Cambrian Burgess Shale-type Lagerstätten in South China: Distribution and significance

Transcription

1 Available online at Gondwana Research 14 (2008) Cambrian Burgess Shale-type Lagerstätten in South China: Distribution and significance Xingliang Zhang a,, Wei Liu a, Yuanlong Zhao b a Department of Geology, and State Key Laboratory for Continental Dynamics, Northwest University, Xian , China b College of Resource and Environment Engineering, Guizhou University, Guiyang , China Received 30 April 2007; received in revised form 20 June 2007; accepted 26 June 2007 Available online 17 July 2007 Abstract The final assembly of the supercontinent Gondwana during the Pan-African orogenic episodes (ca Ma) almost simultaneously took place with the Cambrian explosion that is best manifested by a number of Cambrian Burgess Shale-type Lagerstätten in South China. The relationship between South China and Gondwana during the Cambrian is far from consensus. Burgess Shale-type Lagerstätten may have potential importance for the paleogeographic reconstruction. However, such Lagerstätten have been known in large number only in Laurentia and South China, far less common in Gondwana and other continents. Burgess Shale-type Lagerstätten in South China are not evenly spaced through the Cambrian. They appear to be concentrated in the Lower Cambrian, particularly in the Canglangpuian and Qiongzhusian stages, much reduced in number from the uppermost Lower Cambrian. Of ten reported such Lagerstätten, only the Kaili biota (basal Middle Cambrian) is known to be younger than Early Cambrian. This reduction could be explained by the fact that vast areas of siliciclastic facies in both the western plate interior (platform) and the eastern slope basin during most time of Early Cambrian (Meishucunian to Canglangpuian) is evolved into carbonate facies at the very end of Early Cambrian (Longwangmiaoian). It has been known from this study that both siliciclastic platform facies and slope basin facies (shale basin) could preserve soft-bodied fossils. Cambrian Burgess Shale-type Lagerstätten in South China are of great significance for providing a sequences of exceptionally preserved biota in a chronological succession. Comparison of such Lagerstätten in a chronological framework may give us more details on the Cambrian explosion events International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. Keywords: Burgess Shale-type Lagerstätten; South China; Gondwana; Cambrian; Cambrian explosion 1. Introduction The history of supercontinents and their relation to mantle dynamics and surface processes have recently been the focus of several investigations (e.g.: Maruyama et al., 2007 and references therein). It is generally accepted that the assembly of the supercontinent Gondwana was completed by the end of Ediacaran to Early Cambrian (ca Ma) during the Pan- African orogenic episodes (Li and Powell, 2001; Meert, 2003; Rogers and Santosh, 2004; Santosh et al., 2006), and around the same period, the Iapetus Ocean opened (Grunow et al., 1996). The Neoproterozoic assembly of Gondwana and its relationship Corresponding author. Fax: address: xlzhang@pub.xaonline.com (X. Zhang). to the Ediacaran Cambrian radiation are topics of global interest (McCall, 2006; Meert and Liberman, 2008-this issue). Both Gondwana assembly and the opening of Iapetus Ocean simultaneously took place with Cambrian radiations of numerous animal phyla, which are best manifested by extraordinary fossil records of many Burgess Shale-type Lagerstätten in South China. The hypothetical short-lived supercontinent Pannotia, formed at the latest Neoproterozoic, just before the Cambrian radiations (Dalziel, 1997), comprised Gondwana plus Laurentia adjacent to Amazonia (Li and Powell, 2001). The position of South China relative to Gondwana during the Cambrian is of considerable controversy. The previous paleogeographic reconstruction based on the comparison between trilobite faunas suggested the discrete South China Plate lay within the Redlichiid trilobite biogeographic Realm and was adjacent to the northwest margin of East Gondwana (McKerrow X/$ - see front matter 2007 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. doi: /j.gr

