Horse Jaw Section | South Dakota
Specimen approx. size: 1.25" x 1" x 0.5"
Mesohippus, which means "middle horse" is an extinct genus of early horse. It was common in North America during the early Oligocene. Mesohippus had longer legs than its predecessors and stood about 60 cm tall at the shoulder; it would have been about the size of a medium to large dog. Previous horses had four toes on their feet. Mesohippus was the first three-toed horse in the evolutionary record. The middle toe was the longest and the largest, but all the toes touched the ground and were weight bearing. Mesohippus had not developed a hoof yet, rather it still had pads as seen in Hyracotherium and Orohippus. Unlike earlier horses, its teeth were low crowned and had a single gap behind the front teeth, where the bit now rests with modern horses. Mesohippus was a browser that fed on leaves, tender twigs, fruits, and possibly grass.