The exotic and strange native lifeforms of modern Australia are in part due to Australia's long geological journey across the face of planet Earth. Around 50 million BC Australia was joined with Antarctica and South America in a single continent close to the South Pole. It gradually split with the others and began a trek northwards, where it became isolated by ocean all around. This gave native Australian wildlife perhaps 20 million years of evolution free of effects from the life of other continents. Big changes in climate over this time in Australia also had an impact on the development of life there.