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Adaptations of the Tree Kangaroo

The evolutionary history of tree-kangaroos begins with a rainforest floor-dwelling pademelon-like ancestor. This ancestor evolved from an arboreal possum-like ancestor as is suspected of all macropodid marsupials in Australia and New Guinea. During the late Eocene, the Australian/New Guinean continent began a period of drying that caused a retreat in the area of rainforest, which forced the ancestral pademelons to begin living in a dryer, rockier environment. After some generations of adaptation to the new environment, the pademelons evolved into rock-wallabies (Petrogale spp. ), which developed a generalist feeding strategy due to their dependence on a diverse assortment of vegetation refuges. This generalist strategy allowed the rock-wallabies to easily adapt to malesian rainforest types that were introduced to Australia from Asia during the mid-Miocene. The rock-wallabies that migrated into these introduced forests adapted to spend more time climbing trees. One species in particular, the proserpine rock-wallaby (Petrogale persephone), displays equal preference for climbing trees as for living in rocky outcrops. During the late-Miocene the semi-arboreal rock-wallabies evolved into the now extinct tree-kangaroo genus Bohra. Global cooling during the Pleistocene caused continent-wide drying and rainforest retractions in Australia and New Guinea. The rainforest contractions isolated populations of Bohra which resulted in the evolution of today’s tree-kangaroos (Dendrolagus spp. ), as they adapted to lifestyles in geographically small and diverse rainforest fragments, and became further specialized for a canopy-dwelling lifestyle.

Cynthia Jefferson

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