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Origin, Diversity and Ecology of


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Australian Marsupials
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Darwin (2K) 'On seeing the marsupials in Australia for the first time and comparing them to placental mammals; An unbeliever… might
exclaim "Surely two distinct Creators must have been at work".'

Charles Darwin, 1809-1882.

Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Theria
Infraclass: Marsupialia

Marsupialia is an infraclass of the class Mammalia, and is one of the three mammalian clades, alongside the placentals and the monotremes. Today, marsupials are found only in the Americas and Australasia. There are around 334 species of marsupials, more than 200 in Australia and the islands to the north, around 100 in South America, 13 in Central America and a single species, the Virginia opossum, in North America.

mammal phylo tree (7K)
Phylogenetic tree showing the relationship between the 3 clades of the class Mammalia.

The marsupials are named for their most distinctive feature, the marsupium, or 'pouch', which is used to hold and nourish their poorly developed newborns in many species.

The marsupials were first discovered by European biologists following the discovery of the Americas at the end of the 15th Century. The more distinctive Australian marsupials were discovered in the early 17th Century. There is an (unfortunate) tradition of naming marsupial species in terms of placental mammals they resemble through convergent evolution. For example, the Koala bear is not a bear, the Tasmanian wolf is not a wolf, and the marsupial bandicoot is not a bandicoot.

This site was produced by Sam Kelsey and Stephen Mitchell, Paleobiology students of the University of Bristol, for use as part of the Earth Science Departments' 'Palaeo Files'.