Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a pouch. Marsupials include opossums, Tasmanian devils, kangaroos, koalas, wombats, wallabies, bandicoots, and the extinct thylacine.
Opossums are members of the marsupial order Didelphimorphia endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 120+ species in 19 genera. Opossums originated in South America and entered North America in the Great American Interchange following the connection of North and South America.
Diprotodontia is the largest extant order of marsupials, with about 155 species, including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the hippopotamus-sized Diprotodon, and Thylacoleo, the so-called "marsupial lion".
The Vombatiformes are one of the three suborders of the large marsupial order Diprotodontia. Seven of the nine known families within this suborder are extinct; only the families Phascolarctidae, with the koala, and Vombatidae, with three extant species of wombat, survive.
Australidelphia is the superorder that contains roughly three-quarters of all marsupials, including all those native to Australasia and a single species — the monito del monte — from South America. All other American marsupials are members of the Ameridelphia. Analysis of retrotransposon insertion sites in the nuclear DNA of a variety of marsupials has shown that the South American monito del monte's lineage is the most basal of the superorder.
Mammalia is a class of animal within the phylum Chordata. Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums. Many earlier ideas from Linnaeus et al. have been completely abandoned by modern taxonomists, among these are the idea that bats are related to birds or that humans represent a group outside of other living things. Competing ideas about the relationships of mammal orders do persist and are currently in development. Most significantly in recent years, cladistic thinking has led to an effort to ensure that all taxonomic designations represent monophyletic groups. The field has also seen a recent surge in interest and modification due to the results of molecular phylogenetics.
Pseudocheiridae is a family of arboreal marsupials containing 17 extant species of ringtailed possums and close relatives. They are found in forested areas and shrublands throughout Australia and New Guinea.
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 marsupial 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.
The Macropodiformes, also known as macropods, are one of the three suborders of the large marsupial order Diprotodontia. They may in fact be nested within one of the suborders, Phalangeriformes. Kangaroos, wallabies and allies, bettongs, potoroos and rat kangaroos are all members of this suborder.
The scaly-tailed possum is found in northwestern Australia, where it is restricted to the Kimberley.
The Phalangeridae are a family of mostly nocturnal marsupials native to Australia, New Guinea, and Eastern Indonesia, including the cuscuses, brushtail possums, and their close relatives. Considered a type of possum, most species are arboreal, and they inhabit a wide range of forest habitats from alpine woodland to eucalypt forest and tropical jungle. Many species have been introduced to various non-native habitats by humans for thousands of years.
Petauroidea is a superfamily of marsupials from Australia and New Guinea. It is part of the suborder Phalangeriformes within the order Diprotodontia, which also includes, among others, wombats, kangaroos, cuscuses. The superfamily Phalangeroidea, including cuscuses and brushtail possums and pygmy possums, is the immediate sister group of the Petauroidea.
