Australidelphia

Koala ( Phascolarctos cinereus )

  • Microbiotheria
  • Beutelmulle ( Notoryctemorphia )
  • Dasyuridae behaved ( Dasyuromorphia )
  • Bandicoot ( Peramelemorphia )
  • DIPROTODONTIA

The Australidelphia for which so far there is no German name, in addition to the Ameridelphia form one of the two superorders within the subclass of marsupial ( Metatheria ). They include all members of this group, which are native to Australia, New Guinea and nearby islands, besides also still one living in South America way, the Chiloé opossum ( Dromiciops gliroides ), which is in its own order Microbiotheria. Paleontological they are also handed down from Antarctica.

The group is based next to the biogeographical facts mainly on molecular data. As a common morphological feature a specialization of the tarsal bones is contemplated.

Phylogeny

Different authors vary the information on when the Australidelphia have split from their sister group, the Ameridelphia, between 128 million and 61.7 million years. Recent estimates are based on a separation of about 75 million years ago. The majority of Australidelphia is then probably not migrated across Antarctica to Australia. Only after the extinction of the dinosaurs about 65 million years ago they were able to develop the dominant group of land animals there, however. However, the first fossil evidence of marsupials in Australia date from the epoch of the Eocene, about 54 million years ago, an unambiguous assignment of made ​​in Southeast Queensland find to Australidelphia is not yet assured.

The Australidelphia were followed with the exception of the South American Microbiotheria isolated by the separation of Australia from other continents for 30 million years by the rest of the mammal world, only about 8 million years ago can be found with immigrant rodents ( Rodentia ) representatives of the higher mammals. The migration of modern humans (Homo sapiens) then led about 45,000 years ago, a mass extinction that the entire Australian megafauna and thus their most important group Australidelphia detected.

Cases of convergent evolution

Comparing the Australidelphia with other mammalian groups show some very interesting cases of convergent evolution. It is, for example, both the ants marsupials ( Myrmecobius fasciatus ) as well as the counted among the Laurasiatheria Erdwölfen ( Proteles cristatus) and the aardvarks ( Orycteropus afer) that belong to the Afrotheria, come to a strong recovery of the teeth. By their common life in the underground, the Beutelmulle ( Notoryctemorphia ) that the associated real Laurasiatheria moles ( Talpidae ) and the golden moles ( Chrysocloridae ) have developed highly convergent. Ecological equivalents are kangaroos on the other hand ( Macropodidae ) and ungulates such as odd-toed ungulates ( Perissodactyla ) and Artiodactyla ( Artiodactyla ).

Interestingly, the Australidelphia are also, as some species have taken a passive flyer airspace. This is even happening for three times independently: The Gleitbeutlern ( Petauridae ), the ring marsupials ( Pseudocheiridae ) and the Zwerggleitbeutlern ( Acrobatidae ).

System

The Australidelphia be out here with five orders:

  • The Microbiotheria comprise only a single species, the native to South America Chiloe opossum ( Dromiciops gliroides ).
  • The Beutelmulle ( Notoryctemorphia ) are the marsupial equivalents of moles and include two species in a genus Notoryctes.
  • The Dasyuridae -like ( Dasyuromorphia ) are divided into two living families who Dasyuridae ( Dasyuridae ) and the ants Beutler ( Myrmecobiidae ). Until the 20th century there was a third family Thylacinidae, which included the thylacine ( Thylacinus cynocephalus ). The last animal died in 1936 but in captivity.
  • The bandicoot ( Peramelemorphia ) comprise approximately 20 species, divided into three families.
  • The DIPROTODONTIA are the most species-rich order and include a large variety of types: Among other things, the famous kangaroos ( Macropodidae ) and koalas include ( Phascolarctos cinereus ), the Wombats ( Vombatidae ) but also the three families moving marsupials here.

About the voting lines within this group are unclear. Heather Amrine -Madsen presented in 2003 on the basis of molecular genetic comparisons following cladogram (quoted in Kemp, 2005):

DIPROTODONTIA

Bandicoot ( Peramelemorphia )

Beutelmulle ( Notoryctemorphia )

Dasyuridae behaved ( Dasyuromorphia )

Chiloe opossum ( Microbiotheria )

Other approaches, however, summarize the bandicoots and DIPROTODONTIA to a taxon Syndactyli together, which is morphologically supported by the webbed second and third toe of the hind limbs, but may represent only an analogy. Still other studies put the Chiloé opossum and the DIPROTODONTIA in a common lineage and see the bandicoot as a sister taxon of the remaining Australidelphia. A generally accepted phylogenetic systematics of marsupials there is not so. An attempt at systematization is complicated by large gaps in the fossil record, there are, for example, of the Australian species between the time 55 million years ago and the time 25 million years ago, than today's orders were already largely emerged so far no finds.

Australia (continent) Numbat Aardwolf
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