This 120-million-year-old dinosaur died choking after swallowing 800 stones

It was a lethal case of indigestion.

A newly discovered fossil of an ancient bird reveals a cluster of roughly 800 stones loaded in its throat, suggesting the creature choked to death while trying to cough them up. The bird, about the size of a modern sparrow, dates to around 120 million years ago. Researchers describe the find in December 2025 in Palaeontologia Electronica.

“To our knowledge, this is the first report of significant gastroliths in the esophagus of any fossil animal,” Jingmai O’Connor and her colleagues write in the study.

The specimen provides a rare window into the biology of enantiornithines, a group of extinct birds that thrived during the dinosaur era but vanished at the end of the Cretaceous Period. Unlike modern birds, which sometimes swallow stones to grind food in their gizzards, these ancient relatives appear to have avoided such habits — possibly because carrying extra weight hindered their limited flying skills.

The fossil comes from the Jiufotang Formation in northeastern China, a site famous for preserving feathered dinosaurs and early birds in exquisite detail. This individual, preserved on split rock slabs, includes traces of skin, feathers along its neck and body, and even hints of eye tissue. Scientists named it Chromeornis funkyi, honoring musicians who, like birds, create beautiful sounds.

The stones, each about the size of a grain of sand, form an oval mass near the neck bones. CT scans show a mix of rounded and angular pebbles, far more numerous and larger relative to body size than typical gizzard stones in similar-aged birds. Their position in the throat, rather than the stomach, rules out a normal digestive role.

“We tentatively speculate that the ingested stones are pathological — the product of abnormal behavior, perhaps due to illness,” says lead author Jingmai O’Connor, a paleontologist at the Field Museum in Chicago.

The mass may have been on its way out when the bird died. “The mass may have been in the process of being regurgitated at the time of death, and possibly the cause of death itself (the large size of the mass relative to its body may have caused the bird to asphyxiate),” O’Connor and her colleagues write.

Citations

J. O’Connor et al. A new small-bodied longipterygid (Aves: Enantiornithes) from the Aptian Jiufotang Formation preserving unusual gastroliths. Palaeontologia Electronica. Published online December 2025. DOI: 10.26879/1589