Ursus maritimus tyrannus

The subspecies of polar bear was named by the Finnish paleontologist Björn Kurtén in 1964, based on a single fragmentary right ulna found in the gravels of the Thames at Kew Bridge, London. The fossil was also discovered alongside steppe bison (Bison priscus), reindeer (Rangifer tarandus) and wolves (Canis lupus). == Description ==

The specimen is interpreted to represent a relatively large individual, evidently a subadult due to missing distal epiphysis. The ulna was dated to the early Weichselian of the Late Pleistocene (~70kya). Of the 16 specimens identified as Pleistocene polar bears, this is the only fossil ascribed to this subspecies. == Taxonomy ==

Initially, Kurtén defined the ulna as belonging to no other bear species than Ursus maritimus. At the time of the discovery, it was the largest ursine ulna ever found, leaving only two options for species classification: either famously long-legged Pleistocene Tremarctines or the polar bear. Since no Arctodus bear lived in Pleistocene Britain, Ursus maritimus was chosen as a parent taxon. In 2008, Charles Harington stated that the identification of a polar bear is plausible based on sea level changes and ice conditions in the North Sea of that period. Furthermore, he highlighted the presence of marine mammal fauna (including ringed and bearded seals) near the Kew locality, suggesting that polar bears were also present in the southern North Sea during colder periods of the Weichselian. However, Harington also noted that Andy Currant of the Natural History Museum, London believes that fossil represents a huge brown bear rather than a polar bear, as fauna assemblages from other contemporary British sites, also dominated by steppe bison, reindeer and wolves, preserve gigantic brown bears like the Kew Bridge bear. Andy Currant's opinion that the Kew Bridge fossil belongs to a brown bear, although referred to in a 2007 BBC interview and in studies from 2009 and 2022, awaits scientific verification. ==References==