Evolution
The fossil evidence of the main system has abundant the equid, and it is rejected making an excuse history of the evolution from there. The oldest fossil is Hyracotherium Hyracotherium sp. discovered from the stratum of (Eocene epoch) before 50,000,000 years in North America. The Hyracotherium is known for another name called eohippus Eohippus generally. The Hyracotherium is size of a fox, and the foreleg does not have a hallux, and the fifth finger degenerates if the hind leg is first. I inhabit the forest, and it is thought that it was leaf eating habit (a browser). of the Eocene epoch, a mesohippus of the Oligocene, Mio hips, Para hips, system evolution called Meri tickets of the Miocene become clear afterwards. I was epoch-making with two points of the cicatrization of lower bones of limbs (the ulna and a radius, a tibia and a fibula) which Meri tickets of (the - middle before Miocene) before about 10,000,000 years depended that I acquired the high crown tooth which showed true herbivory, and enabled the run at the high speed. Dry climate spread, and prairie was spreading, and the appearance of Meri tickets was a result of the advances to the grassy plain in those days. A finger became one of them by letting 2. the fourth fingers completely disappear, and the extinct one-toed horse of the genus Pliohippus of (the - latter period during the Miocene) before about 4,000,000 years did a near form to a current horse. I cross the Bering Sea in the glacial epoch of the Pleistocene age, and the group of the horse arrives at the Eurasian Continent and the African Continent and differentiates for Equus (the horse genus) that is a current horse. The equid which stayed in the North and South American Continent became extinct in a glacial epoch. Various kind differentiation is generated from Mio hips and Meri tickets, and the horses showed big development at one time, but the most of the system already become extinct, and the present conditions that an existing descendant becomes only a horse, a zebra, a friend of the ass are contrastive with the prosperity of Ruminantia. Because I compared horses with Ruminantia, and I digested a plant, and ability to constitute again was inferior to protein, it was thought that it was expelled by Ruminantia, but the horse survived it by acquiring a high athletic capability. Most of the wild horses were almost most of the wild horses, but prospered as a domestic animal animal because it was it with the most popular land movement / means of conveyance for the human for long time before an internal combustion engine being invented.