The earliest ancestor to today’s animal was Eohippus which lived about 50 million years ago. It stood only about 25 centimeters high and lived in the American prairies migrating from there to Asia and Europe where it bred rapidly. The Orohippus and Mesohippus appeared some 20 million years later and were bigger animals. But the first of these animals to look like today’s horses was the Parahippus. The Pliohippus, which first appeared on Earth about 10 million years ago, bore and even closer resemblance to the horses of today.