Mammals (class Mammalia /məˈmeɪli.ə/ from Latin mamma "breast") are any members of a clade of endothermic amniotes distinguished from reptiles and birds by the possession of hair,[a] three middle ear bones, mammary glands, and a neocortex (a region of the brain). The mammalian brain regulates body temperature and the circulatory system, including the four-chambered heart.
