Mammal

Warm-blooded, big-brained animal with a backbone. All young mammals are suckled by their mothers. Living mammals, members of the class Mannalia are divided into monotremes such as duck-billed platypus; marsupials, such as kangaroos, whose offspring are not fully formed when born but complete their development attached to a nipple, generally in the mother’s pouch; and placentals, whose offspring are nourished at the embryonic stage by means of a placenta, and are born at an advanced stage of development.