EDITORIAL PREFACE ·i·

TRILOBITE RECORD OF CHINA

Edited by Zhou Zhiyi and Zhen Yongyi

Funded by

Ministry of Science and Technology, PRC Chinese Academy of Sciences National Natural Science Foundation of China

Science Press Beijing

·ii· Trilobite Record of China

Responsible Editress: Hu Xiaochun

Copyright © 2008 by Science Press

Published by Science Press http://www. sciencep. com 16 Donghuangchenggen North Street Beijing 100717 P. R. China

Printed in Beijing, 2008

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the copyright owner.

ISBN 978-7-03-022175-9

EDITORIAL PREFACE ·i·

EDITORIAL PREFACE

In the light of researches published up to 2005, this book aims to provide a review and a complete list of Chinese trilobite genera (or subgenera) with new information about their temporal and spatial distributions, in order to amplify the data compiled by Lu et al. (1965) in the Trilobites of China. We hope that our effort herein will be of significance for palaeontologists who wish to roam about the Chinese trilobite kingdom with ease. Lu et al. (1965) dealt with 376 trilobite genera that were known in China before 1963. By the beginning of 2006, however, there are altogether 1677 genera (or subgenera) recorded in China, with an increase of available generic (or subgeneric) names by 350% in the last 40 years. Many of these newly proposed taxa were published in various regional palaeontological atlases during the late 1970’s and early 1980’s with no full literature review undertaken, and the precise occurrences for most of them were not known. Some of them were even established on poorly preserved, fragmentary, or insufficient specimens, with morphological characters difficult to interpret. A radical revision of the Chinese trilobites is therefore required, and through the collective revisions presented in various chapters of this book, 1317 genera (or subgenera) belonging to 166 families are recognized as valid. The work is largely based on NIGP collections made from the type localities or nearby areas, from which the relevant original specimens were collected. Most of these Chinese trilobite genera were listed by Jell & Adrain (2003) with indication of their known synonyms, and two trilobite orders (Agnostida and Redlichiida) including Agnostina (Shergold & Laurie, 1997), Eodiscina (Jell, 1997), and Redlichiina (Chang et al., 1997) were revised in the second edition of the Treatise on Invertebrate Paleontology edited by R. L. Kaesler (1997). These two comprehensive works have added significant amount of new data to our knowledge and provided us with much valuable information on Chinese trilobites.

Layout

This volume has been prepared since 1996 on the basis of data from the literature published before the end of 2004 and unpublished collections made more recently by the authors of various chapters in the volume, whose work was then coordinated and supplemented by us during 2005–2006. Except for the Cambrian agnostoids that are dealt with in an independent chapter (Chapter 2), Chinese trilobites are separately assembled into eight chapters according to their chronostratigraphic and/or bathymetric occurrences. There are different points of view held by authors of different chapters on the synonymies or the familial assignment of some genera, or even on the generic assignment of some species (see Chapter 11 for details). We have laid stress on uniformity of the presentation, style and format, as well as continuity of the overall account. However, each chapter may be read as a self-contained paper in its own right, and retains its individual viewpoints on the classification and synonymies of the relevant trilobite genera (or subgenera). As some chapters are closely related in contents, a few genera (or subgenera) may repeatedly be listed in different chapters, especially in the chapters 5 and 7. It is however inevitable. Each of these chapters consists mainly of two sections. One is the list of the genera (or subgenera) that were erected based on Chinese material. The other is allocated for a systematical list of all the trilobite genera (or subgenera) that have been recorded in China. At last, based on the updated data, the chronostratigraphic ranges of trilobite families, and the familial and generic biodiversity changes through the Palaeozoic in China are briefly reviewed in Chapter 11.

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Alphabetical list

The available generic (or subgeneric) names, including both invalid (in italics) and valid (in boldfaced Roman letters), are alphabetically listed, and each followed by the author(s) and year of publication, and then in square brackets by the type species (prefixed with *) and its type specimen, horizon (series, stage, or biozone) and locality. In case of the entry of an invalid genus (or subgenus), a suggested senior subjective or objective synonym, or replacement name, is indicated, and, where necessary, a brief discussion is given at the end of the item. However, if authors do not accept some synonymies proposed in the literature, we may not quote the suggestions in the relevant chapters. For example, Fatocephalus and Yuepingia are both simply listed as valid genera in the chapters 6 and 7, regardless of the opinions of Jell (1985), Hughes & Rushton (1990) and Jell & Adrain (2003), who considered Fatocephalus and Yuepingia as junior subjective synonyms of Pseudokainella and Haniwoides respectively.

Systematic list

Genera (or subgenera) are grouped into families (or, in some cases, subfamilies), but their higher-level classification is omitted. Families and assigned genera (or subgenera) are again listed in alphabetical order, and each genus (or subgenus) is followed by the junior synonym(s) (if any) listed in square brackets. Next are data on the taxon’s chronostratigraphic and geographic occurrences, but those on lithostratigraphic horizons are, in general, omitted, as readers may reach the relevant information from the cited systematic publications. A full species list for most of the taxa is skipped, except for those from the Silurian. However, in most cases, if species that need to be transferred from one genus (or subgenus) and reassigned to another on the basis of critical revisions, detailed citations of those species names are given in the relevant entries. The temporal range of each genus (or subgenus) is further summarized in the attached table with indication of the tectonic or geographic unit(s) in which it occurs. In each table, geological ranges of the taxa are represented by thick or dotted lines that indicate respectively the confirmed or inferred occurrences; dashed lines signify gaps within ranges through which a genus or subgenus is assumed to continue; arrows indicate that the forms extend beyond ranges shown. Although major international Palaeozoic chronostratigraphic units have been established, some units within Cambrian and Ordovician remain to be formally named upon their GSSP delimitation (Gradstein et al., 2004). In this regard, international series (epoch) and stage (age) names are preferred for dating the Silurian-Permian trilobites, but some traditional or provincial Cambrian and Ordovician chronostrati- graphic units have to be employed in this volume (see Chapter 1 for details) for the time being. Chronostratigraphic ranges of the Cambrian and Ordovician genera (or subgenera) are given as time intervals defined by international or provincial biozones, while of the Silurian-Permian forms as stages only. In the text, we give each genus (or subgenus) a geographic assignment to region (e.g. North China) or province (e.g. Shanxi) or nearby city (e.g. Huocheng), but more often it is further designated to part of a province (e.g. southern Shaanxi). However, as there are no physical boundaries to formally define these geographical areas within a province, some trilobite localities, such as Taian and Fuxian, may respectively be described as central Shandong and eastern Liaoning in one chapter but as western Shandong and southern Liaoning in the other. It should also be noted that Chongqing has become an administrative division that is independent of the Sichuan Province since 1997. It covers a wide area that was previously part of eastern Sichuan, from which quite many trilobites had been described. In this account, Chongqing is only quoted in chapters 8 and 9, but in other chapters authors prefer to follow the original literature in referring the relevant trilobite locations to as northeastern or southeastern Sichuan. The adoption of these dissimilar toponomical usages by different authors seems unavoidable and we prefer to maintain what they are using in the different chapters. In dealing with the spatial occurrence of trilobites, we consider it the most important to clarify their distribution in relation to the coeval tectonic or geographic units. For this reason, four maps to outline the related units are provided (Figs 1.3 to 1.6).

Editorial preface ·iii·

Bibliography and citations

Cited references are listed in alphabetical order, including almost all the publications on (or related to) the taxonomy of Chinese trilobites. Those published in Chinese or in Russian are translated into English with indication of the original language at the end of the relevant items. According to convention, Chinese authors are listed family name first, which is directly followed by full given name. There were no regulations for the transliteration of Chinese characters into Roman letters before 1978, but the situation has been changed since then when the Chinese Government issued a standard to guide the spelling of Chinese names. Therefore, some authors’ names such as Chang, Chu and Chien that appear in the earlier literature may be changed respectively into Zhang, Zhu and Qian in their later publications. In this volume, we prefer to retain the spelling that a Chinese author has used in each of his (her) original issue, and it may help readers access and trace the exact reference without any confusions. As a result, publications of a Chinese author may be listed in two places, but, in that case, one may find his (or her) variant name indicated within brackets in the author’s earlier publication list. Among others, there are, for example, at least nine separate authors with the family name Zhang, and six with Zhou, whose publications are frequently cited in the text. One may expect a possible confusion among readers when they want to readily find a specific reference. For the purpose of an easy entry into the literature, citation of reference in the text is listed as a combination of the author’s family name and the year of publication. In case of authors with the same family name, who published their papers in the same year, authors’ full names are quoted, such as Zhang Jinlin, 1985 and Zhang Wentang, 1985, and Lin Huanling et al., 2001 and Lin Tianrui et al., 2001. If one or two authors published more than one papers in the same year, the listed year is suffixed by a, b, c and so forth, such as Lu, 1954a, 1954c, and Zhang & Liu, 1986a and 1986b. Publications with three authors referred to the bibliography are further arranged in alphabetical order of the surname of the second author, but those with more than three authors in chronological order. They are generally cited in the text as the senior author and others (e.g. Guo et al., 1996 and Lin et al., 1992). However, in case the first author published several papers in the same year along with two, as well as more than two other authors, different patterns of citation are expressed, such as Peng, Babcock & Lin, 2001a, b and Peng et al., 2001a, b. In order to remove any possible confusion, in the reference list, where necessary, the form of citation used in the text is also indicated in the square brackets at the end of the relevant reference item.

Repositories and their abbreviations

The cited type specimens are deposited at institutions designated by the following abbreviations:

CIGM Chengdu Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Chengdu. CMG China Museum of Geology, Beijing. CUGB China University of Geosciences, Beijing. CUGW China University of Geosciences, Wuhan. DGBU Department of Geology, Beijing (Peking) University, Beijing. EM Geology Department, I’Universite Claude Bernard-Lyon, I-O. N. C. P., France. EPTG The Eighth Petroleum Prospecting Team, Guiyang. ESNU Department of Earth Sciences, Nanjing University, Nanjing. GCSE Geological Centre of Shanghai Economic Zone, Shanghai. GCUX College of Geological Sciences, Chang’an University, Xi’an. GIG Gansu Institute of Geological Sciences, Lanzhou. GIT Guilin Institute of Technology, Guilin. GNWU Department of Geology, Northwest University, Xi’an. GPFU Institute of Geo-palaeontology, Freiburg University, Freiburg. GSHW Geological Survey of Hubei Province, Wuhan.

