<P> The genus Equus , which includes all extant equines , is believed to have evolved from Dinohippus , via the intermediate form Plesippus . One of the oldest species is Equus simplicidens , described as zebra - like with a donkey - shaped head . The oldest fossil to date is ~ 3.5 million years old from Idaho , USA . The genus appears to have spread quickly into the Old World , with the similarly aged Equus livenzovensis documented from western Europe and Russia . </P>
when did equus first appear in fossil record
~ 3.5 million years old