Origin, paleoecology, and paleobiogeography of early Bovini

The earliest Bovini have until now been reported from between 7 and 6 Ma from Africa. It has long been known that Bovini originated from “Boselaphini”, a paraphyletic assemblage of early Bovinae including also the living nilgai (Boselaphus tragocamelus) and chousinga (Tetracerus quadricornis). This paper constitutes the first report that 1) the earliest members of the bovine lineage are present by at least 8.9 Ma; 2) that the origins of this clade (Pan–Bovini) appear to be in Asia south of the Himalayas; 3) that bovines represent a boselaphine lineage that expanded the ancestral dietary niche to include roughage in more open environments; and 4) that this cladeʹs diversification and range extension coincided with global vegetation changes in the latest Miocene. These assessments are based on the description and analysis of new fossil dental material of certain late Miocene “Boselaphini”, including material traditionally assigned to Selenoportax and Pachyportax. It is proposed that the evolution of the large body size and robust dentition characteristic of bovines was driven by climatic and environmental changes, namely an intensification of seasonal aridity in southern Asia during the early late Miocene. Adaptations for a coarser diet would have permitted greater niche separation among large herbivores during dry seasons when commonly preferred food items become scarce.