An apparently very tasty, 500-pound Australian bird was eaten to extinction by humans 50,000 years ago, new research concludes.
The findings, published in the journal Nature Communications, provide the first direct evidence that humans played a substantial role in the extinction of early Australian animals. In this case, the victim was a flightless 7-foot-tall bird known as Genyornis newtoni.
Humans likely enjoyed the bird's meaty goodness, and there's also strong evidence that people were cooking its enormous eggs. Each egg was the size of a cantaloupe and weighed about 3.5 pounds, according to co-author Gifford Miller of the University of Colorado Boulder.
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Miller and his team unearthed prehistoric burnt Genyornis eggshell fragments in tight clusters less than 10 feet in diameter, with no other eggshell fragments nearby. In a press release, he said that some individual fragments from the same clusters had heat gradient differences of nearly 1,000 degrees Fahrenheit, conditions virtually impossible to reproduce with natural wildfires there.
Miller explained that amino acids, the building blocks of proteins, decompose in a predictable fashion inside eggshells over time. When an egg is burned at one end but not the other, the scorching leaves behind a distinctive "gradient" from total amino acid decomposition to minimal. Such a gradient could only be produced by a localized heat source, likely an ember, he said, and not from the sustained high heat produced regularly by Australian wildfires both in the distant past and today.
"We can't come up with a scenario that a wildfire could produce those tremendous gradients in heat," he continued. "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."
'Extinct' Animals Back from the Dead
Providing support to that theory is the presence at other Australian sites of nearly identical fire-toasted emu eggshell fragments dating to the same period. Emus still exist today in Australia, where both their eggs and meat are consumed. They are much smaller than Genyornis was, though, weighing about 100 pounds. They also are fairly prodigious egg layers, with each emu producing about 30–50 eggs per breeding season.
In addition to sharing turf with the early emus, Genyornis roamed the Australian outback with an astonishing menagerie of other now-extinct enormous animals. They included a 1,000-pound kangaroo, a 2-ton wombat, a 25-foot-long-lizard, a 300-pound marsupial lion and a Volkswagen-sized tortoise.
While this motley crew had its own set of predators and prey, life really took a turn for the worse after the arrival of the first humans, the researchers indicate. They point out that more than 85 percent of Australia's mammals, birds and reptiles weighing over 100 pounds went extinct shortly thereafter.
Miller and others suspect Australia's first inhabitants traveled to the northern coast of the continent on rafts launched from Indonesian islands several hundred miles away.
"We will never know the exact time window humans arrived on the continent," he said. "But there is reliable evidence they were widely dispersed across the continent before 47,000 years ago."