·iv· Trilobite Record of China

GSHZ Geological Survey of Henan Province, Zhengzhou. GSI Geological Survey of India, Calcutta. GSJN Geological Survey of Jiangxi Province, Nanchang. GSXU Geological Survey of Xinjiang Uygur Autonomous Region, Ürümqi. GUTG Guizhou University of Technology, Guiyang. HIGC Hunan Institute of Geological Sciences, Changsha. HIGW Hubei Institute of Geological Sciences, Wuhan. HIGZ Henan Institute of Geological Sciences, Zhengzhou. HMB Museum of Natural History, Humboldt-University, Berlin. IGGS Institute of Geology, Chinese Academy of Geological Sciences, Beijing. KGS Kunming Geological School, Kunming. NIGM Nanjing Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Nanjing. NIGP Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing. NMV National Museum of Victoria, Australia. RCPJ Research Centre of Palaeontology, University of Jilin, Changchun. SIGM Shenyang Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Shenyang. SMNH Shanghai Museum of Natural History, Shanghai. SPTC The Second Petroleum Prospecting Team, Chongqing. TIGM Tianjin Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Tianjin. TIU Tohoku Imperial University, Tohoku. UMUT University Museum, University of Tokyo, Tokyo. USNM U. S. National Museum, Washington, D. C. XIG Xinjiang Institute of Geological Sciences, Ürümqi. XIGM Xi’an Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Xi’an. XUST Xi’an University of Science and Technology, Xi’an. YIG Yunnan Institute of Geological Sciences, Kunming. YIGM Yichang Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, Yichang. ZIPG Zhejiang Institute of Petroleum Geology, Hangzhou.

Postscript

Just after the manuscripts of the book have been finalized and accepted for publication, two homonyms, Drepanura and Pionaspis, were further identified from the Chinese trilobite generic names by Özdikmen (2006) and Yang & Peng (2007). According to their suggestion, the replacement names for the preoccupied Drepanura Bergeron, 1899 and Pionaspis Zhang in Qiu et al., 1983 are respectively Neodrepanura Özdikmen, 2006 and Kiyakius Özdikmen, 2006. In this volume, Drepanura is dealt with in chapters 6 and 7 as a valid genus, while Pionaspis is listed in the Chapter 6 as a junior subjective synonym of Blackwelderia Walcott, 1906. As the time concerned, we are not able to make these corresponding changes in the related text and figures before the manuscripts get to print. However, we are able to add Neodrepanura as a valid genus and Kiyakius as an invalid name (a junior subjective synonym of Blackwelderia) in the index.

Acknowledgements

Research was financially supported by the Chinese Academy of Sciences (KZCX3-SW-149), the Ministry of Science and Technology, PRC (2006FY120400, 2006CB806402, G99-A-04, 2001DEB20056)

Editorial preface ·v· and the National Natural Science Foundation of China (No. 40272001, 40532009). Publishing of the work is partly sponsored by the Science Publication Fundation of the Chinese Academy of Sciences. We wish to express our deep indebtedness to the authors for their willingness to contribute and for their patience in carrying out such time-consuming work. Special thanks are due to Lin Huanling, Yuan Jinliang and Zhou Zhiqiang for their enthusiastic assistance to the editorial work on the chapters 2 (Cambrian agnostoids), 6 (Platform-facies non-agnostoids of Late Cambrian (Kushanian, Changshanian and Fengshanian)), 7 (Cambrian (late Taijiangian–Taoyuanian) slope-facies non-agnostoids) and 9 (Silurian). We are also grateful to Nigel Hughes (preface), Luke Strotz (chapter 1), John Pickett (chapter 10), Ian Percival (chapters 5 and 11), John R. Paterson (chapters 3 and 4), Greg Edgecombe (chapter 9), Graham McLean (chapter 2), and Diane Brown (chapter 7) for reading and linguistically checking through part of the manuscripts.

Zhou Zhiyi and Zhen Yongyi September 6, 2006

CHAPTER 10 Devonian, Carboniferous and Permian ·vii·

CONTENTS

EDITORIAL PREFACE ...... Zhou Zhiyi and Zhen Yongyi i CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography...... Zhou Zhiyi and Zhen Yongyi 1 1.1 Trilobite research in China: a historical review ...... 1 1.2 Notes on the chronostratigraphy of trilobite-bearing beds...... 4 1.3 Division of geographical units...... 6 1.4 Outline of Cambrian and Ordovician trilobite biogeography ...... 11 CHAPTER 2 Cambrian agnostoids ...... Peng Shanchi 21 2.1 List of agnostoid genera (or subgenera) erected on Chinese material...... 21 2.2 Occurrences ...... 22 CHAPTER 3 Early Cambrian (Chiungchussuan, Tsanglangpuan and Lungwangmiaoan) ...... Lin Huanling 36 3.1 A brief stratigraphic review ...... 36 3.2 List of genera (or subgenera) erected on Chinese material...... 36 3.3 Occurrences ...... 51 CHAPTER 4 Non-agnostoids of the early Mid Cambrian (Maochuangian and Hsuchuangian) ...... Yuan Jinliang, Li Yue and Zhao Yuanlong 77 4.1 Zonation and correlation...... 77 4.2 List of genera (or subgenera) erected on Chinese material...... 78 4.3 Occurrences ...... 91 CHAPTER 5 Non-agnostoids of Changhian (late Mid Cambrian)...... Yuan Jinliang and Li Yue 108 5.1 Zonation and correlation...... 108 5.2 List of genera (or subgenera) erected based on Chinese material...... 109 5.3 Occurrences ...... 119 CHAPTER 6 Platform-facies non-agnostoids of Late Cambrian (Kushanian, Changshanian and Fengshanian) ...... Zhu Zhaoling 136 6.1 List of genera (or subgenera) erected on Chinese material...... 136 6.2 Occurrences ...... 145 CHAPTER 7 Cambrian (late Taijiangian–Taoyuanian) slope-facies non-agnostoids ...... Peng Shanchi 162 7.1 List of polymerid genera (or subgenera) erected on Chinese material ...... 162 7.2 Occurrences ...... 173 CHAPTER 8 Latest Cambrian and Ordovician...... Zhou Zhiyi and Zhou Zhiqiang 208 8.1 Notes on the stratigraphic framework...... 208 8.2 List of genera (or subgenera) erected on Chinese material...... 211 8.3 Age and occurrences...... 223 CHAPTER 9 Silurian...... Lin Tianrui 275

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9.1 List of genera (or subgenera) erected on Chinese material...... 275 9.2 Occurrences ...... 277 CHAPTER 10 Devonian, Carboniferous and Permian...... Yuan Jinliang and Li Yue 285 10.1 List of genera (or subgenera) erected on Chinese material...... 285 10.2 Occurences...... 288 CHAPTER 11 History of trilobite biodiversity: a Chinese perspective ...... Zhen Yongyi and Zhou Zhiyi 301 11.1 Data and analytical methods ...... 301 11.2 Origin...... 309 11.3 Diversity...... 310 11.4 Radiation events...... 317 11.5 Extinction events...... 322 11.6 Conclusions...... 330 REFERENCES ...... 331 INDEX...... 381 CONTRIBUTORS...... 402

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·1·

CHAPTER 1

Introduction with reference to previous work, stratigraphical and geological settings, and biogeography

Zhou Zhiyi and Zhen Yongyi

Trilobites are fascinating animals belonging to an extinct group of the earliest marine arthropods. They first appeared during the Early Cambrian “explosive” radiation of biota and flourished in the Palaeozoic, but did not survive the end Permian mass extinction. They played an important role in the macroevolution of the Cambrian Evolutionary Fauna and Palaeozoic Evolutionary Fauna (e.g. Sepkoski, 1981; Adrain et al., 1998). Trilobites are most numerous and diversified in rocks of Cambrian and Ordovician age, making up the dominant component of the fauna, though declining progressively in numbers and diversity thereafter. Because of their common occurrence in many sequences and the possession of various exoskeleton features that provide the basis for a detailed taxonomy, trilobites have long been considered as strati- graphically valuable fossils. Their zonal successions, recognised in different Palaeozoic plates, meet with the basic requirements, either regionally or internationally, for the division and correlation of bio-/chrono- stratigraphy. Trilobites have also served as palaeobiogeographical and environmental indicators. During their long history, about 300 m.y., trilobite distribution ranged from low to high palaeolatitudes and they occupied most marine habitats from the inner-shelf to the off-shelf. There are no other Palaeozoic macrofossil groups that have such a wide geographic spread (Fortey & Owens, 1997). Various trilobite biofacies have been recognized in the Palaeozoic for all the major palaeocontinents, with each characterized by a particular association of forms that may suggest a localised environment. Many trilobites, especially those from the inner-shelf facies, are considered endemic but characteristic of extensive palaeogeographic areas (for example, the Ordovician Gondwana, see Zhou & Dean, 1989). Their distributions have provided significant evidence for outlining and reconstructing Early Palaeozoic palaeobiogeography and palaeocontinents (e.g. Whittington & Hughes, 1972; Fortey & Cocks, 2003). China has extensive exposures of Palaeozoic deposits, with many complete stratigraphic sequences and extremely abundant occurrences of trilobite faunas. Chinese palaeontologists have been active in trilobite systematics and biostratigraphy and have become increasingly involved in studies of trilobite biofacies, palaeobiogeography and palaeobiology in the past three decades. All of this research has brought about a substantial advance in trilobitology. Because of their morphological attraction and scientific importance, trilobites have received extensive and intensive studies in China and other countries. Currently, there have been more than 5000 genera recorded worldwide (Jell & Adrain, 2003), with over one-fifth (up to 1120 genera or subgenera) of that total erected based on Chinese material.

1.1 Trilobite research in China: a historical review

Chinese trilobites were described for the first time by Dames (1883) on the basis of Richthofen’s collections made from the Cambrian sequences of Liaoning, southern Northeast China. Five genera and

