bivalve indet. Bivalvia 1 ? Aviculopecten Bivalvia 1 Bys Astartella Bivalvia 1 InSusp Apachella Gastropoda 1 Detr Sample NSM UTM 626865E UTM 4039760N Sakmarian-Artinskian Inner Shelf Dielasma Rhynchonelliformea 53 Ped Heteropecten Bivalvia 41 Bys Septimyalina Bivalvia 36 Bys Composita Rhynchonelliformea 27 Ped Hustedia Rhynchonelliformea 26 Ped Amaurotoma Gastropoda 12 Detr Amphiscapha Gastropoda 11 Rec Crurithyris Rhynchonelliformea 9 Ped Astartella Bivalvia 6 InSusp Orthonema Gastropoda 5 Detr Leptodesma Bivalvia 5 Bys Soleniscus Gastropoda 4 Detr Grammatodon Bivalvia 4 Bys Streptacis Gastropoda 1 Detr Euphemites Gastropoda 1 Detr Naticopsis Gastropoda 1 Detr Bellerophon Gastropoda 1 Detr 168 Unknown Unknown 1 ? Scaphopod? Scaphopoda 1 InDep Sample WSN UTM 673330E UTM 4056510N Sakmarian-Artinskian Outer Shelf Crurithyris Rhynchonelliformea 288 Ped Hustedia Rhynchonelliformea 87 Ped Composita Rhynchonelliformea 66 Ped Elliottella Rhynchonelliformea 59 Rec Pontisia Rhynchonelliformea 30 Ped Anomphalus Gastropoda 3 Detr Astartella Bivalvia 2 InSusp Trepostomata Stenolaemata 2 Susp Crinoidea Crinoidea 1 Susp Sample USNM702e Artinskian Middle Shelf Rhipidomella hessensis Rhynchonelliformea 2168 Ped Hustedia cepacea Rhynchonelliformea 943 Ped Composita apsidata Rhynchonelliformea 428 Ped Rugaria hessensis Rhynchonelliformea 256 Rec Antronaria transversa Rhynchonelliformea 155 Ped Oncosarina whitei Rhynchonelliformea 145 Rec Acosarina dorsisulcata Rhynchonelliformea 132 Ped Crurithyris sp. C Rhynchonelliformea 127 Ped Enteletes subcircularis Rhynchonelliformea 57 Ped Chondronia ningula Rhynchonelliformea 42 Ped Stenoscisma hadrum Rhynchonelliformea 39 Ped Neospirifer notialis Rhynchonelliformea 34 Ped Thamnosia silicica Rhynchonelliformea 34 Rec Chonosteges limbatus Rhynchonelliformea 28 Cem Peniculauris imitata Rhynchonelliformea 22 Rec Linoproductus undatus Rhynchonelliformea 17 Rec Elversella rugosa Bivalvia 11 Bys Antronaria speciosa Rhynchonelliformea 9 Ped Eocamptonectes papillatus Bivalvia 7 Bys 169 Meekella hessensis Rhynchonelliformea 6 Cem Tapinotomaria rugosa Gastropoda 6 Detr Dielasma longisulcatum Rhynchonelliformea 5 Ped Diplanus lamellatus Rhynchonelliformea 4 Cem Heterelasma sp. 4 Rhynchonelliformea 4 Ped Apachella Gastropoda 4 Detr Euconospira Gastropoda 4 Detr Spyridiophora reticulata Rhynchonelliformea 3 Rec Teguliferina compacta Rhynchonelliformea 3 Cem Limbella sp. 1 Rhynchonelliformea 2 Rec Peruvispira delicata Gastropoda 2 Detr Platyceras sp. Gastropoda 2 Para ?Murchisonia (Donaldospira) Gastropoda 2 Detr Bellerophon sp. Gastropoda 2 Detr Compressoproductus sp. 1 Rhynchonelliformea 1 Rec Derbyia crenulata Rhynchonelliformea 1 Cem Goniarina futilis Rhynchonelliformea 1 Cem Stenoscisma doricranum Rhynchonelliformea 1 Ped Stenoscisma sp. Rhynchonelliformea 1 Ped Glabrocingulum Gastropoda 1 Detr Clinodomia obstipa Gastropoda 1 Detr Lacunospira Gastropoda 1 Detr Cassianoides kingorum Bivalvia 1 Bys Prospondylus acinetus Bivalvia 1 Cem Astartella Bivalvia 1 InSusp Nuculanid Bivalvia 1 InDep Crassatellacean Bivalvia 1 InSusp Rostroconch Rostroconchia 1 InSusp Sample USNM716n Artinskian Middle Shelf Oncosarina whitei Rhynchonelliformea 65 Rec Enteletes subcircularis Rhynchonelliformea 55 Ped Linoproductus undatus Rhynchonelliformea 47 Rec Antronaria transversa Rhynchonelliformea 44 Ped Rhipidomella hessensis Rhynchonelliformea 31 Ped Peniculauris imitata Rhynchonelliformea 28 Rec Thamnosia silicica Rhynchonelliformea 24 Rec Antronaria speciosa Rhynchonelliformea 11 Ped Limbella sp. 1 Rhynchonelliformea 8 Rec Tschernyschewia inexpectans Rhynchonelliformea 8 Rec 170 Composita apsidata Rhynchonelliformea 7 Ped Eolyttonia sp. Rhynchonelliformea 4 Cem Meekella hessensis Rhynchonelliformea 4 Ped Acosarina dorsisulcata Rhynchonelliformea 2 Ped Acosarina sp. Rhynchonelliformea 1 Ped Acritosia peculiaris Rhynchonelliformea 1 Cem Acritosia solida Rhynchonelliformea 1 Cem Chonetinella biplicata Rhynchonelliformea 1 Rec Hustedia sp. Rhynchonelliformea 1 Ped ?Soleniscus sp. Gastropoda 1 Detr Lacunospira spinosa Gastropoda 1 Rec Discotropis sp. Gastropoda 1 Rec Omphalotrochus Gastropoda 1 Rec Schizodus cf. supaiensis Bivalvia 1 InSusp Wilkingia? Bivalvia 1 InSusp Sample USNM716o Artinskian Middle Shelf Oncosarina whitei Rhynchonelliformea 79 Rec Peniculauris imitata Rhynchonelliformea 33 Rec Enteletes subcircularis Rhynchonelliformea 23 Ped Linoproductus undatus Rhynchonelliformea 15 Rec Eolyttonia sp. Rhynchonelliformea 14 Cem Thamnosia silicica Rhynchonelliformea 13 Rec Antronaria speciosa Rhynchonelliformea 12 Ped Antronaria transversa Rhynchonelliformea 7 Ped Limbella sp. 1 Rhynchonelliformea 7 Rec Discotropis sp. Gastropoda 4 Rec Composita sp. Rhynchonelliformea 2 Ped Rhipidomella hessensis Rhynchonelliformea 2 Ped Tschernyschewia inexpectans Rhynchonelliformea 2 Rec Astartella Bivalvia 2 InSusp Acosarina dorsisulcata Rhynchonelliformea 1 Ped Acritosia peculiaris Rhynchonelliformea 1 Cem Compressoproductus concentricus Rhynchonelliformea 1 Rec Dielasma longisulcatum Rhynchonelliformea 1 Ped Echinauris sp. Rhynchonelliformea 1 Rec Rugaria hessensis Rhynchonelliformea 1 Rec Stenoscisma pyraustoides Rhynchonelliformea 1 Ped Pectinid Bivalvia 1 Bys 171 MIDDLE PERMIAN Sample CCR UTM679895E UTM4451875N Capitanian Middle Shelf Dyoros Rhynchonelliformea 95 Rec Xestotrema Rhynchonelliformea 60 Ped Yakovlevia Rhynchonelliformea 43 Rec Waagenites Rhynchonelliformea 33 Rec Sphenosteges Rhynchonelliformea 21 Cem Echinalosia Rhynchonelliformea 18 Cem Cleiothyridina Rhynchonelliformea 17 Ped Composita Rhynchonelliformea 15 Ped Phrenophoria Rhynchonelliformea 14 Ped Echinauris Rhynchonelliformea 8 Rec Encruster 1 ? 8 Susp Ctenalosia Rhynchonelliformea 3 Cem Dielasma Rhynchonelliformea 2 Ped Hustedia Rhynchonelliformea 2 Ped Aviculopecten Bivalvia 1 Bys Streblopteria Bivalvia 1 Bys Encruster 2 ? 1 Susp Sample MR UTM658105E UTM4458265N Capitanian Middle Shelf Yakovlevia Rhynchonelliformea 145 Rec Echinauris Rhynchonelliformea 59 Rec Xestotrema Rhynchonelliformea 54 Ped Cleiothyridina Rhynchonelliformea 49 Ped Phrenophoria Rhynchonelliformea 23 Ped Hemiptychina Rhynchonelliformea 4 Ped Crinoidea Crinoidea 3 Susp Composita Rhynchonelliformea 2 Ped Cenorhynchia Rhynchonelliformea 1 Ped Bivalve Bivalvia 1 Bys 172 Trilobite? Trilobita? 1 Detr Sample PALR1 UTM683840E UTM4471832N Capitanian Middle Shelf Xestotrema Rhynchonelliformea 153 Ped Composita Rhynchonelliformea 64 Ped Yakovlevia Rhynchonelliformea 41 Rec Ctenalosia Rhynchonelliformea 18 Cem Hemiptychina Rhynchonelliformea 17 Ped Phrenophoria Rhynchonelliformea 6 Ped Kuvelosia Rhynchonelliformea 2 Rec Sphenosteges Rhynchonelliformea 2 Cem Aviculopecten Bivalvia 2 Bys Bathymyonia Rhynchonelliformea 1 Rec Crinoidea Crinoidea 1 Susp Quadrochonetes Rhynchonelliformea 1 Rec Sample PALR2 UTM683860E UTM4471840N Capitanian Middle Shelf Xestotrema Rhynchonelliformea 283 Ped Hemiptychina Rhynchonelliformea 113 Ped Yakovlevia Rhynchonelliformea 67 Rec Composita Rhynchonelliformea 13 Ped Phrenophoria Rhynchonelliformea 6 Ped Echinalosia Rhynchonelliformea 4 Cem Cleiothyridina Rhynchonelliformea 2 Ped Sample PALR5 UTM684080E UTM4471486N Capitanian Middle Shelf 173 Yakovlevia Rhynchonelliformea 103 Rec Xestotrema Rhynchonelliformea 102 Ped Composita Rhynchonelliformea 30 Ped Hemiptychina Rhynchonelliformea 5 Ped Sponge Demospongia 5 Susp Bathymyonia Rhynchonelliformea 2 Rec Aviculopecten Bivalvia 1 Bys Cenorhynchia Rhynchonelliformea 1 Ped Crinoidea Crinoidea 1 Susp Echinauris Rhynchonelliformea 1 Rec Sample PALR6 UTM684070E UTM4471495N Capitanian Middle Shelf Composita Rhynchonelliformea 183 Ped Hemiptychina Rhynchonelliformea 35 Ped Xestotrema Rhynchonelliformea 31 Ped Yakovlevia Rhynchonelliformea 31 Rec Quadrochonetes Rhynchonelliformea 11 Rec Aviculopecten Bivalvia 1 Bys Streblochondria? Bivalvia 1 Bys Sample PALR7 UTM684055E UTM4471480N Capitanian Middle Shelf Xestotrema Rhynchonelliformea 147 Ped Composita Rhynchonelliformea 49 Ped Yakovlevia Rhynchonelliformea 24 Rec Derbyia Rhynchonelliformea 3 Cem Cleiothyridina Rhynchonelliformea 2 Ped Aviculopecten Bivalvia 2 Bys Hustedia Rhynchonelliformea 1 Ped Phrenophoria Rhynchonelliformea 1 Ped Waagenites Rhynchonelliformea 1 Rec Crinoidea Crinoidea 1 Susp Echinalosia Rhynchonelliformea 1 Cem 174 Sample PALR8 UTM684035E UTM4471490N Capitanian Middle