Gradually, the Mesohippus was succeded by the Miohippus and the Merrychippus. Both species developed high-crowned teeth, which allowed them to feed on grass rather than browsing on leaves.The descendant of the Merrychippus was the Pliohippus, which appears to be the progenitor of the modern species Equus (the Horse).
Horses belong to the family of Equidae of the order of Perissodactyla. The domestic horse is classified as Equus caballus