Miscellaneous Mammals
The mammals are the class of vertebrate animals characterized by
the presence of mammary glands, which in females produce milk for
the nourishment of young; the presence of hair or fur; and endothermic
or "warm-blooded" bodies. The brain regulates endothermic
and circulatory systems, including a four-chambered heart. Mammals
encompass some 5,500 species, distributed in about 1,200 genera,
152 families and up to 46 orders, though this varies with the classification
scheme.
Phylogenetically, Mammalia is defined as all descendants of the
most recent common ancestor of monotremes (e.g., echidnas and platypuses)
and therian mammals (marsupials and placentals.)
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