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Brachyhyops
''Brachyhyops'' is an extinct genus of entelodont artiodactyl mammal that lived during the Eocene Epoch of western North America and southeastern Asia (including Mongolia, China, and Kazakhstan).〔Colbert, E.H. (1937). Notice of a new genus and species of Artiodactyl from the Upper Eocene of Wyoming. American journal of Science, Series 5, 33: 473-474〕〔Colbert, E.H. (1938). Brachyhyops, a new bunodont artiodactyls from Beaver Divide, Wyoming: Annals of the Carnegie Museum. Vol. 27. 87-108〕〔〔Wang, B.-Y., Qiu, Z.-X. (2002). A new species of Entelodontidae (Artiodactyla, Mammalia) from the late Eocene of Nei Mongol, China. Vertebrata PalAsiatica, vol. 40, p. 194-202 (in Chinese with English summary)〕 The first fossil remains of ''Brachyhyops'' are recorded from the late Eocene deposits of Beaver Divide in central Wyoming and discovered by paleontology crews from the Carnegie Museum of Natural History during the early 20th century. The type species, ''Brachyhyops wyomingensis'', is based on a single skull and was named by E.H. Colbert in 1937, but was not officially described until 1938. During the latter half of the 20th century, additional specimens from North America have been recorded from Saskatchewan and as far south as Texas, indicating that ''Brachyhyops'' had a broad distribution and was well-dispersed throughout western North America.
More recent discoveries from Eocene deposits in Mongolia lead to the recognition of a second species of ''Brachyhyops'', ''B trofimovi''.〔Tsubamoto, T., Saneyoshi, M., Watabe, M., Tsogbataar, K., Mainbayar, B. (2011). The Entelodontid Artiodactyl Fauna from the Eocene Ergilin Dzo Formation of Mongolia with Comments on Brachyhyops and the Khoer Dzan Locality. Paleontological Research, 15(4):258-268〕 It is notable that the oldest specimens of ''Brachyhyops'' are middle Eocene in age and have been recorded exclusively from southern Asia, whereas specimens from the late Eocene only occur in the northern part of the continent.〔Tsubamoto, T., Takai., M., Egi, N. (2004). Quantitative analyses of biogeography and faunal evolution of middle to late Eocene mammals in East Asia. Journal of Vertebrate Paleontology, vol. 24, p. 657-667〕 This implies that the genus ''Brachyhyops'' most likely originated in southern Asia, migrated north and eventually dispersed into western North America.
==Discovery==
In 1934, crew members of the Carnegie Museum paleontological expedition discovered the holotype of ''Brachyhyops wyomingensis'' (CM 12048) from the uppermost beds of the Eocene White River Formation, in a member known as the Big Sand Draw Sandstone Lentil, at Beaver Divide, Wyoming.〔〔〔Prothero, D.R., Sanchez, F. (2004). Magnetic stratigraphy of the middle to upper Eocene at Beaver Divide, Fremont County, Central Wyoming. In Lucas, S.S., Zeigler, K.E., Kondrashov, P.E. (eds.) Paleogene Mammals. New Mexico Museum of Natural History and Science Bulletin No. 26, 151-154〕 The specimen consists of a single, exceptionally well preserved, but severely distorted, isolated skull with no mandibles or post cranial material. Since its initial discovery, several other partial specimens of ''Brachyhyops'' have been recorded within North America and Asia. Currently, four species of ''Brachyhyops'' have been recognized; two from Asia and two within North America, and include ''Brachyhyops trofimovi'' from Mongolia, ''B. neimongoliensis'' from northern China, ''B. viensis'' from Saskatchewan, Canada; Wyoming, and New Mexico, USA, and lastly, ''B. wyomingensis'' from Wyoming, Utah, and Texas, USA.
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