Papua New Guinea notable feature in common for the two landmasses is the existence of several species of marsupial mammals, including some kangaroos and possums, which are not found elsewhere. Papua New Guinea is a megadiverse country. Many of the other islands within PNG territory, including New Britain, New Ireland, Bougainville, the Admiralty Islands, the Trobriand Islands, and the Louisiade Archipelago, were never linked to New Guinea by land bridges. As a consequence, they have their own flora and fauna; in particular, they lack many of the land mammals and flightless birds that are common to New Guinea and Australia. Australia and New
Fauna of New Guinea land mass (often called the Melanesian continent) more isolated than the present New Guinea, and farther to the northeast. This may have divided into a Solomons and a New Guinea part. Part of New Britain, Manus Island, and the Cyclops Mountains of northcentral New Guinea are postulated as the only remaining parts of the original New Guinea portion. Southern New Ireland was apparently part of the Solomons mass. In the Pliocene New Guinea rose from the sea bottom, and in the Pleistocene connected with Australia for a sufficient period to permit faunal exchange. The oceanic Pacific Islands received insects from