MICROANATOMY

Detailed explanation-1: -Only two kinds of egg-laying mammals are left on the planet today-the duck-billed platypus and the echidna, or spiny anteater. These odd “monotremes” once dominated Australia, until their pouch-bearing cousins, the marsupials, invaded the land down under 71 million to 54 million years ago and swept them away.

Detailed explanation-2: -The platypus Ornithorhynchus anatinus, is a unique Australian species. Along with echidnas, platypus are grouped in a separate order of mammals known as monotremes, which are distinguished from all other mammals because they lay eggs. The platypus and echidna have both survived by occupying ecological niches.

Detailed explanation-3: -Echidnas and platypus are the only egg-laying mammals, known as monotremes.

Detailed explanation-4: -The monotremes are a group of highly specialised egg-laying predatory mammals, containing the platypus and echidnas. There are only five living species of monotreme, contained within two families: Family Ornithorhynchidae: the platypus, a single species in a single genus, Ornithorhynchus anatinus.