A collection of bird bones sat in lab storage for more than a decade, believed to be the remains of an ancient eagle. Little did scientists know what was hiding in the fossils: “Squawkzilla.”

Heracles inexpectatus was discovered by scientists in New Zealand, according to a study published Wednesday. At about three feet tall, the bird would probably have stood nearly as tall as the average American 4-year-old.

Scientists have been finding enormous prehistoric birds for years, but this one still shocked them. It’s the largest parrot ever known to have walked the Earth. It might have even preyed on other birds.

At an estimated 15 pounds, the now extinct bird beats out all the other parrot competitors, at nearly double the weight of the endangered kakapo, New Zealand’s reigning giant parrot.

The scientists approximated its size based on two leg bones, called tibiotarsi, under the assumption that they both came from the same bird.

The fossils were dug up in 2008 in St. Bathans, New Zealand, in a massive fossil deposit that was once a prehistoric lake, where a team of paleontologists go every year to collect bones.

“My guess is, at the best of times, you could barely see the lake for all the birds that were sitting on it,” Michael Archer, a co-author of the research and paleontologist at the University of New South Wales, told The Washington Post.

The large bones, believed to be those of an ancient eagle, flew under the radar for a decade. It was during a research project in the lab of Flinders University paleontologist Trevor Worthy that a graduate student rediscovered the bones. The student wanted to look at old eagle bones and quickly realized these did not fit the bill. After that, a team of researchers began reanalyzing the findings earlier this year.

The researchers compared the drumstick-like bones to bird skeletons in the South Australian Museum collection and the Smithsonian National Museum of Natural History’s electronic collection. They wanted to see if the remains matched any earlier descriptions of an existing bird species.

“Then, by elimination, we concluded that there was nothing left, and it had all the features of a parrot,” Worthy said. “And while no parrot had ever been found this big, it had to be a parrot.”

The bird probably lived during the Early Miocene, which spanned from about 23 million to 16 million years ago.

Researchers concluded that the bird probably couldn’t fly and consumed what was along the ground and easy to reach, like berries, nuts and seeds, Worthy said.

But that might not have been enough to satiate the giant parrot.

It’s possible the bird had more carnivorous ways, like another New Zealand parrot, the kea, which has been known to attack and subsequently munch upon living sheep if they are stuck in the snow. They can also dig up sea birds from their burrows and eat the chicks, according to Worthy.

Heracles might have even been eating other parrots, Archer said, giving way to a nickname: “Squawkzilla.”

Though researchers do not have the bird’s beak, Archer said he suspects it was large and ferocious. If the bird’s skull is found, scientists will be able to tell whether it had a beak for nuts and seeds, or one for chomping down on other, smaller birds.

Heracles won’t be the final unforeseen fossil from the area. Archer said the team has also found evidence of long-extinct bats, crocodiles and other birds in New Zealand.

“One of the nice aspects of paleontology is how much of what happens depends on serendipity,” Archer said.

There are probably thousands more fossils waiting to be discovered, which will offer clues into who and what used to roam the planet.

“The parrot is just the latest mystery,” Archer said.