<P> For many species, the primary refuge was the relatively cool and well - watered Great Dividing Range . Even today, pockets of remnant vegetation remain in the cool uplands, some species not much changed from the Gondwanan forms of 60 or 90 million years ago . Eventually, the Australia--New Guinea tectonic plate collided with the Eurasian plate to the north . The collision caused the northern part of the continent to buckle upwards, forming the high and rugged mountains of New Guinea and, by reverse (downwards) buckling, the Torres Strait that now separates the two main landmasses . The collision also pushed up the islands of Wallacea, which served as island' stepping - stones' that allowed plants from Southeast Asia's rainforests to colonise New Guinea, and some plants from Australia--New Guinea to move into Southeast Asia . The ocean straits between the islands were narrow enough to allow plant dispersal, but served as an effective barrier to exchange of land mammals between Australia--New Guinea and Asia . </P> <P> Prominent features of the Australian flora are adaptations to aridity and fire which include scleromorphy and serotiny . These adaptations are common in species from the large and well - known families Proteaceae (Banksia), Myrtaceae (Eucalyptus--gum trees), and Fabaceae (Acacia--wattle). Due to the spread of animals, fungi and plants across the single Pleistocene landmass the separate lands have a related biota . There are over 300 bird species in West Papua, of which at least 20 are unique to the ecoregion, and some live only in very restricted areas . These include the grey - banded munia, Vogelkop bowerbird, and the king bird - of - paradise . </P> <P> Australia has a huge variety of animals; some 83% of mammals, 89% of reptiles, 24% of fish and insects and 93% of amphibians that inhabit the continent are endemic to Australia . This high level of endemism can be attributed to the continent's long geographic isolation, tectonic stability, and the effects of an unusual pattern of climate change on the soil and flora over geological time . Australia and its territories are home to around 800 species of bird; 45% of these are endemic to Australia . Predominant bird species in Australia include the Australian magpie, Australian raven, the pied currawong, crested pigeons and the laughing kookaburra . The koala, emu, platypus and kangaroo are national animals of Australia, and the Tasmanian devil is also one of the well - known animals in the country . The goanna is a predatory lizard native to the Australian mainland . </P> <P> As the continent drifted north from Antarctica, a unique fauna, flora and mycobiota developed . Marsupials and monotremes also existed on other continents, but only in Australia--New Guinea did they out - compete the placental mammals and come to dominate . New Guinea has 284 species and six orders of mammals: monotremes, three orders of marsupials, rodents and bats; 195 of the mammal species (69%) are endemic . New Guinea has a rich diversity of coral life and 1,200 species of fish have been found . Also about 600 species of reef - building coral--the latter equal to 75 percent of the world's known total . New Guinea has 578 species of breeding birds, of which 324 species are endemic. Bird life also flourished--in particular, the songbirds (order Passeriformes, suborder Passeri) are thought to have evolved 50 million years ago in the part of Gondwana that later became Australia, New Zealand, New Guinea, and Antarctica, before radiating into a great number of different forms and then spreading around the globe . </P>

What country is both an island and part of the mainland