Found 2 items, similar to Protohippus.
English → English (WordNet) Definition: protohippus protohippus n : Pliocene horse approaching donkeys in size
English → English (gcide) Definition: Protohippus Protohippus \Pro`to*hip"pus\, n. [NL., from Gr. ? first + ? horse.] (Paleon.) A genus of fossil horses from the Lower Pliocene. They had three toes on each foot, the lateral ones being small. [1913 Webster]