Megafauna Extinction Megafauna are a number of large animal species that roamed the earth. They are often defined as species with bodies greater than 30kg, or equal to or greater than 30% greater body mass to their closest living relatives. Many of these species became extinct during the Pleistocene period. When the Aboriginals arrived, dinosaurs were long extinct, but there were a range of very large animals. These animals included giant cows, giant sheep like animals, as well as very large animals resembling huge goannas, emus and kangaroos all 200kg plus.
Megafauna in countries outside Australia consisted of things such as giant buffalo like animals, and the elephant is also a form of Megafauna. There are many theories as to why Megafauna has become extinct, but the two simplistic theories are the ‘blitzkrieg’ model and climate change. Some scientists believe that the extinction of Megafauna in Australia was either caused by a ‘blitzkrieg’ of human caused extinction, or through eco-system disruption caused by humans. This states that the Australian Aborigines may have been the reason for the extinction of Australian Megafauna.
However there is evidence against this theory. There has been a discovery that there was a long overlap in time between when Megafauna existed and humans entered Australia. Fossils were also found over different periods of time, this means man couldn’t have killed them all out in a relatively small era. The hypothesis is based around the fact that the Megafauna became extinct around the same era that humans first came to Australia. As these animals were big and slow, they became ‘easy prey’ for humans; they were hunted to extinction.
The second theory is climate change. Dr Judith Field from the University of Sydney, states that climate change may have driven vegetation change, periodic droughts and increased seasonality changes. The climate changed all the time, all it may have needed was one extended drought for the Megafauna to die out. There is an area of mass fossils in an ancient lake called Alcoota in the Northern Territory, these fossils make up the evidence that Megafauna became extinct due to climate change. Scientists in working in central Australia made a rare scientific discovery.
They found a large number of ‘thunderbird’ fossils in one spot. Thunderbirds were about 3 meters tall and weighed about 500kg. There are two theories for the grouping of fossils in Alcoota. It may have been that the water flow sorted out the bones into one location, Or that the birds all flocked to the waterhole during a drought. This provides evidence that when the water dried up, the birds remained. Then they died there at the waterhole and fossilized to give us the discovery found today.
The water flow theory provides evidence against the drought theory. Bibliography – http://www. abc. net. au/science/features/megafauna/ http://www. abc. net. au/science/ozfossil/megafauna/fauna/fauna. htm http://www. whitehat. com. au/Australia/Animals/MegaFauna. asp http://en. wikipedia. org/wiki/Megafauna http://www. southbank. qm. qld. gov. au/en/Find+out+about/Dinosaurs+and+Ancient+Life+of+Queensland/Megafauna