| Arctotherium Temporal range: Late Pliocene–Middle Pleistocene |
|
|---|---|
| Life restoration of Arctotherium bonariense | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Superfamily: | Arctoidea |
| Family: | Ursidae |
| Subfamily: | Tremarctinae |
| Tribe: | Tremarctini |
| Genus: | †Arctotherium Burmeister, 1879 |
| Species | |
|
|
Arctotherium is an extinct genus of South American short-faced bears within Ursidae of the late Pliocene through the end of the Pleistocene.[1] Their ancestors migrated from North America to South America during the Great American Interchange, following the formation of the Isthmus of Panama. They were endemic to South America, living from ~2.0–0.01 Ma, existing for approximately 1.99 million years. Their closest relatives were the North American short-faced bears of genus Arctodus (A. pristinus and A. simus). The closest living relative would be the spectacled bear (Tremarctos ornatus).[2]
Arctotherium was named by Hermann Burmeister in 1879. It was assigned to Tremarctinae by Krause et al. 2008.[2] A humerus of A. angustidens from Buenos Aires indicates that the big males of this species would have weighed between 1588-1749 kg, standing at least 11 feet (3.4 meters) tall, making it the largest bear and the largest carnivorous land mammal yet known.[3][4] In contrast to their North American cousins, South American short-faced bears showed a trend of declining size and carnivory over time. This has been attributed to increased competition from other, later-arriving or evolving carnivorans, like jaguars or lions, following the early dispersal of short-faced bears to South America.[3][4][5] (The North American carnivorans that invaded South America, including short-faced bears and Smilodon, quickly dominated the predatory niches formerly occupied by South America's native metatherian sparassodont and avian phorusrhacid carnivores.)