Scientists have discovered an enigmatic dinosaur species that lived some 120 million years ago and whose fossil contained hundreds of stones in its throat, a finding that could shed more light on bird evolution.
The new species has been named Chromeornis funkyi after the techno-funk duo Chromeo, and it could be key to understanding how one small group of dinosaurs survived extinction, researchers said.
Analysis of the dinosaur fossil from the Shandong Tianyu Museum of Nature in China revealed it choked to death on rocks, according to a study published in Palaeontologica Electronica. It is not clear why.
“There are thousands of bird fossils at the Shandong Tianyu Museum but on my last trip to visit their collections, this one really jumped out at me,” Jingmai O’Connor, an author of the study, said.
Measuring about the size of a modern sparrow, the dinosaur had similar features to a larger fossil bird called Longipteryx.
“It had really big teeth at the end of its beak, just like Longipteryx, but it’s a tiny little guy,” Dr O’Connor said. “So based on that, I knew it was something new.”
When the palaeontologist examined the fossil under a microscope, she noted something puzzling.
“I noticed that it had this really weird mass of stones in its oesophagus, right up against the neck bones,” Dr O’Connor said.
“This is really weird, because in all of the fossils that I know of, no one has ever found a mass of stones inside the throat of an animal.
Further analysis revealed the stones were swallowed by the animal during its life, instead of just washing up near its body in the lakebed where its fossil formed.
This is akin to a behaviour seen in birds, including chickens, which swallow small stones which are then stored in a muscular stomach called a gizzard, and used to help grind up their food.
But no such gizzard stones have ever been discovered in dinosaur-era fossil birds before.
A CT x-ray scan revealed there were over 800 tiny stones in the fossil bird’s throat. This, according to researchers, is “way more than we would have expected in other birds with gizzards”.
“Some of these stones weren’t even really stones, they seemed to be more like tiny clay balls,” Dr O’Connor said. “With these data, we can very clearly say that these stones weren’t swallowed to help the bird crush its food.”
Since these stones do not appear to be gizzard stones, they must have served a different purpose.
Scientists suspect the fossil bird was sick and “doing weird things”.
“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 oesophagus,” Dr O’Connor said.
“It’s pretty rare to be able to know what caused the death of a specific individual in the fossil record,” she said, adding that “regurgitation of that mass” likely caused it to choke and die.
The fossil bird also offers insights into dinosaur extinction.
C funkyi belonged to a group of birds called the enantiornithines that was the most prevalent during the Cretaceous era over 66 million years ago.
When the dinosaur-killing asteroid hit the planet, enantiornithine birds went extinct.
“During that environmental disaster, the enantiornithines went from being the most successful group of birds to being wiped out,” Dr O’Connor said.
“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.”
