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Maotianshan Shales
The Maotianshan Shales are a series of lower Cambrian deposits in the Chiungchussu formation, famous for their ''Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized organisms or traces. The Maotianshan shales form one of some forty Cambrian fossil locations worldwide exhibiting exquisite preservation of rarely preserved, non-mineralized soft tissue, comparable to the fossils of the Burgess Shale. They take their name from Maotianshan Hill () in Chengjiang County, Yunnan Province, China.
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. It probably dates to about 515 million years ago - a period situated towards the end of the early Cambrian epoch (mid-Cambrian Series 2) and about 7 million years older than the Burgess Shale. The shales also contain the slightly younger Guanshan biota.〔
==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 ''Misszhouia'', a soft-bodied relative of trilobites. Since then, the locality has been intensively studied by scientists 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 reassigned to different groups. Interpretations have led to many refinements of the phylogeny of various groups and even the erection of the new phylum Vetulicolia of primitive deuterostomes.
The Chengjiang biota already has all the animal 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 vertebrates. The Chengjiang fossils comprise the oldest diverse metazoan assemblage above the Proterozoic-Phanerozoic transition, and thus the fossil record’s best data source for understanding the apparently rapid diversification of life known as the Cambrian Explosion.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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