Секторные зубы хищных: строение, эволюция и значение.

Mammal tooth type

Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified fourth upper premolar and the first lower molar. These teeth are also referred to as sectorial teeth.

The name carnivoran is applied to a member of the order Carnivora. Carnivorans possess a common arrangement of teeth called carnassials, in which the first lower molar and the last upper premolar possess blade like enamel crowns that act similar to a pair of shears for cutting meat. This dental arrangement has been modified by adaptation over the past 60 million years for diets composed of meat, for crushing vegetation, or for the loss of the carnassial function altogether found in pinnipeds.

The fossil record indicates the presence of carnassial teeth 50 million years ago, implying that Carnivora family members descend from a common ancestor. The shape and size of sectorial teeth of different carnivorous animals vary depending on diet, illustrated by the comparisons of bear (Ursus) carnassials with those of a leopard (Panthera). Bears, being omnivores, have a flattened, more blunt carnassial pair than leopards. This reflects the bear's diet, as the flattened carnassials are useful both in slicing meat and grinding up vegetation, whereas the leopard's sharp carnassial pairs are more adapted for its hypercarnivorous diet. During the Late Pleistocene – early Holocene a now extinct hypercarnivorous wolf ecomorph existed that was similar in size to a large extant gray wolf but with a shorter, broader palate and with large carnassial teeth relative to its overall skull size. This adaptation allowed the megafaunal wolf to predate and scavenge on Pleistocene megafauna.

Wear and cracking of the carnassial teeth in a wild carnivore (e. g. a wolf or lion) may result in the death of the individual due to starvation. Carnassial teeth infections are common in domestic dogs. They can present as abscesses (a large swollen lump under the eye). Extraction or root canal procedure (with or without a crown) of the tooth is necessary to ensure that no further complications occur, as well as pain medication and antibiotics.