Oldest South Asian tapiromorph (Perissodactyla, Mammalia) from the Cambay Shale Formation, western India, with comments on its phylogenetic position and biogeographic implications

Abstract

A new tapiromorph perissodactyl (Cambaylophus vastanensis gen. et sp. nov.) from the basal Eocene (~54–55 Ma) Cambay Shale Formation, Vastan Lignite Mine, Gujarat, western India, is described for the first time. The new taxon, which represents the earliest known tapiromorph from South Asia and the second perissodactyl group in the Vastan mammal fauna after cambaytheres, is based on a partial maxilla with molars and deciduous premolars. Cambaylophus differs from Eocene tapiromorphs from the Indian Subcontinent mainly in having relatively narrow and less lophodont upper molars with a small, low and lingually shifted parastyle. Phylogenetic analysis suggests that Cambaylophus forms a clade with the early Eocene tapiromorph Gandheralophus from Pakistan, and that it is closely nested with the early Eocene (Bumbanian) tapiromorph Orientolophus from China. The study points out the importance of Cambaylophus in evaluating the evolutionary relationships of early radiation of tapiromorphs and ascertaining the degree of connectivity/isolation of the Indian Subcontinent around the Palaeocene–Eocene boundary, especially in the context of India–Asia collision.