Male mammals

Mammals Temporal range: 225–0 Ma (Kemp) or 167–0 Ma (Rowe) See discussion of dates in text PreЄ Є O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Amniota
Clade:	Synapsida
Clade:	Mammaliaformes
Class:	Mammalia Linnaeus, 1758
Living subgroups
Subclass Yinotheria Infraclass Australosphenida Order Monotremata Subclass Theriiformes Infraclass Holotheria Superlegion Trechnotheria Legion Cladotheria Supercohort Theria Cohort Marsupialia Cohort Placentalia

Mammals are any vertebrates within the class Mammalia (/məˈmeɪli.ə/ from Latin "breast"), a clade of endothermic amniotes distinguished from reptiles (including birds) by the possession of a neocortex (a region of the brain), hair, three middle ear bones and mammary glands. Females of all mammal species nurse their young with milk, secreted from the mammary glands.

Mammals include the biggest animals on the planet, the great whales. The basic body type is a terrestrial quadruped, but some mammals are adapted for life at sea, in the air, in trees, underground or on two legs. The largest group of mammals, the placentals, have a placenta, which enables the feeding of the fetus during gestation. Mammals range in size from the 30–40 mm (1.2–1.6 in) bumblebee bat to the 30-meter (98 ft) blue whale. With the exception of the five species of monotreme (egg-laying mammals), all modern mammals give birth to live young. Most mammals, including the six most species-rich orders, belong to the placental group. The largest orders are the rodents, bats and Soricomorpha (shrews and allies). The next three biggest orders, depending on the biological classification scheme used, are the Primates (apes and monkeys), the Cetartiodactyla (whales and even-toed ungulates), and the Carnivora (cats, dogs, seals, and allies).