The sloth bear (Melursus ursinus), also known as the Indian bear, is a myrmecophagous bear species native to the Indian subcontinent. It feeds on fruits, ants and termites. It is listed as vulnerable on the IUCN Red List, mainly because of habitat loss and degradation. It is the only species in the genus Melursus. It has also been called "labiated bear" because of its long lower lip and palate used for sucking up insects. It has long, shaggy fur, a mane around the face, and long, sickle-shaped claws. It is lankier than brown and Asian black bears. It shares features of insectivorous mammals and evolved during the Pleistocene from the ancestral ursine bear through divergent evolution. Sloth bears breed during spring and early summer and give birth near the beginning of winter. When their territories are encroached upon by humans, they sometimes attack them. Historically, humans have drastically reduced these bears' habitat and diminished their population by hunting them for food and products such as their bacula and claws. Sloth bears have been tamed and used as performing animals and as pets.
Taxonomy George Shaw in 1791 named the species Bradypus ursinus. In 1793, Meyer named it Melursus lybius, and in 1817, de Blainville named it Ursus labiatus because of its long lips. Illiger named it Prochilus hirsutus, the Greek genus name indicating long lips, while the specific name noted its long and coarse hair. Fischer called it Chondrorhynchus hirsutus, while Tiedemann named it Ursus longirostris.
Subspecies and range
Evolution Sloth bears may have reached their current form in the Early Pleistocene, the time when the bear family specialised and dispersed. A fragment of fossilised humerus from the Pleistocene, found in Andhra Pradesh's Kurnool Basin is identical to the humerus of a modern sloth bear. The fossilised skulls of a bear once named Melursus theobaldi found in the Shivaliks from the Early Pleistocene or Early Pliocene are thought by certain authors to represent an intermediate stage between sloth bears and ancestral brown bears. M. theobaldi itself had teeth intermediate in size between sloth bears and other bear species, though its palate was the same size as the former species, leading to the theory that it is the sloth bear's direct ancestor. Sloth bears probably arose during the Middle Pliocene and evolved in the Indian subcontinent. The sloth bear shows evidence of having undergone a convergent evolution similar to that of other ant-eating mammals. The sloth bear is one of eight extant species in the bear family Ursidae and of six extant species in the subfamily Ursinae. One possible phylogeny is based on complete mitochondrial DNA sequences from Yu et al. (2007). The polar bear and the brown bear form a close grouping, while the relationships of the other species are not very well resolved.
A more recent phylogeny is based on the genetic study of Kumar et al. (2017). It concludes that Ursine bears originated around five million years ago, with extensive hybridization among the different species.
Characteristics
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