The genus Cormohipparion was coined for the extinct hipparionin horse "Equus" occidentale, described by Joseph Leidy in 1856.[4] However it was soon argued that the partial material fell within the range of morphological variation seen in Hipparion, and that the members of Cormohipparion belonged instead within Hipparion.[5][6] This rested on claims that pre-orbital morphology did not have any taxonomic significance, a claim that detailed study of quarry sections later showed to be false.[7] The genus was originally identified by a closed off preorbital fossa, but later examinations of the cheek teeth, specifically the lower cheek teeth, of Cormohipparion specimens found that they were indeed valid and distinct from Hipparion.[8] A reappraisal of many horse genera was thus conducted in 1984,[9] and the proposed synonymy was not acknowledged by later literature.[10]C. ingenuum holds the distinction for being the first prehistoric horse to be described in Florida, as well as being one of the most common species of extinct species three-toed horses found to be in Florida.[11]Cormohipparionemsliei has the distinction of being the last hipparion horse known from the fossil record.[12]
The genus is considered to represent an ancestor to Hippotherium.[13] Its fossils have been recovered from as far south as Mexico.[14] Fossils have been found in the Great Plains and Rio Grande regions of North America, Mexico, Florida and Texas, which shows that they were herding animals.[15][16][17][18]
Evolution
A species of Cormohipparion closely related to C. occidentale is thought to have crossed the Bering land Bridge over into Eurasia around 11.4-11 million years ago, becoming the ancestor to Old World hipparionines.[19]
References
^MacFadden, Bruce J.; Skinner, Morris F. (1982). "Hipparion Horses and Modern Phylogenetic Interpretation: Comments on Forsten's View of Cormohipparion". Journal of Paleontology. 56 (6): 1336–1342. ISSN0022-3360. JSTOR1304670.
^Skinner, M. F.; MacFadden, B. J. (1977). "Cormohipparion n. gen. (Mammalia, Equidae) from the North American Miocene (Barstovian-Clarendonian)". Journal of Paleontology. 51 (5). Paleontological Society: 912–926. JSTOR1303763.
^Forsten, A. (1982). "The Status of the Genus Cormohipparion Skinner and MacFadden (Mammalia, Equidae)". Journal of Paleontology. 56 (6). Paleontological Society: 1332–1335. JSTOR1304669.
^MacFadden, B. J.; Skinner, M. F. (1982). "Hipparion Horses and Modern Phylogenetic Interpretation_ Comments on Forsten's View of Cormohipparion". Journal of Paleontology. 56 (6). Paleontological Society: 1336–1342. JSTOR1304670.
^Forsten, Ann (1982). "The Status of the Genus Cormohipparion Skinner and MacFadden (Mammalia, Equidae)". Journal of Paleontology. 56 (6): 1332–1335. ISSN0022-3360. JSTOR1304669.
^MacFadden, BJ (1984). "Systematics and phylogeny of Hipparion, Neohipparion, Nannippus, and Cormohipparion (Mammalia, Equidae) from the Miocene and Pliocene of the new world". American Museum of Natural History.
^Hulbert Jr, R. C. (1988). "A New Cormohipparion (Mammalia, Equidae) from the Pliocene (Latest Hemphillian and Blancan) of Florida". Journal of Vertebrate Paleontology. 7 (4). The Society of Vertebrate Paleontology: 451–468. Bibcode:1988JVPal...7..451H. doi:10.1080/02724634.1988.10011675. JSTOR4523166.
^Skinner, Morris F.; MacFadden, Bruce J. (1977). "Cormohipparion n. gen. (Mammalia, Equidae) from the North American Miocene (Barstovian-Clarendonian)". Journal of Paleontology. 51 (5): 912–926. ISSN0022-3360. JSTOR1303763.