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 (Chinese: ; pinyin: Màotiānshān) 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 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 — toward 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.

Although fossils from the region have been known from the early part of the 10th 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, taxa have been revised or reassigned to different groups. Interpretations have led to many refinements of the phylogeny of groups and even the erection of the new phylum Vetulicolia of primitive deuterostomes.

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