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16 species were described in this work. However, it was not until the early 20th century that systematic descriptions of Chinese trilobites were published. The pioneer works carried out by Walcott (1913) and Sun (1924) laid a foundation for further research on the Cambrian trilobite faunas of North and southern Northeast China. During the 1930–1940’s, more Cambrian trilobites were further described from North (Sun, 1935) and southern Northeast (Endo, 1937, 1944; Resser & Endo, 1937; Kobayashi, 1931, 1933b, 1935) China. Troedsson (1937) dealt with Cambrian and Early Ordovician trilobites collected by Norin, the head geologist of the Sino-Swedish Expedition in Central Asia (1927–1934), from Kuruktag, southeastern Tianshan, Xinjiang. His work has been regarded as the first descriptions of Chinese slope-facies trilobite faunas. Studies on trilobites from the Ordovician (Grabau, 1922; Sun, 1931; Sheng, 1934; Gortani, 1934; Wang, 1938b; Hsü, 1948a; Chang, 1950 (for 1949)), Early Cambrian (Lu, 1941, 1942, 1946), Silurian (Grabau, 1924, 1925; Wang, 1938a; Chen, 1948) and Late Palaeozoic (Grabau, 1936; Sun, 1937; Wang, 1937) were also initiated in this period. The second half of the 20th century witnessed the rapid development of trilobite taxonomy in China. Following the regional geological survey investigation and exploration of mineral resources undertaken in vast areas of China during this period, detailed stratigraphic work was carried out, with a large quantity of fossil collections made from most provinces. In order for this work to be comprehensive, research on stratigraphically valuable fossils, including trilobites, was therefore required. During the first three decades (1950–1970’s) of this period, a total of 137 trilobite articles were published. In the last two decades (1980–1990’s) of the 20th century, taxonomic work was accelerated, due to an increase in the number of active trilobite workers and wider international cooperation. This gave rise to a rapid increase in published studies, with 294 papers published on the trilobites from various ages and regions. Since 2001, the number of trilobite-related publications has reduced to 61, due to a decrease in the number of active trilobite workers. Many of these papers provided significant descriptions for the regional trilobite faunas of the Cambrian (Southwest and Central China: Chang, 1953; Ho & Li, 1959; Lu, 1961; Chang, 1966b; Luo et al., 1994; North and southern Northeast China: Lu, 1954a; Chang, 1959, 1963; Guo & Duan, 1978; Qiu, 1980; Zhang & Yuan, 1981; Zhang & Wang, 1983; Zhou & Zheng, 1980; Nan & Chang, 1985; Lu et al., 1988; Zhang & Liu, 1991; Lu & Zhu, 2001; Kuruktag Mountains of eastern Xinjiang: Zhu & Lin, 1983), Ordovician (Southwest and Central China: Yi, 1957; Sheng, 1958, 1964; Zhou, Yin & Tripp, 1984; Ji, 1986; Zhou & Xiang, 1993; Yin et al., 2000; Zhou, Zhou & Yuan, 2005; northern Tarim of Xinjiang: Zhou, Webby & Yuan, 1995; Zhou et al., 1994; Zhou, Zhou & Yuan, 1998), Silurian (Southwest and Central China: Wu, 1977, 1979; northern Northeast China: Kuo, 1962), Devonian (southeastern Yunnan: Luo & Jiang, 1985) and Carboniferous (southwestern Guizhou: Yuan, 1996). Some studies recorded newly discovered faunas from areas where trilobites were poorly known previously, such as from the Cambrian of the Qilian Mountains (Chu, 1960a, b, c; Chu, 1965), eastern Guizhou and western Hunan (Lu, 1954c; Chien, 1961; Peng, Lin & Chen, 1995; Yuan & Yin, 1998), central and southern Anhui (Lu & Zhu, 1980; Qian, 1985b), Dabashan Mountains (Lee, 1972), southern Hainan (Sun, 1963; Chu & Lin, 1978; Lin & Jago, 1993), northern Northeast China (Duan & An, 2001), and western Yunnan (Sun & Xiang, 1979; Luo, 1982, 1983); from the Ordovician of western Yunnan (Sheng, 1974b; Zhou, Dean & Luo, 1998), southern Tibet (Chien, 1976; Yang, 1990), and Hinggan Mountains (Nan, 1985a, b); from the Silurian (Wu, 1987) and Devonian (Zhou Zhiqiang, 1987) of western Qinling Mountains; and from the Carboniferous of western Yunnan (Yuan, 1984), and Junggar, northeastern Xinjiang (Wu & Feng, 1991). A large number of monographic works published during the last 50 years should be considered among the most fundamental documentations of the trilobite faunas from various regions. These include intensive studies on the Cambrian trilobite faunas from North and southern Northeast China (Chu, 1959; Zhang et al., 1980a; Sun, 1989; Zhu & Wittke, 1989; Qian, 1994; Zhang et al., 1995; Guo et al., 1996), Southwest and Central China (Zhang et al., 1980b), eastern Guizhou and western Hunan (Egolova et al., 1963; Yang, 1978; Lu & Qian, 1983a; Peng, 1987, 1992; Peng & Robison, 2000; Yuan et al., 2002; Peng, Babcock & Lin, 2004a, b), western Zhejiang (Lu & Lin, 1989), eastern Qinling and Dabashan Mountains (Yang et al., 1991, 1993), Ejin Qi of western Inner Mongolia (Lu et al., 1986) and Borohoro Mountains of

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·3· western Xinjiang (Xiang & Zhang, 1985); on the Ordovician trilobite faunas from Southwest China (Lu, 1975), North and southern Northeast China (Zhou & Fortey, 1986), Qilian Mountains (Chang & Fan, 1960), western Hunan (Peng, 1990a, b), southern Jiangsu (Tripp et al., 1989), eastern Gansu (Zhou & Dean, 1986), northwestern Tarim of Xinjiang (Zhou et al., 1998) and Hinggan Mountains (Zhao et al., 1997); on the Silurian trilobite faunas from Southwest China (Zhang Wentang, 1983, 1986a); on the Devonian trilobite faunas from Guangxi and southern Guizhou (Yuan, 1988) and Ejin Qi of western Inner Mongolia (Zhou & Campbell, 1990; Zhou, Siveter & Owens, 2000); and on the Carboniferous trilobite faunas from Guangxi (Yuan & Li, 1995). Some Chinese trilobites have been comprehensively revised since the 1960’s. Lu et al. (1965) systematically revised the trilobites known from China before 1963. Zhang & Jell (1987) re-described the Cambrian trilobites based on well-documented large collections made from North and southern Northeast China and now housed in the Smithsonian Institution. Chang et al. (1997) re-diagnosed all the genera of Redlichiina. These three momentous studies brought about a great advance in Chinese trilobite research. Significant revision work also includes Lu (1962) for the Silurian trilobites, Chang & Jell (1983), Zhou Zhiyi (1987) and Zhou & Hughes (1989) for the Ordovician trilobites and Lane et al. (1988) for the Cambrian trilobites. During the last 30 years, rigorous investigations have been conducted in China on systemic geological boundaries. This gave rise to exhaustive studies on the trilobite faunas across the Cambrian-Ordovician boundary (Zhou & Zhang, 1978; Lu et al., 1981; Lu & Lin, 1984; Peng, 1984; Lu & Zhou, 1990; Lin Tianrui et al., 2001), the Devonian-Carboniferous boundary (Yuan & Xiang, 1998), and the boundaries of Cambrian stages (Yuan et al., 1997; Peng, Babcock & Lin, 2001b; Peng et al., 2001a). As a result, our knowledge of those previously poorly known trilobite faunas is now much improved. It is also worthy of note that a series of regional or provincial palaeontological atlases were published, particularly in the late 1970’s and early 1980’s, with a great number of trilobites recorded and many new forms erected. Although information on precise localities and horizons was not well documented for most of the taxa, these volumes did provide a wealth of data on the geological and geographical distributions of Chinese trilobite faunas. As a whole, the classification, construction and geographic and geological distribution of the Chinese trilobite faunas have yet been generally outlined. This volume deals with 1677 trilobite generic and subgeneric names, of which 1317 are considered as valid. Altogether 1120 from 1677 genera and subgenera were proposed on the basis of Chinese material, but, after a critical revision, 367 of them are proved to be junior synonyms and only 753 of them are recognized as valid (Fig. 1.1) (Note that there are different views held in different chapters about validity of seven names. If one counts them as valid, the number of invalid names will then be 360). The rate of increase in the number of described Chinese taxa is almost synchronous with the development of trilobite studies and is in direct proportion to the increase in the number of publications. Up to 518 Chinese genera and subgenera were erected during 1976–1985 (Fig. 1.1). This is obviously due to the “atlas effect”. However, the early 21st century saw a marked reduction in the number of new names introduced (Fig. 1.1), with this attributed to the decrease in the number of published studies. In addition to taxonomic work, trilobite research in China also involved the ontogeny and phylogeny (Lu, 1939, 1940, 1963, 1964; Kobayashi & Kato, 1951; Chien, 1958; Zhang et al., 1980b; Qian, 1982; Lu & Wu, 1982, 1983; Zhang Xiguang, 1987; Yi, 1988; Zhou et al., 1994; Yuan et al., 2001, 2003; Peng et al., 2003a; McNamara et al., 2003, 2006), morphology of exoskeleton (Lu & Zhou, 1979; Chang, 1979; Han, 1980; Zhou Zhiyi, 1981; Peng, Lin & Li, 2000; Turvey, 2005b), enrollment and coaptative structure (Han, 1978, 1983a, 1984, 1989, 1993a, b, 2002), exuviations (Han & Wang, 1997, 2000), eyes (Zhang & Clarkson, 1990; Han, 2001), biofacies, mode of life and taphonomy (Zhou et al., 1979; Zhou, Zhou & Zhang, 1989; Zhou et al., 1990, 1992, 2000, 2003, 2004; Zhou, Zhou & Yuan, 1999, 2000, 2001; Yuan Wenwei et al., 2000; Turvey & Zhou, 2002, 2004a, b; Turvey, 2005c), biogeography (Lu et al., 1974a, 1976; Yang, 1988b; Zhou & Dean, 1989; Zhang, 2003; Turvey, 2005c), and biodiversification events (Zhou, 2003, 2004; Zhou et al., 2004, 2006). Many of these studies have added much to our knowledge of Chinese trilobites.

·4· Trilobite Record of China

Figure 1.1 Histograms showing the numbers of the genera and subgenera erected on the basis of Chinese material every five years from 1883 to 2006.

1.2 Notes on the chronostratigraphy of trilobite-bearing beds

In this volume we summarize the present knowledge of the chronostratigraphical distribution of Chinese trilobites. Detailed discussion on the division and correlation of the lithostratigraphy and biostratigraphy of trilobite-bearing strata is omitted in the ensuing chapters. However, relevant reference is made to recently published accounts, and readers are referred to those for references to earlier literature.

1.2.1 Silurian–Permian The international Palaeozoic chronostratigraphic units have long been established for Silurian and Upper Palaeozoic rocks. The age determination of the trilobite-bearing strata follows Chen & Rong (1996), Ni et al. (1996), Rong & Chen (2003), and Zhou et al. (2004) for the Silurian, Liao & Ruan (2003) for the Devonian, Wang & Jin (2003) for the Carboniferous, and Jin et al. (2003) for the Permian.

1.2.2 Ordovician The Ordovician chronostratigraphic subdivisions are largely based on the zonal schemes of graptolites and conodonts. Although the work on global boundary stratotype sections and points for the Ordovician System, Series and Stages is almost complete at the time of writing this, only two stages (Tremadocian and Darriwilian) had been formally named during the preparation of Chapter 8 and, therefore, the British chronostratigraphic units (Fortey et al., 2000) were preferred for dating the listed

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·5· trilobites. However, research on the global chronostratigraphic subdivision of the Ordovician has been progressing quickly in recent years. Just after the volume was finalized, five more new stage names (Floian, Dapingian, Sandbian, Katian and Hirnantian) have been ratified by the International Commission on Stratigraphy (Chen, 2006; Chen & Bergström, 2008), and these are listed in Figures 8.1, 11.1–2 and 11.4–6 and Tables 8.1 and 11.1.

1.2.3 Cambrian Only the upper series of the Cambrian System, the Furongian and its lower stage, the Paibian have been defined and ratified by the International Union of Geological Sciences (Peng et al., 2004a, b). In this regard, traditional or provincial Cambrian chronostratigraphic units have to be employed in this account for the time being. The traditional Chinese tripartite Cambrian chronostratigraphic scheme includes 10 stages, formally proposed by Xiang et al. in 1981; however, the non-trilobite Meishucunian Stage included in this scheme was erected earlier in 1977 by Qian Yi. All the stratotype sections of the Middle–Late Cambrian lie in the North China Platform, except for those of the four Early Cambrian stages, which are situated in eastern Yunnan, an inner shelf area of the South China Block. As reviewed by Zhang (2003), there are 36 trilobite zones recognized in the Cambrian. The zonal sequence is followed in this account (chapters 3, 4, 5 and 6),

Figure 1.2 Correlation between the platform-facies and the slope-facies Cambrian series and stages of China.

