The Wet Tropics rainforests are a living museum of plants and animals. The rainforests are descended from the forests of Pangaea and Gondwana hundreds of millions of years ago. Plant and animal fossils tell us that parts of Gondwana was once covered with lush forests, some of their ancestors live in the Wet Tropics of today.
The closest relatives of some Wet Tropics plants and animals live as far as away as South America, New Zealand, and New Caledonia! Isolated from the rest of the world, Australian animals and plants evolved differently to the rest of the world. Fossil pollens indicate that most of Australia was covered by closed forests some 65 million years ago.
As Australia split from Gondwana and moved north, the green rainforests were gradually replaced by forests adapted to dry conditions such as eucalypt forests. It was along parts of the east coast of Australia where regular rain and a humid tropical climate allowed refugial pockets of rainforest to survive. These small green islands on high mountaintops and deep valleys developed their own unique plants and animals. In a wetter times the rainforests have expanded and evolved to fill new environmental niches.
Fifteen million years ago, after Australia had split from Gondwana and moved north adjacent to the Asian continental plate, the Wet Tropics flora and fauna mixed with some from Asia. This has also occurred more recently during ice ages when land bridges assisted wildlife movement.
Today, the Wet Tropics is a living museum of ancient and rare flora and fauna. Some plants, like Idiospermum australiense were around when the dinosaurs roamed the earth and are in a family of their own. The rainforests contain a high representation of primitive flowering plants (see plant evolution).
The Wet Tropics animals also include numerous endemic animals that evolved here in the rainforests over millenia (see animal evolution).
The Wet Tropics evolutionary timeline poster [1.6MB] gives a summary of plant and animal evolution over the ages. Click on it to enlarge.