Science, Tech, Math › Animals & Nature Miohippus Share Flipboard Email Print Miohippus (American Museum of Natural History). Animals & Nature Dinosaurs Prehistoric Mammals Basics Paleontologists Carnivores Dinosaurs & Birds Herbivores Marine Reptiles Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Marine Life Forestry Evolution View More By Bob Strauss Science Writer B.S., Cornell University Bob Strauss is a science writer and the author of several books, including "The Big Book of What, How and Why" and "A Field Guide to the Dinosaurs of North America." our editorial process Bob Strauss Updated March 17, 2017 Name: Miohippus (Greek for "Miocene horse"); pronounced MY-oh-HIP-us Habitat: Plains of North America Historical Epoch: Late Eocene-Early Oligocene (35-25 million years ago) Size and Weight: About four feet long and 50-75 pounds Diet: Plants Distinguishing Characteristics: Small size; relatively long skull; three-toed feet About Miohippus Miohippus was one of the most successful prehistoric horses of the Tertiary period; this three-toed genus (which was closely related to the similarly named Mesohippus) was represented by about a dozen different species, all of them indigenous to North America from about 35 to 25 million years ago. Miohippus was a bit larger than Mesohippus (about 100 pounds for a full-grown adult, compared to 50 or 75 pounds); however, despite its name, it lived not in the Miocene but the earlier Eocene and Oligocene epochs, a mistake for which you can thank the famous American paleontologist Othniel C. Marsh. Like its similarly named relatives, Miohippus lay on the direct evolutionary line that led to the modern horse, genus Equus. Somewhat confusingly, although Miohippus is known by over a dozen named species, ranging from M. acutidens to M. quartus, the genus itself consisted of two basic types, one adapted for life on prairies and the other best suited to forests and woodlands. It was the prairie variety that led to Equus; the woodland version, with its elongated second and fourth toes, spawned small descendants that went extinct in Eurasia at the cusp of the Pliocene epoch, about five million years ago.