A tiny tarsioid primate occurs in early Eocene sediments of the Naran Bulak Formation, southern Gobi Desert, Mongolian People's Republic. The new primate, Altanius orlovi, new genus and species, is an anaptomorphine omomyid and therefore belongs to a primarily American group of primates. Altanius is apparently not a direct ancestor of the Asian genus Tarsius. American rather than European zoogeographic affinities are indicated, and this in turn supports the view that for a time in the earliest Eocene the climate of the Bering Route was sufficiently warm to support a primate smaller than Microcebus.