Pliohippus was an early, one-toed h

Pliohippus was an early, one-toed house that sill had two vestigial side toes on each hoof. It was about the size of a zebra, and slightly smaller than most species of modern horses. For many year, it was thought that Pliohippus was the ancestor of Equus, but Pliohippus had deep pockets on the facial region, and its teeth were strongly curved, while those of Equus are straight.