2 256 X. Zhang et al. / Gondwana Research 14 (2008) et al., 1992). New paleobiogeographic data of Small shelly Fossils, however, suggest that South China was arranged at the western edge of Gondwana rather than along East Gondwana during the Early Cambrian (Steiner et al., in press). Recent phylogenetic biogeographic analysis of Early Cambrian trilobites also supports a distinct biogeographic region between Australia and East Artarctica that constitute the major part of East Gondwana (Lieberman, 2003a; Meert and Lieberman, 2004). Unfortunately, trilobite data of China were not included in this analysis. Recently, Meert and Lieberman (2008-this issue) place South China in an equatorial position north of India, but separated from Australia Antarctica during the Ediacaran interval and also include it as part of the Redlichiid realm. Paleogeographic reconstruction based on paleomagnetic analysis is far from consensus, especially with regard to the position of South China. For instance, Huang et al. (2000) inferred that the South China Plate was adjacent to western Antarctic Australia integral continent of Gondwana, most probably located close to western Australia or as a part of Gondwana. Li and Powell (2001), however, plotted the South China as a discrete plate in the Paleo-Pacific, away from the northeastern margin of East Gondwana. Burgess Shale-type Lagerstätten, used here in a broader sense as exceptional preservation in fine siliciclastic facies, more completely record the marine communities in muddominated substrate, and thus have valuable data for understanding the Cambrian biodiversity and the paleogeographic reconstruction as well. However, such Lagerstätten are not evenly distributed in paleogeographic regions albeit their concentration in the Cambrian (Conway Morris, 1985; Allison and Briggs, 1993). They have been known to be overrepresented in Laurentia (Briggs et al., 1994; Schwimmer and Montante, 2002; Lieberman, 2003b) and South China (Steiner et al., 2005) but far less common in Gondwana and other continents. Except for Laurentia and South China, each Cambrian continent is represented by no more than one Burgess Shale-type Lagerstätte, e.g. the Emu Bay Shale in South Australia of Gondwana (Nedin, 1995) and the Sinsk Lagerstätte in Siberia (Ponomarenko, 2005). No such Lagerstätte has been reported in the Cambrian of North China, Avalonia and Baltica. Burgess Shale-type Lagerstätten appear to be very common in the Cambrian of South China. Steiner et al. (2005) accounted a number of Lower Cambrian Burgess Shale-type Lagerstätten (Burgess Shale-type fossil associations) in this small plate but did not include more recent discoveries, e.g. the Guanshan fauna (Luo et al., 2005, 2006, 2007; Hu et al., 2007), the Balang fauna (Peng et al., 2005), the Shipai fauna (Zhang and Hua, 2005) and the Hetang sponge fauna (Xiao et al., 2005). In this paper, we give a more complete account of Cambrian Burgess Shale-type Lagerstätten of South China in the sense of stratigraphy (Fig. 1) and lithofacies paleogeography (Figs. 2 and 3), and discuss their significance on evolutionary aspects of Cambrian explosion. 2. Localities, faunal composition and stratigraphic range The occurrence of soft-bodied fossils in fine siliciclastic deposits of post-cambrian, e.g. the Ordovician Soom Shale (Aldridge et al., 1994) and the Devonian Hunsrück Slate (Bartels et al., 1998), indicates that Burgess Shale-type Lagerstätten are not confined to the Cambrian. However, they are not evenly spaced through Cambrian. The Lower and Middle Cambrian show a significantly higher concentration of exceptional fauna of this type, particularly in Laurentia and South China (Fig. 1). Upper Cambrian examples have not yet been reported. The case in South China appears to be concentrated in the Lower Cambrian, particularly in the Canglangpuian and Qiongzhusian stages. Fig. 1 shows the stratigraphic range of these Lagerstätten in both the traditional stratigraphic sequences of eastern Yunnan (China) and the new global chronostratigraphic frame Soft-bodied faunas of possible pre-trilobitic age The Niutitang Formation at Zunyi, Guizhou contains three fossiliferous units (Zhao et al., 1999). The basal unit, dominated by dark silt-mudstone (weathering to offwhite), yields softbodied components including entirely preserved sponge fossils, lightly sclerotized bivalved arthropods, and brachiopods with pedicles preserved (Zhao et al., 1999). This unit has been correlated to the upper Meishucunian in eastern Yunnan, and the Tommotian in Siberia (Zhao et al., 1999; Steiner et al., 2005). The stone coal beds of the Hetang Formation at Lantian, southern Anhui Province also yield a diverse assemblage of articulate sponges (the Hetang sponge fauna) including both hexactinellids and demosponges (Xiao et al., 2005). The age of this sponge fauna is constrained to be no older than the Meishucunian and no younger than the Qiongzhusian (Xiao et al., 2005). The fact that no trilobites have been recovered from the fossil beds containing the exceptionally preserved sponge fauna but trilobites of the Qiongzhusian age, e.g. Tsunyidiscus (Steiner et al., 2001) occur