Youping Fm

Hubei - NW. The naming section is located at Youping, Fangxian County, Hubei Province. Named by Lei Yizhen, Zhang Qingru and Sun Quanying in 1979 and formally published in the monograph “Biostratigraphy (5): the Three Gorges Region of the Yangtze River” in 1987.

Lower part is brown, very thick- to thick-bedded conglomerate with sandy conglomerate and sandstone lenses. Middle and Upper parts are alternating beds of brownish red, medium- to thick-bedded conglomerate and silty mudstone, with yellowing brown fine sandstone, coffee mudstone and grayish green sandy conglomerate; mudstone contains abundant calcareous concretions. The thickness is ~270 m.

According to Lei Yizhen et al., the fossil mammals contained in this formation include Rhombomylus sp, Asiocoryphodon lophodontus and Mesonychids. In these fossils, Asiocoryphodon and Rhombomylus were not found in the post-early Eocene strata in the past. In addition, Huang Xueshi has recently found a kind of Hyopsodus, which further demonstrates that the age of the Youping Formation should be early Eocene.