Arctotherium

Arctotherium ("bear beast") is an extinct genus of short-faced bears endemic to Central and South America from the Late Pliocene to the end of the Late Pleistocene. Arctotherium migrated from North America to South America during the Great American Interchange, following the formation of the Isthmus of Panama during the late Pliocene. The earliest recovered remains of Arctotherium are from Central America and northern South America, with specimens referred to Arctotherium c.f. wingei and Arctotherium sp. from the Plio-Pleistocene boundary of Venezuela, and Arctotherium sp. from the Early Pleistocene of El Salvador, dated to between 3Ma and 1.8Ma. Arctotherium reappears later as Arctotherium angustidens ca. 1Ma, which subsequently remains as the only confirmed species for the rest of the Early Pleistocene and early Middle Pleistocene. Around 400,000 years ago, Arctotherium angustidens is replaced in the fossil record by all other species of Arctotherium. Correspondingly, Arctotherium is known from the Blancan and Rancholabrean faunal stages in North America, and the Marplatan, Ensenadan and Lujanian faunal stages of South America. Endemic to the Neotropical realm, Arctotherium is believed to have preferred open habitats with arid and semi-arid climates. While Arctotherium is suggested to have diversified in the tropical Americas, specimens are concentrated in the Southern Cone of South America. Like living bears, species of the genus were omnivorous, with the degree of meat consumption varying between species, with Arctotherium angustidens suggested to have been a highly carnivorous apex predator, while A. wingei was largely herbivorous. Arctotherium angustidens is one of the largest known bears and possibly the largest terrestrial carnivorous mammal ever, with some individuals suggested to exceed 1.2 t (2,645.5 lb) in body mass and reach 3.4 to 4.3 m (11.2 to 14.1 ft) in standing height, while later species such as A. bonariense, A. tarijense and A. wingei were smaller...