Merychippus by Moondawg

Merychippus is a proto-horse that lived between 17 and 11 million years ago in the Miocene period.

It had three toes on each foot and is the first horse known to have grazed. Its name means "ruminant horse", but it is not now thought that Merychippus ruminated.

Merychippus lived in herds. It was about twelve hands (48 inches) tall; at the time it was the tallest equine to have existed. The muzzle was longer, the jaw deeper, and the eyes wider apart than any other horse-like animal to date. The brain was also much larger, making it smarter and more agile. Merychippus was the first equine to have the distinctive head of today's horses. The foot was fully supported by ligaments, and the middle toe developed into a hoof, which did not have a pad on the bottom. In some Merychippus species, the side toes were larger, whereas in others, they had become smaller and only touched the ground when running. Its teeth were like those of Parahippus (the extra crest that was variable in Miohippus was permanent in Merychippus, and the other teeth were beginning to form a series of tall crests with higher crowns).