Wednesday, July 8, 2009

Mammals - General Information

The Wet Tropics region is home to about a third of Australia's 315 mammal species - including unique green possums, fierce marsupial cats, kangaroos which climb trees and rare bats. As well as relatively common mammals like the platypus and wallaby which are widespread over the continent, the Wet Tropics is home to 13 mammal species which are found nowhere else in the world. All except two of them - the endangered Tropical Bettong and Mahogany Glider - are rainforest dwellers. They include two tree-kangaroos, a rat-kangaroo, four ringtail possums, a melomys and an antechinus.

Other Wet Tropics mammals are found in rainforest to the north in Cape York - the striped possum, prehensile-tailed rat, and the white-tailed Rat. Others also occur in to the south - the yellow-footed antechinus, spotted-tailed quoll and the white-footed dunnart (found 4000km south in Victoria and Tasmania).

Some of the Wet Tropics rainforest species have close relatives in New Guinea and Southeast Asia. When Australia became isolated after the break-up of the supercontinent of Gondwana, it drifted northward. About 15 million years ago it bumped into the Asian continental place. This collision allowed an exchange to take place between two sets of animals and plants which had evolved in isolation. Asian flora and fauna, including many placental rats, moved into Australia. At the same time Australian species moved north. Many of them colonised New Guinea, a new high altitude land mass created by the 'bow wave' of Australia's northerly drift. As a result, some of the unusual mammals of the Wet Tropics also live with our northern neighbours - the Long-tailed Pygmy Possum in Papua New Guinea and the Tube-nosed Insectivorous Bat in Southeast Asia.

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