in upsections of both localities suggests that the basal Niutitang and the Hetang sponge faunas are probably pre-trilobitic in age, probably equivalent to the stage 2 of Series 1 in the new subdivision of Cambrian System (Fig. 1) Exceptionally preserved biotas of the Qiongzhusian Entirely preserved sponge larvae, juveniles and adults of mainly hexactinellids have been described from the Niutitang Formation at Sancha (the Sancha sponge fauna), Dayong (Zhangjiajie), Hunan Province (Steiner et al., 1993, 2005). Steiner et al. (2005) correlated the Sancha sponge fauna to the Chengjiang and Zunyi biotas (both are Qiongzhusian in age, see below) for the co-occurrence of sponges Triticispongia diagonota and Saetaspongia densa. However, the spongebearing black shale is overlain by the upper silt-shale units containing trilobite Hunanocephalus, which suggests that the Sancha sponge fauna may be older than the Chengjiang biota, probably equivalent to the middle fossil unit of the Niutitang Formation at Zunyi, Guizhou (Zhao et al., 1999). The Zunyi biota was described from the top unit of the Niutitang Formation (dominated by dark green silt-mudstones) at Zunyi, northern Guizhou (Zhao et al., 1999; Steiner et al., 2005) and at Cengong, eastern Guizhou (Steiner et al., 2005). The faunal composition shows some similarities to the

3 X. Zhang et al. / Gondwana Research 14 (2008) Fig. 1. Subdivision of Cambrian in global stratigraphy and eastern Yunnan, China, showing the stratigraphic range of Burgess Shale-type Lagerstätten in South China. Chengjiang biota, both of which are dominated by arthropods and sponges. Common taxa include arthropods Isoxys, both morphs of Naraoia spinosa and Skiodia, sponges Choiaella and Hyalosinica, and many others (Steiner et al., 2005). In comparison with the Chengjiang Lagerstätte, soft-bodied components are relatively rare and the preservational quality is far less exquisite in the Zunyi biota. This biota is of Qiongzhusian age because of occurrence of trilobite Tsunyidiscus, estimated to be slightly older than the Chengjiang biota (Steiner et al., 2005). The well-known Chengjiang Lagerstätte is widely distributed in the eastern Yunnan (Zhang et al., 2001) and yields abundant soft-bodied fossils of diverse phyla (Hou et al., 2004; Chen, 2004) including agnathous vertebrates (Shu et al., 1999). A recent study indicated that at least 150 metazoan genera were present in this Lagerstätte (Chen et al., 2002). The age of the Chengjiang Lagerstätte is no doubt Qiongzhusian that was correlated to the late Atdabanian in Siberian sequences (Zhang et al., 2001). The diversity and preservational quality of the biota are on a par with the Burgess Shale Lagerstätte Exceptionally preserved biotas of the Canglangpuian age Apart from the Chengjiang biota, there is an additional horizon, i.e. the Wulongqing Formation (the former Wulongqing Member of the Canglangpu Formation, late Canglangpuian in age), yielding diverse soft-bodied fossils, named as the Guanshan fauna (Luo et al., 2005) in many localities of eastern Yunnan. Soft-bodied fossils hitherto described include Vetulicola (Luo et al., 2005), unnamed eocrinoids (Hu et al., 2007)

4 258 X. Zhang et al. / Gondwana Research 14 (2008) Fig. 2. Facies reconstruction of South China during the Early Cambrian based on Feng et al. (2004), indicating the distribution of Burgess Shale-type Lagerstätten with numbers. 1, the Hetang sponge fauna; 2, the basal Niutitang sponge fauna; 3, the Sancha sponge fauna; 4, the Zunyi biota; 5, the Chengjiang biota; 6, the Guanshan fauna; 7, the Balang fauna; 8, the Shipai fauna; 9, an un-named soft-bodied fauna in southern Shaanxi Province. and lightly sclerotized arthropods such as Isoxys, Tuzoia and Guangweicaris (Luo et al., 2006, 2007). The Balang fauna is described from the upper part of the siltmudstone dominated Balang Formation at Wenglingtang, western suburb of Kaili City, Guizhou Province (Peng et al., 2005). The fauna is characteristic by abundant entirely preserved eocrinoids (making up one third of total 3000 specimens or so) and trilobites. Soft-bodied components are rare and only worm fossils have been mentioned (Peng et al., 2005). On the basis of trilobite biostratigraphy, the Balang fauna can be correlated to early Duyunian in age (Peng et al., 2006), equivalent to the Canglangpuian in eastern Yunnan (Peng, 2003). Mudstones and shales of the Lower Cambrian Shipai Formation in the Three Gorge area, Hubei, China, are richly fossiliferous, containing common shelly fossils and abundant soft-bodied fossils (Zhang and Hua, 2005). Identifiable, nonmineralized taxa include components of the Chengjiang fauna, such as Vetulicola, a