Equus scotti is a true caballine horse that is more closely related to modern horses than to zebras and asses. Equus scotti may be synonymous with Equus lambei, another generally smaller horse known from the Pleistocene of North America, but this is uncertain.[3] Although it has been suggested that Equus scotti may be synonymous with living Equus ferus[3], North American horses diverged from their Eurasian counterparts around 800,000 years ago, following the first dispersal of horses out of North America, with some interbreeding after the initial split.[4]
Paleontological excavations have identified the locations of numerous places where E. scotti occurred. The species was named from Rock Creek, Texas, United States, where multiple skeletons were recovered. A closely related fossil find was made of Equus bautistensis in California; this species appeared closely related, but of a slightly more primitive form than E. scotti.[5] However, E. bautistensis was redefined as a junior synonym of E. scotti in 1998 by paleontologist E. Scott,[6] who also assigned fossils from the Anza-Borrego Desert in California, tentatively interpreted to represent E. bautistensis, to E. scotti.[7]
The distribution of the species includes: "Alberta, Ontario, Saskatchewan and Yukon (Canada) and in California, Florida, Idaho, Kansas, Nebraska, New Mexico, Oklahoma and Texas (United States)".[3]
^C. R. Harington and Donna Naughton (2003) Annotated Bibliography of Quaternary Vertebrates of Northern North America: With Radiocarbon Dates, University of Toronto Press, 539 pages ISBN0-8020-4817-X
^Childs Frick (1921) Extinct Vertebrate Faunas of the Badlands of Bautista Creek and San Timoteo Cañon, Southern California, University of California Press, 424 pages
^Eric Scott (1998) Equus scotti from southern California, Journal of Vertebrate Paleontology 18(3): 76-A
^Eric Scott (2006) Extinct horses and their relatives, Fossil Treasures of the Anza-Borrego Desert: the Last Seven Million Years, ed. G.T. Jefferson and L. Lindsey, Sunbelt Publications, p. 253 - 271