Ancient Bird Swallowed 800 Rocks and Choked to Death, Scientists Say

Around 120 million years ago, a bird swallowed over 800 tiny stones and choked to death as a result. Paleontologists aren’t sure why.

Like many recent fossil “discoveries,†researchers with the Field Museum were browsing through a collection of old fossils when they noticed something that appeared to be an entirely new species.

They found that it represented a new species of bird (and therefore dinosaur) and named it Chromeornis funkyi, or a “Funky Chromeo bird,†in honor of the electro-funk band. But the most striking thing about Chromeornis, according to the researchers, was its apparent cause of death: suffocation from swallowing rocks.

The fossil, discovered at the Shandong Tianyu Museum of Nature in China, is the subject of an upcoming paper in Palaeontologia Electronica.

The story of an unlucky bird

The researchers, led by Field Museum curator Jingmai O’Connor, first encountered Chromeornis during a stroll through Shandong Tianyu Museum’s bird fossil collection. They noticed a tiny, sparrow-sized chunk of rock preserving a fossil with features resembling a larger bird species called Longipteryx, O’Connor recalled to Gizmodo in an email.

“It had really big teeth at the end of its beak, just like Longipteryx, but it’s a tiny little guy,†she added in a statement. “So based on that, I knew it was something new.â€

But that was merely the beginning of the oddities seen in the fossil. When the team examined it under a microscope, they found “an unusual mass of stones†inside the creature’s esophagus, right up against the neck bones, O’Connor noted in her email. Subsequent analyses of the rocks’ placement and chemical compositions strongly suggested that they were indeed swallowed by the bird and could not have just gathered around it during fossilization.

That said, birds swallowing rocks isn’t unheard of—certainly not to the researchers, who had previously studied this exact phenomenon. Species such as owls and chickens will add some rocks to their meal to grind it up in a muscular organ called the gizzard.

“But in the thousands of fossil birds in the same group as this little fossil, none have ever been found with gizzard stones,†the researchers said in the release. So, the mystery deepened.

Unlucky, sick, rocky

Then again, the team wasn’t averse to the possibility that the little bird could be the first of its kind to be found with gizzard stones. To check this hypothesis, the researchers tried comparing the volume, quantity, and size of the stones to actual gizzard stones identified in other fossilized birds. They also conducted a CT scan of Chromeornis to get a closer look at the fossil.

“We found over 800 tiny stones in this bird’s throat—way more than we would have expected in other birds with gizzards,†O’Connor said in the statement. “And based on their density, some of these stones weren’t even really stones; they seemed to be more like tiny clay balls.â€

Basically, these stones weren’t performing any digestive functions for the bird, she added. So the team came up with another hypothesis: could it have been sick?

“When birds are sick, they start doing weird things,†O’Connor explained in the statement. “It swallowed too many, and it tried to regurgitate them in one big mass. But the mass of stones was too big, and it got lodged in the esophagus.â€

All this said, we should add a note of caution. Paleontological findings are often open to interpretation, which has led to plenty of rediscoveries over the years. At the same time, it means most fossil descriptions—including this one—represent just one team’s take. It’s worth waiting for follow-up studies and independent analyses to see whether the broader paleontology community is on the same page about this freaky bird and how it died.

Of birds long gone

This strange yet tragic tale of Chromeornis speaks to a bigger picture of extinction and survival in prehistoric times, according to the researchers. Birds belonging to the same group as Chromeornis were presumably the most populous group of birds in the final chapters of the dinosaur era.

Then the asteroid collision around 66 million years ago completely wiped out all non-avian dinosaurs, leaving behind the birds that have stuck around to this very day.

“Understanding why they were successful but also why they were vulnerable can help us predict the course of the mass extinction we’re in now,†O’Connor said in the statement. “Learning about Chromeornis and other birds that went extinct could ultimately help guide conservation efforts today.â€