Shelf Xestotrema Rhynchonelliformea 106 Ped Composita Rhynchonelliformea 104 Ped Yakovlevia Rhynchonelliformea 62 Rec Cleiothyridina Rhynchonelliformea 14 Ped Hustedia Rhynchonelliformea 13 Ped Hemiptychina Rhynchonelliformea 6 Ped Phrenophoria Rhynchonelliformea 1 Ped Aviculopecten Bivalvia 1 Bys Sample USNM706b Wordian Middle Shelf Heteralosia hystricula Rhynchonelliformea 4050 Cem Spiriferella gravis Rhynchonelliformea 3315 Ped Dyoros (Dyoros) planiextensus Rhynchonelliformea 2123 Rec Hustedia pugilla pluscula Rhynchonelliformea 1990 Ped Cyclacantharia kingorum Rhynchonelliformea 1818 Cem Paucispinifera quadrata Rhynchonelliformea 1433 Rec Rhamnaria kingorum Rhynchonelliformea 1387 Rec Dyoros (Dyoros) extensus Rhynchonelliformea 1367 Rec Composita enormis Rhynchonelliformea 922 Ped Reticulariina cerina Rhynchonelliformea 718 Ped Liosotella wordensis Rhynchonelliformea 569 Rec Petasmatherus opulus Rhynchonelliformea 558 Ped Stenoscisma renode Rhynchonelliformea 548 Ped Derbyia filosa Rhynchonelliformea 508 Cem Echinauris lateralis Rhynchonelliformea 459 Rec Meekella skenoides Rhynchonelliformea 423 Cem Grandaurispina gibbosa Rhynchonelliformea 396 Rec Liosotella tetragonalis Rhynchonelliformea 359 Rec Platyceras (Orthonychia) bowsheri Gastropoda 219 Para Collemataria elongata Rhynchonelliformea 199 Cem Xenosteges quadratus Rhynchonelliformea 194 Cem Dielasma gracile Rhynchonelliformea 163 Ped Derbyia pannucia Rhynchonelliformea 155 Cem 175 Composita parasulcata Rhynchonelliformea 139 Ped Platyceras Gastropoda 133 Para Neophyricadothyris conara Rhynchonelliformea 121 Ped Spiriferella levis Rhynchonelliformea 113 Ped Echinosteges tuberculatus Rhynchonelliformea 107 Rec Paucispinifera auriculata Rhynchonelliformea 103 Rec Tautosia transenna Rhynchonelliformea 82 Ped Cartorhium chelomatum Rhynchonelliformea 76 Ped Crurithyris tholiaphor Rhynchonelliformea 62 Ped Derbyia texta Rhynchonelliformea 61 Cem Rhynchopora palumbula Rhynchonelliformea 59 Ped Phrenophoria subcarinata Rhynchonelliformea 56 Ped Thedusia procera Rhynchonelliformea 55 Ped Hustedia sp. Rhynchonelliformea 45 Ped Spiriferellina hilli Rhynchonelliformea 45 Ped Cooperina inexpectata Rhynchonelliformea 42 Cem Paraspiriferina rotundata Rhynchonelliformea 39 Ped Cenorhynchia fracida Rhynchonelliformea 36 Ped Pseudodielasma ovatum Rhynchonelliformea 36 Ped Allorhynchus permianum wordense Rhynchonelliformea 35 Ped Babylonites carinatus Gastropoda 30 Rec Bothrionia nasuta Rhynchonelliformea 29 Rec Petrocrania teretis Craniiformea 28 Cem Cyrtorostra varicostata Bivalvia 27 Bys Composita sp. Rhynchonelliformea 26 Ped Reticulariina sp. 1 Rhynchonelliformea 24 Ped Heterelasma concavum Rhynchonelliformea 23 Ped Peruvispira delicata Gastropoda 22 Detr Dielasma sp. Rhynchonelliformea 21 Ped Paraspiriferina laqueata Rhynchonelliformea 18 Ped Babylonites conicus Gastropoda 17 Rec Wellerella girtyi girtyi Rhynchonelliformea 16 Ped tiny Pleurotomarian Gastropoda 16 Detr Leurosina lata Rhynchonelliformea 15 Ped Cyclacantharia kingorum agaricoidea Rhynchonelliformea 15 Cem Tropidelasma anthicum Rhynchonelliformea 15 Cem Spiriferinaella scalpata Rhynchonelliformea 14 Ped Dielasma adamanteum Rhynchonelliformea 13 Ped Dyoros (Lissosia) concavus Rhynchonelliformea 11 Rec Echinauris sp. Rhynchonelliformea 11 Rec Paranorella sp. 1 Rhynchonelliformea 11 Ped Texarina elongata Rhynchonelliformea 11 Ped Costispinifera costata Rhynchonelliformea 10 Rec Neospirifer amphigyus Rhynchonelliformea 10 Ped 176 Dielasma zebratum Rhynchonelliformea 9 Ped Metriolepis pulvinata Rhynchonelliformea 9 Ped Tapinotomaria? Gastropoda 9 Detr Babylonites Gastropoda 8 Rec Apachella huecoensis Gastropoda 8 Detr Eolyttonia progressa Rhynchonelliformea 8 Cem Bothrionia transversa Rhynchonelliformea 7 Rec Cancrinella expansa Rhynchonelliformea 7 Rec Leptodesma Bivalvia 7 Bys Dielasma compactum Rhynchonelliformea 6 Ped Undulella undulata Rhynchonelliformea 6 Ped Procostatoria gloveri Bivalvia 6 Bys Rhynchonellid indet. Rhynchonelliformea 5 Ped Prospondylus acinetus Bivalvia 5 Cem Megousia definita Rhynchonelliformea 4 Rec Leiorhynchoidea amygdaloidea Rhynchonelliformea 4 Ped Pseudodielasma sp. Rhynchonelliformea 4 Ped Astartella Bivalvia 4 InSusp Compressoproductus rarus Rhynchonelliformea 3 Rec Compressoproductus sp. 2 Rhynchonelliformea 3 Rec Heterelasma pentagonum Rhynchonelliformea 3 Ped Schizodus texanus Bivalvia 3 InSusp Permophorus Bivalvia 3 InSusp Bellerophon (Bellerophon) kingorum Gastropoda 3 Detr Costispinifera rugatula Rhynchonelliformea 2 Rec Dyoros (Tetragonetes) wordensis Rhynchonelliformea 2 Rec Paucispinifera sp. Rhynchonelliformea 2 Rec Waagenoconcha magnifica Rhynchonelliformea 2 Rec Ptygmactrum spiculatum Rhynchonelliformea 2 Ped Heteroschizodus macomoides Bivalvia 2 InSusp Edmondia Bivalvia 2 InSusp Cypricardinia? Bivalvia 2 InSusp Bellerophon sp. Gastropoda 2 Detr Gastropoda indet. Gastropoda 2 Detr Meekospira? Gastropoda 2 Detr Pegmavalvula gloveri Bivalvia 2 Cem Guizhoupecten cheni Bivalvia 2 Bys Myalinid? Bivalvia 2 Bys Bivalve indet. Bivalvia 2 Bys Procostatoria sexaradiata Bivalvia 2 Bys Liosotella parva Rhynchonelliformea 1 Rec Paucispinifera transversa Rhynchonelliformea 1 Rec Discotropis publicus Gastropoda 1 Rec Sallya cf. striata Gastropoda 1 Rec 177 Lacunospira Gastropoda 1 Rec Ectoposia wildei Rhynchonelliformea 1 Ped Glossothyropsis rectangulata Rhynchonelliformea 1 Ped Heterelasma solidum Rhynchonelliformea 1 Ped Heterelasma sp. Rhynchonelliformea 1 Ped Hustedia sculptilis Rhynchonelliformea 1 Ped Notothyris venusta Rhynchonelliformea 1 Ped Spiriferellina paucicostata Rhynchonelliformea 1 Ped Nuculavis levatiformis Bivalvia 1 InDep Tapinotomaria coronata Gastropoda 1 Detr Glyptotomaria (Glyptotomaria) pistra Gastropoda 1 Detr Eirlysia reticulata Gastropoda 1 Detr Strobeus Gastropoda 1 Detr Subulitid Gastropoda 1 Detr Kalodomia rugosa Gastropoda 1 Detr Stegocoelia? Gastropoda 1 Detr Discotomaria Gastropoda 1 Detr Naticopsis Gastropoda 1 Detr Anisopyge perannulata Trilobita 1 Detr Ctenalosia fixata Rhynchonelliformea 1 Cem Derbyia sp. Rhynchonelliformea 1 Cem Lepidocrania sublamellosa Craniiformea 1 Cem Permanomia texana Bivalvia 1 Cem Heteropecten vanvleeti Bivalvia 1 Bys Girtypecten sublaqueatus Bivalvia 1 Bys Pterinopectinella spinifera Bivalvia 1 Cem Acanthopecten coloradoensis Bivalvia 1 Bys Sample USNM732c Wordian Middle Shelf Dyoros (Dyoros) convexus Rhynchonelliformea 179 Rec Rhamnaria kingorum Rhynchonelliformea 40 Rec Echinauris lateralis Rhynchonelliformea 36 Rec Liosotella wordensis Rhynchonelliformea 19 Rec Hustedia sp. Rhynchonelliformea 18 Ped Spiriferella clypeata Rhynchonelliformea 16 Ped Paucispinifera quadrata Rhynchonelliformea 14 Rec Collemataria elongata Rhynchonelliformea 12 Cem Grandaurispina gibbosa Rhynchonelliformea 11 Rec Arionthia germana Rhynchonelliformea 11 Ped Reticulariina cerina Rhynchonelliformea 10 Ped 178 Derbyia texta Rhynchonelliformea 10 Cem Guizhoupecten cheni Bivalvia 8 Bys Composita parasulcata Rhynchonelliformea 5 Ped Cyclacantharia kingorum Rhynchonelliformea 5 Cem Meekella skenoides Rhynchonelliformea 5 Cem Liosotella tetragonalis Rhynchonelliformea 4 Rec Pseudoleptodus grandis Rhynchonelliformea 3 Cem Echinosteges tuberculatus Rhynchonelliformea 2 Rec Spiriferellina hilli Rhynchonelliformea 2 Ped Spiriferinaella scalpata Rhynchonelliformea 2 Ped Heteralosia hystricula Rhynchonelliformea 2 Cem Tropidelasma sp. Rhynchonelliformea 2 Cem Allorhynchus permianum wordense Rhynchonelliformea 1 Ped Cartorhium chelomatum Rhynchonelliformea 1 Ped Composita enormis Rhynchonelliformea 1 Ped Dielasma sp. Rhynchonelliformea 1 Ped Paraspiriferina rotundata Rhynchonelliformea 1 Ped Stenoscisma renode Rhynchonelliformea 1 Ped Xenosteges quadratus Rhynchonelliformea 1 Cem Cyrtorostra varicostata Bivalvia 1 Bys Sample USNM737w Wordian Middle Shelf Dyoros (Dyoros) convexus Rhynchonelliformea 68 Rec Echinauris lateralis Rhynchonelliformea 29 Rec Arionthia germana Rhynchonelliformea 12 Ped Rhamnaria kingorum Rhynchonelliformea 11 Rec Liosotella wordensis Rhynchonelliformea 10 Rec Paucispinifera quadrata Rhynchonelliformea 10 Rec Spiriferella sp. Rhynchonelliformea 9 Ped Grandaurispina gibbosa Rhynchonelliformea 7 Rec Liosotella tetragonalis Rhynchonelliformea 7 Rec Hustedia sp. Rhynchonelliformea 7 Ped Eolyttonia progressa Rhynchonelliformea 7 Cem Liosotella