·6· Trilobite Record of China

with the Inouyella Zone added at the base of the Changhian according to Yuan Jinliang et al. (2000) and the Prochungia-Paracoosia Zone (originally proposed from eastern Liaoning by Zhang, 1999) merged into the Chuangia Zone of the Changshanian (see Chapter 6). The other Chinese Cambrian chronostratigraphic standard, as recently established by Peng et al. (2000) and Peng (2000), is a four-folded scheme, including nine stages. Except for the lowermost non-trilobite series, the Diandongian, the stratotype sections are all located in the Jiangnan slope-facies belt or Jiangnan Area of the South China Block. Based on the agnostoid and polymerid trilobites, altogether 26 zones have been proposed (see Peng et al., 2000; Peng & Babcock, 2001), most of which are employed in chapters 2, 4, 5 and 7. The slope-facies trilobites have proved to be more widely spread than those from the platform-facies, and, therefore, of greater significance to correlations in worldwide scale. Specific identification may give compelling evidence of age-equivalence, but trilobite zones erected in the platform-facies succession are mostly genus-range-based and provide only a general age indication. Because of the lack of tie points, precise correlation between both Cambrian chronostratigraphic zonal sequences is still not possible yet, but a rough correlation is given in tabular form respectively in Figures 2.1, 3.1, 4.1, 5.1 and 11.3, and, accordingly, a general stage-to-stage correlation is suggested in Figure 1.2. The FAD of the conodont species Iapetognathus fluctivagus is internationally employed to define the base of the Ordovician. Critical studies on the regional zonal sequences suggest that the Cambrian- Ordovician boundary in China should fall within the trilobite Hysterolenus Zone in the slope areas or within the trilobite Yosimuraspis Zone in the North China Platform (see Chapter 8 for details). Strata between the Ordovician and the Fengshanian or the Taoyuanian are therefore assigned to an unnamed pre-Tremadocian or latest Cambrian stage in this account.

1.3 Division of geographical units

The Phanerozoic geological evolution of China is complex. The Palaeozoic history is essentially one of disintegration of the Kazakhstan Mid Plate, and of repeated rifting, dispersal, collision, amalgamation and accretion involving the southern marginal areas of the Siberia and North China plates, and the northern marginal areas of the Tarim, North China and South China plates. From the Mid Triassic onwards the geological development of China is mainly influenced by the amalgamation of western Yunnan, western Sichuan, Qinghai and Tibet into the Eurasian continent following northward subductions of the India Plate. As a result, the framework and division of tectonic or geographic units are varied in different periods. In dealing with the spatial occurrence of trilobites, it is requisite to document their distribution in relation to coeval geographic units. In China, most of the trilobite genera and subgenera occur in the Cambrian and Ordovician, with only a small percentage recorded from the Silurian and Late Palaeozoic. In this account, the updated Late Palaeozoic geographic regions (Liao & Ruan, 2003; Wang & Jin, 2003) are followed (Figs 1.5 and 1.6), and, because of the close similarity, the palaeogeographic pattern of the Ordovician is considered to be applicable also to that of the Silurian. Our attention is, therefore, concentrated mainly on exploring the division of Cambrian and Ordovician geographic units.

1.3.1 Methods in the division of Cambrian and Ordovician geographic units Similar aspects of the Chinese Cambrian and Ordovician geographic units were presented respectively by Xiang et al. (1981), Peng (2000) and Zhang (2003), and by Lai et al. (1982), Wang (1985), Wang Xiaofeng (1989), Chen & Rong (1992) and Chen et al. (1995, 2003). However, there are considerable differences amongst the previously proposed models, particularly in the extents of some units and their boundaries. In order to provide more precise data on regional assignments of the related trilobites, some of the extensive and scattered publications on Chinese regional geology are further consulted. The Cambrian and Ordovician strata of China are widely distributed in three cratonic plates (South China, North China and Tarim), and are also sporadically exposed in a number of terranes (islands, or

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·7· dislocated micro-blocks) surrounded by mobile belts of different ages (Ren et al., 1999). It is indeed a difficult task to divide the Cambrian and Ordovician tectonic or geographic regions of China, as much of the evidence has been destroyed by repeated consolidation and deformation due to later tectonic processes. As a result, the original morphology and tectonic framework of each region were changed almost beyond recognition. To outline each of the regions, it is essential to understand the regional history of stratigraphic development, distribution of coeval strata, litho/bio-facies (especially the marginal facies), configuration of palaeogeography, and the diagnostic fossils (chiefly the shallow-water endemics). In detecting boundaries between adjacent regions, it is of particular significance to trace the remains of sutural zones that represent the relics of finite ocean basins developed between the plates or terranes during the Cambrian and Ordovician, and the conjunctional zones, along which amalgamation took place in the later periods. Accordingly, 11 Cambro-Ordovician geographic regions, corresponding mainly to different allochthonous continental masses (plates and terranes), are erected herein. As described below, the patterns of the first-order geographic units of Cambrian (Fig. 1.3) and Ordovician (Fig. 1.4) are almost the same, but exhibit some differences in the subdivision of the second-order units.

1.3.2 Cambrian and Ordovician geographic regions 1) Northern Xinjiang Region, part of the mobile zone between the Siberia and Tarim plates, with the Ebinur-Kangur Fault or Eren Habirga Fault as the southern boundary, a boundary between the Tarim and Kazakhstan Mid plates during the Middle Ordovician–late Ludlow (Silurian); consisting of two terranes, the Junggar-Turpan-Hami and Altay, with no reliable Cambrian rocks reported (Lin et al., 1996a); only the Altay Terrane developed with Ordovician deposits and may have formed part of the southern marginal area of the Siberia Plate at least in the Late Ordovician (Zhou, Lin & Ni, 1996; Zhou Zhiyi et al., 1996a, b). 2) Hinggan Region, the mobile zone between the Siberia and North China plates, having the Xar Moron Fault as its southern boundary; being separated into several terranes of different ages, from two (the Ergen-Hinggan and Yichun) of which reliable Early Cambrian and Ordovician rocks are recorded (Nan et al., 1992; Zhang et al., 1994; Zhao et al., 1997). 3) Middle Tianshan-Beishan Region, part of the Kazakhstan Mid Plate during the Cambrian–Middle Ordovician, but incorporating with the Tarim Plate along the Narat-Maanqiao Fault in the late Middle Ordovician or by the Caradoc (Zhou, Lin & Ni, 1996; Lin et al., 1996a, b; Zhou Zhiyi et al., 1996a, b). 4) Tarim Region, an independent plate (Zhou & Chen, 1990, 1992) with no distinct Early Palaeozoic suture zones that have been discovered to the south of it, but with the Kegang Fault and Qiemo-Xingxingxia strike-slip Fault forming the western and eastern sections of the southern boundary respectively; it can be subdivided into two areas by the Tarim northern margin (southern slope of Halikshan-south Qarqi) Fault, the Bachu-Kalpin Area (4-1 of Figs 1.3 and 1.4, the Tarim Block proper) and Southern Tianshan Area (4-2 of Figs 1.3 and 1.4, marginal basin or trough fringing the northern margin of the Tarim Block) (Zhou, Ni & Yuan, 1995; Zhou, Lin & Ni, 1996; Lin et al., 1996a, b; Ni et al., 2001). 5) North China Region, including the Yellow River Area (5-1 of Figs 1.3 and 1.4), or the North China Platform, with the Luonan-Gushi and Wulian-Rongcheng faults as its southern boundary (Fan & Yang, 1994); Ordos Area (5-2 of Fig. 1.4), a western marginal area of the platform during the late Arenig–early Ashgill (Zhou, Zhou & Zhang, 1989) bordered on the Helanshan-western-margin strike-slip Fault and Liupanshan Fault due west (Zhou, Lin & Ni, 1996); Dunhuang-Alexa Area (5-2 of Fig. 1.3; 5-3 of Fig. 1.4), a dislocated old landmass lacking Early Palaeozoic deposits, possibly derived from the northern margin of the North China Platform, with the Annanba-Donglük Fault and Longshoushan Southern Marin-Yuanshanzi strike-slip Fault as the southern boundary (Zhou, Lin & Ni, 1996); and Qaidam-Qilian Area (5-3 of Fig. 1.3; 5-4 of Fig. 1.4), consisting of the Qaidam and Middle Qilian terranes and the Altun faulted-Block, with the southern boundary defined by the Altun strike-slip Fault and Urt Moron-Nomhon Fault (Zhou, Lin & Ni, 1996). 6) Kunlun-Qinling Region, as a polycyclic orogenic belt that crosses over the mainland of China. In addition to the West Kunlun Ordovician Terrane that belongs to a displaced landmass of the North China Plate proper (Zhou, Lin & Ni, 1996) in the western section of the region, several Early Palaeozoic

·8· Trilobite Record of China

terranes or micro-blocks are recognized from the eastern section, including the North, Middle and South Qinling (Xiang et al., 1981; Yang, 1988a), or the North Qinling and Wudang (Shang et al., 1994), of which only the North Qinling Terrane lies to the north of the Fengxian-Shangnan-Shangcheng crust-convergent zone, forming part of the southern marginal area of the North China Plate, but the others were considered as micro-blocks superimposed on the northern marginal area of the South China Plate (Yang, 1988a; Shang et al., 1994). According to Fan & Yang (1994), the southern boundary of the region extends eastwards along respectively the Kangxiwar Fault, A’nyemaqen Fault and Northern Margin (Lueyang-Chengkou-Xiangfan) Fault of the Yangtze Block, and this point of view is adopted in Figure 1.4. As Peng (2000) treated the Zheng’an-Yunxi-Junxian-Xichuan-Chuxian area as part of the northern slope of the Cambrian South China Plate, in Figure 1.3 part of the eastern section of the southern boundary of the region is therefore drawn along the northern margin (extending approximately from Zheng’an to Xichuan) of the Wudang Terrane (Shang et al., 1994). 7) Northern Qiangtang-Simao Region, considered to be the Variscan-Indosinian mobile zone of the South China Plate (Fan et al., 1994), or a northern extension of Indochina (now called Annamia, see Fortey & Cocks, 2003) Terrane (Metcalf, 1988; Wu et al., 1995; Jin, 1996; Zhou, Dean & Luo, 1998; Zhou et al., 2001). The terrane has previously been regarded as a Gondwanaland-derived, allochthonous landmass (Metcalf, 1988, 1992, 1996). The region lies to the west of the Honghe-Longmenshan Fault and to the northeast of the Nandinghe-Lancangjiang-Kon Kara Fault (Fan & Yang, 1994; Zhou et al., 2001), containing some interjacent micro-blocks in eastern West Yunnan, western Sichuan, northeastern Tibet and Karakorum, where only Ordovician and Silurian rocks were reported (Fan et al., 1994; Zhou et al., 2001).

