the earliest horse: an extinct Eocene dog-sized animal of the genus with four-toed forelegs, three-toed hindlegs, and teeth specialized for browsing
Word origin
C19: New Latin, from eo- + Greek hippos horse
eohippus in American English
(ˌioʊˈhɪpəs)
noun
an extinct progenitor (genus Hyracotherium) of the modern horse, found in the Lower Eocene of W U.S.: it was about the size of a fox and had four toes on the front feet and three on the hind