Are Humans To Blame For Mysterious Extinction of 500 Pounds Flightless Birds Roughly 50,000 Years Ago

extinct_bird

Roughly 50,000 years ago, an Australian bird species went extinct, not because of competition for space or resources but because its eggs were simply too delicious.

Australia is a land of giant animals: spiders with foot-long leg spans,bats with six-feet wingspans, lizards reaching up to 200 pounds. The continent has a fascinating history of terrifyingly huge animals.

The flightless bird, known as Genyornis newtoni, was nearly 7 feet tall and appears to have lived in much of Australia prior to the establishment of humans on the continent 50,000 years ago, said CU-Boulder Professor Gifford Miller.

 Research published recently in Nature Communications suggests that humans contributed to the species’ demise by eating their melon-sized eggs.
emu-eggs

Before humans arrived in Australia about 50,000 years ago, these flightless birds lived across much of the continent. But they mysteriously went extinct shortly thereafter. Now, evidence of human-scorched eggshells suggests that the new arrivals were cooking up the eggs for supper, likely putting a large dent in the birds’ reproductive success, a new study shows. Notably, the finding supports the idea that ancient people contributed to the bird’s eventual demise, the study authors said.

The charred shell fragments were usually found in “a tight cluster” near other fragments that weren’t burnt at all, meaning it’s unlikely something like a wildfire burned the eggs.



The Genyornis eggs are thought to have been roughly the size of a cantaloupe and weighed about 3.5 pounds, Miller said.Genyornis roamed the Australian outback with an astonishing menagerie of other now-extinct megafauna that 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. More than 85 percent of Australia’s mammals, birds and reptiles weighing over 100 pounds went extinct shortly after the arrival of the first humans.

genyornis-size

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.”

Another line of evidence for early human predation on Genyornis eggs is the presence of ancient, burned eggshells of emus — flightless birds weighing only about 100 pounds and which still exist in Australia today — in the sand dunes. Emu eggshells exhibiting burn patterns similar to Genyornis eggshells first appear on the landscape about 50,000 years ago, signaling they most likely were scorched after humans arrived in Australia, and are found fairly consistently to modern times, Miller said.

More than 85 percent of the continent’s megafauna went extinct not long after humans arrived.

The reasons for these extinctions are hotly debated. Some scientists say humans are to blame, others credit climate change and some say it’s likely a mixture of both.

But the continental drying of Australia, from about 60,000 to 40,000 years ago, is likely not the main reason for these animals’ extinctions, Miller said. The rate and magnitude of this climate change was as severe as earlier climate shifts, but large megafauna extinctions did not accompany these earlier changes, he said.

“Ours is the first study to show with direct evidence that early humans in Australia also preyed on the now-extinct megafauna,” he told Live Science.

References:

sciencedaily.com

livescience.com