brachiopod Diandongia pista with pedicle preserved, and a palaeoscolecidan Maotianshania. Cambrorhytium, co-occurring both in the Burgess Shale and the Chengjiang Lagerstätte, was also recovered. This fossil assemblage is hereby referred to as the Shipai fauna, and its age is confined to the Canglangpuian (Zhang and Hua, 2005). The Yanwangbian Formation at Xixiang, southern Shaanxi Province is characteristic by sandstones interbedded with many layers of yellowish green shales. The shales yield abundant shelly fossils like trilobites, bradoriids and brachiopods (Chen and Zhang, 1987; Chen, 1999), as well as many soft-bodied fossils. This rock unit is usually correlated to the Canglangpuian in eastern Yunnan (Chen and Zhang, 1987). Soft-bodied components of this fossil assemblage have not yet been described. Fig. 4 shows a lightly sclerotized arthropod Primicaris (Fig. 4C) and a palaeoscolecidan (gen. et sp. indet, Fig. 4B) The Middle Cambrian Kaili Lagerstätte The Kaili biota is the only known exceptionally preserved biota of the Middle Cambrian age and also the youngest one (basal middle Cambrian) in South China. The type locality lies in the middle to upper part of the Kaili Formation at Balang Village. A recent intensively excavated locality at Miaobanpo, 1200 m north to the type locality, is proven to be very productive and yields many exciting discoveries including a large number of well-preserved eocrinoids (e.g. Fig. 4A) and many more taxa previously only known from Lagerstätten in Laurentia, e.g. Marrella, Mollisonia, Ottoia, Wiwaxia, etc. More than 110 metazoan genera of ten phyla are present in the Kaili biota. The distinctive character of the faunal composition is its abundant eocrinoids and planktonic trilobites. More information on the Kaili biota can be found in the two volume

5 X. Zhang et al. / Gondwana Research 14 (2008) Fig. 3. Facies reconstruction of South China during the earliest Middle Cambrian based on Feng et al. (2004), a dark triangle in the shale basin facies indicating the location of the Kaili biota. treatments in Acta Palaeontologica Sinica (suppl.) 1994 and 1999, and also in Zhao et al. (2002, 2005). 3. Lithofacies and paleogeographic distribution of Lagerstätten The succession of the Lower Cambrian in the South China Plate demonstrates a wide range of lithofacies (Fig. 2); the west margin is elevated to form two paleoislands; the plate interior, i.e. the vast area in the west is dominated by clastic platform, with carbonate platform existing in minor areas; down to the east, a wide northeast extended stripe is a shale-dominated slope basin (Feng et al., 2004). Fine siliciclastic facies of many horizons are well developed in both the clastic platform facies and the slope basin facies, which are suitable environments for the preservation of the Burgess Shale-type Lagerstätten. Indeed, nine such Lagerstätten of Lower Cambrian have been found with a wide distribution, six in the clastic platform facies and three in the slope basin facies (Fig. 2). Many more may remain to be found in the remainder vast areas. At the end of the Early Cambrian (Longwangmiaoian) and the beginning of the Middle Cambrian, the former paleoislands in the west margin of the South China was expanded to form a larger, united paleoland and a new paleoisland was elevated in the southwestern interior. The clastic platform facies was restricted to a narrow belt along the paleoland and the large area of the plate interior (west part of the South China) was evolved into carbonate platform facies with evaporates developed interiorly. The former slope basin (shale facies) became narrower; its lithofacies differentiated into carbonate basin facies in northeast and southwest ends of the basin stripe and shale facies was retained only in the middle part of the former slope basin (Fig. 3). Such lithofacies and paleogeographic frame was retained throughout the remainder of Cambrian. Therefore, it is apparent that fine siliciclastic facies is tremendously reduced during Middle and Late Cambrian, which is consistent with the fact that few Burgess Shale-type Lagerstätten have been known from this time range. The Kaili biota (basal Middle Cambrian) is the only known such Lagerstätte younger than Early Cambrian in South China, which occurs in the shale facies of the slope basin (Fig. 3). 4. Significance Cambrian Burgess-Shale-type Lagerstätten have been important in three respects. First, they preserve soft-bodied as well as skeletonized animals and thus give us an unrivaled insight into the Cambrian life (Gould, 1989; Briggs et al., 1994; Conway Morris, 1998; Hou et al., 2004), in particular, those entirely soft-bodied animals which would normally stand no chance of fossilization. Second, their preservation is exceptional, allowing interpretation of anatomical details. The study of

