Oligocene horses

Mesohippus (Greek: / meaning "middle" and / meaning "horse") is an extinct genus of early horse. It lived 37 to 32 million years ago in the Early Oligocene. Like many fossil horses, Mesohippus was common in North America. Its shoulder height is estimated at 60 cm.

Miohippus (meaning "small horse") is an extinct genus of horse existing longer than most Equidae. It lived in what is now North America from 32 to 25 million years ago, during the late Eocene to late 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 Paleogene period.

left|thumb|Life restoration Archaeohippus (Greek: "ancient" (archaios), "horse" (hippos)) is an extinct three-toed member of the family Equidae known from fossils of early Oligocene to middle Miocene age. The genus is noted for several distinct skeletal features. The skull possesses deeply pocketed fossa in a notably long preorbital region. The genus is considered an example of phyletic dwarfism with adults estimated at being on average 20 kilograms in weight. This is in contrast to the most common equid of the period, Miohippus. Characters of the teeth show a mix of both primitive and advance

left|thumb|Life restoration Kalobatippus ('stilt walking horse') is a genus of anchitheriinae equid. It gets its name from the elongated bones between the ankle/wrist and the toes. Kalobatippus ate leaves and was characterized by unusually long legs. It lived 24 to 19 million years ago. Estimated body mass for Kalobatippus is .