GC: n
S: UH (last access: 25 May 2025); NatGeo (last access: 25 May 2025).
N: 1. From base of New Latin Mammalia (Linnaeus), class name, noun derivative from neuter plural of mammālis, from Latin mamma “breast, udder” + -ālis. The first known use of mammal was in 1811.
2. Any of a class (Mammalia) of warm-blooded higher vertebrates (such as placentals, marsupials, or monotremes) that nourish their young with milk secreted by mammary glands, have the skin usually more or less covered with hair, and include humans.
- Human beings, dogs, and cats are all mammals.
3. mammal. Also known as: Mammalia.
- mammal, (class Mammalia), any member of the group of vertebrate animals in which the young are nourished with milk from special mammary glands of the mother. In addition to these characteristic milk glands, mammals are distinguished by several other unique features. Hair is a typical mammalian feature, although in many whales it has disappeared except in the fetal stage. The mammalian lower jaw is hinged directly to the skull, instead of through a separate bone (the quadrate) as in all other vertebrates. A chain of three tiny bones transmits sound waves across the middle ear. A muscular diaphragm separates the heart and the lungs from the abdominal cavity. Only the left aortic arch persists. (In birds the right aortic arch persists; in reptiles, amphibians, and fishes both arches are retained.) Mature red blood cells (erythrocytes) in all mammals lack a nucleus; all other vertebrates have nucleated red blood cells.
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Except for the monotremes (an egg-laying order of mammals comprising echidnas and the duck-billed platypus), all mammals are viviparous—they bear live young. In the placental mammals (which have a placenta to facilitate nutrient and waste exchange between the mother and the developing fetus), the young are carried within the mother’s womb, reaching a relatively advanced stage of development before birth. In the marsupials (e.g., kangaroos, opossums, and wallabies), the newborns are incompletely developed at birth and continue to develop outside the womb, attaching themselves to the female’s body in the area of her mammary glands. Some marsupials have a pouchlike structure or fold, the marsupium, that shelters the suckling young.
The class Mammalia is worldwide in distribution. It has been said that mammals have a wider distribution and are more adaptable than any other single class of animals, with the exception of certain less-complex forms such as arachnids and insects. This versatility in exploiting Earth is attributed in large part to the ability of mammals to regulate their body temperatures and internal environment both in excessive heat and aridity and in severe cold.
4. Mammals; Paleontology: mammal, mammalian.
- … warm-blooded hairy quadrupeds having lungs, a four-chambered heart, a left aortic arch, non-nucleated red blood corpuscles, mammary glands for suckling the young and many other features which distinguish them from the reptiles which are believed to have been their ancestors. The lower jaw consists of a single bone on each side, the “dentary” which articulates with the squamosal bone; this contrasts with the jaws of other vertebrates which articulate with the quadrate bone. The teeth of mammals are heterodont and are in sockets. The majority of present-day mammals have a placenta but the two primitive groups, Monotremes and Marsupials have not.
- Mammal: term used by Parks Canada.
S: 1 & 2. MW (last access: 25 May 2025). 3. EncBrit (last access: 25 May 2025). 4. TERMIUM PLUS (last access: 25 May 2025).
SYN: 1. mammalia. 2. mammalian. (depending on context)
S: 1. EncBrit (last access: 25 May 2025). 2. TERMIUM PLUS (last access: 25 May 2025); GDT (last access: 25 May 2025).
