Fauna of Indonesia - Origin of Indonesian Fauna

Origin of Indonesian Fauna

The origin of fauna in Indonesia is heavily affected by geographical and geological events on the Asian continental landmass and the Australasian continental landmass (now Australia). The present New Guinea island was connected with the present Australia continent, forming a supercontinent called the southern supercontinent Gondwana. This supercontinent began to break up 140 million years ago, and the New Guinea region (previously known as Sahul) moved towards the equator. As a result, animals from New Guinea traveled to the Australian continent and vice versa, creating many different species living in different ecosystems. This activities continued to occur until the two regions separated completely.

The influence of the Asian continental landmass, on the other hand, was the result of the reformation of the Laurasia supercontinent, which existed after the breakup of Rodinia around 1 billion years ago. Around 200 million years ago, the Laurasia supercontinent split completely, forming Laurentia (now America) and Eurasia continents. The mainland of the Eurasia continent, including China, was not separated completely from the Indonesian archipelago. As a result, animals from the Eurasia mainland could travel to the archipelago, and, under a different ecosystems, new forms of species were formed.

In the nineteenth century, Alfred Russel Wallace proposed the idea of the Wallace Line, a notional line dividing the Indonesian archipelago into two regions, the Asian zoogeographical region (Sundaland) and the Australasian zoogeographical region (Wallacea). The line runs through the Malay Archipelago, between Borneo and Sulawesi (Celebes); and between Bali and Lombok. Although the distance from Bali to Lombok is relatively short, only about 35 kilometres, the fauna distribution is still affected by the line. For example, a group of birds would refuse to cross even the smallest stretches of open water. A second line, lying east, known as the Webber Line, has also been proposed to separate between "transition species" and species of Australian origin.