Printouts Monotremes are the most primitive mammals. Today, monotremes live only in Australia and New Guinea. The young get milk from a gland on the mother's belly. The platypus lays her eggs on the bank of a stream, then curls around the eggs to protect them and keep them warm. Spiny anteaters lay a single egg in a temporary protective pouch on the mother's belly.
Monotremes have hair like other mammals, and the females produce milk.
They have a low metabolic rate and a temperature slightly lower than that of placental mammals.