irregularis Rhynchonelliformea 4 Rec Cooperina inexpectata Rhynchonelliformea 4 Cem Derbyia sp. Rhynchonelliformea 4 Cem Composita enormis Rhynchonelliformea 3 Ped Cyclacantharia kingorum Rhynchonelliformea 3 Cem Allorhynchus permianum wordense Rhynchonelliformea 2 Ped Paraspiriferina sp. Rhynchonelliformea 2 Ped 179 Stenoscisma sp. Rhynchonelliformea 2 Ped Pseudoleptodus grandis Rhynchonelliformea 2 Cem Babylonites sp. Gastropoda 1 Rec Cartorhium retusum Rhynchonelliformea 1 Ped Composita parasulcata Rhynchonelliformea 1 Ped Dielasma sp. Rhynchonelliformea 1 Ped Hustedia pugilla pugilla Rhynchonelliformea 1 Ped Neophricadothyris sp. Rhynchonelliformea 1 Ped Reticulariina sp. Rhynchonelliformea 1 Ped LATE PERMIAN Sample ET-B Lat 23° 49' 11.1" N Long 108° 52' 4.2" E Wuchiapingian Middle/Outer Shelf Spinomarginifera Rhynchonelliformea 60 Rec Ensipteria Bivalvia 35 Bys Bellerophon Gastropoda 16 Detr Araxathyris Rhynchonelliformea 9 Ped Phricodothyris Rhynchonelliformea 6 Ped Promytilus Bivalvia 5 Bys Cystothalamia Porifera 5 Susp Parallelodon Bivalvia 4 Bys Orthonema Gastropoda 4 Detr Stutchburia Bivalvia 3 InSusp Ananias Gastropoda 3 Detr Echinoidea Echinoidea 3 Detr Lopingoceras Nautiloidea 2 Nek Astartella Bivalvia 2 InSusp Eotomariid Gastropoda 2 Detr Palaeostylus Gastropoda 2 Detr Perigeyerella Rhynchonelliformea 2 Cem cf. Pegmavalvula Bivalvia 2 Cem Grammatodon Bivalvia 2 Bys Crinoidea Crinoidea 2 Susp Crenispirifer Rhynchonelliformea 1 Ped Dielasma Rhynchonelliformea 1 Ped Gujocardita Bivalvia 1 InSusp cf. Wilkingia Bivalvia 1 InSusp cf. Pyramus Bivalvia 1 InSusp 180 Soleniscus Gastropoda 1 Detr cf. Streptacis Gastropoda 1 Detr Streptorhynchus Rhynchonelliformea 1 Cem Bivalve indet. 1 Bivalvia 1 InSusp Bivalve indet. 2 Bivalvia 1 InSusp Sample ET-C Lat 23° 49' 11.1" N Long 108° 52' 4.2" E Wuchiapingian Middle/Outer Shelf Crurithyris Rhynchonelliformea 16 Ped Cystothalamia Porifera 10 Susp Ensipteria Bivalvia 9 Bys Bellerophon Gastropoda 9 Detr Crinoidea Crinoidea 8 Susp Spinomarginifera Rhynchonelliformea 7 Rec Soleniscus Gastropoda 7 Detr Grammatodon Bivalvia 7 Bys Araxathyris Rhynchonelliformea 6 Ped Lopingoceras Nautiloidea 6 Nek Leptodus Rhynchonelliformea 6 Cem Streptacis Gastropoda 5 Detr Strobeus Gastropoda 4 Detr Crenispirifer Rhynchonelliformea 3 Ped Gujocardita Bivalvia 3 InSusp Ananias Gastropoda 3 Detr Eotomariid Gastropoda 3 Detr Palaeostylus Gastropoda 3 Detr Orthonema Gastropoda 3 Detr Meekospira Gastropoda 2 Detr Etheripecten Bivalvia 2 Bys Terebratulida Rhynchonelliformea 1 Ped Astartella Bivalvia 1 InSusp Schizodus Bivalvia 1 InSusp Parallelodon Bivalvia 1 Bys Orthotetida Rhynchonelliformea 1 Cem Costatoria Bivalvia 1 Bys Towapteria Bivalvia 1 Bys Echinoidea Echinoidea 1 Detr 181 Sample MA1 Lat 23° 46' 21.6" N Long 108° 51' 23" E Wuchiapingian Outer Shelf Spinomarginifera Rhynchonelliformea 46 Rec Stutchburia Bivalvia 33 InSusp Streptorhynchus Rhynchonelliformea 16 Cem Cystothalamia Porifera 11 Susp Crurithyris Rhynchonelliformea 10 Ped Ananias Gastropoda 10 Detr Meekospira Gastropoda 7 Detr Ensipteria Bivalvia 7 Bys Retispira Gastropoda 6 Detr Perigeyerella Rhynchonelliformea 6 Cem Worm tubes 6 Susp Bryozoa Stenolaemata 5 Susp Echinoidea Echinoidea 4 Detr Permoperna Bivalvia 4 Bys Soleniscus Gastropoda 3 Detr Zhonguaspira Gastropoda 3 Detr Strobeus Gastropoda 2 Detr Goniasma Gastropoda 2 Detr Manzanospira Gastropoda 2 Detr Septopora Stenolaemata 2 Susp Permocalculus Algae 2 Algae Haydenella Rhynchonelliformea 1 Rec Lopingoceras Nautiloidea 1 Nek Astartella Bivalvia 1 InSusp Streptacis Gastropoda 1 Detr Trepostome? Stenolaemata 1 Susp Acanthocladia Stenolaemata 1 Susp Sample MA2 Lat 23° 46' 24.4" N Long 108° 51' 41" E Changhsingian Middle/Inner(?) Shelf "Hydrozoa" Hydrozoa 309 Susp Porcellia Gastropoda 57 Detr Callitomaria Gastropoda 52 Detr 182 Notothyris Rhynchonelliformea 34 Ped Palaeostylus Gastropoda 23 Detr Manzanospira Gastropoda 22 Detr Crenispirifer Rhynchonelliformea 21 Ped Trachyspira Gastropoda 19 Detr Dielasma Rhynchonelliformea 17 Ped Meekospira Gastropoda 16 Detr Soleniscus Gastropoda 16 Detr Naticopsis Gastropoda 15 Detr Sollasia Porifera 12 Susp Trachydomia Gastropoda 11 Detr Pan&Erwin Genus C Gastropoda 8 Detr Crurithyris Rhynchonelliformea 5 Ped Prelissorhynchia Rhynchonelliformea 5 Ped Warthia Gastropoda 5 Detr Acosarina Rhynchonelliformea 3 Ped Pleurotomarian 1 Gastropoda 3 Detr Anomphalus Gastropoda 3 Detr Streptorhynchus Rhynchonelliformea 3 Cem Cystothalamia Porifera 3 Susp Araxathyris Rhynchonelliformea 2 Ped "Chonosteges" Rhynchonelliformea 2 Cem Derbyia Rhynchonelliformea 2 Cem Spinomarginifera Rhynchonelliformea 1 Rec Permophricodothyris Rhynchonelliformea 1 Ped Nautiloid Nautiloidea 1 Nek Platyzona Gastropoda 1 Detr Girtypecten Bivalvia 1 Bys Grammatodon Bivalvia 1 Bys Palaeofusulina Fusulinida 1 Algae Sample MA3 Lat 23° 46' 21" N Long 108° 51' 23.2" E Wuchiapingian Middle Shelf Ensipteria Bivalvia 54 Bys Manzanospira Gastropoda 48 Detr Retispira Gastropoda 44 Detr Spinomarginifera Rhynchonelliformea 29 Rec Streptorhynchus Rhynchonelliformea 29 Cem Orthonema Gastropoda 21 Detr 183 Ananias Gastropoda 16 Detr Grammatodon Bivalvia 13 Bys Araxathyris Rhynchonelliformea 12 Ped Rectambitus Rhynchonelliformea 11 Ped Gujocardita Bivalvia 9 InSusp Crinoidea Crinoidea 9 Susp Promytilus Bivalvia 7 Bys Echinoidea Echinoidea 7 Detr Dielasma Rhynchonelliformea 6 Ped Permophricodothyris Rhynchonelliformea 6 Ped Stutchburia Bivalvia 5 InSusp Soleniscus Gastropoda 5 Detr "Hydrozoa" Hydrozoa 5 Susp Myophoriid Bivalvia 3 InSusp Stegocoelia (Donaldospira) Gastropoda 3 Detr Strobeus Gastropoda 3 Detr Perigeyerella Rhynchonelliformea 3 Cem Permoperna? Bivalvia 3 Bys Cystothalamia Porifera 3 Susp Nautiloidea Nautiloidea 2 Nek Astartella Bivalvia 2 InSusp Meekospira Gastropoda 2 Detr Palaeostylus Gastropoda 2 Detr Callitomaria Gastropoda 2 Detr Streptacis Gastropoda 2 Detr Notothyris Rhynchonelliformea 1 Ped Lopingoceras Nautiloidea 1 Nek Solemya Bivalvia 1 InSusp Chiton? Polyplacophora 1 Detr Cylindritopsis Gastropoda 1 Detr Zhonguaspira Gastropoda 1 Detr Naticopsis Gastropoda 1 Detr "Lopha" Bivalvia 1 Cem Parallelodon Bivalvia 1 Bys Pectinoid Bivalvia 1 Bys Sample MA3A Lat 23° 46' 21" N Long 108° 51' 23.2" E Wuchiapingian Middle Shelf Bellerophon Gastropoda 57 Detr 184 Manzanospira Gastropoda 28 Detr Ensipteria Bivalvia 23 Bys Spinomarginifera Rhynchonelliformea 21 Rec Orthonema Gastropoda 20 Detr Araxathyris Rhynchonelliformea 19 Ped Ananias Gastropoda 19 Detr Streptorhynchus Rhynchonelliformea 17 Cem Echinoidea Echinoidea 10 Detr Dielasma Rhynchonelliformea 9 Ped Glabrocingulum Gastropoda 9 Detr Crinoidea Crinoidea 9 Susp Permophricodothyris Rhynchonelliformea 8 Ped Soleniscus Gastropoda 8 Detr Streptacis Gastropoda 6 Detr Perigeyerella Rhynchonelliformea 5 Cem Grammatodon Bivalvia 5 Bys Promytilus Bivalvia 4 Bys Gujocardita Bivalvia 3 InSusp Stutchburia Bivalvia 3 InSusp Permophorus Bivalvia 2 InSusp Sanguinolites Bivalvia 2 InSusp Nuculopsis Gastropoda 2 InDep Strobeus Gastropoda 2 Detr Lopingoceras Nautiloidea 1 Nek Nautiloid? Nautiloidea 1 Nek Edmondia Bivalvia 1 InSusp Pyramus Bivalvia 1 InSusp Schizodus Bivalvia 1 InSusp Goniasma? Gastropoda 1 Detr Palaeostylus Gastropoda 1 Detr Zhonguaspira Gastropoda 1 Detr Cystothalamia Porifera 1 Susp Permocalculus Algae 1 Algae Scaphopoda Scaphopoda 1 InDep Sample EP Lat 37° 18' 30.7" N Long 23° 25' 21.7" E Wuchiapingian/Changhsingian Middle/Outer Shelf Crurithyris Rhynchonelliformea 119 Ped Paraspiriferina Rhynchonelliformea 92 Ped 185 Schuchertella Rhynchonelliformea 69 Cem "Tautosia" Rhynchonelliformea 42 Ped Uncinunellina Rhynchonelliformea 38 Ped Martinia Rhynchonelliformea 34 Ped Transcaucasathyris Rhynchonelliformea 17 Ped Orthonema Gastropoda 13 Detr Lepetopsis Gastropoda 12 Detr Porcellia Gastropoda 11 Detr Hustedia Rhynchonelliformea 9 Ped Spirigerella Rhynchonelliformea 9 Ped Leptodus Rhynchonelliformea 8 Cem Crenispirifer Rhynchonelliformea 8 Ped Allorhynchus Rhynchonelliformea 7 Ped Productid Rhynchonelliformea 7 Rec Ananias Gastropoda 6 Detr Dielasma Rhynchonelliformea 6 Ped Permoperna Bivalvia 5 Bys Epicelia Rhynchonelliformea 5 Cem Palaeostylus Gastropoda 5 Detr Worthenia? Gastropoda 5 Detr Plectelasma Rhynchonelliformea 5 Ped Bellerophontid Gastropoda 4 Detr Straparella Gastropoda 4 Detr Orthotichia Rhynchonelliformea 4 Ped