Carnivora

Carnivora [kär′niv·ə·rə]

(vertebrate zoology)

A large order of placental mammals, including dogs, bears, and cats, that is primarily adapted for predation as evidenced by dentition and jaw articulation.

---

Carnivora

One of the larger orders of placental mammals, including fossil and living dogs, raccoons, pandas, bears, weasels, skunks, badgers, otters, mongooses, civets, cats, hyenas, seals, walruses, and many extinct groups organized into 12 families, with about 112 living genera and more than twice as many extinct genera. The subdivision of the order into three superfamilies has long been practiced and the following groups seem appropriate: Miacoidea, Canoidea, and Feloidea. The primary adaptation in this order was for predation on other vertebrates and invertebrates. A few carnivorans (for example, bear and panda) have secondarily become largely or entirely herbivorous, but even then the ancestral adaptations for predation are still clearly evident in the structure of the teeth and jaws. The Carnivora have been highly successful animals since their first appearance in the early Paleocene.

Structural adaptations involve the teeth and jaws. The dentition is sharply divided into three functional units. The incisors act as a tool for nipping and delicate prehension, and the large, interlocking upper and lower canines for heavy piercing and tearing during the killing of prey. The cheek teeth are divided into premolars (for heavy prehension) and molars (for slicing and grinding), which may be variously modified depending on the specific adaptation, but there is a constant tendency for the last (fourth) upper premolar and the first lower molar to enlarge and form longtitudinal opposed shearing blades (the carnassials). In all carnivorans the jaw articulation is arranged in such a manner that movement is limited to vertical hinge motions and transverse sliding. The temporal muscle dominates the jaw musculature, forming at least one-half of the total mass of the jaw muscles.

The earliest fossil records are early Paleocene, but the earliest well-represented material comes from the middle Paleocene of North America. During the Paleocene and Eocene the stem-carnivorans or miacoids underwent considerable diversification in both the Old and New World. At the end of Eocene and beginning of Oligocene time throughout the Northern Hemisphere, a dramatic change took place within the Carnivora; this was the appearance of primitive representatives of modern carnivoran families. See Mammalia, Pinnipeds