Maotianshan shale

Maotianshan Shale Stratigraphic range: Qiongzhusian ~515 Ma PreЄ Є O S D C P T J K Pg N ↓
Outcrop of the Maotianshan Shale, site of the discovery of the Chengjiang Biota
Type	Member
Unit of	Chiungchussu Formation
Area	multiple 10,000 km2 (3,900 sq mi)
Thickness	50 m (160 ft)
Lithology
Primary	Shale
Other	Mudstone
Location
Region	Chengjiang County, Yunnan
Country	China
Type section
Named for	Maotianshan Hill
Location	Maotianshan Hill
Region	Chengjiang County, Yunnan
Country	China

The Maotianshan Shales are a series of Early 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 Early 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.