Biology

Eocene and Oligocene: early equids Hyracotherium Orohippus  Epihippus  Mesohippus  Miohippus Miocene and Pliocene: true equines  Kalobatippus  Parahippus  Merychippus  Hipparion  Pliohippus  Dinohippus  Plesippus  Modern horses  Equus  Pleistocene extinctions  Return to the Americas Toes The ancestors of the horse came to walk only on the end of the third toe and both side toes. Skeletal remnants show obvious wear on the back of both sides of metacarpal and metatarsal bones, commonly called the “splint bones”. They are the remnants of the second and the fourth toe. Modern horses retain the splint bones; they are often believed to be useless attachments, but they in fact play an important role in supporting the carpal joints (front knees) and even the tarsal joints (hocks). Teeth Throughout the phylogenetic development, the teeth of the horse underwent significant changes. The type of t...