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 Papua and New Guinea British New Guinea, was annexed outright on 4 September 1888 and possession passed to the newly federated Commonwealth of Australia in 1902 and British New Guinea became the Australian Territory of Papua, with Australian administration beginning in 1906. The Australian Naval and Military Expeditionary Force seized German New Guinea and the neighbouring islands of the Bismarck Archipelago for the Allies in 1914, during the early stages of the First World War. At the 1919 Paris Peace Conference following the war, Australian Prime Minister Billy Hughes sought to secure possession of New Guinea from the defeated German Empire: telling the Conference: