U. rossicus dental specimens when separated into groups of different ontogenetic stages do not show significant variations in
dental microwear, suggesting the diets of these bears stayed fairly constant over the course of their lifetimes. The microwear features of the labial surfaces of its
incisors suggest that
U. rossicus had a diet of coarse, dry vegetation and frequently engaged in
rhizophagy. Cave bear teeth show greater wear than most modern bear species, suggesting a diet of tough materials. However,
tubers and other gritty food, which cause distinctive tooth wear in modern brown bears, do not appear to have constituted a major part of cave bears' diets on the basis of dental microwear analysis. The morphological features of the cave bear chewing apparatus, including loss of premolars, have long been suggested to indicate their diets displayed a higher degree of
herbivory than the
Eurasian brown bear. Indeed, a solely vegetarian diet has been inferred on the basis of tooth morphology. Results obtained on the stable isotopes of cave bear bones also point to a largely vegetarian diet in having low levels of
nitrogen-15 and
carbon-13, which are accumulated at a faster rate by carnivores as opposed to herbivores. Cave bears of the
last ice age lacked the usual two or three premolars present in other bears; to compensate, the last molar is very elongated, with supplementary cusps. ==References==