6 260 X. Zhang et al. / Gondwana Research 14 (2008) Fig. 4. Soft-bodied fossils from the Cambrian of South China. Scale bars, 1 cm in A, D and E, 5 mm in the remainder photographs. A, eocrinoids (gen. et sp. indet) from the Kaili biota; B, a palaeoscolecidan (gen. et sp. indet) from the Yanwangbian Formation at Xixiang, southern Shaanxi, China; C, Primicaris larvaformis from the same locality and the same horizon to B; D, enigmatic metazoan Phlogites from the Chengjiang Lagerstätte preserved in life position, four individuals attaching to a trilobite genal spine (indicated by numbers); E, Misszhouia longicaudata from the Chengjiang Lagerstätte, showing a healed injury (bite mark) in the antero-right of the cephalon. F, fine details of gill structures in a specimen of Misszhouia longicaudata from the Chengjiang Lagerstätte. soft-part morphology alongside the morphology of the shell or skeleton allows better comparison with extant forms and provides valuable phylogenetic information (Selden and Nudds, 2004). Third, Cambrian Burgess-Shale-type Lagerstätten yield many peculiar animals which may represent extinct classes and phyla, e.g. vetulicolians (Shu et al., 2001a). Cambrian Burgess Shale-type Lagerstätten in South China, taking together, are of great significance for containing a sequences of exceptionally preserved biota in many horizons, which more completely record a succession of biological communities in marine mud-dominated substrates. A number of animals, previously known only from the Burgess Shale, have been found in South China. Comparison of such fossiliferous horizons in a chronological framework gives us an insight into events of Cambrian explosion. Moreover, comparative studies between a single lineage from different horizons may reveal evolutionary trend of the lineage through time. A number of arthropod lineages such as naraoiids, leanchoiliids and canadaspids are good examples for such comparative studies (Zhang et al., in press). Two pre-trilobitic Lagerstätten, i.e. the Hetang sponge fauna and the basal Niutitang sponge fauna, record a diverse assemblage of entirely preserved sponges including both hexactinellids and demosponges but are lack of soft-bodied components of other phyla, e.g., lightly sclerotized arthropods, priapulids, etc. This, in conjunction with the fact that such sponge fauna is sub-dominated (second only to arthropods) and co-occurring with many soft-bodied animal phyla in the succeeding Chengjiang and Zunyi Lagerstätten (Qiongzhusian), suggests that sponge is diverged earlier than many other animals that are typical in the Chengjiang Lagerstätte, much of the sponge diversification at the class-level occurring between the Meishucunian and Qiongzhusian.

7 X. Zhang et al. / Gondwana Research 14 (2008) The Chengjiang Lagerstätte demonstrates the maximum diversity and disparity of animals in Cambrian, recording the most magnificent episode of Cambrian explosion. Of thirty-five living phyla more than half had their origins in the Cambrian; many of them including vertebrates (Shu et al., 1999) make their first appearance in the Chengjiang Lagerstätte. That reveals a crucial aspect of the structure of the metazoan radiation; much of it involves the origins of the living phyla. A new phylum Vetulicolia (Shu et al., 2001a) was established based on the material from this Lagerstätte and recently also recovered from the Guanshan and Shipai faunas (Luo et al., 2005; Zhang and Hua, 2005). In addition, fossils of the Chengjiang Lagerstätte are most exquisitely preserved, which makes interpretation of morphological details possible. For instance, fine details of gill structures are superbly preserved in arthropod Misszhouia (Fig. 4F). By comparison with extant representatives in morphological details, some animal groups demonstrate a evolutionary stasis, remaining very similar since their first appearance in the Chengjiang Lagerstätte, e.g. urochordates (Shu et al., 2001b), priapulids (Huang et al., 2003, 2004a), sipunculids (Huang et al., 2004b) and chaetognaths (Chen and Huang, 2002), whereas others, particularly arthropods, show tremendous innovation. High quality of fossil preservation in the Chengjiang Lagerstätte is also reflected in ecological aspects. A healed injury (bite mark, Fig. 4E) in a naraoiid arthropod records a nonlethal predation probably caused by the Cambrian giant predator, Anomalocaris. The enigmatic animal Phlogites have been preserved in life position, four individuals attaching to a trilobite genal spine (Fig. 4D). Despite intensive