Figure 1.3 Cambrian geographic units of China (applied on Tables 2.1, 3.1, 4.1, 5.1, 6.1 and 7.1). 1. Northern Xinjiang Region; 2. Hinggan Region; 3. Middle Tianshan-Beishan Region; 4. Tarim Region: 4-1. Bachu-Kalpin Area, 4-2. Southern Tianshan Area; 5. North China Region: 5-1. Yellow River Area, 5-2. Dunhuang-Alexa Area, 5-3. Qaidam-Qilian Area; 6. Kunlun-Qinling Region; 7. Northern Qiangtang-Simao Region; 8. South China Region: 8-1. Yangtze Area, 8-2. Jiangnan Area, 8-3. Cathaysia Area, 8-4. Jiangbei Area; 9. Baoshan-northern Tibet Region; 10. Southern Tibet Region; and 11. Hainan Region: 11-1. Wuzhishan Area, 11-2. Sanya Area.

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·9·

8) South China Region, subdivided on the basis of regional facies differentiation into the Yangtze (Lu et al., 1974a, 1976) (8-1 of Figs 1.3 and 1.4), Jiangnan (Lu et al., 1974a, 1976) (8-2 of Figs 1.3 and 1.4) and Pearl River (Lu et al., 1974a, 1976) or Cathaysia (Zhou et al., 1993) (8-3 of Figs 1.3 and 1.4) areas. Zhou et al. (1993) suggested the Shaoxing-Jiangshan-Yichun-Shaodong-Nanning-Pingxiang Fault as the northwestern boundary of the Cathaysia Area, a view we follow here. As indicated by Zhou et al. (1979), the three areas were developed along a bathymetric gradient from a shallow shelf to a deep basin, with the Jiangnan Area representing a shelf slope. The distribution of the Cambrian (Zhou et al., 1979) and Ordovician (Rong & Chen, 1987) litho/biofacies suggests that the boundary between the Yangtze and Jiangnan areas was varied in different periods. In Figures 1.3 and 1.4, we prefer to employ the Xiangqian- Jiangnan Fault (Yang, 1987) to separate both areas, a boundary between the platform and slope facies during the Late Cambrian and Tremadocian (Zhou et al., 1993, fig. 4-1). Note that, as compared with Figure 1.4, an additional shelf slope, the Jiangbei Area (8-4), is further subdivided from the region in Figure 1.3, following Peng (2000). 9) Baoshan-northern Tibet Region, a northern extension of the Sibumasu Terrane (Metcalf, 1988, 1992, 1996; Zhou, Dean & Luo, 1998; Zhou et al., 2001), which is considered as an allochthonous continent sliver that rifted and drifted away from Gondwana (Metcalf, 1988, 1992, 1996). It is situated to the south of the Northern Qiangtang-Simao Region and to the north of the Yarlung Zangbo River Fault (Fan et al., 1994). Early Palaeozoic strata are exposed in the intervening micro-blocks, i.e. the Baoshan area, westernmost Yunnan (Cambrian–Silurian, see Xiang et al., 1981; Lai et al., 1982; Ni et al., 1982) and the Xainza (Qajoriêbu) area, Tibet (Ordovician and Silurian, see Chen Tingen, 1986; Ni, 1986). 10) Southern Tibet Region, part of the India Plate (Fan et al., 1994). The Cambrian and Ordovician rocks were recorded at Nyalam near Mount Qomolangma (Yin, 1974; Wang, 1974) and the Zanda (Toling) in the Ngari area (Guo et al., 1991).

Figure 1.4 Ordovician geographic units of China (applied on Tables 8.1 and 9.1). 1. Northern Xinjiang Region; 2. Hinggan Region; 3. Middle Tianshan-Beishan Region; 4. Tarim Region: 4-1. Bachu- Kalpin Area, 4-2. Southern Tianshan Area; 5. North China Region: 5-1. Yellow River Area, 5-2. Ordos Area, 5-3. Dunhuang-Alexa Area, 5-4. Qaidam-Qilian Area; 6. Kunlun-Qinling Region; 7. Northern Qiangtang-Simao Region; 8. South China Region: 8-1. Yangtze Area, 8-2. Jiangnan Area, 8-3. Cathaysia Area; 9. Baoshan-northern Tibet Region; 10. Southern Tibet Region; and 11. Hainan Region: 11-1. Wuzhishan Area, 11-2. Sanya Area.

·10· Trilobite Record of China

11) Hainan Region, corresponding to the entire Hainan Island south of the Qiongzhou Straits, being considered as a micro-block or terrane disassociated from the Indochina-South China Sea Plate since the Late Cretaceous (Yang, 1994). It is subdivided by the Jiusuo-Lingshui Fault into two areas, the Sanya (11-2 of Figs 1.3 and 1.4) where shelf deposits developed, and the Wuzhishan (11-1 of Figs 1.3 and 1.4), interpreted as a mobile zone that edged the shelf (Wang Xiaofeng, 1989). However, reliable Cambrian and Ordovician strata have only been reported from the Sanya Area (Xiang et al., 1981; Zhen et al., 1992).

1.3.3 Assembly of continental masses China is a complex assembly of allochthonous continental masses. Units or regions now in close proximity (Figs 1.3, 1.4) were distantly separated from each other during the Early Palaeozoic, and the assembly of those landmasses was likely a long-sustained process that extended from the Carboniferous to the Cenozoic. A southward accretion of the Eurasia continent is well demonstrated in China by evidence sourced mainly from stratigraphic and palaeontological research. In the mid Late Carboniferous (Moskovian), the Middle Tianshan-Beishan Region (3 of Figs 1.3 and 1.4) joined with the Northern Xinjiang Region (1 of Figs 1.3 and 1.4), signifying a final incorporation of the Kazakhstan Mid Plate into the Siberia Plate (Ruan & Liao, 1996). However, it was not until the late Guadalupian (Maokouan) of the Permian that the Tarim Region (4 of Figs 1.3 and 1.4) combined with the primitive Eurasia (Ruan & Liao, 1996; see also Fang et al., 2001). Almost at the same time, amalgamation of the North China Region (5 of Figs 1.3 and 1.4) with the Hinggan Region (2 of Figs 1.3 and 1.4) was also completed (Fan & Yang, 1994). The Tarim Region probably merged with the North China Region during the Lopingian of Late Permian, marked by its merger with the Qaidam-Qilian Area (5-3 of Fig. 1.3; 5-4 of Fig. 1.4) (Ruan & Liao, 1996).

Figure 1.5 Devonian geographic units of China (applied on Table 10.1). After Liao & Ruan (2003, fig. 1) with modification. 1. Junggar-Hinggan Region; 2. Tarim Region; 3. North China Region; 4. Qinling Region; 5. South China Region; 6. Hoh Xil-Bayan Har Region; 7. Tibet-western Yunnan Region; and 8. Himalaya Region.

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·11·

The integration of the South China Region (8 of Figs 1.3 and 1.4) with the North China Region took place during the Mid Triassic (late Anisian–Ladinian) (Chen, Xu & Xu, 1998) following the final closure of the Kunlun-Qinling Sea. From the Late Triassic onwards, the Northern Qiangtang-Simao Region (7 of Figs 1.3 and 1.4), Baoshan-northern Tibet Region (9 of Figs 1.3 and 1.4) and Southern Tibet Region (10 of Figs 1.3 and 1.4) successively drifted northwards during the late Norinian–Rhaetian (Late Triassic), Kimmeridgian (Late Jurassic) and Oligocene (Late Palaeogene)–early Miocene (Early Neogene) (Chen & Yang, 1996) respectively, and eventually formed part of mainland China (Wang, 1984; Chen, 1992; Chen & Yang, 1996). According to Liu et al. (1992), sea-floor spreading of the South China Sea has taken place three times since the mid–late Eocene (Mid Palaeogene) with the last episode occurring in the late Miocene. This information may point towards the probable time when the Hainan Region (11 of Figs 1.3 and 1.4) finally came to be tightly associated with the South China Region.

Figure 1.6 Carboniferous geographic units of China (applied on Table 10.2 for the geographic distribution of Carboniferous and Permian trilobites). After Wang et al. (2003, fig. 1) with modification. 1. Junggar-Hinggan Region; 2. Tarim Region; 3. Qilian-Helan Region; 4. North China Region; 5. Qiangtang-Hengduan Region; 6. South China Region; and 7. Himalaya Region.

1.4 Outline of Cambrian and Ordovician trilobite biogeography

Of 1317 trilobite genera and subgenera recorded from Palaeozoic rocks in China, 809 (61% of the total) are represented in Cambrian strata, and 315 (about 24%) occur in the Ordovician. After the end Ordovician mass extinction event, trilobites lost their earlier prominence, and became a minor component of marine faunas in the Silurian and Late Palaeozoic in China. Only 50 forms (4% of the total) are recorded in the Silurian, and 149 (11%) in the Late Palaeozoic. Although the Chinese biogeography of the Permian (Xu & Yang in Yin et al., 1988; Jin et al., 2003), Carboniferous (Tang in Yin et al., 1988; Wang & Jin, 2003), Devonian (Liao & Ruan, 2003) and Silurian (Rong & Chen, 2003) has been well outlined, a trilobite-constrained pattern for the country is still in the vague, largely because of insufficient data. However, what evidence from trilobites that is available supports the view that South China may have formed an independent faunal province, in particular during the Telychian of the late Llandovery (Rong & Chen, 2003), when the endemic forms, such as Conorocephalus, Kailia, and Rongxiella, dominated the onshore faunas in the Yangtze area.

·12· Trilobite Record of China

In this section, biogeographic links among the Chinese plates and terranes are further reviewed on the basis of the complete dataset available for the Cambrian and Ordovician trilobite record in China. As indicated by Fortey (1975), Fortey & Owens (1978), Zhou et al. (1989, 1990, 1992) and Fortey & Cocks (2003), trilobites usually decrease their endemicity from the interior towards exterior biofacies belts in a plate or terrane, and elements which are endemic to a particular plate or plates are the most important indicators in defining biogeographic units. Therefore, in the following discussion, the platform/inner-shelf faunas, and endemic trilobites in particular, are emphasized, although, as indicated by Zhou & Dean (1989), a few endemics restricted to the deep-water facies are also significant enough for defining faunal provinces.

