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Definition: mammal from The Penguin Dictionary of Psychology

Any member of the Mammalia class of vertebrates. Mammalian characteristics include, in addition to the obvious mammary glands for milk secretion and suckling, hair, a diaphragm for respiration, a lower jaw consisting of a single pair of bones, and the ossicles of the middle ear.


mammal

From The Columbia Encyclopedia
an animal of the highest class of vertebrates, the Mammalia. The female has mammary glands, which secrete milk for the nourishment of the young after birth. In the majority of mammals the body is partially or wholly covered with hair; the heart has four chambers, and only the left aortic arch is present; and a muscular diaphragm separates the chest from the abdominal cavity. Mammals are warm-blooded; that is, they have a relatively constant body temperature independent of the temperature of their surroundings. The mature red blood cells (erythrocytes) usually lack a nucleus. Except for the egg-laying monotremes (the platypus and the echidna, or spiny anteater), mammals give birth to live young. A marsupial is born in a more undeveloped state than the young of other mammals, although all are relatively helpless at birth. In some marsupials and in higher mammals the young receive prenatal nourishment through a placenta . The order Carnivora, or flesh-eating animals, includes terrestrial…
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Full text Article mammal

From Philip's Encyclopedia
The feet of mammals evolved in many different...
Any member of the class Mammalia of vertebrate animals characterized by mammary glands in the female and full, partial or vestigial hair covering. Mammals are warm-blooded. They have a four-chambered heart with circulation to the lungs separate from the rest of the body. Mammals usually bear fewer…
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Full text Article mammal

From Word Origins
Etymologically, mammal denotes an ‘animal that suckles its young’. The word is a derivative of mammalia [18], the term for that whole class of animals, coined by the Swedish naturalist Linnaeus from Latin mammālis ‘of the breast’. This in turn was based on mamma ‘mother, breast’, which has been…
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Full text Article mammal

From The Columbia Encyclopedia
an animal of the highest class of vertebrates, the Mammalia. The female has mammary glands, which secrete milk for the nourishment of the young after birth. In the majority of mammals the body is partially or wholly covered with hair; the heart has four chambers, and only the left aortic arch is…
| 416 words
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Full text Article MAMMALS

From National Geographic Answer Book: 10,001 Fast Facts About Our World Full text Article LIFE ON EARTH
LONGEST GESTATION AFRICAN ELEPHANT / 660 days ASIATIC ELEPHANT / 600 days BAIRD'S BEAKED WHALE / 520 days WHITE RHINOCEROS / 490 days WALRUS / 480 days GIRAFFE / 460 days TAPIR / 400 days DROMEDARY / 390 days FIN WHALE / 370 days LLAMA / 360 days Mammals are vertebrates distinguished by their…
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Full text Article mammal

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Any of a large group of warm-blooded vertebrate animals characterized by having mammary glands in the female; these are used for suckling the young. Other features of mammals are hair (very reduced in some species, such as whales); a middle ear formed of three small bones (ossicles); a lower jaw…
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Full text Article mammal

From Britannica Concise Encyclopedia
Any member of the class (Mammalia) of warm-blooded vertebrate s having four limbs (except for some aquatic species) and distinguished from other chordate classes by the female’s milk-secreting glands and the presence of hair at some stage of development. Other unique characteristics include a jaw…
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Full text Article MAMMALS

From The Welsh Academy Encyclopaedia of Wales
Some of the earliest evidence of mammals in the world has been found in Wales, particularly in quarries of a region to the south of Bridgend in the Vale of Glamorgan . For instance, Morganucodon watsoni , a shrew-like mammal that lived some 200 million years ago, was first discovered in 1947 in…
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Full text Article MAMMALS

From The Arctic Guide: Wildlife of the Far North
ALL MAMMALS , from humans to lemmings to muskoxen to whales, share certain physical features. All mammals possess modified sweat glands called mammary glands, which in a female can produce milk. All have body hair, at least at the beginning of their lives, and all have a four-chambered heart, …
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Full text Article MAMMALS: SEA MAMMALS

From National Geographic Answer Book: 10,001 Fast Facts About Our World Full text Article LIFE ON EARTH
Whales, dolphins, and porpoises are sea mammals known as cetaceans. Some scientists believe these animals descend from a land-dwelling ancestor that resembled a small semiaquatic deer. Over time, bodies became streamlined, rear legs were lost, front legs became flippers, and a powerful, fluked tail…
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Full text Article marine mammals

From Science Encyclopedia: Encyclopedia of Marine Science
The nearly extinct humpback whale can be found in...
Marine mammals are warm-blooded animals with hair on their bodies; they produce milk for their young such as cetaceans (whales, dolphins, and porpoises) and pinnipeds (seals, sea lions, and walruses). These mammals spend most of their lives in the marine environment. Marine mammals, such as the…
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