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
Territory of New Guinea Australia, assumed a mandate from the League of Nations for governing the Territory on 17 December 1920. The terms of the mandate were not received in Australia until April 1921. This mandate was enacted and administered by the Australian Government through the New Guinea Act 1920 until the outbreak of the Pacific War and Japanese invasion in December 1941 brought about its suspension. Shortly after the start of the Pacific War, the island of New Guinea was invaded by the Japanese. Most of West Papua, at that time known as Dutch New Guinea, was occupied, as were large parts of