Incisors (from Latin incidere, "to cut") are the first kind of tooth in heterodont mammals. They're located in the premaxilla above and mandible below. Function In many herbivorous or omnivorous mammals, such as the human and the horse, they're adapted for shearing sharply. In cats, the incisors are small; biting off meat's done with the canines and the carnassials. In elephants, the upper incisors are modified into curved tusks, just as's the case with Narwhals, where normally one of them deve… (More on Incisor)