Mesohippus (Greek: μεσο/meso meaning "middle" and ιππος/hippos meaning "horse") is an extinct genus of early horse. It lived some 40 to 30 million years ago from the Middle Eocene to the Early Oligocene.[1] Like many fossil horses, Mesohippus was common in North America. It grew up to lengths of 4 feet long and stood at 2 feet tall.[2]