It is very similar to the Kamchatka brown bear, though it has a more elongated skull, a less elevated forehead, somewhat longer nasal bones and less separated zygomatic arches, and is somewhat darker in color, with some individuals being completely black, a fact which once led to the now refuted speculation that black individuals were hybrids of brown bears and Asian black bears. Adult males have skulls measuring 38.7 cm (15.2 in) long and 23.5 cm (9.3 in) wide. They can occasionally reach greater sizes than their Kamchatka counterparts: the largest skull measured by Sergej Ognew(1931) was only slightly smaller than that of the largest Kodiak brown bear (the largest subspecies of brown bears) on record at the time.