1.4.1 Cambrian With the exceptions of northern Xinjiang and southern Tibet, Cambrian trilobites are widely recorded throughout China. However, most of them are described from South and North China, and Tarim (southern Xinjiang), in focus of which the Cambrian biogeography of China has previously been well delineated. The whole of China was considered to be assignable to a single biogeographic realm in the Cambrian by both Lu et al. (1974a, named as the Oriental Realm; see also Lu, 1981) and Zhang (2003, as the Perigondwanan Realm; see also Kobayashi, 1976 and Palmer & Repina, 1993). This realm was recognized on the basis of several endemic clades, including, amongst others, the superfamilies Redlichioidea and Dameselloidea and families, such as, Crepicephalidae, Kaolishaniidae, Inouyiidae, Lisaniidae, Ptychaspididae, Sunaspididae and Tsinanidae. All of these flourished in China and are typical of most of the Chinese Cambrian faunas. As depicted by Lu et al. (1974a and references therein) and Zhang (2003 and references therein), outside of China, the distribution of most of the related genera was largely restricted to southeast, central and south Asia, Middle East, Australia and Antarctica, indicating that the primary biogeographic links of China are with the eastern Gondwana and other eastern Peri- Gondwana blocks, though limited faunal connections with western Gondwana and western Peri-Gondwana are also traceable. A similar view was also held by Yang (1988b), who however added the suggestion that there existed an additional independent biogeographic unit (called the Hinggan-Mongolia Province) to the north of the realm (called the Asian-Australian Realm instead of the Oriental Realm). This point is supported by a few late Early Cambrian (Lungwangmiaoan) forms that were recently reported from the Yichun Terrane of the Hinggan Region (2 of Fig. 1.3) by Duan & An (2001), including Inouyina, Jangudaspis, Laminurus, Onchocephalina, Proerbia and Pseudozacanthopsis, all of which exhibit a strong faunal affinity with Siberian assemblages.

1.4.1.1 Eastern Peri-Gondwanan terranes Only a few Cambrian trilobites were reported from several of the allochthonous Peri-Gondwanan terranes. Based particularly on the inner-shelf inhabitants among the taxa recorded, the biogeographic attribute of each of these terranes is suggested as follows. Middle Tianshan-Beishan Region/Terrane (Region 3 of Fig. 1.3): It was referred to the Tarim Province by Yang (1988b), though the occurrences of late Early Cambrian benthic trilobites such as Edelsteinaspis, Serrodiscus, Calodiscus, Tannudiscus, Pagetides and Poliellina (see Zhou, Li & Qu, 1982; Xiang & Zhang, 1985; Zhang Tairong, 1987b) in the region may suggest a close faunal link with Sayan-Altay and Tuva of Russia, and display evident affinities with Siberia and Laurentia rather than Tarim (Zhou, Lin & Ni, 1996). It is interesting to note that a similar contemporaneous fauna was also recorded from the Karaganda area, Kazakhstan (Ivshin, 1979). This indicates that, during the Early Cambrian, the Middle Tianshan-Beishan Region, or even possibly the entire Kazakhstan Mid-Plate, might have been located not far from the Siberia Plate. However, the early Mid Cambrian faunas of the region were characterized by the occurrences of Galahetis and Xystridura (Zhang, 1981; Zhou, Li & Qu, 1982; Xiang & Zhang, 1985), indicating closest affinities with those of Australia and Antarctica (Lin & Jago, 1993; Brock et al., 2000). The late Mid–Late Cambrian trilobites recorded in this region are mostly slope-facies types, except for the Ejin Banner area, where a shallow-water fauna was reported (Lin et al.,

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·13·

1996a), including forms that are typical of the coeval fauna of North China Plate, such as Amphoton and Crepicephalina, and of Australia, such as Amphoton. Moreover, in the Late Cambrian, the occurrence of Atopasaphus, Golasaphus and Lorretina from a shallow-outer-shelf fauna in Ejin Banner (Lu et al., 1986) also supports a close biogeographic connection with Australia. Hainan Region/Terrane (Region 11 of Fig. 1.3): Only a few inner-shelf-facies trilobites, such as Galahetis and Xystridura, have been reported from the early Mid Cambrian in the Sanya Area (11-2 of Fig. 1.3) (Sun, 1963; Chu & Lin, 1978; Zeng et al., 1992; Lin & Jago, 1993), which are again taken to be indicative of a closest faunal link with eastern Gondwana as well as with the Middle Tianshan-Beishan Terrane. Northern Qiangtang-Simao Region/Terrane (Region 7 of Fig. 1.3): Only a single genus Kunmingaspis was documented from the Early Cambrian of northwestern Yunnan (Leng, 1983; Hughes et al., 2002). Elsewhere, this form has been employed as a zonal fossil to define the uppermost horizon of the Lower Cambrian in South China and Tarim. There have also been three trilobite genera Calvinella, Haniwa and Mictosaukia described from Batang, western Sichuan (Zhu, 1982). All of them also frequently occur in the late Upper Cambrian (Fengshanian) of the North and South China plates, and Mictosaukia was also regarded as one of the key trilobite genera of the Australian Payntonian fauna (Brock et al., 2000). Baoshan-northern Tibet Region/Terrane (Region 9 of Fig. 1.3): Only Late Cambrian trilobites have been described from the Baoshan area, westernmost Yunnan (e.g. Luo, 1982, 1983; Sun & Xiang, 1979). As listed in Chapter 7, the faunas consist of 38 polymerid genera and subgenera, 30 of which are shared with those of the slope belt (Area 8-2 of Fig. 1.3) of the South China Plate, suggesting a shallow-outer- shelf setting. Demonstrated by a number of associated common shallow-water elements, such as Black- welderia, Changia, Chuangia, Dictyella, Easaukia, Haniwa, Kaolishania, Kaolishaniella, Mansuyia, Mansuyites, Mictosaukia, Monkaspis, Parachangshania (Parachangshania), Prosaukia and Tsinania, the terrane shows a unique provincial link with South China, Australia and, in particular, North China.

1.4.1.2 Eastern Peri-Gondwanan plates Cambrian trilobite faunas heterogeneously developed in the three Chinese cratonic plates, due to the differing geological evolution of each region. In the South China Plate (Region 8 of Fig. 1.3) and Tarim Plate (Region 4 of Fig. 1.3), the complete successions of the slope-facies Cambrian trilobites and platform-facies Early Cambrian trilobites are well documented, but the platform-facies Mid–Late Cambrian trilobites only sporadically occur in the limestone intercalations of the dolomite strata. In contrast, in the Yellow River Area (5-1 of Fig. 1.3) of the North China Plate (Region 5 of Fig. 1.3), the platform-facies trilobites have been widely recorded in the late Early–Late Cambrian, but none were recorded from the early Early Cambrian, as this component of the strata (Chiungchussuan-lower Tsanglangpuan) is absent. The slope-facies trilobites are only distributed in the Qaidam and Middle Qilian terranes (Area 5-3 of Fig. 1.3), although Early Cambrian trilobites have not been found in this area. All of the Chinese plates may have been situated in low latitude zones during the Cambrian (e.g. Burrett et al., 1990). Lu et al. (1974a) was the first to note the ecological differentiation of the Cambrian faunas in the Chinese plates, and, accordingly, they classified the faunas into three types: North China, Transitional and Southeast China. Zhou et al. (1979) revealed that the Cambrian faunas were differentiated along a bathymetric gradient from the shallow platform in the west to the deep basin in the east of South China, and suggested that the North China, Transitional and Southeast China faunas may well represent the trilobite associations indicative of respectively platform, slope and basin environments. Since then, further research has been carried out in China (Yang, 1988b; Lin et al., 1990, 1992, 2001; Peng, 2000; Zhang, 2003) and the distribution patterns of the Cambrian trilobite faunas have well been established in time and space for all the Chinese plates, except the Qaidam and Middle Qilian terranes (Area 5-3 in Fig. 1.3), where the biofacies model is not well delineated yet. Despite this, judging from the faunal sequences and palaeogeographic framework (Lin et al., 1996b) of these two terranes, it is evident that most of the trilobites were associated with slope-facies environments, except for a few genera that might be classified as shallow-water dwellers. Largely based on the similarity between the shallow-water trilobite faunas, Lu et al. (1974a) and Lu

·14· Trilobite Record of China

(1981) referred both the North China and Yangtze platforms to a biogeographic unit, the North China Province. Yang (1988b), however, considered the South China, North China and Tarim plates to represent three independent provinces, but more recent research suggests that the Tarim Cambrian biota is most similar to that of the South China Plate (Zhou & Chen, 1990, p. iv; 1992, p. ii; Zhou, Lin & Ni, 1996, pp. 11, 20). Except for an endemic genus Tianshanocephalus, all the platform-facies trilobites that have been described from the Lower Cambrian in the Tarim, including Bathynotus, Chittidilla, Jingyangia, Kepingaspis, Kunmingaspis, Meitanella, Paokannia, Redlichia (Redlichia), Tsuyidiscus (Tsunyidisus), and Ushbaspis (see Chapter 3), are in common with the coeval faunas from the Yangtze Platform, indicating that both blocks may have formed a single biogeographical unit at least during this period. Following the Late Tsanglangpuan transgression, the Yangtze Sea became deeper (Zhou et al., 1979), whilst the North China Block was drowned, becoming a vast shallow epiric sea. This event caused many endemic taxa to evolve in both separate cratonic areas. According to Chapter 3, in the late Early Cambrian there are 26 genera and subgenera regarded as endemics to the North China Platform, belonging to the Ptychopariidae (15, e.g. Probowmania (Probowmania), Paraziboaspis), Redlichiidae (4, e.g. Leptored- lichia, Neoredlichia), Agraulidae (4, e.g. Pseuoplesiagraulus), Protolenidae (1), Zacanthoididae (1) and Inouyidae (1), while there are 28 endemic taxa recorded from the Yangtze Platform, including eight from the Protolenidae (e.g. Ichangia, Szechuanolus), five from the Ptychopariidae (e.g. Yuhsienszella, Xilinxia), three each from the Redlichiidae (e.g. Breviredlichia) and Yinitidae (e.g. Paokannia), two each from the Zacanthoididae (e.g. Chuchiaspis) and Dolichometopidae (e.g. Hoffetella), and one each from the Agraulidae, Dorypygidae, Hicksiidae, Inouyidae and Palaeolenidae. Therefore, during the late Early Cambrian (late Tsanglangpuan–Lungwangmiaoan), significant differences between the platform-facies endemic trilobites from North and South China may signify them as separate biogeographic units, although a faunal link between both platforms is also indicated by the co-occurrence of dorypygids Bonnia and Kootenia (Kootenia), oryctocephalid Cheiruroides, palaeolenid Megapalaeolenus, ptychopariids Eoptychopaia (Eoptychopaia), Probowmania (Gunnia) and P. (Mufushania), and redlichids Redlichia (Redlichia) and R. (Pteroredlichia). In comparison with the highly diverse Mid–Late Cambrian trilobites recorded in the North China Platform, only a few taxa occur in the vast area of a restricted platform belt of the Yangtze Area (8-1 of Fig. 1.3), and almost all of them are identical with the contemporaneous forms of the North China Platform, such as, Bailiella, Dapingia, Kailiella, Proasaphiscus, Kaotaia, Proasaphiscus, Probow- maniella, Solenoparia (Solenoparia) and Tonkinella from the Maochuangian and Hsuchuangian (Chapter 4); Lisania, Manchuriella, Poshania, Protohedinia, Solenoparia (Solenoparia) and Szeaspis from the Changhian (Chapter 5); and Blackwelderia, Calvinella, Enshia, Haniwa, Liaoningaspis, Mictosaukia, Prosaukia, Pseudosolenopleura and Saukia from the Late Cambrian (Chapter 6). Lu et al. (1974a) believed that the faunal difference between both platforms (North China and Yangtze) was lithofacies- controlled. This view was supported by a preliminary report on the Cambrian of southeastern Yunnan (Luo, 1984), where exposes a complete rock sequence of the open-platform-facies. It bears the Mid–Late Cambrian trilobite faunas that are identical with those of the North China Platform in terms of genus diversity and composition.

