Tree-kangaroos are macropods adapted for life in trees. They inhabit the tropical rainforests of New Guinea and far northeastern Queensland, and some of the islands in the region. Most tree-kangaroos are considered threatened due to hunting and habitat destruction.
The Lumholtz Tree-Kangaroo (Dendrolagus lumholtzi) is a noctural arboreal macropodid that spend the majority of their lives in trees. The majority of their movement and feedings occur and night so it is difficult to study these creatures regardless of their diminishing population. The tree kangaroo is the only true arboreal member of the kangaroo family https://en.wikipedia.org/w/index.php?title=Tree-kangaroo&action=edit#https://en.wikipedia.org/w/index.php?title=Tree-kangaroo&action=edit# . Tree kangaroos live primarily in the rainforests of Australia and New Guinea. DNA shows that the tree kangaroo split away from the rock wallabies between 5 and 7 million years ago according to fossil records. These fossil records also show that when plate tectonics shifted north the Australian plates brought New Guinea and Northern Australia into the Tropic Zone providing the perfect environment for tree kangaroos with no competition For example, the Seri's tree-kangaroo (D. stellarum) has been described as a subspecies of the Doria's tree-kangaroo (D. dorianus), but some recent authorities have treated it as a separate species based on its absolute diagnostability. It has further been suggested that the D. mayri taxon may represent a valid species, but as it is known only from a single preserved specimen, most authorities have retained it as a subspecies of D. dorianus. The case for the golden-mantled tree-kangaroo (D. pulcherrimus) is comparable to that of D. stellarum. It was initially described as a subspecies of D. goodfellowi, but recent authorities have elevated it to species status based on its absolute diagnostability. A population of the Tenkile recently discovered from the Bewani Mountains may represent an undescribed subspecies. The Tree Kangaroo can be filed as a macropod
Unlike their ground dwelling kangaroo cousins the tree kangaroo contains some different characteristics that give these macropods the ability to live in trees. Tree kangaroos have shorter yet broader hind feet which contain longer curved nails, as well as sponge like grip on its paws and soles of its feet to enable a heightened climbing ability. The tree kangaroo has a much larger and pendulous tail than the ground dwelling kangaroos, giving the tree kangaroo fantastic balance while swinging from trees. The male Lumholtz Tree Kangaroo averages size is about 15.6 lbs where the average female weighs in at about 13.2 lbs. The average size of a male when measure from head to the base of the tail is about 23.3 inches long with an average tail length of 27.4 inches. The average size of a female when measure from head to the base of the tail is about 21.8 inches with an average tail length of about 27.5 inches. The tail on both the male and female of this species is the same size, if not longer than the body, proving the importance of the tail which is primarily used for balance. Tree-kangaroos do not sweat, in order to cool their bodies they lick their forearms and allow the moisture to evaporate.  there are about 50 tree kangaroos left in the wild.
Distribution and habitat
They inhabit the tropical rainforests of New Guinea and far northeastern Queensland, and some of the islands in the region — in particular the Schouten Islands and the Raja Ampat Islands near the northwestern coast of New Guinea. Although most are found in mountainous areas, several species also occur in lowlands, such as the aptly named lowlands tree-kangaroo. Most tree-kangaroos are considered threatened due to hunting and habitat destruction. Because most of their motion and living involves climbing and jumping from tree to tree, they developed better locomotion. Tree kangaroos thrive in tree tops as opposed to their cousin the kangaroo which survives on mainland in Australia. Two species of kangaroo are found in Australia, Bennett's (Dendrolagus bennetianus) which is found north of the Daintree River and Lumholtz's (Dendrolagus lumholtzi). Tree kangaroos have adapted better to regions of high altitudes.  Tree kangaroos have at least fifteen known subspecies living in Papua New Guinea and Australia. Tree kangaroos must find places comfortable and well adapted for breeding as they only give birth to one joey per year. They are known to have one of the most relaxed and leisurely birthing seasons. They breed cautiously in treetops during monsoon season. Their habitats are breeding grounds for danger as they can easily fall pray to their natural predator, amethystine pythons, which also climbs and lives amongst the treetops in the forests. Tree kangaroos are known to be able to live in both mountainous regions and low-land locations. 
The evolutionary history of tree-kangaroos begins with a rainforest floor dwelling pademelon-like ancestor (Thylogale spp.). 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. The retreat of the rainforest 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.). The rock-wallabies 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.
Tree-kangaroos are slow and clumsy on the ground. They move at about walking pace and hop awkwardly, leaning their body far forward to balance the heavy tail. But in trees they are bold and agile. They climb by wrapping the forelimbs around the back of a tree and hopping with the powerful hind legs, allowing the forelimbs to slide. They are expert leapers; 9 metres (30 ft) downward jumps from one tree to another have been recorded, and they have the extraordinary ability to jump to the ground from 18 metres (59 ft) or more without being hurt.
Tree-kangaroos' main diet are leaves and fruit that it can find up in the tree; from time to time they will also scavenge on the ground for them. Other components of the tree-kangaroos' eating habits are grains, flour, eggs, sap, young birds, and tree bark.
The two most relevant threats to all species of tree-kangaroos are habitat loss and hunting. Tree-kangaroo habitats are being replace by logging and timber production; along with coffee, rice and wheat production. This habitat loss can make the tree-kangaroos more open to predators, like domestic dogs. Being hunted by native tribles and communities also steeply contribute to the tree-kangaroos' population decline.  Research has been conducted on the Lumholtz tree-kangaroo, a species that dwells in the rain forests of southern Australia to determine the average cause of death. This research showed that out of every 27 deceased tree-kangaroos 11 of them had been killed by vehicles, 6 were killed by dogs, 4 by parasites and the other 6 from other causes. 
A female tree kangaroo's fertile period is estimated to be about two months long. Tree Kangaroos in their reproductive mode are a bit extreme compared to most marsupials. They have one of the longest marsupial offspring development/maturation periods and if compared to other marsupials similar in size they have the longest. Not much is known about the reproduction of the tree kangaroo in the wild, the only published data is from those that were in captivity. However, observed in these captivity studies was that pouch life for the young is 246-275 days long and weaning occurred 87-240 days later. Female tree kangaroos reach sexual maturity as early as 2.04 years and males at 4.6 years.
Back and tail of a Buergers' Tree-kangaroo (D. g. buergersi
Two Goodfellow's Tree-kangaroos, Dendrolagus goodfellowi
Buergers' Tree-kangaroo (Dendrolagus goodfellowi buergersi)
Matschie's tree-kangaroo(Dendrolagus matschiei)
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