Australidelphia is the superorder that contains roughly three-quarters of all marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...

s, including all those native to Australasia
Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes...

 and a single species from South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. (All other American marsupials are members of the Ameridelphia
Ameridelphia is traditionally a superorder that includes all marsupials living in the Americas except for the Monito del Monte...

.) Analysis of retrotransposon
Retrotransposons are genetic elements that can amplify themselves in a genome and are ubiquitous components of the DNA of many eukaryotic organisms. They are a subclass of transposon. They are particularly abundant in plants, where they are often a principal component of nuclear DNA...

 insertion sites in the nuclear DNA
Nuclear DNA
Nuclear DNA, nuclear deoxyribonucleic acid , is DNA contained within a nucleus of eukaryotic organisms. In mammals and vertebrates, nuclear DNA encodes more of the genome than the mitochondrial DNA and is composed of information inherited from two parents, one male, and one female, rather than...

 of a variety of marsupials has shown that the Monito del Monte's lineage
Lineage (evolution)
An evolutionary lineage is a sequence of species, that form a line of descent, each new species the direct result of speciation from an immediate ancestral species. Lineages are subsets of the evolutionary tree of life. Lineages are often determined by the techniques of molecular systematics.-...

 is the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...

 of the superorder. The Australian australidelphians form a clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

, for which the name Euaustralidelphia ("true Australidelphia") has been proposed (the branching order within this group is yet to be determined). The study also showed that the most basal of all marsupial orders are the other two South American lineages (Didelphimorphia
Opossums make up the largest order of marsupials in the Western Hemisphere, including 103 or more species in 19 genera. They are also commonly called possums, though that term technically refers to Australian fauna of the suborder Phalangeriformes. The Virginia opossum was the first animal to be...

 and Paucituberculata, with the former probably branching first). This indicates that Australidelphia arose in South America and likely reached Australia in a single dispersal event
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...

 after Microbiotheria split off.

The order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

s within this group are listed below:
  • Order Microbiotheria
    The Monito del Monte is the only extant member of its family and the only surviving member of an ancient order, the Microbiotheria. The oldest microbiothere currently recognised is Khasia cordillerensis, based on fossil teeth from Early Palaeocene deposits at Tiupampa, Bolivia...

    (1 species)
    • Family Microbiotheriidae: Monito del Monte
      Monito del Monte
      The Monito del Monte The Monito del Monte The Monito del Monte (Spanish for "little mountain monkey", Dromiciops gliroides, is a diminutive marsupial native only to southwestern South America (Chile and Argentina). It is the only extant species in the ancient order Microbiotheria, and the sole New...

  • Order Dasyuromorphia
    The order Dasyuromorphia comprises most of the Australian carnivorous marsupials, including quolls, dunnarts, the numbat, the Tasmanian devil, and the recently extinct thylacine...

    (71 species)
    • Family †Thylacinidae
      The animals in the Thylacinidae family were all carnivorous marsupials from the order Dasyuromorphia. The only recent member was the Thylacine , which became extinct in 1936...

      : Thylacine
      The thylacine or ,also ;binomial name: Thylacinus cynocephalus, Greek for "dog-headed pouched one") was the largest known carnivorous marsupial of modern times. It is commonly known as the Tasmanian tiger or the Tasmanian wolf...

    • Family Dasyuridae
      Dasyuridae is a family of marsupials native to Australia and New Guinea, including 61 species divided into 15 genera. Many are small and mouse-like, giving them the misnomer marsupial mice, but the group also includes the cat-sized quolls, as well as the Tasmanian Devil...

      : antechinus
      Antechinus is a genus of dasyurid marsupial that is indigenous to Australia and New Guinea. The majority of Antechinus species occur in Australia and only two species have been described in New Guinea...

      es, quoll
      The quoll, or native cat, is a carnivorous marsupial native to mainland Australia, New Guinea and Tasmania. It is primarily nocturnal and spends most of the day in its den. There are six species of quoll; four are found in Australia and two in New Guinea...

      s, dunnart
      Dunnarts are furry narrow-footed marsupials the size of a mouse, members of the genus Sminthopsis. They are mainly insectivorous. A male dunnart's Y chromosome has only 4 genes, making it the smallest known mammalian Y chromosome....

      s, Tasmanian Devil
      Tasmanian Devil
      The Tasmanian devil is a carnivorous marsupial of the family Dasyuridae, now found in the wild only on the Australian island state of Tasmania. The size of a small dog, it became the largest carnivorous marsupial in the world following the extinction of the thylacine in 1936...

      , and allies
    • Family Myrmecobiidae: Numbat
      The numbat , also known as the banded anteater, or walpurti, is a marsupial found in Western Australia. Its diet consists almost exclusively of termites. Once widespread across southern Australia, the range is now restricted to several small colonies and it is listed as an endangered species...

  • Order Peramelemorphia
    The order Peramelemorphia includes the bandicoots and bilbies: it equates approximately to the mainstream of marsupial omnivores...

    (21 species)
    • Family Thylacomyidae: bilbies
      Bilbies are desert-dwelling marsupial omnivores; they are members of the order Peramelemorphia. Before European colonisation of Australia, there were two species. One became extinct in the 1950s; the other survives but remains endangered....