1.4.2 Ordovician Trilobite evidence indicates that all the plates and most of the terranes in China exhibit a close biogeographic link to each other and may have formed part of eastern Peri-Gondwana during the Ordovician (e.g. Zhou & Dean, 1989; Webby et al., 2000; Fortey & Cocks, 2003). The exceptions to this are the Altay Terrane of the Northern Xinjiang Region (1 of Fig. 1.4) and the Ergen-Hinggan Terrane of the Hinggan Region (2 of Fig. 1.4), where trilobite faunas show a strong affinity with those of Siberia and Laurentia as suggested by the Late Ordovician record of Calyptaulax and Isotelus (respectively described by Zhang (1981) as Calliops taimyricus Balashova and Fuyunia junggarensis Hsiang & Zhang; see Zhou, Lin & Ni, 1996) in the former (the Altay Terrane), and by the occurrences of Mid and Late Ordovician forms such as Parasphaerexochus, Pliomerellus, Quinquecosta (see Zhao et al., 1997), Cybelurus (see

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·15·

Xiang & Mao, 1986), Eorobergia (see Xiang & Mao, 1986, as ?Kainella sp.), Cybeloides, Calyptaulax, Isotelus (see Nan, 1985b), and the monorakids Ceratoevenkaspis and Isalauxina (ZZY collection) in the latter (the Ergen-Hinggan Terrane).

1.4.2.1 Eastern Peri-Gondwanan terranes Ordovician trilobites are only sporadically documented from a number of Peri-Gondwanan terranes in China, where the framework of biofacies differentiation, either in space or in time, is usually poorly known. Therefore, their biogeographic relationships to the related geographic units or plates are only briefly discussed herein based on the rather incomplete faunal data, chiefly those recorded from shallow water marine successions. Middle Tianshan-Beishan Region/Terrane (Region 3 of Fig. 1.4): The only inner-shelf trilobite fauna was described from the Caradoc at Ejin Banner, western Inner Mongolia (Zhou Zhiqiang & Zhou Zhiyi, 2006). The dominant forms, such as Bulbaspis, Collis, Pliomerina, Sinocybele and Basilicus (Basiliella), are also extremely diverse in the coeval fauna of Kazakhstan, especially that of the Chu-Ili Terrane (see Fortey & Cocks, 2003), and some of the taxa are even the same at species level. The region also has close biogeographic links to the North China Plate, where coetaneous shallow-water associations characteristic of Pliomerina and Basilicus (s.l.) were recorded from the Altun Mts, eastern Xinjiang (Area 5-4 of Fig. 1.4) (Zhou et al., 1995) and southern Ningxia and central Shaanxi (Area 5-1 of Fig. 1.4) (Zhou, Li & Qu, 1982). A deeper-water Caradoc trilobite faunule reported from northern Tarim (Zhang, 1981) including Bulbaspis, Sinocybele and Basilicus (Basiliella) also exhibits an affinity with this Kazakhstan fauna. This may be caused by the amalgamation of the Middle Tianshan-Beishan Terrane with the Tarim Plate, a tectonic event that may have taken place by the Caradoc as suggested by Zhou, Lin & Ni (1996). The genera from this region in common with the inshore sites of eastern Australia (Webby, 1971; Edgecombe et al., 1999a, 2004; Edgecombe & Webby, 2006) are Pliomerina, Sinocybele and Basilicus (Basiliella). Sharing of these taxa suggests that these two regions may belong to a biogeographically significant faunal province, or the Eokosovopeltis-Pliomerina Province (Webby, 1987; Webby et al., 2000). Hainan Region/Terrane (Region 11 of Fig. 1.4): Only a few outer-shelf-facies trilobites were reported from the Late Ordovician in the Sanya area (Zeng et al., 1992), of which the Caradoc genera Ampyxinella, Birmanites, Dionide and Bulbaspis are mostly the widespread forms. As deep-water faunas of the Tarim and South and North China plates had already become uniform in composition during the Caradoc (Fig. 1.7F), the biogeographic affinities of these plates with the region in question are difficult to affirm, but Bulbaspis alone may suggest a faunal link with the Middle Tianshan-Beishan Terrane and even with the Tarim Plate. Southern Tibet Region (Region 10 of Fig. 1.4): Only a few Arenig trilobites are known from this region, including Basilicus (Basilicus) (as Isoteloides bolingensis), Hystricurus and Pliomerina (as Ngaricephalus) from Ngari, southwestern Tibet (Yang, 1990) and Pseudocalymene (as Eucalymene tuberculata) from Nyalam of the Mount Qomolangma (Chien, 1976). All of these trilobite taxa occur also in the coeval faunas of the North China Plate, where the genus Pseudocalymene is associated, as at Nyalam, with the nautiloid Pomphoceras, which is an element typical of the Yellow River Fauna (Chen et al., 1984). Baoshan-northern Tibet Region/Terrane (a northern extension of the Sibumasu Terrane) (Region 9 of Fig. 1.4): Various Late Ordovician trilobites have been described from the Pagoda-facies (see Lindström et al., 1991) rocks in southern Thailand (Fortey, 1997) and westernmost Yunnan (Sheng, 1974b), all belonging to a wide-spread, deep-water-biofacies fauna. Some forms are also considered identical, even at species level, with the taxa from South China (Fortey & Cocks, 1998). However, the Llanvirn inner-shelf-facies fauna (Reed, 1917; Sheng, 1974b) from the Baoshan area seems to be a mixture of trilobites exhibiting two different biogeographic affinities, with Basilicus (Basilicus) and Pliomerina typical of the contemporaneous fauna of North China, and Hexacopyge, Neseuretus, Prionicheilus, Reedocalymene, and Sinocybele found in South China. Therefore, there remain ambiguities in the explanation for the alignment of this Cimmerian terrane (the Sibumasu Terrane). Fortey & Cocks (1998, 2003) favoured its close biogeographic and physical proximity to South China, but Zhou, Dean & Luo

·16· Trilobite Record of China

(1998) preferred the reconstructions proposed by Scotese & McKerrow (1991) and Metcalfe (1992), in which the West Malaysia-Thailand Peninsula was located close to the North China Plate on the palaeoequator, while Shan State of Burma and the Baoshan-northern Tibet Region may have been sited in a low latitudinal zone not far from the South China Plate. Northern Qiangtang-Simao Region/Terrane (Region 7 of Fig. 1.4): The Tremadocian-early Arenig shallow-water trilobites from Karakorum, southwestern Xinjiang include Neopsilocephalina, Psilocepha- lina, Psilocephalops and Songtaoia (as Yinjiangia karakolumensis) described by Zhang Tairong (1991), and Asaphopsoides (as Asaphus elegantulus; see Jell & Stait, 1985) described by Gortani (1934). A less diverse late Arenig inner-shelf fauna, comprising Hungiodes, Liomegalaspides, Neseuretus and Ogyginus, was recorded from Dali, western Yunnan (Zhou, Dean & Luo, 1998) and a fauna containing Neseuretus and Aristocalymene (as Neseuretus muliensis; see Turvey, 2005b) was described from Muli, southwestern Sichuan (Lee, 1978). Most of the components from this region are in common with the Yangtze Platform, demonstrating a very close faunal link that existed between this Cimmerian terrane (the Indochina or Annamia Terrane) and the South China Plate. However, occurrences of Asaphopsoides, Neseuretus and especially Ogyginus indicate a western Gondwanan and western Peri-Gondwanan faunal affinity, and suggests that the Annamia Terrane may have been situated at higher latitudes or in a more westerly position as compared with the South China Plate (Zhou, Dean & Luo, 1998; Fortey & Cocks, 2003).

1.4.2.2 Eastern Peri-Gondwanan plates Ordovician trilobites are well recorded in three cratonic plates: the South China Plate (Region 8 of Fig. 1.4) [including also the Wudang or South Qinling Terrane of the Kunlun-Qinling Region (6 of Fig. 1.4)], North China Plate (Region 5 of Fig. 1.4) [including also the West Kulun, a displaced landmass of the North China Plate proper (Zhou, Lin & Ni, 1996), now located on the western end of the Kunlun-Qinling Region; the Qaidam and Middle Qilian terranes and the Altun faulted block (Area 5-4 of Fig. 1.4), see Zhou, Lin & Ni, 1996] and Tarim Plate (Region 4 of Fig. 1.4). All of them were situated in low latitude zones during the Ordovician (Webby et al., 2000; Cocks & Torsvik, 2002; Turvey, 2005c). In each of them trilobite faunas display a progressive onshore to offshore transition in composition and diversity. Ecological differentiation of the faunas and their response to biofacies have been explored along environmental gradients (inner shelf to off-shelf slope) from west to east and from south to north of South China (Zhou, Zhou & Yuan, 1999, 2000, 2001; Zhou et al., 2000, 2003, 2004; Yin et al., 2000; Yuan Wenwei et al., 2000; Turvey & Zhou, 2002, 2004a, b; Turvey, 2005c), from east to west of North China (Zhou, Zhou & Zhang, 1989) and from south to north of Tarim (Zhou et al., 1990, 1992). Along with this the temporal and spatial distribution of the Ordovician trilobite faunas has well been outlined for all the Chinese plates, except for those of the Qaidam-Qilian terranes (Area 5-4 of Fig. 1.4), as the biofacies patterns are not well established yet in these area. They contain mainly deeper-water forms, but also include a few shallow-water genera (Zhou et al., 1996a, b). Early studies indicated that, as a whole, the respective trilobite faunas of the South China and North China plates were closely comparable in the Tremadocian, but became distinct from each other afterwards (Zhou & Fortey, 1986), while those from the Tarim Plate were analogous to the faunas of the South China Plate through the whole Ordovician, suggesting that both were closely situated palaeogeographically (Zhou & Chen, 1990, 1992; Zhou, Lin & Ni, 1996). The points of view are supported by a further comparison between the inner-shelf/platform faunas of the three plates, and those trilobites with significant biogeographic implications are further reviewed herein. Tremadocian trilobite faunas of North China are characterized by distinctive endemics, such as Koraipsis and Penchiopsis, in addition to a few bathyurids, while those of South China are marked by Dactylocephalus, Tungtzuella and Psilocephalina. However, most of the other trilobite taxa from both plates are in common, including genera such as Chosenia, Songtaoia, Wanliangtingia and Yosimuraspis. It is interesting to note that some trilobites typical of either of the two plates co-occur in the contemporaneous faunas of Australia and northern Iran (the Alborz Terrane). The Tremadocian trilobites described from northern Iran by Bruton et al. (2004) and Ghobadi Pour (2006) include Asaphellus inflatus Lu, Psilocephalina lubrica Hsu, Dactylocephalus, Kayseraspis, Peltabellia, and Illaenus hinomotoensis

