Carnivora(redirected from Musteloid)
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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
an order of mammals.
The body length ranges from 13 cm (short-tailed weasel) to 3 m (bears), while the weight, from 30 g to 700 kg. Carnivores are mainly flesh-eating animals; some are omnivorous or herbivorous. The canine teeth are well developed. The molars of most species have sharp cusps; more rarely the cusps are blunt. In many carnivores the fourth upper premolar and the first lower molar are opposite one another, are enlarged, and are adapted for tearing meat; these are the carnassial teeth. The extremities have four or five digits; the claws are well developed, sometimes retractile. In the skull the orbit is usually in communication with the temporal fossa. Carnivore young are born blind and helpless.
Carnivores are distributed throughout the world, except Australia. They are descended from primitive insectivores. The first carnivores were the now-extinct creodonts.
The order Carnivora is usually divided into two suborders: Arctoidea and Aeluroidea. The former includes the families Canidae, Ursidae, Procyonidae, and Mustelidae, while the latter includes Viverridae, Hyaenidae, and Felidae.
Many carnivores are beneficial animals, providing valuable furs and destroying harmful rodents. Some, such as the wolf, destroy domestic animals.
REFERENCESMlekopitaiushchie Sovetskogo Soiuza, vol. 2. parts 1–2. Edited by V. G. Geptner and N. P. Naumov. Moscow, 1967–72.
Zhizn’ zhivotnykh, vol. 6. Moscow, 1971.
I. I. SOKOLOV