The Australian continent has never been connected to Asia, divided from it by the Wallace line between Indonesia and New Guinea, as can be seen in this Google earth image. Asian animals are found to the west of that line so there are no apes, monkeys, squirrels, cats, deer and pigs native to the island continent, though the last 3 were introduced by European settlers. Most of the plants and animals of Australia, New Guinea and New Zealand are closely related to those of South America from where the marsupials entered Australia. Southern Africa shares ancient Proteaceae plants. Australia, Africa and South America were joined to Antarctica and all formed part of the ancient super continent of Gondwana before it broke up 100 million orbits ago. Continental plate tectonics is carrying Australia north at around 6 cm a year towards Asia. Snakes & rodents arrived in Australia from Asia drifting on floating trees during the last 20 million years & humans entered the continent around 70 thousand years ago.