Ursinae
Ursinae is a subfamily of Ursidae (bears) named by Swainson (1835). It was assigned to Ursidae by Bjork (1970), Hunt (1998) and Jin et al. (2007). Classification. The genera "Melursus" and "Helarctos" are sometimes also included in "Ursus". The Asiatic black bear and the polar bear used to be placed in their own genera, "Selenarctos" and "Thalarctos"; these are now placed at subgenus rank. A number of hybrids have been bred between American black, brown, and polar bears (see Ursid hybrids).