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 scotti assigned fossils from the Anza-Borrego Desert in California, tentatively interpreted to represent "E. bautistensis", to "E. scotti". One of the reported locations farthest south in the Americas is Pali Aike National Park in Chile. Equus scotti Equus scotti (translated from Latin as Scott's horse, named after vertebrate paleontologist William Berryman Scott) is an extinct species of "Equus", the genus that includes the horse. "E. scotti" was native to North America and likely evolved from earlier, more zebra-like North American equids early in the Pleistocene Epoch. The species may have crossed from North America to Eurasia over the Bering land bridge