During the late Eocene, the Australian/New Guinean continent began a period of drying that caused a retreat in the area of rainforest,[3] which forced the ancestral pademelons to begin living in a drier, rockier environment.

[4] 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.

One species in particular, the Proserpine rock-wallaby (Petrogale persephone), displays equal preference for climbing trees as for living in rocky outcrops.

[14] The case for the golden-mantled tree-kangaroo (D. pulcherrimus) is comparable to that of D. stellarum; it was first described as a subspecies of D. goodfellowi,[10] though recent authorities have elevated it to species status based on its absolute diagnostability.

[8] A population of the tenkile (Scott's tree-kangaroo) recently discovered from the Bewani Mountains may represent an undescribed subspecies.

Their habitats are breeding grounds for danger, as they can easily fall prey to their natural predator, the amethystine python, which also climbs and lives in the treetops.

The grizzled tree-kangaroo grows to a length of 75–90 cm (30 to 35 in), with males being considerably larger than females, and its weight is 8–15 kg (18-33 lb).

Like terrestrial kangaroos, tree-kangaroos do not sweat to cool their bodies, rather, they lick their forearms and allow the moisture to evaporate in an adaptive form of behavioural thermoregulation.

They move at approximately human walking pace and hop awkwardly, leaning their body far forward to balance the heavy tail.

[citation needed] The main diet of the tree-kangaroo is leaves and fruit that it gathers from the trees, but occasionally scavenged from the ground.

[19] Some captive tree-kangaroos (perhaps limited to New Guinea species) eat protein foods such as eggs, birds and snakes, making them omnivores.

[19] Research conducted on Lumholtz's tree-kangaroo, a species that dwells in the rain forests of northeastern Australia, determined the frequency of causes of death.

These include populations of Goodfellow's (D. goodfellowi) and Matschie's (D. matschiei), with smaller numbers of Lumholtz's (D. lumholtzi), Grizzled (D. inustus), and Doria's (D. dorianus) tree kangaroos.

In November 2014 at the Adelaide Zoo, an orphaned tree-kangaroo joey was transferred to the pouch of a yellow-footed rock-wallaby when his mother was killed by a falling branch.