''Protarctos'' is an extinct genus of basal ursine bear that lived in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Early Pleistocene The Early Pleistocene is an unofficial epoch (geology), sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently esti ...

Description

Species of ''Protarctos'' were closer in size to the

American black bear The American black bear (''Ursus americanus''), or simply black bear, is a species of medium-sized bear which is Endemism, endemic to North America. It is the continent's smallest and most widely distributed bear species. It is an omnivore, with ...

(''Ursus americanus'') and the

Asian black bear The Asian black bear (''Ursus thibetanus''), also known as the Asiatic black bear, moon bear and white-chested bear, is a medium-sized bear species native to Asia that is largely adapted to an arboreal lifestyle. It is distributed from southeast ...

(''U. thibetanus''). They differ from other ursines in the primitive nature of their dental morphology.

Systematics

Although some paleontologists recognized the species of ''Protarctos'' as members of the genus ''Ursus'', at least one phylogenetic analysis from Wang et al. 2017 found the genus to be an evolutionary grade outside the last common ancestor of the

spectacled bear The spectacled bear (''Tremarctos ornatus''), also known as the South American bear, Andean bear, Andean short-faced bear or mountain bear and locally as jukumari ( Aymara and Quechua), ukumari ( Quechua) or ukuku, is a species of bear native to ...

(''Tremarctos ornatus'') and the

brown bear The brown bear (''Ursus arctos'') is a large bear native to Eurasia and North America. Of the land carnivorans, it is rivaled in size only by its closest relative, the polar bear, which is much less variable in size and slightly bigger on av ...

(''U. arctos''). The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

is ''Protarctos boeckhi'' (Schlosser, 1899), followed by species referred into the genus such as ''P. abstrusus'' (Bjork, 1970), ''P. yinanensis'' (Li, 1993), and ''P. ruscinensis'' (Depéret, 1890). Each of the species can be differentiated by slight differences in the morphology of the skull, molar dental morphology and size of the specimens. However, there are some authors that feel all species ''Protarctos'' should be classified as subspecies or as junior synonyms of ''

Ursus minimus ''Ursus minimus'' (the Auvergne bear) is an extinct species of bear, endemic to Europe during the Pliocene and Pleistocene, living from 5.3 to 1.8 Mya, existing for about . ''U. minimus'' appears to have given rise to '' Ursus etruscus''. The r ...

''.

Geological range

This genus small bear has been found in fossil localities from Eurasia and North America. While ''Protarctos'' has been recovered from Pliocene-aged formations in Europe and North America, the genus lasted longer in Asia from the Pliocene to early Pleistocene.

Paleobiology

Despite their primitive dental morphology in comparison with modern ursines, they still show evidence of moderate herbivory. Based on analysis on the teeth of ''P. abstrusus'', it has found that the teeth showed signs of dental caries. This suggests these bears were eating high amounts of a diet high in fermentable-carbohydrates or sugars, leading to the probability these bears also undergo hibernation as seen in modern species of the genus '' Ursus''.

References

{{Taxonbar, from1=Q56326812, from2=Q56313824, from3=Q120549436, from4=Q120549449, from5=Q120549421 Fossil taxa described in 1945 Pliocene bears Pliocene mammals of North America Prehistoric mammal genera Ursinae Biota of Idaho Ellesmere Island