Heteropecten Bivalvia 3 Bys Anomphalus Gastropoda 3 Detr Soleniscus Gastropoda 3 Detr Licharewiina Rhynchonelliformea 3 Ped Grammatodon Bivalvia 2 Bys "Limatula" Bivalvia 2 Bys Pegmavalvula Bivalvia 2 Cem Sicelia Rhynchonelliformea 2 Cem Glabrocingulum Gastropoda 2 Detr Lamellospira Gastropoda 2 Detr Streptacis Gastropoda 2 Detr Strobeus Gastropoda 2 Detr Lopingoceras Nautiloidea 2 Nek Cenorhynchia Rhynchonelliformea 2 Ped "Spiriferinaella" Rhynchonelliformea 2 Ped Spiriferinid 1 Rhynchonelliformea 2 Ped Spiriferinid 2 Rhynchonelliformea 2 Ped Stenoscisma Rhynchonelliformea 2 Ped Acanthocladia Stenolaemata 2 Susp Promytilus? Bivalvia 1 Bys 186 Tropidelasma Rhynchonelliformea 1 Cem Apachella Gastropoda 1 Detr Platyzona Gastropoda 1 Detr "Sinistral" Gastropoda 1 Detr Trachydomia Gastropoda 1 Detr Phestia? Bivalvia 1 InDep Nautiloid Nautiloidea 1 Nek Rugosa Rugosa 1 MC Cartorhium Bivalvia 1 Ped Crinoidea Crinoidea 1 Susp Sample LE1 Lat 37° 19' 32.4" N Long 23° 27' 24.1" E Wuchiapingian/Changhsingian Middle/Outer Shelf Transennatia Rhynchonelliformea 69 Rec Crurithyris Rhynchonelliformea 28 Ped "Worthenia" Gastropoda 26 Detr Astartella Bivalvia 23 InSusp Meekospira Gastropoda 22 Detr Donaldina Gastropoda 21 Detr Orthonema Gastropoda 21 Detr Palaeostylus Gastropoda 21 Detr Orthotichia Rhynchonelliformea 17 Ped Bellerophontid Gastropoda 13 Detr Spirigerella Rhynchonelliformea 11 Ped Ploceozyga Gastropoda 9 Detr "Stegocoelia" Gastropoda 9 Detr Leptodesma Bivalvia 7 Bys Pseudozygopleura Gastropoda 6 Detr Soleniscus Gastropoda 6 Detr Derbyia Rhynchonelliformea 6 Cem Athyridid Rhynchonelliformea 5 Ped "Tapinotomaria" Gastropoda 4 Detr Platyzona Gastropoda 3 Detr Strobeus Gastropoda 3 Detr Acanthocladia Stenolaemata 3 Susp Rhamnaria Rhynchonelliformea 2 Rec Girtyspira Gastropoda 2 Detr Streptacis Gastropoda 2 Detr Streblopteria Bivalvia 2 Bys 187 Licharewiina Rhynchonelliformea 1 Ped Rugosa Rugosa 1 MC Naticopis Gastropoda 1 Detr Grammatodon Bivalvia 1 Bys Crinoidea Crinoidea 1 Susp Echinoidea Echinoidea 1 Detr Sample LE2 Lat 37° 19' 32.4" N Long 23° 27' 24.1" E Wuchiapingian/Changhsingian Middle/Outer Shelf Palaeostylus Gastropoda 30 Detr Astartella Bivalvia 28 InSusp Crurithyris Rhynchonelliformea 24 Ped Transennatia Rhynchonelliformea 20 Red Orthonema Gastropoda 18 Detr "Worthenia" Gastropoda 18 Detr Orthotichia Rhynchonelliformea 17 Ped "Stegocoelia" Gastropoda 13 Detr Bellerophontid Gastropoda 12 Detr Streptacis Gastropoda 12 Detr Derbyia Rhynchonelliformea 8 Cem "Meekospira" Gastropoda 8 Detr Gastropoda indet Gastropoda 7 Detr Leptodesma Bivalvia 7 Bys Girtyspira Gastropoda 6 Detr Ploceozyga Gastropoda 6 Detr Sollasia Porifera 3 Susp Crinoidea Crinoidea 2 Susp Cooperina Rhynchonelliformea 2 Cem Gujocardita Bivalvia 2 InSusp Netschajewia Bivalvia 2 InSusp Notothyris Rhynchonelliformea 2 Ped Encrusting sponge Porifera 2 Susp Streblopteria Bivalvia 2 Bys "Tapinotomaria" Gastropoda 2 Detr Athyridid Rhynchonelliformea 1 Ped Grammatodon Bivalvia 1 Bys Bivalve indet. Bivalvia 1 InSusp Cartorhium Rhynchonelliformea 1 Ped Cassianoides Bivalvia 1 Bys 188 Licharewiina Rhynchonelliformea 1 Ped Naticopsis Gastropoda 1 Detr Paraspiriferina Rhynchonelliformea 1 Ped Pectinid Bivalvia 1 Bys Platyzona Gastropoda 1 Detr Promytilus Bivalvia 1 Bys Sanguinolites Bivalvia 1 InSusp Schizodus Bivalvia 1 InSusp Fenestrate Stenolaemata 1 Susp Sample LE3 Lat 37° 19' 31.5" N Long 23° 27' 19.2" E Wuchiapingian/Changhsingian Middle/Outer Shelf Orthonema Gastropoda 71 Detr Bellerophontid Gastropoda 14 Detr Girtyspira Gastropoda 13 Detr Astartella Bivalvia 12 InSusp Palaeostylus Gastropoda 9 Detr "Stegocoelia" Gastropoda 9 Detr Soleniscus Gastropoda 7 Detr "Meekospira" Gastropoda 6 Detr Glabrocingulum Gastropoda 5 Detr Amblysiphonella? Porifera 4 Susp Bivalvia indet. Bivalvia 3 InSusp Hydrozoan? Hydrozoa 3 Susp Gastropoda indet. Gastropoda 2 Detr Naticopsis Gastropoda 2 Detr Streptacis Gastropoda 2 Detr Grammatodon Bivalvia 1 Bys Leptodesma Bivalvia 1 Bys Orthotichia Rhynchonelliformea 1 Ped Paraspiriferina Rhynchonelliformea 1 Ped Platyzona Gastropoda 1 Detr Crinoidea Crinoidea 1 Susp Trachydomia Gastropoda 1 Detr Sample LE4 Lat 37° 19' 31.5" N Long 23° 27' 19.2" E 189 Wuchiapingian/Changhsingian Middle/Outer Shelf Orthonema Gastropoda 32 Detr "Meekospira" Gastropoda 14 Detr "Stegocoelia" Gastropoda 11 Detr Girtyspira Gastropoda 10 Detr Palaeostylus Gastropoda 10 Detr Soleniscus Gastropoda 8 Detr Gastropod 1 Gastropoda 7 Detr Streptacis Gastropoda 7 Detr Astartella Bivalvia 6 InSusp "Tapinotomaria" Gastropoda 5 Detr Bellerophontid Gastropoda 2 Detr Grammatodon Bivalvia 2 Bys Netschajewia Bivalvia 2 InSusp Crinoidea Crinoidea 1 Susp Bryozoa Stenolaemata 1 Susp Anomphalus Gastropoda 1 Detr Athyridid Rhynchonelliformea 1 Ped Orthotichia Rhynchonelliformea 1 Ped Pseudozygopleura Gastropoda 1 Detr Sanguinolites Bivalvia 1 InSusp Streblopteria Bivalvia 1 Bys "Worthenia" Gastropoda 1 Detr Sample LE Float Lat 37° 19' 32.4" N Long 23° 27' 24.1" E Wuchiapingian/Changhsingian Middle/Outer Shelf "Spirorbis" Microconchida 130 Cem Waagenites Rhynchonelliformea 80 Rec Ananias Gastropoda 78 Detr Donaldina Gastropoda 50 Detr Leptodesma Bivalvia 18 Bys Chonetid Rhynchonelliformea 12 Rec Sponge? Porifera 10 Susp Etheripecten Bivalvia 9 Bys Grammatodon Bivalvia 9 Bys Palaeoneilo Bivalvia 6 InDep Phestia Bivalvia 6 InDep 190 Meekospira Gastropoda 6 Detr Leptodus Rhynchonelliformea 6 Cem Marginifera Rhynchonelliformea 5 Rec Licharewiina Rhynchonelliformea 5 Ped Rugosa Rugosa 5 MC Spiroscala Gastropoda 5 Detr Brachiopoda Rhynchonelliformea 5 Nuculopsis Bivalvia 4 InDep Productid 1 Rhynchonelliformea 3 Rec Araxathyris Rhynchonelliformea 3 Ped Permophorus Bivalvia 3 InSusp Streblopteria Bivalvia 3 Bys Trepostomata? Stenolaemata 3 Susp Transennatia Rhynchonelliformea 2 Rec Acosarina Rhynchonelliformea 2 Ped Disphenia Rhynchonelliformea 2 Ped Spiriferinid Rhynchonelliformea 2 Ped Bellerophontid Gastropoda 2 Detr Glabrocingulum Gastropoda 2 Detr Goniarina Rhynchonelliformea 2 Cem Bakevellia Bivalvia 2 Bys Fenestrata Stenolaemata 2 Susp Productid 2 Rhynchonelliformea 1 Rec Cleiothyridina Rhynchonelliformea 1 Ped Crurithyris Rhynchonelliformea 1 Ped Enteletes Rhynchonelliformea 1 Ped Hustedia Rhynchonelliformea 1 Ped Prolecanitid Ammonoidea 1 Nek Astartella Bivalvia 1 InSusp Edmondia Bivalvia 1 InSusp Schizodus? Bivalvia 1 InSusp Anomphalus Gastropoda 1 Detr Girtyspira Gastropoda 1 Detr Helminthochiton Polyplacophora 1 Detr Palaeostylus Gastropoda 1 Detr Shansiella Gastropoda 1 Detr Soleniscus Gastropoda 1 Detr Cooperina Rhynchonelliformea 1 Cem Cyndalia Rhynchonelliformea 1 Cem Cyrtorostra? Bivalvia 1 Bys Tambanella Bivalvia 1 Bys 191 APPENDIX 3: DIVERSITY AND PALEOBIOGEOGRAPHY “X” Symbol and numbers indicate that genus was recorded in that time interval; “---“ indicates that the genus is inferred to be present based on prior and later occurrences but was not directly recorded. Station numbers for bivalve and rhynchonelliform brachiopod biogeography are from Figure 3.8, with these additional stations: 39 – Kanin Peninsula 40 – Verkoyansk 41 – Kolyma-Omolon 42 – Transcaucasus 43 – Transbaikal 44 – Madgascar 45 – Wrangell, Alaska 192 AMMONOIDS Roadian Wordian Capitanian Wuchiapingian Changhsingian Abadehceras X Abichites X Adrianites X X Agathiceras X X Allothalossoceras X Altudoceras X X X Anatsabites X Anderssonceras X Anfuceras X Angrenoceras X Anotoceras Araxoceras X Aricoceras X X Aristoceratoides X X Artinskia X Aulacogastrioceras X Avushoceras X Bamyaniceras X X Bukkenites Cardiella X Changhsingoceras X Chekiangoceras X Cibolites X X Cyclolobus X X X Daraelites --- X Daubichites X 193 Demarezites X X Difuntites X X Discophiceras Doryoceras X Doulingoceras X Dzhulfites X Dzhulfoceras X Elephantoceras X X X Eoaraxoceras X Eohyattoceras X Epadrianites X X X Epiglyphioceras X X Episageceras X X X Epitauroceras X Epithalassoceras X X Erinoceras X X X Eumedlicottia X X X Gaetanoceras X X Glassoceras X Glyptophiceras Guiyangoceras X Hoffmannia X Hyattoceras X X X X Iranites X Jilingites X X Julfotoceras X X Kingoceras X Kymatites 194 Laibinoceras X Lanceoloboceras X X X Lenticoceltites X Lingzhouceras X Liuzhouceras X X X Medlicottia --- X X X Meitianoceras X Metacrimites --- X X Metagastrioceras X Metalegoceras X Metaricoceras X Mexicoceras X X Mongoloceras X X Neoaganides X --- --- X X