About 50,000 years ago, giant megafauna—such as a "1,000-pound kangaroo" and "Volkswagen-sized tortoise"—roamed Australia, Phys.org reports. Those animals started disappearing around the same time the first humans set foot in the area, likely after arriving aboard boats from Indonesia. Now, for the first time, researchers believe they've found evidence that humans—not climate change—were a major cause of those extinctions. That evidence comes in the form of partially burned eggshells belonging to the Genyornis newtoni, a 500-pound, 7-foot-tall, flightless bird. "We consider this the first and only secure evidence that humans were directly preying on now-extinct Australian megafauna," lead researcher Gifford Miller says in a statement.
Miller published his findings Friday in Nature Communications. Phys.org reports there was significant evidence the fragments from the cantaloupe-sized eggs found at more than 200 sites around Australia were cooked by humans for consumption and not burned by wildfires. They appeared to have been burned on just one side, and shell fragments showed drastic differences in how much they'd been heated, according to the Washington Post. "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," Miller says, per Phys.org. If humans were in fact eating the eggs, that would significantly hamper the bird's reproduction, the study finds. (Scientists also recently figured out what killed the real King Kong.)