excavation, there is no unequivocal echinoderm in the Chengjiang Lagerstätte. Therefore, the discovery of eocrinoids from the Guanshan and Balang faunas is of great significance for our understanding the early evolution of echinoderms. Eocrinoids in these two fauna also provide new information to the investigation of the life style of this animal group (Hu et al., 2007). The composition of the Kaili biota (basal Middle Cambrian) shows many similarities to the Burgess Shale biota because a number of dominant taxa in the Burgess Shale, e.g. Marrella, Ottoia, Canadaspis, etc., have continued to be found in this biota, which indicates that the Burgess Shale community is also flourished in the South China. Most importantly, a diverse assemblage of eocrinoids in this biota records the early episode of echinoderm diversification. 5. Conclusion The final formation of Gondwana was broadly synchronous with the biological innovation event: Cambrian explosion (Li and Powell, 2001; Meert, 2003; Rogers and Santosh, 2004; Meert and Lieberman, 2008-this issue), as was recorded in Cambrian Burgess Shale-type Lagerstätten. Such Lagerstätten have been known to be widely distributed throughout South China and not evenly spaced through Cambrian, most concentrated within the Early Cambrian. This is consistent with the wide distribution of siliciclastic facies during most time of Early Cambrian and the marked reduction thereafter. Burgess Shale-type Lagerstätten in the Cambrian of South China show a succession of exceptionally preserved biotas in a single tectonic unit, and therefore, are crucial for understanding the evolutionary aspects of Cambrian explosion. Among them, the Chengjiang Lagerstätte is of particular importance for yielding first body fossils of many bilateral metazoan phyla including vertebrates and the extinct phylum Vetulicolia. Acknowledgements We would like to thank Shigenori Maruyama and Degan Shu for inviting us to contribute to this special volume, and Tao Dai for linguistic assistance. Thanks also go to J.G. Meert, M. Steiner and an anonymous reviewer for their constructive comments and suggestions. Financial support for this research is provided by the Major Basic Research Projects of the Ministry of Science and Technology of China (Grant: 2006CB806400), the Natural Science Foundation of China (NSFC, Grants: and ) and the Program for Changjiang Scholars and Innovative Research Team in Universities (PCSIRT). WL is also funded by the National Basic Science Talent Training Project of the Natural Science Foundation of China (Grant: J ). References Aldridge, R.J., Theron, J.N., Gabbott, S.E., The Soom Shale: a unique Ordovician fossil horizon in South Africa. Geology Today 10, Allison, P.A., Briggs, D.E.G., Exceptional fossil record: Distribution of soft-tissue preservation through the Phanerozoic. Geology 21, Bartels, C., Briggs, D.E.G., Brassel, G., The Fossils of Hunsrück Slate. Cambridge University Press, Cambridge. Briggs, D.E.G., Erwin, D.H., Collier, F.J., The Fossils of the Burgess Shale. Smithsonian Institution Press, Washington DC and London. Chen, R.-Y., Bradoriids from the Lower Cambrian of Xixiang in Shaanxi Province. Professional Papers of Stratigraphy and Palaeontology 27, (In Chinese). Chen, J.-Y., The Dawn of Animal World. Jiangsu Science and Technology Press, Nanjing. Chen, J.-Y., Huang, D.-Y., A possible Lower Cambrian chaetognath (arrow worm). Science 298, 187. Chen, R.-Y., Zhang, F.-Y., Cambrian strata of Nanzheng and Xixiang of Shaanxi Province. Journal of Northwest University 2, (In Chinese). Chen, L.-Z., Luo, H.-L., Hu, S.-X., Yin, J.-Y., Jiang, Z.-W., Wu, Z.-L., Li, F., Chen, A. L., Early Cambrian Chengjiang Fauna in Eastern Yunnan, China. Yunnan Science and Technology Press, Kunming. Conway Morris, S., Cambrian Lagerstätten: their distribution and significance. Philosophical Transactions of the Royal Society of London. B311, Conway Morris, S., The Crucible of Creation. Oxford University Press, Oxford. Dalziel, I.W.D., Neoproterozoic Paleozoic geography and tectonics: Review, hypothesis, environmental speculation. Geological Society of America Bulletin 109, Feng, Z.-Z., Peng, Y.-M., Jin, Z.-K., Bao, Z.-D., Lithofacies Paleogeography of the Cambrian and Ordovician in China. Petroleum Industry Press, Beijing. Gould, S.J., Wonderful life: the Burgess Shale and the Nature of History. W. W. Norton & Co, New York. Grunow, A.M., Hanson, R., Wilson, T., Were aspects of Pan-African deformation related to Iapetus opening. Geology 24, Hou, X.-G., Aldridge, R.J., Bergström, J., Siveter, D.J., Siveter, D.J., Feng, X.-H., The Cambrian Fossils of Chengjiang, China: the Flowering of Early Animal Life. Blackwell, Oxford.

