Platacanthomyids (Rodentia, Mammalia) from the Late Miocene Yuanmou Hominoid Locality of Yunnan, China

Abstract Remains of platacanthomyids from Leilao, a late Miocene hominoid locality in Yuanmou, Yunnan, China are described. Five species in three genera are recognized: Neocometes sp., Platacanthomys dianensis Qiu, 1989, Typhlomys aff. T. primitivus Qiu, 1989, T. hipparionum Qiu, 1989 and T. storchi n. sp. Leilao is the only locality that produces fossils of all three known genera of the family Platacanthomyidae. The new species T. storchi is characterized by its huge dimensions and continuous endoloph(id)s and ectoloph(id)s incorporated with the anteroloph(id)s and posteroloph(id)s to encircle the occlusal surface. That the genus Neocometes from southeastern Asia shows a tendency of forming an ectoloph on the upper molars and an endolophid on the lower molars indicates that the South China species probably represents an evolutionary lineage independent from that of European Neocometes. Both P. dianensis and T. aff. T. primitivus exhibit more derived dental morphology than the related species from Shihuiba of Lufeng, suggesting a younger age of the Leilao Fauna, which is incompatible with the conclusion drawn from the studies of other groups of small mammals.