Any member of the ungulate family Equidae, which includes the modern horse s, zebra s, and ass es, all in the genus Equus , as well as more than 60 species known only from fossils.
Equines descended from the dawn horse (see Eohippus ). Wild horses, which once inhabited much of northern Eurasia, were smaller and had shorter legs than their domesticated descendants. See also Przewalski's horse .