Neoaricoceras X Neogeoceras X X X Neoglassoceras X Neostacheoceras X Newellites X Nielsenoceras X Nodosageceras X X Ophiceras X Otoceras Paedopronorites X Palermites X X Paraceltites X X X Parakufengoceras X Paramexicoceras X X 195 Parapronorites --- X Parasicanites X Paratirolites X Paratongluceras X X Penglaites X Pentagonoceras X Pericarinoceras X Pericycloceras X Peritrochia X Perrimetanites X Perrinites X Phisonites X Pleuronodoceras X Popanoceras X Prionolobus Propinacoceras X X X Proptychites Prostacheoceras X X Prototoceras X Pseudagathiceras X Pseudogastrioceras X X X Pseudogyronites Pseudometalegoceras X Pseudosverdrupites X Pseudotirolites X Pseudovidrioceras X X Qinglongites X Retiogastrioceras X X 196 Roadoceras X X Rotodiscoceras X Sangzhites X X X Schizoloboceras X Shangraoceras X X X Shengoceras X Shevyrevites X Shouchangoceras X X X Sicanites --- X Sizilites X X Sosioceras X Sosiocrimites X X X Spirolegoceras X Stacheoceras X X X X X Stenolobulites X Strigogoniatites X X X Sundaites X X Sverdrupites X Syrdenites X X Tapashanites X Tauroceras X X Texoceras X Thalassoceras --- X Timorites X X X Tongluceras X X Vishnuites Waagenoceras X X Xenodiscus X X X 197 BIVALVES Roadian Wordian Capitanian Wuchiapingian Changhsingian Acanthopecten 4,6 4,6,7,35,38 4,34,35 Actinodontophora 35 --- --- --- 34,35 Alula 4 --- --- --- 34 Annuliconcha 6 6,14,35,38 Aphanaia --- 26 26 Astartella 4 4,20? 26,34,35,43 8,9,34,35 34 Astartila 25 26,27 25,26,27 Atomodesma 25,27 --- 26 21,27 23,27 Aviculopecten 4,6,35 4,6,12,18,35,38,43 4,36 30,34,35,38 35 Aviculopinna 4 4,35 --- --- 6,35 Bakevellia 4 34 --- 8,34,35,38 34,35 Calcicanicularia 26 --- 26 Cardiomorpha --- --- --- 34 Cassianoides 6 --- 26 Celtoides 4 4 4 Chaenomya --- --- --- --- 34,36 Claraia 8,34,44 21,34 Claraioides 34 42 Clavicosta 23? Cleidophorus 10 Corrugopecten --- --- 26,27 --- 27 Cosmomya 25 Costatoria 35 Crenipecten 34 34 198 Cyrtorostra 4,6 4,6,20,35 4,6,25,26,36,43 8 21,23 Deltopecten 35 Denguiria 14 6 Dolponella 23 Dunbarella 23? Dyasmya 20 Edmondia 4 4,12,20,35,38 4,6,34 9,10,34,35 34,35 Elimata 26 --- 26 8,9,10 Elversella 6 Ensipteria 35 --- 34 34 Eoastarte 4,6 --- --- --- 34 Eocamptonectes 4,6 6 4,6,25?,36 34 34 Etheripecten 26 26,27,38 26,27,34 21,23,27,34 21,23,27,34 Euantiostreon 34 Euchondria 6,25 6 34,35 34,38 34 Euchondrioides 34 Fasciculiconcha --- --- --- --- 34 Fletcheripecten 27 Fransonia 6 6 Gervillia 14 --- --- --- Gigantocyclus 14 Girtypecten 4,6 4,6,7 6,36 34 34 Glabripecten 27 Globicarina --- --- 27 Gloverilima 7 6 Glyptoleda 25 26? 26,27,41 Goniophora 4 Grammatodon 4,30 --- --- 9,34 --- 199 Guizhoupecten 6 6,26,34,35 34,38 34 Gujocardita 34 34 34,35 Hayasakapecten 35 34,35 --- 34 Heteropecten 6 4,6,34 4,6,27,34 23 27,34 Heteroschizodus 6 6 Hunanopecten 34 34 Intomodesma 41 44 Janeia --- 20? --- 9,10,34 34 Kaibabella 4,6 --- 26 38 Kolymia 43 43 41 Leptochondria 4,6 --- 30,34 34 Leptodesma 6,35 12,35 6,43 30,38 6,34 Liebea 20?,38 --- 8,9,10,38,45 34 Limatulina --- 12 Limipecten --- --- 34 34,35 34 Lyroschizodus 6,30 14 6 Maitaia 41 41 43 Manzanella 4 Marmaronia 16 Megadesmus 25 26 26,27 21 27? Megalodon 30 --- --- --- --- Merismopteria --- 43 26,43 Middalya 25 Myalina 4,30 4 4,6,36 35 6 Myalinella 38 Myofossa 26 Myomedia 26 26 Myonia 26 26,27,43 26,27,41,43 200 Neoschizodus 34,35 --- --- 34,35 Netschajewia --- 35 --- 10,35,38 34 Notomya --- --- 26,27 Novaculapermia 6 Nuculana 4,25 --- --- --- --- Nuculavus 4 --- --- --- --- Nuculites --- --- --- 35 Nuculopsis 4 4,14,20,27,34,38,41 4,26,27,34 34,41,45 6,34 Nuncundata --- --- 26,27 Oblicarina --- 26 26 Obliquipecten 6 4,6 Orientopecten 34 Oriocrassatella 4,25 38 26 10 Pachymyonia --- 27 26,27,41 Palaeolima 30 34 34 21,30,34,38,45 34 Palaeoneilo 4 14,41 34,41 30,34,35,45 21 Palaeosolen 26 Paleowaagia 6 6 Paleyoldia 26 Paradoxipecten 34 34 34 Parallelodon 25 4,12,14,26,35 6,26,27,35,36 8,10,34 --- Paraschizodus 6 --- 6 Pegmavalvula 6 6,7 --- --- --- Permanomia 6 6 Permartella 30 Permoceramus 26 Permoperna 35 34,35,36 34 34 Permophorus 4 4,5 4,6 8,9,10,21,34 6,21,34,35 201 Pernopecten 6,30 6,35,38 6,34 34,35,38 34,35 Phestia 25 20,34 26,34 8,9,10,21,30,34,45 34 Pleurikodonta 26 26 Pleurophorina 10 Polidevcia 4,41 4,26?,41 4,27,41,43 41 Praeamonotis 26 Procostatoria 6 4,6 4 Promyalina 34 34 Promytilus 4,35 35 27,34 8,30,34 34,35 Prospondylus 6,30 6 6 Pseudobakewellia 10 Pseudomonotis 4,6,25 4,6,12,18,27,38 4,27,34 8,9,10,34,38 34 Pseudomyalina 25 Pseudonucula 26 Pseudopermophorus 4 4 --- 35 Pterinopectinella 6 Pteronites --- --- --- 38 Pyramus --- 26 26,27 --- 23,34,35 Qinghaipecten 38 Quadratonucula --- --- 27 Rimmyjimina 4 --- --- 30 --- Saikraconcha 30 Sanguinolites 4,30 12,34,35 34 10,21 34 Scaphellina 4,6 4,6 Schizodus 4,6,7,25 4,5,6,14,20,34,35,38 4,6,26,34,35 8,9,10,21,34 6,23?,34 Sedgwickia --- --- --- 30,34 34 Septimyalina --- --- --- --- 35 Shikamaia 30 13,14,30 202 Solemya 4 Solenomorpha --- --- 35 Streblochondria 4,6 6,27,38 4,6,41,27 8,10?,27 Streblopteria 4,6,25 4,6,12,35 6,27,41,43 --- 23,34 Striochondria --- 26 Stutchburia 4,25 4 26,34 8,9,10,34 6,34 Tambanella 34,35 Towapteria 35 --- 34 35 Trabeculatia 41 27,28 Undulomya 25 Vacunella 26 26,40 26,27 --- 34,35 Vngripecten 4,6 20 41 Volsellina --- 26 26 Wilkingia 4,46 4,12,35,43 4,6,34,43 8,9,10,21,34 6,34 BRACHIOPODS Roadian Wordian Capitanian Wuchiapingian Changhsingian Acanthocrania X X X Cardiocrania X Crania X Lepidocrania X X X Orbiculoidea X X --- X Petrocrania --- X X Lingularia --- X X --- X Roemerella X Acolosia 6 Acosarina 6 38 18,34,35 13,17,18,19,21,31,34,38 13,31,32,34 203 Acritosia --- 20,31 Actinoconchus --- 37 Adriana 31 Alatochonetes 34 Alatoproductus 33? 34 34 34 Alatorthothetina 34 Alispiriferella --- 35 35 Allorhynchus 6 6 6,24 35 34 Alphaneospirifer 34,35 24,34,38 24,31,34,36,38 Altiplecus 6 --- 6,34,37 Ambikella 27 27 27 27 Ambocoelia --- --- --- --- 34 Ametoria 6 Amygdalocosta 27 Anaptychius 7 Anchorhynchia 19 --- --- 34 Anemonaria 7?,37 37 2,35,36 Aneuthelasma 7 6 Anidanthus 4 5,37 34,36,37 17,19,21,22,30,34,36,38 17,23,34,36 Anomaloria --- 31 6,12 Anteridocus 6 --- 6 Antiquatonia --- 4 --- --- 30 Aperispirifer 27 26,27 26,27 --- 27 Aphaurosia 6 Araxathyris ` 13,18,24,31,34,36,38 Araxilevis 18,35 Arcticalosia 1 Arctitreta --- 36? 1,26,27? 23? 23 204 Arionthia 6 6 6 Asioproductus 34 34 Asperlinus 31 36 19 Astegosia 31 6 Attenuatella 6 6,19,26 6,26,35 27,28 23,27,31 Aulosteges --- 37* 35*,25* 19*,25* 19* Bathymyonia 4 4 4,16,36 Beecheria --- 24 1,19 19 34 Betaneospirifer 23 Bibatiola 31 Bilotina 20,31 Binderochonetes 37 Biplatyconcha 23,24 Birchsella 26 Blasispirifer 35 Bothrionia 6 6 Bothrostegium 6 Brachythyris --- --- --- 24 Bryorhynchus --- 6 6 Buxtonia --- 37 --- 38 34,38 Cactosteges 6 Callispirina --- 18,29,31 1,6,35 19,21,23,31 18?,19 Callytharrella 19 Camarophorinella 34 17,33 17,34 Cancellospirifer 14 Cancrinella 4,6,17 4,6,18,27,29,31,35,37,38 1,4,6,27,36,37 8,21,23,27?,34 21,23,38 Capillomesolobus 35 Capillonia 26 26? 27 205 Caricula 30,31 Cartorhium 6 6,19 --- --- 34 Cathaysia 34 24,34,38 17,24,34,36 Cathayspiriferina 34,35 Cathayspirina 34 Caucasoproductus 36 Celebetes 20,31 Cenorhynchia 6 6 4 Ceocypia 31 --- 15,19 Chaoiella 19 --- 19 19 Chaoina 34 Chapursania 19 Chilianshania --- 38 Chondronia 6 Chonetella --- --- 19,24 19,23?,24,34,38 19,34,36 Chonetina 17 31 19,34 8,19 Chonetinella 6 29?,31 6 21,23? 34 Chonetinetes 6,7 --- 6 Chonopectoides 18 31? Chonosteges 6 31 --- --- 30 Chonostegoides 18 21 Cleiothyridina 6,26 6,7,16,18,26,29,31,36,37 1,2,4,6,19,21,24,25,27,35 8,18,19,21,22,23?,24,25,27,34 19,23,24 Collemataria 6,7 6 6 Collumatus 6 Comelicania 18 13,18 Comelicothyris 13 Composita 4,6,7 4,5,6,7,16,31,38 4,6,18,19 Compressoproductus 6 6,11,12,18,19,35?,37 6,19,24,34,36,37 17,18,19,21,24 17,23,31,34,36 206 Comuquia --- 11,31 24 Cooperina 6,7 6,7,14,31 6 Coscinarina 12,14 Coscinophora 6 Costatispirifer 24? Costatumulus 33 --- 24 21,23,24,34 34 Costicrura 7 Costiferina 19 18 16,19,21 18,19,21,23,25 21 Costispinifera 6 6 --- --- 30 Costisteges 34 Craspedalosia 1 8 Craspedona 6 6 Crenispirifer --- 6 6,34 18,33,34,38 24,30,34,38 Cruricella 29?,31 24 21 31 Crurithyris 6,33 6,14,18 1,6,34 10,18,27?,33,34,38 13,30,34,36 Cryptospirifer 33 18 Ctenalosia 6 6 4,6 34* Cyclacantharia 6 6,14,31 6 Cyndalia 15 Cyrolexis 35,36 24 34 Cyrtella --- 26 26 31 23? Darbandia 19 Dasyalosia 10 Deltarina 6 Demonedys --- 31 --- 23? 