Examples of representing beings: dogs, cats, horses, giraffes, elephants, apes, humans, bats, whales, dolphins, opossums, kangaroos, platypus. Basic morphology: hair, diaphragm muscle, mammary glands, enucleated red blood cells. Skin: impermeable, hairy. Respiration: pulmonary. Circulation: closed and complete, heart with four chambers. Nitrogen waste: urea. Thermal control: homeothermic. Types of reproduction: sexual, internal fecundation, oviparous monotremes (prototherians), marsupials (metatherians), placental (eutherians).
