The Collaborative International Dictionary
Miohippus \Mi`o*hip"pus\ (m[imac]`[-o]*h[i^]p"p[u^]s), n. [NL., fr. Gr. mei`wn less + "ippo`s horse.] (Paleon.) An extinct Miocene mammal of the Horse family, closely related to the genus Anhithecrium, and having three usable hoofs on each foot.
Wikipedia
Miohippus (meaning "small horse") was a genus of prehistoric horse existing longer than most Equidae. Miohippus lived in what is now North America during the Oligocene approximately 32-25 million years ago. While descending genera of this species lived during the Miocene period, Miohippus was a horse of the Oligocene. According to the Florida Museum of Natural History, Othniel Charles Marsh first believed Miohippus lived during the Miocene and thus named the genus using this incorrect conclusion. More recent research provides evidence that Miohippus actually lived during the Oligocene.
Miochippus species are commonly referred to as the three-toed horses. Their range was from Alberta, Canada to Florida to California.
Usage examples of "miohippus".
But what gained greatest attention, especially from ranchers in the west, was his discovery in subsequent years of handsome skeletons of four of the progenitors of the horse: eohippus, mesohippus, miohippus and the crucial, determinative merychippus.