Tech & Science

New Theory on the Extinction of Australian Megafauna

The extinction of the Australian megafauna was caused by humans, not by climate change

Scientists found a new explanation on the disappearance of Australian megafauna. While the previous theory stated that climate change was responsible with their extinction, scientists from Monash University in Victoria, Australia, and the University of Colorado Boulder in the U.S. discovered that humans might actually be blamed.

The Australian megafauna meant 1,000 pound kangaroos, 500 pound flightless birds, 25 foot long lizards, or huge tortoises. After the arrival of humans, 85 percent of these huge animals disappeared.

In order to gather all the necessary information, researchers studied the sediment core in the Indian Ocean off the southwestern Australian coast. The core offers a good insight on the past since it is made of layers that have gradually been deposited one on top of the others. It contains dust, ash, pollen, and the spores of Sporormiella, a fungus found in the feces of herbivore animals.

Scientists studied the quantities of fungus present on the sediments from 150,000 years ago to 45,000 years ago. They discovered that their number decreased severely over this period. The initial abundant number of these spores showed that these large animals populated the Australian coast up until 45,000 years ago. However, the decreasing number of fungus suggested the decreasing numbers among the megafauna populations.

The fungus brings further evidence useful to the research. It suggests that the area was rich in biodiversity. The region was one of the first on the continent to host humans. Also, the high number of trees and shrubs proves it hosted a large number of animal species. Due to the beneficial environment, there is no evidence of a climate change that had occurred during the extinction of the megafauna.

The previous study that blamed the climate change for the megafauna extinction suggested that climatic events occurred 70,000 years ago and changed Australia from a wooden landscape rich in eucalyptus to a dry landscape with scarce vegetation. They used the drying lakes in central Australia as evidence for the loss of water resources necessary for the large mammals.

However, the new study found that humans killed the megafauna over a longer period of time. They found evidence that humans used to cook the eggs of Genyornis newtoni, a 7 foot tall bird.

These results are significant since they offer a perspective on former animal populations that are now extinct and how the first humans affected these populations.
Image Source: Wikimedia Commons

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