Horses used to be smaller. Przewalski's horse, the closest thing to a pre-domesticated horse, is about 660lb. A modern draft horse is over 2000lb. 50 mya, Eoh

Horses used to be smaller. Przewalski's horse, the closest thing to a pre-domesticated horse, is about 660lb. A modern draft horse is over 2000lb. 50 mya, Eohippus was around 20lb - the size of a fox.