20 million years ago - Australia's splendid isolation
Australia's Miocene fact file
Position
- Australian was isolated from all other continents and had slowly begun to drift northwards.
Climate
- During the early Miocene, northern Australia had a warm, wet climate. It became cooler and drier by the late Miocene.
Setting
- In the early Miocene, New Guinea was a series of islands on the northern edge of the tectonic plate carrying Australia. (A tectonic plate is a large area of the Earth's crust that drifts as one piece over the molten mantle below.) From about 15 million years ago, as the Australian plate crumpled up against the South-East Asian plate, larger areas of New Guinea rose above sea level.
Vegetation
- Northern Australia was covered in lush rainforest.
- The Miocene was a time of enormous richness and variety of plant and animal life in Australia, equal to that found today in the rainforests of Borneo and the Amazon.
Rainforest.
Photo: S Humphreys © Australian Museum.
Animals
- In Australia the early relatives of many of familiar present-day animals had evolved including possums, kangaroos, koalas, bats, crocodiles, snakes, lizards, frogs, millipedes, beetles and many kinds of birds.
- Many less familiar animals also lived in Australia during the Miocene such as, marsupial lions, flesh-eating kangaroos, cleaver-headed crocodiles, thunder birds, horned turtles and strange 'thingodontans'.
What was happening in the rest of the world
- The Southern Ocean had formed and started to cool Antarctica.
- North America had ancient forms of horses, rhinoceroses and camels.
- Ancient relatives of cats, pigs, cattle, deer and giraffes lived in Europe and Asia.
- Ancestral forms of elephants spread out from Africa into Europe, Asia and North America.
