Qingtoushan Formation

The Qingtoushan Formation is a Middle Permian-age geologic formation in the Qilian Mountains of Gansu, China. It is known for its diverse tetrapod fauna known as the Dashankou fauna, which likely dates to the Roadian, and includes some of the oldest known therapsids.^[1] This formation was previously erroneously named as the Xidagou Formation, a name which applies to otherwise Triassic strata in the northern Qillian Mountains. The formation is over 300 metres thick, and primarily consists of purple-red coarse sandstones, with minor purple mudstone.^[2]

Qingtoushan Formation
Stratigraphic range: Middle Permian, Roadian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Underlies	Sunan Formation
Overlies	Yaogou Formation
Thickness	Over 300 metres
Lithology
Primary	Sandstone
Other	Mudstone
Location
Region	Gansu
Country	China
Extent	Qilian Mountains
Type section
Named by	Liu et al
Year defined	2012