    • Family †Chaeropodidae: Pig-footed Bandicoot
      Pig-footed Bandicoot
      The Pig-footed Bandicoot, Chaeropus ecaudatus, was a small marsupial of the arid and semi-arid plains of Australia. The distribution range of the species was later reduced to an inland desert region, where it was last recorded in the 1950s, and is now presumed to be extinct.-Classification:This...

    • Family Peramelidae
      Peramelidae is the family of marsupials that contains all of the extant bandicoots. One known extinct species of bandicoot, the Pig-footed Bandicoot, was so different than the other species that it was recently moved into its own family. There are four described fossil Peramelids...

      : bandicoot
      Bandicoots are a group of about 20 species of small to medium-sized, terrestrial marsupial omnivores in the order Peramelemorphia.- Etymology :...

      s and allies
  • Order Notoryctemorphia (2 species)
    • Family Notoryctidae: marsupial moles
  • Order Diprotodontia
    Diprotodontia is a large order of about 120 marsupial mammals including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the rhinoceros-sized Diprotodon, and Thylacoleo, the so-called "marsupial lion"....

    (117 species)
    • Family Phascolarctidae
      Phascolarctidae is a family of marsupials of the order Diprotodontia, consisting of only one extant species, the Koala, six well known fossil species, with another 5 less well known fossil species, and 2 fossil species whose taxonomy is debatable but is put in this group...

      : Koala
      The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....

    • Family Vombatidae: wombat
      Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...

    • Family Phalangeridae
      Phalangeridae is a family of nocturnal marsupials native to Australia and New Guinea, including the cuscuses, brushtail possums, and their close relatives...

      : brushtail possums and cuscuses
    • Family Burramyidae: pygmy possums
    • Family Tarsipedidae: Honey Possum
      Honey Possum
      The honey possum or tait, its Native Australian name or noolbenger is a tiny Australian marsupial weighing just seven to eleven grams for the male, and eight to sixteen grams for the female—about half the weight of a mouse. Their physical size ranges from a body length of between 6.5 –...

    • Family Petauridae
      The family Petauridae includes 11 medium-sized possum species: four striped possums, the six species wrist-winged gliders in genus Petaurus, and Leadbeater's Possum which has only vestigal gliding membranes...

      : Striped Possum
      Striped Possum
      The Striped Possum is a member of the Petauridae family, one of the marsupial families. The species is black with three white stripes running head to tail, and its head has white stripes that form a 'Y' shape...

      , Leadbeater's Possum
      Leadbeater's Possum
      Leadbeater's Possum is an endangered possum restricted to small pockets of remaining old growth mountain ash forests in the central highlands of Victoria north-east of Melbourne...

      , Yellow-bellied Glider
      Yellow-bellied Glider
      The Yellow-bellied Glider is an arboreal and nocturnal gliding possum that lives in a narrow range of native eucalypt forests down eastern Australia, reaching from northern Queensland to Victoria.-Habitat:...

      , Sugar Glider
      Sugar Glider
      The sugar glider is a small gliding possum originating from the marsupial family.The sugar glider is native to eastern and northern mainland Australia and is also native to New Guinea and the Bismarck Archipelago.- Habitat :Sugar gliders can be found all throughout the northern and eastern parts of...

      , Mahogany Glider
      Mahogany Glider
      The mahogany glider is an endangered gliding possum native to a small region of coastal Queensland.-Appearance:A nocturnal arboreal marsupial, the mahogany glider closely resembles the sugar glider, the squirrel glider and the yellow-bellied glider., but is noticeably larger than any of its...

      , Squirrel Glider
      Squirrel Glider
      The Squirrel Glider is a nocturnal gliding possum, one of the wrist-winged gliders of the genus Petaurus.-Habitat:...

    • Family Pseudocheiridae
      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.-Characteristics:...

      : ringtailed possums and allies
    • Family Potoridae: potoroos, rat kangaroos, bettongs
    • Family Acrobatidae
      Acrobatidae is a small family of gliding marsupials containing two genera, each with a single species, the Feathertail Glider from Australia and Feather-tailed Possum from New Guinea....

      : Feathertail Glider
      Feathertail Glider
      The Feathertail Glider , also known as the Pygmy Gliding Possum, Pygmy Glider, Pygmy Phalanger, Flying Phalanger and Flying Mouse, is the world's smallest gliding possum and is named for its long feather-shaped tail. Although only the size of a very small mouse , it can leap and glide up to 25 metres...

       and Feather-tailed Possum
      Feather-tailed Possum
      The Feather-tailed Possum is a species of marsupial in the Acrobatidae family. It is found in West Papua, Indonesia and Papua New Guinea.It is the only species in the genus Distoechurus....

    • Family Hypsiprymnodontidae
      The Hypsiprymnodontidae are a family of macropods, one of two families containing animals commonly referred to as rat-kangaroos. There is a single known extant genus and species in this family, the Musky Rat-kangaroo, Hypsiprymnodon moschatus, which occurs in northern Australia and New Guinea....

      : Musky Rat-kangaroo
      Musky Rat-kangaroo
      The Musky Rat-kangaroo is a marsupial species found in the rainforests of northeast Australia. Although some scientists place this species as a subfamily of the family Potoroidae, the most recent classification places it in the family Hypsiprymnodontidae with prehistoric rat-kangaroos.It is the...

    • Family Macropodidae: kangaroos, wallabies, and allies
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