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 Scientists said on Friday burn patterns detected on eggshell
fragments indicate that the humans who first arrived in Australia
roughly 50,000 years ago gathered and cooked the big bird's eggs,
playing havoc with its reproductive success.
The study is the first to provide direct evidence that these early
human inhabitants preyed on the remarkable large animals that once
thrived in Australia but disappeared after people got there,
University of Colorado geological sciences professor Gifford Miller
said.
Genyornis, at almost 7 feet tall (2 meters) and perhaps 500 pounds
(225 kg), was much bigger than today's large flightless birds like
the ostrich or emu. It possessed powerful legs, small wings, large
claws and a big beak for eating fruit, nuts and maybe small prey.
 It was a member of a family of giant birds called dromornithids,
some reaching 10 feet (3 meters) tall and 1,100 pounds (500 kg),
that was related to ducks, geese and swans. Genyornis vanished
around 47,500 years ago, Miller said.
The researchers analyzed burned Genyornis eggshell fragments, some
only partially blackened, discovered at more than 200 sites. The
eggs were the size of a cantaloupe, weighing about 3-1/2 pounds (1.5
kg).
"We conclude that the only explanation is that humans harvested the
giant eggs, built a fire and cooked them, which would not blacken
them, then discarded the fragments in and around their fire as they
ate the contents," Miller said.
"Wild or natural fires could not produce such patterns. We have no
direct evidence that humans hunted the adults, but loss of eggs
certainly reduced reproductive success."
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There has been a long-running debate over whether people caused the
extinction of Australia's unique collection of large animals, also
including a 25-feet-long (7.5 meters) monitor lizard called
Megalania, a nearly rhinoceros-sized wombat called Diprotodon, large
marsupial predators and 1,000-pound (450-kg) kangaroos.
More than 85 percent of Australia's large mammals, birds and
reptiles disappeared after people arrived.
Some experts blame human hunting, while others blame climate shifts,
in particular continental drying from about 60,000 to 40,000 years
ago. With the new study, published in the journal Nature
Communications, the case for a human role becomes stronger, Miller
said.
(Reporting by Will Dunham; Editing by Sandra Maler)
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