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Maotianshan - Wikipedia, the free encyclopedia Page 1

Maotianshan Shales From Wikipedia, the free encyclopedia

The are a series of lower deposits in the Chiungchussu formation,[1] famous for their Konservat Lagerstätten , or high number of preserved in place. The Maotianshan shales form one of some forty Cambrian locations worldwide exhibiting exquisite preservation of rarely preserved, non-mineralized soft tissue, comparable to the fossils of the Burgess . They take their name from Maotianshan Hill (Chinese: 帽天山; pinyin: Màoti ānsh ān) in County, Province, .

The most famous assemblage of organisms are referred to as the Chengjiang biota for the multiple scattered fossil sites in Chengjiang. The age of the Chengjiang Lagerstätte is locally termed Qiongzhusian, a stage indisputably correlated to the late Atdabanian Stage in Siberian sequences of the middle of the Lower Cambrian.[2][3] It dates to between 525 and 520 million ago - a period situated in the middle of the Maotianshania cylindrica , a fossil early Cambrian epoch and at least some 10 million years older than the . The shales also [2] nematomorph worm, Early Cambrian, contain the slightly younger Guanshan biota . Chengjiang Maotianshan Shales

Contents

1 History and scientific significance 2 Preservation and 3 Chengjiang fauna 4 Guanshan fauna 5 See also 6 Footnotes 7 References 8 External links

History and scientific significance

Although fossils from the region have been known from the early part of the twentieth century, Chengjiang was first recognized for its exquisite states of preservation with the 1984 discovery of the naraoiid , a soft-bodied relative of . Since then, the locality has been intensively studied by scientists from throughout the world, yielding a constant flow of new discoveries and triggering an extensive scientific debate surrounding the interpretation of discoveries. Over this time, various taxa have been revised or re-assigned to different groups. Interpretations have led to many refinements of the phylogeny of various groups and even the erection of the new Vetulicolia of primitive .

The Chengjiang biota already has all the groups found in the Burgess Shale; however, since it is ten million years older, it more strongly supports the deduction that metazoans diversified earlier or faster in the early Cambrian than does the Burgess Shale fauna alone. The preservation of an extremely diverse faunal assemblage renders the Maotianshan shale the world’s most important locality for understanding the evolution of early multi-cellular life, and particularly the members of phylum Chordata, which includes all . The Chengjiang fossils comprise the oldest diverse metazoan assemblage above the - transition, and thus the fossil record’s best data source for understanding the apparently rapid diversification of life known as the . Preservation and taphonomy

Further information: Burgess shale type preservation

Fossils occur in a section of mudstone fifty meters thick in the Yuanshan Member of the Qiongzhusi Formation. The Yuanshan Member is extensive, covering tens of thousands of square kilometers of eastern Yunnan Province, where there are numerous, scattered outcrops yielding fossils. Studies of the strata are consistent with a tropical environment with sea level changes and tectonic activity. The region is believed to have been a shallow sea with a muddy bottom. The preserved fauna is primarily benthic and was likely buried by periodic turbidity currents, since most fossils do not show evidence of post mortem transport. Like the younger Burgess Shale fossils, the paleo-environment enabled preservation of non- mineralized, soft body parts. Fossils are found in thin layers less than an inch thick. The soft parts are preserved as aluminosilicate films, often with high oxidized iron content, and often exhibiting exquisite details.

The Chengjiang beds are very deeply weathered, as evidenced by their low specific gravity (i.e. they are very lightweight).[4] Trace fossils are abundant.[5] Chengjiang fauna

Further information: List of Chengjiang Biota species by phylum

http://en.wikipedia.org/wiki/Maotianshan_Shales 25.11.2012 18:57:43 Maotianshan Shales - Wikipedia, the free encyclopedia Page 2

The Chengjiang biota comprises an extremely diverse faunal assembly, with some 185 species described in the literature as of June 2006. Of these, nearly half are , few of which had the hard, mineral- reinforced characteristic of all later arthropoda; only about 3% of the organisms known from Chengjiang have hard shells, and most of those are the trilobites, of which there are five species, all of which have been found with traces of legs, antennae, and other soft body parts, an exceedingly rare occurrence in the fossil record. Phylum Porifera (; 15 species) and (16 species) are also well represented. Other phyla represented are Brachiopoda, , , , Echinodermata, , , Phoronida, Protista, and Chordata. About one in eight are problematic forms of uncertain affinity, some of which may have been evolutionary experiments that lanceolata, Maotianshan survived for only a brief period as benthic environments rapidly changed in the Cambrian. Chengjiang is the Shales, Chengjiang County, Yunnan richest source of the , often considered a distinct phylum, with six genera represented: Province Luolishania , , Cardiodictyon , (also known from the Burgess Shale), , and .

Perhaps the most important fossils from Chengjiang are eight possible members of phylum Chordata, the phylum to which all vertebrates belong. The most famous is , possibly a very primitive agnathid (i.e., jawless ). Similar to Myllokunmingia is ercaicunensis , another primitive fish-like animal.

The enigmatic lividum is considered to be the earliest , possessing many of the characteristic features and providing an anatomical link between and . Haikouella lanceolata is described to be the earliest -like chordate. This fish-like animal has many similarities to Y. lividum , but also differs in several aspects: it has a discernible heart, dorsal and ventral aorta, gill filaments, and a (neural chord).

