Brachyhyops
|
Brachyhyops Temporal range: Middle to Late Eocene |
|
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | †Entelodontidae |
| Genus: |
†Brachyhyops Colbert, 1937 |
| Type species | |
|
Brachyhyops wyomingensis Colbert, 1937 |
|
| Species | |
|
|
| Synonyms | |
|
|
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). 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. 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. This implies that the genus Brachyhyops most likely originated in southern Asia, migrated north and eventually dispersed into western North America.
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. 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.
Holotype (CM 12048) of Brachyhyops wyomingensis was diagnosed by Edwin H. Colbert in 1938 as a medium sized skull with a relatively short snout and a length that is comparable to the skull of a modern peccary. The portion of the skull behind the eye socket is greater compared to the portion of the skull in front of the eye socket due to the short size of the snout. The dentition is I3(?)-C1-P4-M3, indicating in the upper jaw the number of incisors, canines, premolars, and molars respectively. Colbert compared B. wyomingensis to Helohyus, Chaeropotamus, Achaenodon, and Parahyus based on tooth shape. No mandibles were preserved with the holotype specimen and therefore dentition of the lower jaws could not be determined. The overall width of the skull is broad and having widely separated parietal crests. In addition, the zygomatic arches are deepened and expanded below and behind the eye socket, contributing to the wide skull shape, which is very similar to other entelodonts. The rear portion of eye socket is closed and situated directly above the last two molars. Articulation surfaces for the lower jaws; the glenoids, are broad, shallow, and situated around the occlusal line of the upper cheek teeth. Both paroccipital processes are short and parietals are weakly developed. The basicranium, or occiput, is considered basal.
...
Wikipedia