Former name of a genus of ancestral horses, commonly called dawn horses, that flourished in North America during the Early Eocene Epoch (54.8–49 million years ago).
It is now classified with European species in the genus Hyracotherium . Eohippus stood 1–2 ft (30–60 cm) high at the shoulders and was adapted to running, with hind legs longer than the forelegs. The body was lightly constructed, with slender legs and elongated feet that were functionally three-toed (though the front feet had four toes). The skull varied from shortened (primitive) to relatively long (more horselike).