carnassials

Carnassials are the specialized cutting teeth of many carnivorous mammals. In most members of the order Carnivora, the carnassial pair consists of the upper fourth premolar (P4) and the lower first molar (M1). When the jaws close, the blades formed by these teeth slide past one another, producing a scissor-like slicing action that efficiently shears flesh for quicker processing and digestion. This adaptation complements the canines in gripping and tearing meat.

Anatomy and variation: The upper P4 and the lower M1 bear sharp, blade-like edges that meet along the bite plane. The exact shape and degree of specialization vary among families, with feliforms (such as cats and hyenas) and caniforms (such as dogs, bears, and seals) typically retaining a pronounced carnassial pair, while some omnivorous species show reduced or less specialized carnassials.

Ecology and evolution: Carnassial teeth are a diagnostic feature of many carnivorans and are closely associated with a carnivorous or largely carnivorous diet. Their development is traceable in the fossil record, where the presence and robustness of carnassials indicate a tendency toward flesh processing rather than crushing or grinding.

Etymology: The term derives from Latin carnis, flesh, and means meat cutters.