page_title: Mammals of Australia
section_title: Placental mammals
hierarchical_section_title: Mammals of Australia / Placental mammals
context_page_description: The mammals of Australia have a rich fossil history, as well as a variety of extant mammalian species, dominated by the marsupials, but also including monotremes and placentals. 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 mammalian predators in Australia, the Tasmanian tiger and the marsupual lion, bore a striking resemblance to large canids such as the gray wolf and large cats respectively; gliding possums and flying squirrels have similar adaptations enabling their arboreal lifestyle; and the numbat and anteaters are both digging insectivores. Most of Australia's mammals are herbivores or omnivores.
context_section_description: Australia has indigenous placental mammals from two orders: the bats, order Chiroptera,  represented by six families, and the mice and rats, order Rodentia, family Muridae. Bats and rodents are relatively recent arrivals to Australia. Bats probably arrived from Asia, and they are present in the fossil record only from as recently as 15 mya. Although 7% of the world's bats species live in Australia, there are only two endemic genera of bats. Rodents first arrived in Australia 5 to 10 mya and underwent a wide radiation to produce the species collectively known as the "old endemics". The old endemics are represented by 14 extant genera. About a million years ago, the rat entered Australia from New Guinea and evolved into seven species of Rattus, collectively called the "new endemics".
  Since human settlement, many placental mammals have been introduced to Australia and are now feral. The first was the dingo; fossil evidence suggests that people from the north brought the dingo to Australia about 5000 years ago. When Europeans settled Australia they intentionally released many species into the wild, including the red fox, brown hare, and the European rabbit. Other domestic species have escaped and over time have produced wild populations, including the cat, fallow deer, rusa deer, chital, domestic horse, donkey, pig, domestic goat, water buffalo, and dromedary. Only three species of Australia's non-indigenous placental mammals were not deliberately introduced: the house mouse, black rat and brown rat.      
                                                   
  Forty-six marine mammals from the order Cetacea are found in Australian coastal waters, but since many of these species have a global distribution, some authors do not consider them Australian species. There are nine species of baleen whale, including the enormous humpback whales and southern right whales. Dwarf minke whales are common off Great Barrier Reef in winter. There are 37 species of toothed whale, which include all six genera of the family Ziphiidae (beaked whales), and 21 species of oceanic dolphin, including the Australian snubfin dolphin, a species first described in 2005 that is endemic to Australia. Some oceanic dolphins, such as the orca, can be found in all waters around the continent; others, such as the Irrawaddy dolphin, are confined to the warm northern waters. The dugong (order Sirenia) is an endangered marine species that inhabits the waters of northeastern and northwestern Australia, particularly the Torres Strait. It can grow up to 3 metres (9.8 ft) long and weigh as much as 400 kilograms (880 lb). The dugong is the only herbivorous marine mammal in Australia, feeding on sea grass in coastal areas. 
  Ten species of seals and sea lions (superfamily Pinnipedia) live off the southern Australian coast and in Sub-Antarctic Australian territories.
caption: The dingo was the first placental mammal introduced to Australia by humans.
exif: {}