Temporal range: 225–0 Ma (Kemp) or 167–0 Ma (Rowe) See
discussion of dates in text |Examples of various mammalian
orders, click the image and scroll down for individual
descriptions| Mammals (class Mammalia (pron.: //)) are a clade
of warm-blooded amniotes. Among the features that distinguish
them from the other amniotes, the reptiles and the birds, are
hair, three middle ear bones, mammary glands in females, and a
neocortex (a region of the brain). The mammalian brain regulates
body temperature and the circulatory system, including the four-
chambered heart. The mammals include the largest animals on the
planet, the rorqual whales, as well as some of the most
intelligent, such as elephants, some primates and some
cetaceans. The basic body type is a four-legged land-borne
animal, but some mammals are adapted for life at sea, in the
air, in the trees, or on two legs. The largest group of mammals,
the placentals, have a placenta which feeds the offspring during
pregnancy. Mammals range in size from the 30–40 mil