23? Derbyia 6,7,19 4,5,6,7,18,31,35,36,37 4,6,19,24,26,30,34,35 8,13,15,18,19,25,34,35,38 6,13,19,21,30,32,34,36,38 Derbyoides --- --- 34,35 --- 30 Dictyoclostoidea 34 207 Dictyoclostus --- 5 --- 38 6?,30,34,38 Dicystoconcha 34,36 Dielasma 6 5,6,13,16,18,31,35,36 1,4,6,18,19,35,37 10,18,19,21,24,34,38 13,21?,30,31,34,38 Dielasmina 6,19,24 23 Diplanus --- 31 --- 15 Disphenia 15 Divaricosta 6 Dongpanoproductus 34* Dorashamia 18* Dyoros 6,7 5,6 4,6 Dyschrestia 20,31 Echinalosia 26 26,27 1,4,19,26,27 19,25,27 23 Echinauriella 11 Echinauris 6,7 6,7,14,31,37 26,34,36,37 19,23?,34,30 30 Echinoconchus 19 18 16,21? 21,34,38 21,30,31 Echinosteges 6 6 6 35 Ectoposia 6 6 Edriosteges 6 --- 18,34,35,36 18,21,33,34 34 Elassonia 6 Eliva --- --- 6 25? 34? Elivina --- 19 6,19,24,36 19,21,24 Entacanthadus 16 Enteletella 17 17,36 Enteletes 6,19 6,11,12,13,14,35 6,19,24,34,35,36,37 17,18,19,24,34,38 18,19,30,34,36,38 Enteletina 34 Eolaballa 34 Eolyttonia 6 6,31 30?,35 --- 35 Epicelia 15 208 Erismatina 31 Falafer 15,34 34 Fallaxoproductus 35 Fanichonetes 34 Fascicosta 6 Filiconcha 26 26 27 Fletcherithyris 26 26,27 24,26,27 13,25,27 Fredericksolasma 17 --- --- 17 Fusichonetes 34 Fusiproductus 34 Fusispirifer --- 26 26 21,24 23 Gefonia 31 19,34 18,19,38 Gemmellaroia 12,14 14 Gerassimovia 17 17 Geyerella 6 11,12,13,14 6,35 17,38 34,36,38 Gilledia 26 26,27 26,27 Girlasia 36 Girtyella --- --- 4 --- 24? Gjelispinifera --- --- --- 24,25 Glabrichonetina 23 Glendonia 26 Globiella --- 37 --- 19 Globosobucina 31 Glossothyropsis 6 5,6,26 1,6 Glyptorhynchia 17 34 Glyptosteges --- --- --- --- 31 Goleomixa 31 24 --- 31? Goniarina 6 --- 35 15 209 Grandaurispina 6 6,20 Grigorjevaelasma 11 Gruntea 24 Gruntelasma 11 Gundarolasmina 17 Gypospirifer --- 35,37 Haydenella 18,31,36 19,34,35,36 17,18,19,24,30,31,34,38 17,18,24,30,34,36,38 Hemiptychina 11,31,36 4,19,24,36,37 19,21,24,34,38 19,34 Hercosestria 6 6 6 Hercosia 6 --- --- 34 Heteralosia 6 5,6,31 5,6 Heterelasma 6 5,6 4,6 13,19 13,23? Heterelasmina 17 11 --- 17 17 Himathyris 19 24 Holosia 6 6 6 Holotricharina 6,7 Horridonia --- 16 37 10,27 Hoskingia 26? --- --- 25 23 Huatangia 34 Hustedia 4,6,7 5,6,7,16,19,29,30,31,35,37 1,4,6,16,19,24,34,35,36,37 19,24,25,31,33,34,35 6?,19,23,30,34,38 Hybostenoscisma 34,36 Hystriculina --- --- 4 Incisius 11,31 --- 24 34 Isogramma --- --- 34* --- 30 Janiceps 18,34 13,18,34 Jinomarginifera 24 24 Jisuina 12,26 Juresania --- 20,35 210 Juxathyris 34 Kaninochonetes 39 Kaninospirifer 37 Karavankina --- 13 Kasetia 33 Keyserlingina 31 6,31 34 34 Kiangsiella --- --- 34,35,36 19 19 Kochiproductus 37 6?,37 4,6,35 8 Kotlaia --- 16,18 --- --- 19 Kozlowskia --- 20,31 26,35 Krotovia --- --- 16,18 17,21,24 23?,24 Kutorginella 6,7 31 --- 19 Kuvelousia --- --- 1,4 Labaella 36 Labaia 34 21,24 27? Ladoliplica 34 Lamellosia 6 Lamnaespina --- --- --- 27 Lamnimargus 21,22,23,24 21,36 Lampangella 31 Laterispina 34 34 Latiflexa 36 Latispirifer 25 Leiorhynchoidea 6 4,5,6 1,6 6 Lepidospirifer --- --- --- 24? Leptodus --- 11,13,14,19,31,35,37 4,6,18,24,26,30,34,35,36,37 13,17,18,19,21,24,25,31,32,33, 34,35,38 13,17,18,19,24,30,31,34,36,38 Lethamia 26 27 26,27 27 27? 211 Leurosina 6 6 Levenolasma 17 Lialosia 23? Licharewia --- --- 1 Licharewiconcha 36 Licharewiella 34 34 Licharewiina 36 Limbella --- --- 37 Linoldhamina 24 Linoproductus 33 6,13,16,18,19,29,31,33,35,3 6,38 1,16,19,21,24,26,34,36 13,19,21,24,32,34,38 13,19,21,23,30,36,38 Liosotella 6,33,37 5,6,37 4,6,16,18,36 6?,8,20,21,34,38 34 Lipanteris --- --- 26 Lirellaria --- 19 6 Lissochonetes 4 --- 2,4,19,21,35 19,21 21,34 Lithocotia 31 Liveringia 25 25 Loxophragmus 33 --- 34 Madarosia 6 6 Magniplicatina 19,26 18,19,26,36 26 Maorielasma --- 26,27 26,27 27 27 Marginalosia 24 23,24?,27 Marginifera --- 5,13,16,18,19,31,37 19,24,36,37 17,19,21,23,24,34 6?,13,17,19,30,34,36 Marinurnula --- 26 26,27 27 Martinia --- 5,6,11,13,16,19,35 1,2,6,18,19,24,26,34,35,36,37 8,13,17,19,20,21,24,27,30,31, 34,38 13,19,23,24,27,34,36,38 Martiniopsis 26,33 19,31,35 26 18,19,23,24,27 23,27,31 Matanoleptodus 34 Meekella 6,7 6,7,14,16,18,31 6,18,30,34,35,36,37 18,19,31,34,38 30,31,34,36,38 212 Megalosia 24 24 23 Megapleuronia 12 Megasteges --- --- --- 23,24,25 23 Megousia 6,17 6,35 6,35,36 --- 35 Mesolobus --- --- 34 Metriolepis 6 6 6 Micraphelia --- 6 6 --- 30 Mingenewia --- --- --- --- 23 Monticulifera 38 34 --- 23 Nakmusiella 24 Nantanella 34 Neochonetes 19,33 6,18,20,34,38 6,18,19,27,30,34,35 13,19,23,24,25,31,34,35 23,30,34 Neophricadothyris 6,7 6,11,13,18 --- 20 30 Neoplicatifera 33 38 24,34 34 Neopsilocamara 24 Neorichthofenia 34 Neospirifer 6,7,17,26 5,6,31,35,37 1,24,25,36,37 19,21,22,23,24,25,27 13,19,21,23,24,30,31,38 Nikitinia 36 Niutoushania 34 34 Niviconia 6 Notolosia 25 25 Notospirifer 27 26,27 26,27 27 27 Notothyris 6 6,18,31 19,24,34,36,37 13,17,18,21,24,31,34,38 13,17,23,34,36,38 Odontospirifer 4 Ogbinia 18,19,33 18,24 18,19,21 Oldhamina 18,19,24,34,35,38 30,31,24,34,38 Oligothyrina --- 7 Ombonia 6 6,12 6 21 13,19 213 Orbicoelia --- 31 --- --- 13,19,21,34 Orthotetes --- 37 Orthothetina 19 18,19,30,38 18,26,34,35 18,20,21,34,38 13,18,19,31,34,35 Orthothrix 19 10,19 35 Orthotichia --- 11,18,19,31,36,37 1,19,34,35,36,37 18,19,21,23 18,19,30,34 Otariella 18? --- 23 Paeckelmannella 37 1 8,24 Pakistania 6 Paracrurithyris 24,34,36 Paralyttonia 31 --- --- 30 Paramarginifera --- --- 37 34 13,31,35 Paramesolobus 19 --- --- 21,23 21 Paranorella 6 6 6 6 Paraorthotetina 34 34 Paraplicatifera 18 Parapulchratia 31,34 34 Paraspiriferina 6 6,24 6 19,24,31,33,34 23?,30,34 Parenteletes --- --- --- --- 19 Paryphella 34 34 34 Paucispinauria 26 26 Paucispinifera 6,7? 6 6,36 Peltichia --- 19 34 17,18,24,34,35,36,38 24,31,32,34,38 Peniculauris 6,7 4 36 Perditocardinia 19 Perigeyerella 20,31 34 34 34,38 Permasyrinx 26 Permianella 34 31,34 34,36 Permophricodothyris 19,33 4,14,31,33,38 1?,18,19,24,34,35 17,18,19,24,33,34,38 23?,24,34,38 214 Permospirifer 27? 27 Permundaria 30,35 34 --- 23? Petasmaia 6 Petasmatherus 6 6 4,6 Phrenophoria 6 6 4,6 Plectelasma --- 6 4,6 Plekonella --- 26,27 26,27 27 27 Pleurelasma 6 Plicatifera --- --- --- --- 30 Plicochonetes 34 Poikilosakos --- --- --- 18 Polymorpharia 6 6 Pondospirifer 24 Pontielasma 31 Pontisia 6,7 7,19,31 24 Praeangustothyris 36 Prelissorhynchia 35 18,34,38 13,31?,34,36,38 Probolionia --- --- 36 Proboscidella --- --- 19 19 Prorichthofenia 6 Pseudoantiquatonia 19,33 24 Pseudodielasma 6 6 6 Pseudohaydenella 34 Pseudolabaia 34 --- 34 Pseudoleptodus 6 6,24,30 5 --- 30 Pseudosyrinx --- --- 26 Pseudowellerella 11 --- 18,27 27 Psilocamara --- --- 19 19,24,34 23 215 Pteroplecta 21 23 Pterospirifer 10 Ptilotorhynchus 6 6 Ptygmactrum 6 6 Punctoproductus 34 Punctospirifer --- 31?,37 --- 23 Pustula --- --- --- --- 13,21 Pustuloplica 26 27 27 27 Pyandzhelasma 17 Pygmochonetes 38 34 --- 34 Qinglongia 34 Quadrochonetes --- --- 4 Quinquenella --- 29 --- 24 23 Rallacosta --- 6 6 34 Ramavectus --- 31 Rectambitus 34 Reticularia --- 13 Reticulariina 6 6 6 19 23,30 Reticulatia 19 18,35 --- 13,18,23? 30 Retimarginifera 19 19,31 --- 24 21,23,30 Rhamnaria 6 6 6 Rhipidomella --- 29,31,37 18,19,34 13,19,34 30,32,34,36 Rhombospirifer 37 Rhynchopora 4,6,17 4,5,6,35 1,4,6,16,19,35,36 19,23? 30 Rhytisia 6 Richthofenia 11,31,38 18,19,24,34,35,36,37 13,17,19,24,34 13,17,19,34,36 Rigbyella 31 6 34 Rostranteris 17 5,11,14,19 6 17 17,34,36 216 Rugaria --- 31 --- 19,21 23 Rugatia 6,7 --- 4 Rugivestis --- --- 24 24 Rugosochonetes 38 Sarganostega --- 6 6 Sarytchevinella 31 Scacchinella --- 12 35 17 17,36 Scapharina 6 Schellwienella --- 37 --- --- 21* Schizophoria --- 12 37 21 30,31,34,38 Schizopleuronia 34 Schuchertella --- 16,31,37 --- 15,19,32,34 13,32,34 Septacamarella 10 Septospirigerella 18 --- 13?,31 Seseloidea 16 Sestropoma 6 6 Sicelia 12 --- 15,21 Sicularia 12 Simplicarina 6 Sokelasma 11 Sowerbina --- 2 --- 27? Sphenalosia 4 3 Sphenosteges 14 4 Spinifrons 7? 7? --- --- 30 Spinomarginifera 18,19,37 18,26,34,35,36 13,18,19,20,21,24,30,31,32,33, 34,38 13,18,19,21,23,24,31,32,34,35, 36,38 Spinomartinia 26 --- 26,27 27 Spirelytha --- --- 1 24? 217 Spiriferella 6 5,6,27,31,35,37 1,2,4,6,35,36,37 8,19,21,22,23,24,27,34,35,38 19?,21,23,24,27,30 Spiriferellina 6,33 5,6,7,14,18,26,29,31,37 1,2,6,18,19,24,27,34,35 10,13,18,19,21,23,24,30,35,38 13,23,30,34 Spiriferinaella 6 6 34 Spirigerella --- 19 18,19,24,34,35 18,19,21,24,31,34,38 13,19,21,23,34 Spirisosium 12 Spyridiophora --- --- 30 Squamularia --- 16,19,33? 