The first three-fingered horse - Mesohippus, living in Oligocene (about 37 million years ago), and the middle finger at him is already larger lateral. Mesohippus was in size with a sheep (about 60 sm). He was pad-footed with three toes on all four feet with a tiny 4th vestigial front toe.
Compared to Hyracotherium, the back less arched, legs a bit longer, the neck a bit longer, the face longer, cerebral hemispheres larger.
Because this new version of the horse was larger and with longer limbs would be faster it is believed that the fawn like spots would probably start to disappear at this point as they would not be needed as much for camouflage. Scientists think that a plain color or a brown Mesohippus with spots just on the rump might have been a common sight during this era.