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 late Eocene to late Oligocene. 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 Paleogene period.