Supersizing Eggs Drove Giant Ancient Aussie Bird To Extinction

Posted: Feb 1 2016, 9:16pm CST | by , in News | Latest Science News


Supersizing Eggs Drove Giant Ancient Aussie Bird to Extinction
Illustration of giant bird known as Genyornis newtoni, surprised on her nest by a predatory lizard. Credit: Peter Trusler, Monash University

Burnt eggshell fragments found on various sites point to human's role in ancient bird's demise.

Around 50,000 years ago, a massive ancient bird inhabited Australia. The giant bird, known as Genyornis newtoni, weighed around 500 pounds and was nearly 7 feet tall, but unfortunately it disappeared from the surface of the Earth.

Now researchers have found strong evidence suggesting that humans are directly responsible for the extinction of this huge bird. Humans have supersized even back then without a McDonald's.

Researches from the University of Colorado Boulder have found burnt eggshell fragments of the bird on various sites, indicating humans used to cook and eat its eggs, thereby reducing the population of the bird. This is the first direct evidence that humans played a major role in the demise of the ancient bird.

"We consider this the first and only secure evidence that humans were directly preying on now-extinct Australian megafauna," said professor Gifford Miller from CU-Boulder. "We have documented these characteristically burned Genyornis eggshells at more than 200 sites across the continent." 

Researchers collected heaps of unburned eggshells from more than 2,000 sites across Australia, primarily from the sand dunes where the giant bird nested thousands of years ago while burned eggshell fragments were discovered in 200 locations. All the eggshells were at least 45,000 years old, roughly the size of cantaloupe and weighted about 3.5 pounds. Researchers found that burned eggs are either completely or partially blackened which is an indication that eggs are exposed to wide range of temperatures and possibily munched on the eggs.

Amino acids, the building block of protein’s decomposition revealed that the eggs were burned by a localized human heat source rather than wildfires because eggshells were blackened from one side but not from the other. Moreover, some fragments had temperature gradient difference of nearly 1,000 degrees Fahrenheit, which is virtually impossible with natural wildfires.

"We can't come up with a scenario that a wildfire could produce those tremendous gradients in heat," said Miller. "We instead argue that the conditions are consistent with early humans harvesting Genyornis eggs, cooking them over fires, and then randomly discarding the eggshell fragments in and around their cooking fires."

Another thing that supports the idea is that the burnt eggshell of emus, another endemic Australian bird which still exists today, has been found in the sand dunes and they also showed burn patterns similar to Genyornis eggs.

The disappearance of ancient Australian megafuana is a longstanding mystery. Scientists are not sure whether the humans, climate change or the combination of both drove them to extinction. Humans arrived here around 50,000 years ago and ever since the region started to lose its major megafuana. 

“We will never know the exact time window humans arrived on the continent. But there is reliable evidence they were widely dispersed across the continent before 47,000 years ago,” said Miller. 

“In the Americas, early human predation on the giant animals is clear – stone spear head are found embedded in mammoth bones. The lack of clear evidence regarding human predation on the Australia’s megafuana had, until now, been used to suggest no human-megafuana interactions occurred, despite evidence that most of the giant animals still roamed Australia when humans colonized the continent.” 

More than 85% of Australia’s mammals, reptiles and birds went extinct shortly after the arrival of humans in the continent including a 1000-pound kangaroo, a 2-ton wombat, a 25-foot-long-lizard, a 300-pound marsupial lion and a large vehicle-sized tortoise.

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Hira Bashir covers daily affairs around the world.




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