Fauna of Australia - Mammals

Mammals

Australia has a rich mammalian fossil history, as well as a variety of extant mammalian species, dominated by the marsupials. The fossil record shows that monotremes have been present in Australia since the Early Cretaceous 145–99 MYA, and that marsupials and placental mammals date from the Eocene 56–34 MYA, when modern mammals first appeared in the fossil record. Although marsupials and placental mammals did coexist in Australia in the Eocene, only marsupials have survived to the present. The placental mammals made their reappearance in Australia in the Miocene, when Australia moved closer to Indonesia, and bats and rodents started to appear reliably in the fossil record. The marsupials evolved to fill specific ecological niches, and in many cases they are physically similar to the placental mammals in Eurasia and North America that occupy similar niches, a phenomenon known as convergent evolution. For example, the top predator in Australia, the Tasmanian Tiger, bore a striking resemblance to canids such as the Gray Wolf; gliding possums and flying squirrels have similar adaptations enabling their arboreal lifestyle; and the Numbat and anteaters are both digging insectivores. For the most part, mammals are not a highly visible part of the faunal landscape, as most species are nocturnal and many arboreal. Furthermore, there are few extant large ground-dwelling species.