Carnassials are large teeth found in many carnivorous mammals, used for shearing flesh and bone in a scissor or shear-like way. In the Carnivora, the carnassials are the modified last upper premolar and the first lower molar, but in the prehistoric creodonts, the carnassials were further back in the jaw — first upper and second lower or second upper and third lower molars. Carnassials are the defining characteristic of the Carnivora order; that is, they're the one thing that all of the ani… (More on Carnassial)