Echidnas, sometimes known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. The four extant species, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs. Their diet consists of ants and termites, but they are not closely related to the true anteaters of the Americas. They live in Australia and New Guinea. Echidnas evolved between 20 and 50 million years ago, descending from a platypus-like monotreme. This ancestor was aquatic, but echidnas adapted to life on land. The platypus (Ornithorhynchus anatinus) is a semiaquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth. The unusual appearance of this egg-laying, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, with some considering it an elaborate hoax. taken from "Johnson's household book of nature, containing full and interesting descriptions of the animal kingdom, based upon the writings of the eminent naturalists, Audubon, Wallace, Brehm, Wood and others" edited by Hugh Craig, published 1880.