The discovery of the Leaid Conchostracan fossils from Upper Permian Taohaiyingzi Formation in Inner Mongolia and Its geological significance

In 1984, the Late Permian Leaid fossils (Conchostraca) were found for the first time by Professor Shen Yanbin in Gansu Provence. Thay occur in the Upper Permian Sunan Formation near Qinglong area of Yugur Autonomous County of Sunan, Gansu Province. In 2009, the Late Permian Leaid fossils were found from Upper Permian Taohaiyingzi Formation by the authors in Taohaiyingzi Town, Jarud Banner of Inner Mongolia. Thay occur in the Upper Permian Taohaiyingzi Formation and are composed of 3 genera and 8 speices, i.e., Bulbileaia orientalis Niu(gen. et sp. nov.), Praemonoleaia elliptica Niu(gen. et sp. nov.), P. oblonga Niu (gen. et sp. nov.), P. ovalis Niu (gen. et sp. nov.), P. rotunda Niu(gen. et sp. nov.), P. subtriangularis Niu (gen. et sp. nov.), P. ampulliformis Niu (gen. et sp. nov.), and Hemicycloleaia curtus Niu (sp.nov.). The carapace volve of genus Bulbileaia Niu (gen.nov.) is small in size and oval in shape, and has one radial ridge in front of the carapace volve of this genus. There are three small tumours on the birth shell of this genus. There is one radial ridge in front of the carapace volve of the genus Praemonoleaia Niu(gen. et sp. nov.). This radial ridge on the carapace volve of this genus is straight, vertical to the dorsal margin of the carapace volve of this genus. It had not achieved the ventral margin of the carapace volve of this genus. According to characteristics of the carapace volve from genus Praemonoleaia Niu (gen.nov.), Bulbileaia Niu (gen.nov.) and Petschoria Zaspelova, a new Subfamily Praemonoleaiinae Niu (subfam. nov.) has been established by the authors. The discovery of the Leaid conchostracan fossils in the Da Hinggan Mountains of Inner Mongolia is of important significance for the correlation and division of strata.