Equus scotti is an extinct species in the genus that contains horses, Equus. This name translates to “Scotti’s Horse” from Latin, and was given to the extinct equine by a paleontologist of vertebrates named William Berryman Scott. Native to North America, it is thought that Equus scotti evolved from a creature that resembled a zebra more than a horse during the early Pleistocene Epoch http://en.wikipedia.org/wiki/Pleistocene_Epoch. It is also thought that this early horse used the Bering land bridge to come to North America from Eurasia during the Pleistocene.
Equus scotti was one of the last native horses in North America, becoming extinct during the mass extinction of large animals in the last ice age approximately ten thousand years ago. Horses were not in North America until nearly ten thousand years later, appearing when conquistadors brought them over by ship. Some of those horses escaped, becoming ancestors to modern horses.
The specimen from which this species was named was found in Rock Creek, Texas, along with many other E. scotti remains. E. scotti remains have been found at many other locations, including the far south location of Pali Aike National Park in Chile. One fossil was found in California, named Equus bautisensis and showed many similarities to Equus scotti but was a bit more primitive. However, E. bautisensis was found to be a different species than E. scotti, although in the same genus, and was given a separate classification.
Image Caption: A mounted skeleton of Equus scotti at the AMNH, constructed out of two skeletons. Credit: Gidley, James Williams/Wikipedia