Hipparion

Hipparion (Greek, "pony") is an extinct genus of horse that lived in North America, Asia, Europe, and Africa. This was during the Miocene to Pleistocene epochs ~23 million years to 780,000 years ago. They lived for a total of 22 million years. 
"Hipparion"'s feet had three vestigial outer toes (in addition to its hoof).