Horses once had five distinct toes. Image by ScienceBriefss
It is largely accepted that horses that live today have only single-toed hooves

It is largely accepted that horses that live today have only single-toed hooves. Previous research has shown that their ancestors had maximum three or four functional toes. However, a new study published today claims that Mesohippus, a horse which lived 35 million years ago, had five distinct toes. The same is similar for a more recent horse relative from 5 million years ago. In the modern horse, the four of the fingers have gradually reduced with evolution until they became the ridges of the horse hooves.

Read the full story: http://www.sciencemag.org
Scientific publication: The Royal society Publishing