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
Australia–Papua New Guinea relations Territory of Papua) came under Australian administration in 1902, following annexation by the United Kingdom. In 1920, Australia was given a League of Nations mandate to rule German New Guinea, and in 1945 Papua and New Guinea were combined in an administrative union. Papua New Guinea was ruled by Australia until independence in 1975. The two countries retained close relations, with Australia supplying development aid. Papua New Guinea's political institutions are modeled on the Westminster system, shared by Australia. Relations between Prime Minister Michael Somare (PNG) and Prime Minister John Howard (Australia) were often strained, a strain which culminated in