Assessment of dental ontogeny in late Miocene hipparionines from the Lamagou fauna of Fugu, Shaanxi Province, China

A collection of 28 hipparionine skull and mandible fossils with a dated age of approximately 7.4 Ma from Fugu, Shaanxi, northwestern China (belonging to Hipparion chiai and Hipparion cf. coelophyes) shows an age distribution in a successive development sequence. By observing the dentitions in these fossil materials, knowledge of dental ontogeny has been gained, such as the opening time of the posterior wall of post-fossettes, the displacement of the plis hypostyle, the morphologic changes of the protocone and hypocone, etc. Additionally, 4 isolated maxillary cheek teeth and 2 mandibular cheek teeth were cut into slices in the traditional manner for authentication. These discoveries indicate that both of the hipparionine species in the Lamagou fauna are Hipparion cf. chiai exactly and offer further insight into the morphologic changes that occur during dental wear in hipparionines, which may greatly promote the morphological and taxonomic study of hipparionine species.