Horses made a major impact on human history.  They helped us travell faster, have fun, and settle the west.  Horses we at every settlement standing beside the person who settled the area, horses were standing beside the people who won every battle, anywhere a person went, the horse was with them.  Beside every human foot print, there was a horse hoof print.  Horses should've been credited just as much as any of us humans.

The known history of the modern horse starts with Eohippus,  Mesohippus, and then Merychippus. The Merychippus showed distinct changes, like,  the legs became longer, the back straighter, (Eohippus had an arched back) and the whole animal was larger.  Pliohippus had long legs with a single hoof on each. The modern horse is known as Equus.