8 262 X. Zhang et al. / Gondwana Research 14 (2008) Hu, S.-X., Luo, H.-L., Hou, S.-G., Erdtmann, B.D., Eocrinoid echinoderms from the Lower Cambrian Guanshan fauna in Wuding, Yunnan, China. Chinese Science Bulletin 52, Huang, D. Y., Chen, J. Y., Vannier, J., Saiz-Salinas, J.I., 2004a. Early Cambrian sipunculan worms from southwest China. Proceedings of the Royal Society of London B271, Huang, D. Y., Vannier, J., Chen, J.-Y., Anatomy and life styles of Early Cambrian priapulid worms exemplified by Corynetis and Anningella from the Early Cambrian Maotianshan Shale (SW China). Lethaia 37, Huang, D. Y., Vannier, J., Chen, J.-Y., 2004b. Recent Priapulidae and their Early Cambrian ancestors: comparisons and evolutionary significance. Geobios 37, Huang, B.-C., Zhu, R.-X., Otofuji, Y., Yang, Z.-Y., The Early Paleozoic paleogeography of North China block and other major blocks of China. Chinese Science Bulletin 45, Li, Z.-X., Powell, C.M., An outline of the palaeongeographic evolution of the Australasian region since the beginning of the Neoproterozoic. Earth- Science Review 53, Lieberman, B.S., 2003a. Biogeography of the Cambrian radiation: Deducing geological processes from trilobite evolution. Special Papers in Palaeontology 70, Lieberman, B.S., 2003b. A new soft-bodied fauna: the Pioche Formation of Nevada. Journal of Paleontology 77, Luo, H.-L., Fu, X.-P., Hu, S.-X., Li, Y., Chen, L.-Z., You, T., Liu, Q., New vetulicoliids from the Lower Cambrian Guanshan fauna, Kunming. Journal of the Geological Society of China 79, 1 6. Luo, H.-L., Fu, X.-P., Hu, S.-X., Li, Y., Chen, L.-Z., You, T., Liu, Q., New bivalved arthropods from the Lower Cambrian Guanshan fauna in the Kunming and Wuding areas. Acta Palaeontologica Sinica 45, Luo, H.-L., Fu, X.-P., Hu, S.-X., Li, Y., Hou, S.-G., You, T., Pang, J.-Y., Liu, Q., A new arthropod, Guangweicaris Luo, Fu et Hu gen. nov. from the Early Cambrian Guanshan fauna, Kunming, China. Journal of the Geological Society of China 81, 1 7. Maruyama, S., Santosh, M., Zhao, D., Superplume, supercontinent, and post-perovskite: Mantle dynamics and anti-plate tectonics on the Core Mantle Boundary. Gondwana Research 11, McCall, J.G.H., The Vendian (Ediacaran) in the geological record. Gondwana Research 10, McKerrow, W.S., Scotese, C.R., Brasier, M.D., Early Cambrian continental reconstruction. Journal of the Geological Society (London) 149, Meert, J.G., Proterozoic East Gondwana: Supercontinent assembly and breakup, Special Publication 206. Eos Transactions AGU 84 (37), 372. Meert, J.G., Lieberman, B.S., A palaeomagnetic and palaeobiogeographical perspective on latest Neoproterozoic and Early Cambrian tectonic events. Journal of the Geological Society (London) 161, Meert, J.G., Lieberman, B.S., The Neoproterozoic assembly of Gondwana and its relationship to the Ediacaran Cambrian radiation. Gondwana Research. Journal of the Geological Society (London) 14, 5 21 (this issue). doi: /j.gr Nedin, C., The Emu Bay Shale, a Lower Cambrian fossil Lagerstätte, Kangaroo Island, South Australia. In: Jell, P.A. (Ed.), APC94: Papers from the First Australian Palaeontological Convention. Association of Australiasian Palaeontologists Memoir, vol. 18, pp Peng, S.-C., Chronostratigraphic subdivision of the Cambrian of China. Geologica Acta 1, Peng, J., Zhao, Y.-L., Wu, Y.-S., Yuan, J.-L., Tai, T.-S., The discovery of the Early Cambrian Balang fauna in Kaili, Guizhou. Chinese Science Bulletin 50, (in Chinese). Peng, J., Zhao, Y.-L., Yang, X.