Equus (genus) 54 million years ago (Mya). These animals had three toes on the hind feet and four on the front feet with small hooves in place of claws, but also had soft pads.<ref name="doi10.1126/science.1105458"></ref> Equids developed into larger, three-toed animals (e.g. "Mesohippus") during the Oligocene and Miocene. From there, the side toes became progressively smaller through the Pleistocene until the emergence of the single-toed "Equus". The genus "Equus", which includes all extant equines, is believed to have evolved from "Dinohippus", via the intermediate form "Plesippus". One of the oldest species is "Equus simplicidens", described as zebra-like with a donkey-like head shape.
Equus lambei Furthermore, evidence from "E. lambei" mtDNA now proves that modern horses are not so far removed from their ancient ancestors. Many scientists believe that a good argument can be made that "E. caballus", too, should receive protection as a form of native wildlife in North America. However, this topic is still highly debated by wild horse management agencies. This debate has significant implications to wildlife management in North America, including protection and conservation for modern species. Equus lambei Equus lambei (common names include Yukon horse, and Yukon wild horse) is an extinct species of the genus "Equus". "Equus lambei" ranged