Tremarctos is a genus of the monophyletic bear subfamily Tremarctinae, endemic to Americas from the Pliocene to recent. The northern species, the Florida short-faced bear (T. floridanus), went extinct in the Late Pleistocene. The sole living Tremarctos species is the South American spectacled bear (T. ornatus). Tremarctos is also the only living genus under the Tremarctinae subfamily, with the other short-faced bears (Plionarctos, Arctodus, and Arctotherium) all being extinct.
Taxonomy
The genus name Tremarctos was created in 1855 by Alfred Gervais. While his suggestion for making Tremarctos a separate genus was rejected, after further studies comparing skeletal structures of the teeth and jaws of Tremarctos to other bear species his suggestion was later accepted.
The word Tremarctos is derived from the Greek language and translates to "hole bear" in English, due to the entepicondylar foramen on the humerus. However, the name "hole bear" could also come from the fact that the tan facial markings appear on the face except around the bear's eyes, making it look like the bear has holes for eyes, giving it the name Jukumari in Andean languages.
Unlike almost all other extant bears (from the Ursinae subfamily), tremarctine bears like Tremarctos appear to have a disproportionately shorter snouts, giving them the name "short-faced." This apparent shortness is an illusion caused by the deep snouts and short nasal bones of tremarctine bears compared with ursine bears; Tremarctinae had shorter and taller skulls, but not a shorter face than most living bears.
In addition to being brachycephalic, tremarctine bears' skulls possessed well developed zygomatic arches and glenoid mandibular fossas, a premasseteric fossa on the mandible (except for Plionarctos), with tremarctine bears often possessing an entepicondylar foramen on the humerus. Moreover, tremarctine bears' orbits are also bigger, more rounded and lateralized. Unlike tremarctine bears, ursine bears...
