" The evolutionary lineage of the horse is among the best-documented in all palaeontology. The history of the horse [family] began during the Eocene Epoch, which lasted from about 56 million to 33.9 million years ago. During the early Eocene there appeared the first ancestral horse, a hoofed, browsing mammal, designated correctly as Hyracotherium, but more commonly called Eohippus, the Fossils of Eohippus, which have been found in both North America, and Europe, show an animal that stood 4.2 to 5 hands about 42.7 to 50.8 cm, or 16.8 to 20 inches high, diminutive by comparison with the modern horse, and had an arched back and raised hindquarters."