Monotremata

Monotremes are mammals that lay eggs (Prototheria) instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). The only surviving examples of monotremes are all indigenous to Australia and New Guinea, although there is evidence that they were once more widespread. Among living mammals they include the platypus and four species of echidnas (or spiny anteaters) For more information about Monotremata visit the Wikipedia Entry Get back to Synapsida
Platypus	†Steropodon	† Megalibgwilia
Short-beaked echidna	Long-beaked echidna