18,19,24,34,35,36 17,18,19,21,24,31,33,34,36,38 23,24,31,34,28 Stenoscisma 6,26 5,6,11,14,16,18,19,29,31,35, 37 1,6,24,34,35,36 10,17,18,19,21,23,24,25,27,33, 34,38 13,24,30,34,38 Stepanoviella 18 --- --- 34 Stereochia --- 29,31 24 24? Stictozoster --- 29,31 Streptorhynchus --- 5,12,18,29,31,38 19,25,35,36,37 8,10,18,19,21,24,25,34,38 24,34,38 Strigirhynchia 6 Striochonetes 31 34 Strophalosia --- 6 34,37 8,10,21,23?,34 23?,36 Strophalosiina 24,26,34,35,36 17,24,34 17,34,36 Sulcataria --- --- 19 19,23 Sulciplica --- 27? 26 Svalbardia --- --- --- 21 Syringothyris --- --- --- --- 23? Taeniothaerus --- --- 24 24,25 23? Taprosestria 6 Tautosia 6 6 6,34 Tenuichonetes 33 38 34 21,34,38 34,38 Terebratuloidea 11,19,31 18,19,34 19,24,30,34,38 18,34,38 Terrakea 26,27 26,27,37 2,26,27 27 23,27 Tethyochonetes 19? 35 24,32,34,38 24,32,34,38 218 Tethysiella 36 Texarina 6 6 Thamnosia 5 5 1,2,4,6 Thedusia 6 6 6 Timaniella --- 4 4,36 Timorina 16 6 Tipispirifer 19,31 Tiramnia --- 19 --- --- 23 Tomiopsis 1,26,27 26,27 2,25,26,27 19,21,24,25,27 23,27 Tongzithyris 34 Tornquistia --- 31 Torynechus --- --- 6 Transcaucasathyris 18 Transennatia 19 11,30,31,35 24,26,30,34,35,36 18,19,21,24,30,32,33,34 23,24,31,34,36,38 Trigonotreta --- --- --- 22,24 Tropidelasma 6 6 6 15,21 34 Tschernyschewia --- 16,37 19,34 13,18,19,34 13,31,34,35 Tyloplecta --- 18 19,34 13,18,19,24,31,34 13,24,34,36 Uncinella 31 19 Uncinunellina --- 5?,14,31,37 24,30,34,37 18,19,23?,24,32,34 17,30,34,36,38 Undulella 6 6 Urushtenia 31 36 Urushtenoidea 35,38 24,26,34 Vediproductus 33 18,20 30,34 34 Waagenites 37 4,25,36 19,25,34,38 30,34 Waagenoconcha 6,17,19,37 5,6,35,37 19,24,35,36,37 8,19,21,23,24,25,27,34,38 19,21,23,30,34 Waterhouseiella 31 Wellerella 4,6 4,5,6,18,31 4,19 17,18,19 17,38 219 Whitspakia 18 19,24,35 18,19,21 19 Wyndhamia --- 26,27 1,27,37 Xenosaria 6 Xenosteges 6 6,7,31? 6 Xestotrema --- 4 4 Xizispirifer 34 Yakovlevia 6,37 4,5,6,35,37 1,2,4,36,37 Yochelsonia 25 Zhejiangoproductus 34 Zhejiangospirifer 24 24 Zhongliangshania 34 Zhuaconcha 34 BRYOZOANS Roadian Wordian Capitanian Wuchiapingian Changhsingian Acanthocladia X X X X Alternifenestella X X Anisotrypella X X X Araxopora X X X --- X Arcticopora X X X X X Ascopora X Callocladia X Cavernella X --- X Clausotrypa X X X Coelocaulis X X Coeloclemis X X Corynotrypa --- --- --- X 220 Coscinium X X X X Cyclotrypa X X X --- --- Cystodictya X X Dichotrypa X Dybowskiella X X X X Dyscritella X X X X --- Dyscritellina X X X Epiactinotrypa X Eridopora X X X X Etherella X Evactinostella X Exfenestella X X X X Fabifenestella X X X X Fenestella X X X --- X Filites X X Fistulamina X X Fistulipora X X X X X Fistuliramus X X X X Fistulocladia X X Fistulotrypa X Flexifenestella X Gilmoropora X Girtypora X X Girtyporina X X X X Goniocladia X X X X Hayasakapora X X Hexagonella X X X Hinganella X X 221 Hinganotrypa X X Hyalotoechus X Hyphasmopora X X Iraidina X Kalvariella X --- X X Kingopora X X X Laxifenestella X X X X Leioclema X X X --- --- Liguloclema X Lyrocladia X X Mackinneyella X X X X Maychella X X X Maychellina X X Meekopora X X X Meekoporella X Minilya X X X Monotrypa X X X Morozoviella X Nematopora X Neoeridocampylus X Neoeridotrypella X X X Nickelsopora X --- --- X X Ogbinopora X X Pamirella X X X Parafenestralia X X Paralioclema X X X X X Parametelipora X X Parapolypora X --- X 222 Parastenodiscus X Paucipora X Penniretepora X X X X X Permofenestella X X Permoheloclema X X Permopora X X Picnopora X Pictatella X Pinegopora X X Polypora X X X X X Polyporella X X X Polyporellina X X Primorella X X X Prismopora X Protoretepora X X X X X Pseudobatostomella X X X X X Pseudopolypora X Ptylopora X X X Ramipora X X Rectifenestella X X X X X Reteporidra X X X Rhabdomeson X X X X Rhombopora X X X Rhombotrypella X X X Ropalonaria --- X X --- --- Ruzhencevia X Ryhopora X Saffordotaxis X 223 Sakagamiina X Septopora X X X Shulgapora X X Spinofenestella X X X X Stellahexaformis X Stenodiscus X X X --- Stenopora X X X X X Stomatopora X --- --- --- --- Streblascopora X X X X X Streblotrypa X X X Streblotrypella X X Synocladia X X X X Tabulipora X X X Tavayzopora X Thamniscus X X X Timanodictya X X X Timanotrypa X X X Triznella X X Ulrichotrypa X X X Ulrichotrypella X X Wjatkella X X CORALS Roadian Wordian Capitanian Wuchiapingian Changhsingian Acaciapora --- X Akagophyllum X X Allotropiochisma --- --- X X 224 Allotropiophyllum --- X --- X Amplexocarinia X X X X Amplexus X Araeopora X Aridophyllum X --- X Asserculinia --- X X X X Atopophyllum X Axopinnophyllum X Bradyphyllum --- X X Calophyllum X X X X Carinowaagenophyllum X Carinthiaphyllum --- X Chusenophyllum X Cladochonus X Cladopora X Cravenia X Cyathaxonia X Cyathocarinia X X --- X Cystomichelinia --- X --- X Duplophyllum X X X Endothecium --- --- --- --- X Euryphyllum X --- X Gertholites --- --- --- X Geyerophyllum X Gundarina X Hayasakaia --- --- --- X Heritschioides --- X Houchangocyathus X 225 Huayanophyllum X --- --- X Ipciphyllum X X X X Iranophyllum X X Khmeria X X --- X Leonardophyllum --- X --- X Liangshanophyllum --- X --- X X Liauria X Lonsdaleia --- X X Lonsdaleiastraea X Lophocarinophyllum X X X X Lophophyllidium X X X X X Lytvolasma X X X X Metasinopora X Metriophyllum X X X Michelinia --- X --- X X Microcyathus X Miyagiella X Monothecalis --- X Multimurinus --- X Multithecopora X X --- X Neomultithecopora X Numidiaphyllum X Omaniphyllum X Ophryphyllum X Paracaninia X X X X Paraipciphyllum X Paralleynia X Parapolythecalis X 226 Parawentzelella X X Pavastehphyllum --- X Pentamplexus X X Pentaphyllum X X X X X Petraiella X Pleramplexus --- X --- --- X Polythecalis (Polythecalis) X X Praetachylasma X Praewentzelella X X Protomichelinia --- X X X Prowentzelellites X Pseudofavosites X --- --- X Pseudohuangia --- X --- X Pseudopolythecalis X Rotiphyllum X Sakamotosawanella X X Sarcinophyllum X Sinopora X X X Soshkineophyllum X X Stereostylus X Stylidophyllum --- X Szechuanophyllum X X X Tetraporinus --- X Thamnopora X --- --- X Thomasiphyllum --- X X Tibetophyllum X X Timorphyllum X X --- X Trachypsammia X 227 Ufimia X X X X X Verbeekiella X X Waagenophyllum X X X X Waanerophyllum X Wentzelella X X Wentzelellites --- X X Wentzelloides X Wentzellophyllum X X Xizangophyllum X Yatsengia X X X Yokoyamaella X Zhenganophyllum X Zhurihephyllum --- X CRINOIDS Roadian Wordian Capitanian Wuchiapingian Changhsingian Agnostocrinus --- X Arroyocrinus --- X Basleocrinus --- X Calceolispongia --- X Cibolocrinus --- X Coenocrinus X Cyathocrinites --- --- --- X Dichocrinus --- X Embryocrinus --- X Erisocrinus --- X --- X Graphiocrinus --- X 228 Meganotocrinus X Metacalceolispongia X Metaindocrinus X Metallagecrinus --- X Monobrachiocrinus --- X Neocamptocrinus X X --- X Nowracrinus --- X Paragaricocrinus X Parspaniocrinus X Platycrinites --- X ? Stachyocrinus --- X Strobocrinus X Stuartwellercrinus --- X Tetrabrachiocrinus X Texacrinus --- --- --- X Tribrachyocrinus --- X Trinalicrinus X Tunisiacrinus X Woodocrinus --- --- --- X GASTROPODS Roadian Wordian Capitanian Wuchiapingian Changhsingian Aclisina X --- --- --- X Aiptospira X Ambozone --- X Ananias X X --- X --- Anomphalus X X --- X X 229 Apachella X X Austroscalata X Babylonites X X X Baylea X X X Bellerophon X X X X X Borestus --- --- --- --- --- Brochidium X X --- --- --- Byzantia X Callistadia X X Callitomaria X X Carinella X Ceraunocochlis X X Cibecuia X X Cinclidonema --- --- --- X Coelostylina X --- Collabrina --- --- --- --- X Colpites X X Cyclites --- X X Cyclobathmus X Cycloscena --- --- X Cylindritopsis X X X --- X Dichostasia X X Diploconcula X Discotomaria X X Discotropis X X X Donaldina --- X --- --- X Eirlysia X X X Eosinocerithium X 230 Erwinispira X Euconospira X X Euphemites X X X --- X Euphemitopsis X X X Extendilabrum X Girtyspira X --- X --- X Glabrocingulum X X X --- --- Glyptospira X --- --- --- X Glyptotomaria X X --- --- --- Goniasma X X --- X X Gosseletina --- X --- --- --- Heshanietta X Hesperiella X Hypselentoma --- --- X Ischnoptygma X Keeneia --- --- X Kinishbia X Labridens X X Lacunospira X X Lamellospira X X Laxella --- --- --- --- X Leptetopsis X X X Leptoptygma --- --- --- --- X Luciella X X --- --- Luciellina --- --- --- --- --- Luoguella X Luoguispira X Manzanospira X X X X 231 Meekospira X X X X X Microlampra X Microptychis --- --- --- --- X Mirochiliticus