-L., Trilobites of the upper part of the Lower Cambrian Balang Formation, southeastern, Guizhou Province. Acta Palaeontologica Sinica 45, (in Chinese with English summary). Ponomarenko, A.G., Unique Sinsk Localities of Early Cambrian Organisms (Siberian Platform). Nauka, Moscow. (in Russian). Rogers, J.J.W., Santosh, M., Continents and Supercontinents. Oxford University Press, Oxford. Santosh, M., Morimoto, T., Tsutsumi, Y., Geochronology of the khondalite belt of Trivandrum Block, Southern India: Electron probe ages and implications for Gondwana tectonics. Gondwana Research 9, Schwimmer, D.R., Montante, W.M., Exceptional fossil preservation in the Conasauga Formation, Middle Cambrian of Western Georgia. Annual Meeting of GSA, Abstract with program 31, 65. Selden, P., Nudds, J., Evolution of Fossil Ecosystems. The University of Chicago Press, Chicago. Shu, D.-G., Chen, L., Han, J., Zhang, X.-L., 2001b. An Early Cambrian tunicate from China. Nature 411, Shu, D.-G., Conway Morris, S., Han, J., Chen, L., Zhang, X.-L., Zhang, Z.-F., Liu, H.-Q., Li, Y., Liu, J.-N., 2001a. Primitive deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China). Nature 414, Shu, D.-G., Luo, H.-L., Conway Morris, S., Zhang, X.-L., Hu, S.-X., Chen, L., Han, J., Zhu, M., Li, Y., Chen, L.-Z., Lower Cambrian Vertebrates from South China. Nature 402, Steiner, M., Li, G.-X., Qian, Y., Zhu, M.-Y., Erdtmann, B.-D., in press. Neoproterozoic to Early Cambrian small shelly fossil assemblages and a revised biostratigraphic correlation of the Yangtze Platform (China). Palaeogeography Palaeoclimatology Palaeoecology. doi: /j.palaeo Steiner, M., Mehl, D., Reitner, J., Erdtmann, B.D., Oldest entirely preserved sponges and other fossils from the Lowermost Cambrian and a new facies reconstruction of the Yangtze platform (China). Berliner Geowissenschaftlicher Abhandlung, E Paläobiologie 9, Steiner, M., Zhu, M.-Y., Weber, B., Geyer, G., Lower Cambrian of eastern Yunnan: trilobite-based biostratigraphy and related faunas. Acta Palaeontologica Sinica 40, (Suppl.). Steiner, M., Zhu, M.-Y., Zhao, Y.-L., Erdtmann, B.D., Lower Cambrian Burgess Shale-type fossil associations of South China. Palaeogeography, Palaeoclimatology, Palaeoecology 220, Xiao, S.-H., Hu, J., Yuan, X.-L., Parsley, R.L., Cao, R.-J., Articulated sponges from the Lower Cambrian Hetang Formation in southern Anhui, South China: their age and implication for the early evolution of sponges. Palaeogeography, Palaeoclimatology, Palaeoecology 220, Zhang, X.-L., Hua, H., Soft-bodied fossils from the Shipai Formation, Lower Cambrian of the Three Gorge area, South China. Geological Magazine 142, Zhang, X.-L., Shu, D.-G., Li, Y., Han, J., New sites of Chengjiang fossils: Crucial windows on the Cambrian explosion. Journal of the Geological Society (London) 158, Zhang, X.-L., Shu, D.-G., Erwin, D.H., (in press). Cambrian naraoiids. Journal of Paleontology, Memoir. Zhao, Y.-L., Steiner, M., Yang, R.-D., Erdtmann, B.D., Guo, Q.-J., Zhou, Z., Wallis, E., Discovery and significance of the Early Cambrian metazoan biotas from the Lower Cambrian Niutitang Formation, Zunyi, Guizhou, China. Acta Palaeontologica Sinica 38, (Suppl.). Zhao, Y.-L., Yun, J.-L., Zhu, M.-Y., Yang, R.-D., Guo, Q.-J., Peng, J., Yang, X.-L., Progress and significance in research on the early Middle Cambrian Kaili biota, Guizhou Province, China. Progress in Natural Science 12, Zhao, Y.-L., Zhu, M.-Y., Babcock, L.E., Yun, J.-L., Parsley, R.L., Peng, J., Yang, X.-L., Wang, Y., Kaili biota: a taphonomic window on diversification of metazoans from the basal Middle Cambrian, Guizhou, China. Journal of the Geological Society of China 79,