Mammals of Australia introductions of placental mammals into Australian fauna were about (rats), several thousand years ago (dingo), and 200 years ago (many species); the last two were made by humans. Some claims were made about placental mammal fossils from the Eocene of Australia, called "Tingamarra". These claims are based on only one found tooth having some characteristic features of condylarth, and were discussed widely. But both the age and placental nature of these fossils were challenged by other researchers. Monotremes are mammals with a unique method of reproduction: they lay eggs instead of giving birth to live young. Two of the five
Fauna of New Guinea his life. The mammal fauna of New Guinea is composed of all extant subclasses of mammal: the monotremes, placentals and marsupials. New Guinea contains the largest number of monotreme species of any land mass, with only one species absent: the platypus ("Ornithorhynchus anatinus"). The marsupial fauna of New Guinea is diverse, consisting of the three orders: Dasyuromorphia, Peramelemorphia and Diprotodontia. The native placental mammals are solely represented by the rodents and bats. There are approximately the same number of placental species as marsupials and monotremes. New Guinea's monotremes are restricted to the family Tachyglossidae, also known as "echidnas". There are