Oligokyphus (Cynodontia: Tritylodontidae) from the Lower Lufeng Formation (Lower Jurassic) of Yunnan, China

ABSTRACT

We describe Oligokyphus lufengensis sp. nov. from the Dull Purplish Beds of the Lower Lufeng Formation, Yunnan, China. The holotype of O. lufengensis is similar to Oligokyphus from Germany, England, and North America in possessing two longitudinal rows of three principal cusps and a posterolingual accessory cusp on the lower postcanines. By contrast, all other known tritylodontids have two principal cusps on the lower postcanines. O. lufengensis is distinguished from other species of Oligokyphus by lacking the anterior cingulum on the lower postcanines. The discovery of Oligokyphus lufengensis suggests that the Dull Purplish Beds are coeval with the Kayenta Formation of North America and the fissure deposits yielding Oligokyphus in England, and that they are no older than Hettangian in age (Early Jurassic). The broad distribution of Oligokyphus indicates that there were interchanges among the terrestrial vertebrate faunas of North America, Europe, and China during the Early Jurassic.