X Mourlonia X X X X Mourlonopsis X X X Naticasinus --- --- --- --- X Naticopsis X X X X X Natiria --- X Ninglangella X Omphaloptychia --- --- --- --- --- Omphalotrochus --- --- X Orthonema X X --- --- X Palaeostylus X --- X X X Pandospira --- --- X Pernotrochus X Peruvispira X X X X X Pharkidonotus X Phymatopleura --- --- X X Planotectus X X Platyceras X X X Platyteichum X X X --- X Platyworthenia X X Platyzona X X --- --- X Plicatus X Ploceozyga --- --- --- X X Polygyrina X X Porcellia --- --- X X X 232 Propupaspira X Pseudozygopleura --- X X --- X Ptychobellerophon X Ptychomphalina X --- X Ptychosphaera X Retispira X X X X X Rhabdocantha X Rhabdotocochlis --- --- --- X Sallya X X Scutularia X Shedhornia X Shwedagonia X X Soleniscus --- X X X X Spinella X Spirocyclina --- --- --- --- --- Spironemella --- --- X X Spiroscala X Spirovallum --- --- --- --- X Stachella --- --- --- --- --- Stegocoelia X X X --- X Straparella --- --- --- --- X Straparollus X X --- X Streptacis --- --- X X X Strianematina X Strobeus X X --- X X Strotostroma X Stuoraxis X Tapinotomaria X X 233 Tetrabubispira X Trachydomia --- --- --- --- X Trachyspira --- X X --- X Trypanostylus --- --- --- --- --- Tunstallia X Walnichollsia --- X X Warthia X X X --- --- Worthenia X X X --- --- Yunnania --- --- --- --- --- Zhonguaspira X X NAUTILOIDS Roadian Wordian Capitanian Wuchiapingian Changhsingian Alexandronautilus X Aphelaeceras --- --- --- --- X Aulagonoceras X Aulametacoceras --- --- --- --- --- Bitaunioceras --- X Brachycycloceras --- X --- --- X Coelogasteroceras X --- --- X X Cooperoceras Dolorthoceras --- --- --- X X Domatoceras X --- --- X X Ephippioceras Foordiceras --- X X X X Gaolingoceras X Hunanoceras X X 234 Liroceras --- X --- X X Lopingoceras --- --- --- X X Mariceras Metacoceras X X --- X X Michelinoceras --- X --- X X Mooreoceras X X Neoclavinautilus X Neocycloceras --- --- --- X X Neotainoceras X Nodonautilus X Nodopleuroceras X X Paranautilus X X Paratylonautilus X Peripetoceras --- --- --- X X Permonautilus X X Pleuronautilus X X X X Pselioceras X X Pseudorthoceras X X --- --- X Pseudotemnocheilus X Pseudotitanoceras X X Siamnautilus X Stearoceras X X X X X Stenopoceras X --- --- X X Styrionautilus X Syringonautilus X X Tainionautilus X X Tainoceras X X X X X Temnocheilus --- X --- X X 235 Tirolonautilus X X Titanoceras --- --- --- X Tylonautilus --- --- --- --- X SPONGES Roadian Wordian Capitanian Wuchiapingian Changhsingian Acoelia X Actinocoelia --- X --- --- X Ambithalamia X Amblysiphonella --- X X X X Amphorithalamia X Anthracosycon --- X Auriculospongia X Belyaevaspongia X X Bicoelia --- --- X Bisiphonella X --- --- X Bothroconus X Carphites X Catenispongia --- X Cavusonella X X --- X Celyphia X X --- Chaunactis --- X Chinaspongia X Coelocladia --- --- --- --- X Coelocladiella --- --- --- X Collatipora X X X Colospongia --- X X X X 236 Corynospongia X Crymocoelia X Cryptocoelia X --- Cystauletes --- X X X X Cystothalamia --- X X X X Daharella X Defordia --- X Discosiphonella --- X --- --- X Djemelia X Docoderma --- X Enoplocoelia X Estrellospongia X Exaulipora X Exotubispongia X Fistulosponginina X Follicatena X --- Gigantospongia X Girtyocoelia --- X X X X Glomocystospongia X --- --- X Graminospongia X --- --- X Grossotubenella X X Guadalupia X X Haplistion X X --- X Heliospongia --- X X Henricellum X --- Heptatubispongia --- X Huayingia X Imbricatocoelia X --- X X 237 Imperatoria --- X Incrustospongiella X Intrasporeocoelia X X X X Intratubospongia X X --- X Jereina X X Lemonea --- X X Lichuanospongia X X Maeandrostia --- --- --- --- X Medenina X Microsphaerispongia X Minispongia X X Multistella X Neoguadalupia X Neoheliospongia X X X Oculospongia X --- --- --- Paradeningeria X --- --- --- Parahimatella X Parauvanella --- X X --- X Paronadella X --- --- --- Permocorynella X --- --- X Phraethalamia X Pisothalamia X Platythamiella X X --- X Polycystocoelia X --- X X Polyedra X Polyophidium X Polytubifungia X Precorynella X --- --- X 238 Preeudea X Preperonidella --- X X X X Prestellispongia X Preverticillites X X X X Pseudoamblysiphonella X Pseudoguadalupia X Pseudohimatella X Pseudomultistella X Pseudovirgula X Pseudovirgulopsis X Raanespongia X Radicanalospongia X Radiofibra X Radiotrabeculopora --- X --- --- X Rahbahthalamia X Ramostella X Rhabdactinia X X X X Ropalospongia X Saginospongia X Salzburgia --- X --- X --- Scheiella X Scheiia X Solenolmia X --- X --- Sollasia --- X X X X Solutossaspongia --- --- --- --- X Sphaerocoelia X --- --- --- Sphaeropontia X Spinospongia X 239 Stellispongiella X X --- X Stioderma --- X X Stromatidium X Stylocoelia X Stylothalamia X --- --- --- Subascosymplegma X --- X X Tebagathalamia X --- --- X Thallospongia X Thaumastocoelia --- X X X --- Tongluspongia X Toomyeospongia X Tristratocoelia X X --- X Uvanella X --- --- X Uvothalamia X Vermispongiella X Vesicocaulis X --- --- --- Vesicotubularia X Virgaspongiella X Virgola X X --- X Welteria X --- --- --- Wewokella --- X --- X TRILOBITES Roadian Wordian Capitanian Wuchiapingian Changhsingian Acanthophillipsia X X Acropyge X --- X X Ampulliglabella X 240 Anisopyge X X X Cheiropyge --- --- X X X Delaria X X X Ditomopyge --- --- --- X Endops X Hildaphillipsia --- X Iranaspidion X Kathwaia X --- X X Microphillipsia X Neogriffithides --- X Neoproteus --- X Nipponaspis --- --- X Novoameura --- X Paraphillipsia --- X X X X Permoproteus X Pseudophillipsia X X X X X Timoraspis X Triproteus --- X Vidria X X
Abstract (if available)
Abstract
The replacement of Paleozoic brachiopod-dominated marine benthic communities by post-Paleozoic assemblages dominated by molluscs was one of the most significant ecological transitions in the Phanerozoic, completely restructuring benthic ecosystems and paving the way for modern marine communities. The timing of the abrupt diversity switch has been tightly constrained to the catastrophic mass extinction at the Permian-Triassic boundary. In contrast, the shift in ecological dominance, as measured by relative abundance in marine communities, has only been assumed to be synchronous with the taxonomic change. This assumption ignores environmental changes throughout the Permian as well as potential effects of the earlier end-Guadalupian extinction (at the end of the Middle Permian). In order to test whether the ecological transition was contemporaneous with the end-Permian taxonomic shift, I quantified Permian community change based on fossil assemblages collected from the western United States (Early and Middle Permian, 15 samples), Greece (Late Permian, 6 samples), and China (Late Permian, 6 samples). All assemblages were derived from offshore carbonate deposits formed in tropical environments.
Linked assets
University of Southern California Dissertations and Theses
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Asset Metadata
Creator
Clapham, Matthew Eric
(author)
Core Title
Community paleoecology and global diversity patterns during the end-Guadalupian extinction (middle-late Permian) and the transition from the Paleozoic to modern evolutionary faunas
School
College of Letters, Arts and Sciences
Degree
Doctor of Philosophy
Degree Program
Geological Sciences
Publication Date
09/28/2006
Defense Date
08/03/2006
Publisher
University of Southern California
(original),
University of Southern California. Libraries
(digital)
Tag
Guadalupian,Lopingian,mass extinctions,molluscs,OAI-PMH Harvest,paleoecology
Language
English
Advisor
Bottjer, David J. (
committee chair
), Caron, David A. (
committee member
), Corsetti, Frank A. (
committee member
), Fischer, Alfred G. (
committee member
)
Creator Email
clapham@usc.edu
Permanent Link (DOI)
https://doi.org/10.25549/usctheses-m48
Unique identifier
UC148537
Identifier
etd-Clapham-20060928 (filename),usctheses-m40 (legacy collection record id),usctheses-c127-13445 (legacy record id),usctheses-m48 (legacy record id)
Legacy Identifier
etd-Clapham-20060928-0.pdf
Dmrecord
13445
Document Type
Dissertation
Rights
Clapham, Matthew Eric
Type
texts
Source
University of Southern California
(contributing entity),
University of Southern California Dissertations and Theses
(collection)
Repository Name
Libraries, University of Southern California
Repository Location
Los Angeles, California
Repository Email
cisadmin@lib.usc.edu
Tags
Guadalupian
Lopingian
mass extinctions
molluscs
paleoecology