The earliest occurrence of Equus in South Asia

Fossil horses are ubiquitous members of late Neogene and Quaternary ecosystems in Eurasia and Africa. The genus Equus is conventionally thought to be a Pleistocene immigrant into Eurasia from North America, and the concurrent appearance of these monodactyl equids in Eurasia around 2.58 Ma is accepted as the Equus Datum. Here, we report on a specimen of Equus found near the village of Jhil, from the latest Pliocene of the Upper Siwaliks of India. The specimen was recovered from sediments that are lithologically equivalent to the Upper Pliocene Saketi Formation, and have been dated paleomagnetically to lie just below the Gauss–Matuyama boundary, therefore, the latest Pliocene. Our comparative work shows that the anatomy of Jhil specimen is consistent with the Early Pleistocene Siwalik horse, Equus sivalensis. Our finding extends the temporal distribution of this species into the latest Pliocene, and adds to our understanding of the variation in this species of horse. We also argue that along with potential latest Pliocene occurrences of Equus from Europe, and accounting for the Signor–Lipps effect, the Equus Datum should be revised as a latest Pliocene event.