A group of air breathing animals h...

a warm-blooded animal (including humans) that nourishes its young with milk secreted by mammary glands and has skin usually more or less covered with hair ....... back

Any animal which gives birth to live young, is warm-blooded and suckles or provides milk for its young.

mamma: breast, teat] • Any animal of the class Mammalia, characterized by the production of milk by the female mammary glands and the possession of hair for body covering.