North American Black Bear (ursus americanus) approx length 12"

Polar Bear

(ursus maritimus) approx length 15"

Bears

Black bear (left), Polar bear (below) and grizzly bear (below right) shows comparison between canines and incisors of each species.  The polar bear has longer canines and more pointed and powerful incisors that reflect its nearly fulltime carnivourous lifestyle.  On the other hand the black bear is mostly a vegetarian and has smaller, more blunt incisors.  The grizzly is similar to the black bear in diet but it can be distinguished by more robust incisors.

Black bear (top) and Polar bear (below) shows comparison between premolars and molars of both species. A red arrow indicates the upper premolar and lower molar that in other carnivores is the carnassial blade for slicing off chunks of flesh.  In the black bear (and in all others except the polar bear) the blade is non-existant, but the polar bear does have the beginnings of a carnassial blade, marked by the higher crowns on the teeth and the fact that there is a very small cutting edge present on both teeth.

Black bear top view - note the shape of the nasal bones and width of the skull

Polar bear top view - note the relative narrowness of the skull and wider muzzle

Grizzly Bear (subspecies of brown bear)

(ursus horribilis) approx length 12" (this is the skull of a relatively small animal.  The Kodiak subspecies of brown bear can equal the largest polar bears in size.

At left is a view of the premolar teeth of a grizzly (brown) bear.  Like the black bear its carnassial molar is essentially undeveloped, but the presence of extra and larger premolars can help distinguish the two species.

Black bear top view - note the wide forehead and large cranium

Polar bear top view - note the similarity to the black bear skull.