The family Petauridae includes 12 medium-sized possum species: four striped possums, and the seven wrist-winged gliders, including Leadbeater's Possum which has only vestigal gliding membranes. Most of the wrist-winged gliders (subfamily Petaurinae) are native to Australia, most of the striped possums (subfamily Gymobelideus) to New Guinea, but some members of each are found on both sides of Torres Strait.
All petaurids have obvious facial markings, a well-defined dorsal stripe, very lage lower front incisors, and four-cusped molars. Despite their distinctive appearance, petaurids are closely related to the ringtailed possums (family Pseudocheiridae) and are grouped together with them to form the superfamily Petauroidea.
Members of the Petaurinae (wrist-winged glider subfamily) are herbivorous, specialising on sap and nectar, but taking a wide variety of supplemental foods. The subfamily appears to have evolved in the open forests of Australia—gliding membranes are an adaptation which aids mobility when the forest canopy is incomplete, and are of little use in rainforests— but now has representatives in New Guinea and many of the smaller islands nearby. Their similarities to the unrelated flying squirrels are an example of convergent evolution.
The striped possums, on the other hand, (subfamily Gymobelideus) are thought to have evolved on New Guinea, and the sole Australian species (the Striped Possum of Cape York) is considered a recent immigrant. All members of this subfamily are insectivores, and have specalised structures for catching insects: a heel-like structure on the wrist that is thought to be used to tap on wood to locate insect larvae. and an elongated fourth finger to extract them from their burrows.