Earliest polar bear

The very first form of polar bear was the tyrant polar bear (Ursus maritimus tyrannus), which stood 1.83 m (6 ft) at the shoulder, measured 3.7 m (12 ft 2 in) long, and had an average weight of 1 tonne (1.2 tons) or more. Evolving from an isolated population of Arctic brown bears during the mid-Pleistocene epoch (250,000-100,000 years ago), this fossil subspecies was the largest bear ever and the largest terrestrial carnivore ever.