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·17·

Kobayashi. The occurrence of the first three suggests a close link to South China, and the others are common elements of the North China faunas. In Australia, Shergold (1991) reported Asaphellus cf. trinodosus Chang, Koraipsis, Kayseraspis and Psilocephalina cf. lubrica Hsu from the northern part of the Amadeus Basin, Jell & Stait (1985) described Asaphellus cf. trinodosus Chang, Asaphopsoides, Chosenia, Dikelokephalina asiatica Kobayashi, Hystricurus penchiensis Lu from Tasmania, and Laurie and Shergold (1996) recorded Penchiopsis from the Canning Basin. These trilobite records show a remarkable similarity to those of North China, but a close link with South China also exists at either specific or generic rank, as indicated by the occurrence of Psilocephalina cf. lubrica Hsu, Asaphopsoides and Chosenia. From the Arenig to Caradoc, trilobite faunas of North China with endemic forms like Eoisotelus, Lonchobasilicus and Pliomerina, in addition to a variety of species of Basilicus (s.l), are quite distinct from those of South China, which are characterized by having Birmanites, Calymenesun, Fenghuang- chengia, Hexacopyge, Liomegalaspides, Meitanopsis, Mioptychopyge, Ningkianites, Omeipsis and Taihung- shania. The faunal differences may imply a faunal separation between the two Chinese plates. Among the Arenig–Llanvirn trilobites, Prosopiscus was widely distributed in Australia, South and North China, Sibumasu, Himalayas and Argentine Precordillera, being of important biogeographic significance (Webby et al., 2000; Paterson, 2004). As indicated by Paterson (2004), the genus originated in the early Arenig of Australia, with the early species P. lauriei Paterson from northwestern New South Wales, is closely related to P. magicus Zhou from the North China Plate, suggesting a biogeographic link between North China and Australia at least during the Arenig. Webby (1971, 1974, 1985, 1987, 1992) and Webby et al. (2000) suggested a biogeographically distinctive Eokosovopeltis-Pliomerina Province in the Caradoc to cover part of the eastern Peri-Gondwanan regions, including East Australia, East Asia and Kazakhstan, and probably the Argentine Precordillera (Edgecombe, 1999b). However, the eponymous forms Eokosovopeltis and Pliomerina recorded from New South Wales (Webby, 1971, 1974) and Tasmania (Corbett & Banks, 1974; Edgecombe et al., 1999a, 2004) were lacking in all geographic units of East Asia during the Caradoc, except the North China Plate, where, as mentioned above, Pliomerina occurs though with no associated Eokosovopeltis present. A few deeper water taxa with more restricted distribution, including the distinctive three-segmented raphiophorid genus Nanshanaspis, are also in common between the Qaidam-Qilian Area (5-4 of Fig. 1.4) (Chang & Fan, 1960; Zhou et al., 1995) and southern Tasmania (Burrett et al., 1983), suggestive again of strong biogeographic relationships between Australia and North China. Though as noted by Webby et al. (2000), faunal links based on the available biotic data from Australia were in general with the Chinese plates, it is more likely that Australian trilobite faunas had closest affinities with those of North China during the Arenig–Caradoc. In Tarim, only a bathyurid Aksuaspis is recorded in the Tremadocian dolomite at Kalpin (Zhou, Zhou & Yuan, 1998), but the occurrence of a few trilobites, including Asaphopsoides, Paraszechuanella [=Pseudocalymene, see Bruton et al., 2004], and Psilocephalina described by Zhou (see Lin, Zhou & Luo, 1990) from a shallow outer-shelf Nileid Biofacies at Uligezhitag (Zhou et al., 1990, 1992) suggests a close faunal links with South China. From the Arenig onwards, the shallow-water trilobites were all associated with carbonate buildups, and have been proved to be of worldwide distribution, except all Liomegalaspides, an Arenig form typical of the coeval fauna in South China, which was described from the platform-facies of Tarim (Zhou, Zhou & Yuan, 1998, as Megalaspides angustus and M. sp.). However, there was also developed a unique provincial link with the South China Plate, including the occurrence of a number of common shallow outer-shelf elements, of which the characteristic forms are Birmanites, Calymenesun, Lisogolites, Mioptychopyge, Ovalocephalus, Reedocalymene, Sinocybele, Taklamakania, Xiushuilithus, Yanhaoia and Zhenganites (see Zhang, 1981; Zhou et al., 1990, 1992, 1998; Yuan & Zhou, 1997). The early–mid Ashgill inner-shelf/platform trilobite faunas are almost completely absent in China, with the exception of a few forms that were reported from the mid-Ashgill carbonate buildups in the eastern margin of the Jiangnan Area (Zhou et al., 2004). Occurrence of the Nankinolithus fauna from deeper sites (areas 4-2, 5-2, 8-2 of Fig. 1.4) may, however, suggest that the faunal connection became closer again between the South China-Tarim and North China plates during this time interval. Comparatively uniform patterns of provincialism might continue to exist during the Hirnantian, when

·18· Trilobite Record of China

there were only few trilobites (largely immigrants from high-latitude Gondwana) occurring in the Chinese plates, comprising Dalmanitina (Songxites) (note that it includes also a series of species previously assigned to Dalmanitina (Dalmanitina) Read, 1905; see Chapter 8 for details) (in areas 4-1, 5-4, and region 8, see Fig. 1.4), Eoleonaspis (in area 5-4 and region 8), Niuchangella (in region 8 and, according to the new unpublished data, in area 4-1), Platycoryphe (in area 5-4 and region 8) and Solariproetus (in area 5-4).

1.4.3 Biogeographic affinities of Chinese Cambrian and Ordovician plates – a cluster analysis In order to express the preliminary observations more rigorously, cluster analysis of biogeographic

CHAPTER 1 Introduction with reference to previous work, stratigraphical and geological settings, and biogeography ·19· links on the basis of trilobite genera and subgenera respectively from six time intervals (Lungwang- miaoan, Changhian, latest Cambrian–Tremadocian, Arenig, Llanvirn and Caradoc) of the South and North China and Tarim plates was conducted using Simpson’s coefficient (Fig. 1.7). This analysis reveals that the Chinese plates belonged to a single biogeographic unit during the Changhian and latest Cambrian– Tremadocian, and their platform/inner-shelf and outer-shelf/slope facies areas are separated into two distinct clusters (Fig. 1.7B, C). The Lungwangmiaoan clusters (Fig. 1.7A) suggest that the South China-Tarim and North China plates may well be referred to two independent biogeographic units, as evidenced by the occurrence of two different platform/inner-shelf faunas respectively in both units. The analysis further indicates that the South China-Tarim and North China plates were biogeographically separated also during the Arenig (Fig. 1.7 D), as evidenced by different faunas distributed either in shallow or in deep-water sites. A similar pattern is also depicted by the Llanvirn (Fig. 1.7E) and Caradoc (Fig. 1.7F) faunas, but the trilobites from the deep-water facies of the North China Plate progressively become more analogous to those of South China-Tarim, indicating that a faunal exchange between offshore sites of both geographic units may have started long before the Ashgill when the Nankinolithus fauna testifies to a shared biogeographic link amongst the Chinese plates.

1.4.4 Conclusion Trilobite evidence indicates that all the plates and most of the terranes in China exhibit a close biogeographic link and may have formed part of eastern Peri-Gondwana during the Cambrian and Ordovician, with the exception of the Altay Terrane of the Northern Xinjiang Region, the Yicun and Ergen-Hinggan terranes of the Hinggan Region and the Early Cambrian Middle Tianshan-Beishan Terrane, where trilobite faunas instead show a strong affinity with those of Siberia and Laurentia. Well-defined biogeographic patterns are depicted mainly by the shallow-water components of the Cambro–Ordovician trilobites, especially among the South China, Tarim and North China plates. Synthetic analysis suggests that the Chinese eastern Peri-Gondwanan plates and terranes may be signified as belonging to a single biogeographic province during the Mid–Late Cambrian, Tremadocian and Ashgill, but exhibit significant differences and may, therefore, be separated into two subprovinces during the Early Cambrian and Arenig–Caradoc. One consists of South China, Tarim and Annamia in both periods; the other may include North China, Sibumasu, southern Tibet, Tianshan-Beishan and possibly Hainan in the Arenig–Caradoc, but is only represented by the North China Plate in the Early Cambrian according to the information we yet have. However, the trilobites of deep-water facies from the relevant Chinese geographic

Figure 1.7 Clusters of Cambrian and Ordovician geographic units on the basis of trilobite faunas using Simpson’s coefficient, indicating the biogeographic affinities of Cambrian and Ordovician trilobites occurring in the shallow-water (areas 4-1, 5-1, 8-1) and deep-water facies (areas 4-2, 5-2, 5-3/5-4, 8-2, 8-4) belts of Tarim (Region 4), North China (Region 5) and South China (Region 8) plates (Figs 1.3 and 1.4). A. Lungwangmiaoan; B. Changhian; C. latest Cambrian–Tremadoc; D. Arenig; E. Llanvirn; F. Caradoc. Data on the taxonomy and temporal and geographic distributions are essentially after those compiled in chapters 3, 5 and 8. However, in Fig. 1.4 the boundaries marked between the inner-shelf/platform and outer-shelf/slope facies areas of the South China and Tarim plates are applicable, respectively, for the Tremadoc and Tremadoc-early Arenig only, but, in fact, the position of the boundaries varies throughout different time intervals of the Ordovician. The assignment of part of the Arenig–Caradoc taxa to the second order geographic units of South China and Tarim is, therefore, modified from that of the Chapter 8 according to the updated biofacies data (as aforementioned in the text) when coding. Note also that: 1) only few Tremadoc and Arenig platform trilobites were recorded from the Area 4-1, which are not coded; 2) the coded trilobites from the Qaidam-Qilian Area (Cambrian: 5-3 of Fig. 1.3; Ordovician: 5-4 of Fig. 1.4) are mainly deeper-water forms, but also mixed up with a few from shallow sites (see text); 3) the widespread Changhian agnostoids are excluded when coding; 4) the slope facies trilobites from the western marginal area (5-2 in Fig. 1.4) of the North China Platform occur only from the late Arenig onwards; 5) only a single Wangcunian subgenus Centropleura (Centropleura) and a few Caradoc offshelf pelagic trilobites were recorded in the Cathaysia Area (8-3) of South China, and most of them extended their distribution to the adjacent shelf slope (the Jiangnan Area, 8-2), all of which are not coded.

·20· Trilobite Record of China

units progressively become more unified from the Llanvirn to Caradoc before the subprovinces eventually broke down by the Ashgill. This pattern of trilobite biogeographic proviciality seems to exhibit a cyclic nature, which is approximately synchronous to the cyclic process of origination, development and dispersion of the Cambrian Evolutionary Fauna (Sepkoski, 1981) during the Early Cambrian to Tremadocian and the Whiterock Fauna (Adrain et al., 1998) during the Arenig to Ashgill in eastern Peri-Gondwana.