Xiagou Formation

Xiagou Formation
Stratigraphic range: late Aptian ~123–113 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Xinminbao Group
Underlies	Zhonggou Formation
Overlies	Chijinpu Formation
Lithology
Primary	Mudstone
Other	Shale, siltstone
Location
Coordinates	39°54′N 96°48′E / 39.9°N 96.8°E / 39.9; 96.8
Approximate paleocoordinates	39°06′N 97°30′E / 39.1°N 97.5°E / 39.1; 97.5
Region	Gansu
Country	China
Extent	Changma Basin
Type section
Named for	Xiagou
Xiagou Formation (China)

The Xiagou Formation is the middle strata of the Xinminbao Group. It is named for its type site in Xiagou, in the Changma Basin of Gansu Province, northwestern China and is considered Early Cretaceous in age. It is known outside the specialized world of Chinese geology as the site of a Lagerstätte in which the fossils were preserved of Gansus yumenensis, the earliest true modern bird.