At present, there is no agreement as to the systematic placement of the Vetulicola, represented by seven species from Chengjiang: originally described as arthropods, the Vetulicola were later erected as a new phylum of primitive deuterostomes by D.G. Shu et al. (Shu 2001). Another researcher places them with the urochordates, based on putative affinity with the Phylum Chordata. They are thought to have been swimmers that either were filter feeders or detritivores.

Some two dozen animals from the Chengjiang biota are problematic regarding phylogenetic assignment. Among these, saron , the alleged predatory terror of the early Cambrian, is the most famous. Shu (2006) recently described psygmoglena as a possible bilateran missing link between fronds and Cambrian ctenophores. Guanshan fauna

This fauna is similar and also contains vetulicolians. See also

Geography of China , Wonderful Life Footnotes

1. ^ Lipps, Jere H; Signor, Philip W (1992). Origin and early evolution of the Metazoa (http://books.google.ca/books?id=gUQMKiJOj64C&pg=PA338) . ISBN 978-0-306-44067-0. http://books.google.ca/books?id=gUQMKiJOj64C&pg=PA338. 2. ^ a b Zhang, Xingliang; Wei Liu, Yuanlong Zhao (2008). "Cambrian Burgess Shale-type Lagerstätten in South China: Distribution and significance" (http:// spamsights.org/cambrian/science_papers/Lagerstatten%20Distribution%202008.pdf) . Gondwana Research 14 (1–2): 255–262. doi:10.1016/j.gr.2007.06.008 (http://dx.doi.org/10.1016%2Fj.gr.2007.06.008) . http://spamsights.org/cambrian/science_papers/Lagerstatten%20Distribution%202008.pdf. 3. ^ Rozanov, A. Yu.; Maoyan Zhu, K. L. Pak and P. Yu. Parkhaev (2008). "The 2nd Sino-Russian Symposium on the Lower Cambrian Subdivision" (http:// www.springerlink.com/content/l70876jn8q5412k0) . Paleontological Journal 42 (4): 441–446. doi:10.1134/S0031030108040151 (http://dx.doi.org/10.1134% 2FS0031030108040151) . http://www.springerlink.com/content/l70876jn8q5412k0. 4. ^ Geology . 2008. 5. ^ Zhang, X. G.; Bergström, J.; Bromley, R. G.; Hou, X. G. (2007). "Diminutive trace fossils in the Chengjiang Lagerstätte". Terra Nova 19 (6): 407. doi:10.1111/j.1365-3121.2007.00765.x (http://dx.doi.org/10.1111%2Fj.1365-3121.2007.00765.x) . References

Conway-Morris, S. (2003). The Cambrian "explosion" of metazoans and molecular biology: would Darwin be satisfied? Int J Dev Biol, 47(7-8), 505-515. Fossils of the Chengjiang Maotianshan Shale (http://www.fossilmuseum.net/Fossil_Sites/Chengjiang.htm) - URL retrieved September 20, 2006 Hou, Xian-Guang; Aldridge, Richard J., Bengstrom, Jan; Siveter, David J. ;Feng, Xiang-Hong 2004; The Cambrian Fossils of Chengjang, China, Blackwell Science Ltd, 233 pp. Preservation, Taphonomy and Palaeoecology of the Chengjiang Biota (http://palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/chngjang/) - URL retrieved September 20, 2006 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 1999, Lower Cambrian Vertebrates from South China, Nature 402 pp 42–46. Shu, D. G., Morris, S. C., Han, J., Chen, L., Zhang, X. L., Zhang, Z. F., et al. (2001). Primitive deuterostomes from the Chengjiang Lagerstatte (Lower Cambrian, China). Nature, 414(6862), 419-424. http://en.wikipedia.org/wiki/Maotianshan_Shales 25.11.2012 18:57:43 Maotianshan Shales - Wikipedia, the free encyclopedia Page 3

Shu, D., Morris, S. C., Zhang, Z. F., Liu, J. N., Han, J., Chen, L., et al. (2003). A new species of yunnanozoan with implications for evolution. Science, 299(5611), 1380-1384. Shu, D. G., Morris, S. C., Han, J., Zhang, Z. F., & Liu, J. N. (2004). Ancestral from the Chengjiang deposits of China. Nature, 430(6998), 422-428. Shu, D. G., Morris, S. C., Han, J., Li, Y., Zhang, X. L., Hua, H., et al. (2006). Lower Cambrian vendobionts from China and early diploblast evolution. Science, 312(5774), 731-734. Waloszek, D., & Maas, A. (2005). The evolutionary history of crustacean segmentation: a fossil-based perspective. Evol Dev, 7(6), 515-527. Xian-guang, H., Aldridge, R. J., Siveter, D. J., & Xiang-hong, F. (2002). New evidence on the anatomy and phylogeny of the earliest vertebrates. Proc Biol Sci, 269(1503), 1865-1869. Zhang, X.; Han J.; Zhang Z.; Liu H.; and Shu D. (2003) Reconsideration of the supposed naraoiid larva from the Early Cambrian Chngjiang Lagerstätte, South China. Palaeontology 46(3):447-66. Zhang, X. G., & Hou, X. G. (2004). Evidence for a single median fin-fold and tail in the Lower Cambrian , Haikouichthys ercaicunensis. J Evol Biol, 17(5), 1162-1166. External links

"Chengjiang" (http://www.uni-wuerzburg.de/palaeontologie/Stuff/casu30.htm) (Web page). http://www.uni-wuerzburg.de/palaeontologie/ Stuff/casu30.htm. Retrieved November 22, 2005. http://www.fossilmuseum.net/Fossil_Sites/Chengjiang/Chengjiang-Biota.htm

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