Ursus, Gulo and Borophagus

Ursus arctos (Linneaus 1758 ; up to 3m in length) is the extant grizzly bear. It has a deeper face than Ursus maritimus and the two do not nest together in the LRT.

Ursavus tedfordi (Hoffman 1887, late Miocene) is a genus derived from Ursus arctos and basal to all other more derived Carnivora on this branch in the LRT.

Ursus americanus (Palla 1780; up to 35cm skull length) is the extant American black bear restricted to temperate climates. It has a shorter skull than U maritimus and the tooth cusps are flatter, traits of an omnivore closer to Potos (above).

Ursus maritimus (Phipps 1774; up to 3m in length) is the extant polar bear restricted to cold climates. Bear-like taxa evolved several times. Here the polar bear most closely resembles the small, tropical, arboreal kinkajou, Potos.

Gulo gulo (Linneaus 1758; up to 110 cm in length) is the extant wolverine, a ferocious predator resembling a small bear. Here it nests with Borophagus, an extinct bear basal to Ursus and Ailuropoda.

Borophagus secudus (Cope 1892; Middle Miocene to Late Pliocene; skull length 17cm) is one of the larger bone-crushing or hyena-like 'dogs'. Here it nests with the South American dog Chrysocyon. The premaxilla extends to mid-canine and touches the frontals in this clade. This abundant predator may have been the apex predator of its time in North America.

Cope ED 1892. A hyena and other Carnivora from Texas. American Naturalist 26:1028–1029.

Hofmann A 1892. Beiträe zur miocaenen Säugetierfauna der Steiermark. Jahrb Geol Reichanst, 42(1): 63−76.

Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

Jiangzuo Q and Flynn JJ 2020. The earliest ursine bear demonstrates the origin of plant-dominated omnivory in Carnivora. IScience CellPress doi.org/10.1016/j.isci.2020.101235

Pallas PS 1780. Spicilegia zoologica (Berlin, 1767—1780).

Phipps CJ 1774.A voyage towards the North Pole: undertaken by His Majesty's command. J. Nourse, London.

Qiu Z-X, Deng T and Wang B-Y 2014. A late Miocene Ursavus skull from Guanghe, Gansu, China. Vertebrata PalAsiatica 52(7):265–302.

wiki/Ursavus
wiki/Ursus
wiki/Borophagus
wiki/Gulo