(1) The development of the horse has been recorded from the beginning through all of its evolutionary stages to the modern form. It is, in fact, one of the most complete and well-documented chapters in paleontological history. Fossil finds provide us not only with detailed information about the horse itself, but also with valuable insights into the migration of herds and even evidence for speculation about the climatic conditions that could have instigated such migratory behavior.
(2) It has been documented that, almost twelve million years ago at the beginning of the Pliocene Age, a horse, about midway through its evolutionary development, crossed a land bridge where the Bering Straits are now located, from Alaska into the grasslands of Europe. The horse was the hipparion, about the size of a modern-day pony with three toes and specialize cheek teeth for grazing. In Europe the hipparion encountered another less advanced horse called the antitheres, which had previously invaded Europe by the same route, probably during the Miocene Period. Less developed and smaller than the hipparion, the anchitheres was completely replaced by it. By the end of the Pleistocene Age both the anchitheres and the hipparion had become extinct in North America, where they had originated. In Europe they had evolved into an animal very similar to the horse as we know it today. It was the descendant of this horse that was brought by the European colonist to the Americas.