As you may know, Australia is a "separate creation" in the words of early naturalists. We have few native placental mammals and along with New Guinea, the massive island to the north (which was once joined as the continent Sahul) this is the only place you can find all three surviving mammal groups. Marsupials make up by far the bulk and fill almost every niche, of the marsupials, the Diprotodontids in turn make up the bulk of them. Koalas, wombats, kangaroos etc, possums and many of our extinct megafauna belong to this group. The key feature is a "vegetarian" skull with molars separated from front incisors as well as two of the hind toes being fused into a "grooming claw" (once you see this feature you will look for it in other species!). Possums are well represented and here are a couple of them:
Eastern Pygmy Possum (Cercartetus nanus) by
Nathan Litjens, on Flickr
The Eastern pygmy possum is one of the smaller species at no larger than a mouse. Feeding on nectar and insects they are common but rarely seen.
North Kimberley sugar glider (Petaurus sp) by
Nathan Litjens, on Flickr
This is the currently undescribed "Kimberley sugar glider" from the far, remote Northwest. Handheld shot - was lucky to see this individual low on a tree and used my macro lens. Uncropped.
Short eared brushtail possum (Trichosurus caninus) by
Nathan Litjens, on Flickr
The short eared brushtail possum is found on the mid east coast in wetter forests. A large species about the size of a large cat.
Striped Possum (Dactylopsila trivirgata) by
Nathan Litjens, on Flickr
The common striped possum is native to Australia and New Guinea (where there are an additional 2 species). These guys occupy the exact same niche as Aye Ayes of Madagascar, using a long finger to probe logs to extract grubs.
Common ringtail possum (Pseudocheirus peregrinus) by
Nathan Litjens, on Flickr
Ringtail possums are very abundant in places. There are several species, mostly in the far northeastern rainforests and many more in New Guinea. This is the common, garden variety Eastern ringtail.
Southern Common Cuscus (Phalanger mimicus by
Nathan Litjens, on Flickr
Cuscus are more represented in New Guinea west to Sulawesi in Indonesia. This is the rare southern cuscus, native to far northern Cape York at the tip of Australia. Very lucky to see this one.