Wulanxire Fm

Central-Eastern Inner Mongolia. The naming section is located in the central part of the northern margin and on the southeastern margin of the North Height of Weijing, Siziwang Banner, Inner Mongolia. First named the Ulan Shireh bed by C.P. Berkey, W. Granger and F.K. Morris in 1929 and later renamed the Ulan Shireh Formation by Fei Wenzhong, Zhou Mingzhen and Zheng Jiajian in 1963.

Synonym: Ulan Shireh Fm

A sequence of variegated muddy deposits dominated by red mudstone, > 50 m in thickness.

The mammal fossils in the formation had been collected and studied by the Central Asian Expedition of the Natural History Museum of the United States as early as in 1925 and 1928. In addition, fossils were taken by the Sino-Soviet Paleontological Investigation Team in 1959 and a research team of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, in 1975 and 1981 respectively. In 1983 Ye Jie conducted a relatively detailed study of this fauna. Up to now, the fossils found in this formation include more than 30 species such as Eudinoceras mongoliensis, Shamolagus grangeri, Yuomys weijingensis, Sarkastodon mongoliensis, Hapalodectes serus, Acrotitan ulanshirehensis, Teleolophus medius, Lophialetes expeditus, Breviodon minutus and Gobiohyus orientalis. According to the composition of the fauna, it belongs to the Irdinmanhan Stage undoubtedly, and the age should be middle Middle Eocene.