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 species are poorly known, and thus an accurate comparison is difficult. Butterflies are the best known invertebrate group, and are represented in New Guinea by about 735 species, which is about 4.2% of the world total of 17,500 species. New Guinea is a large island located north of Australia, and south-east of Asia. It is part of the Australian Plate, known as Sahul, and once formed part of the supercontinent Gondwana. The origin of most New Guinea fauna is closely linked to Australia. Gondwana began to break up 140 million years ago, and Sahul separated from Antarctica 50 million years