This image depicts the evolution of digit reduction, from four toes to three toes to a single toe in Eohippus, Mesohippus, Merychippus, and Equus. McHorse, modified from W.D. Matthew ...

It's fitting that the earliest horses in the world roamed the prairies of Wyoming. According to findings published through ...

And speaking of ponies, some of the earliest horses wandered the same forests – Eohippus and other horses that stood on several hoofed toes and were the size of a small dog – as well as the ...

Prehistoric animals that roamed the world during the last ice age about 50-million years ago are featured on a new block of four 32-cent U.S. stamps out today. They are the ancestors of some of ...