Photo: Jingmai O'Connor
A prehistoric bird that lived on Earth 120 million years ago has left scientists with a medical mystery. Researchers discovered 800 small stones in its throat, which almost certainly caused its death by choking. However, why a sparrow-sized bird swallowed such a large number of stones remains unknown, Science Alert reports.
The discovery raises intriguing questions about the diet, behavior, and physiology of prehistoric birds—especially since the mass of stones found in the recently identified Chromeornis funkyi does not resemble those observed in modern birds.
The bird’s remains were found in a type of fossil deposit known as a lagerstätte, a sedimentary layer that preserves organisms in exceptional detail, often including soft tissue features.
Soft traits, such as skin outlines around the neck, wings, and legs, feathers, traces of dark eye pigment, and even hints of muscle tissue, were preserved. Harder body parts, such as the beak and bones, were also intact.
Scientists determined that the bird weighed around 33 grams and belonged to an extinct family of long-billed birds—small birds with teeth at the tip of a long, beak-like snout. Its closest relative is the genus Longipteryx.
Examination of the bird revealed that its throat was filled with stones, a phenomenon not seen in fossils before. A detailed analysis showed that the stones’ mineral composition differed both from each other and from the rocks surrounding the fossil, indicating the bird swallowed them during its lifetime rather than postmortem.
Some birds swallow stones to aid digestion. These stones, called gastroliths, are stored in a muscular part of the stomach known as the “gizzard,” which helps grind and break down food. When the stones become too smooth to grind food effectively, birds regurgitate them and replace them with new ones.
However, birds in the family that includes Chromeornis—including Chromeornis itself—show no evidence of having a gizzard. Moreover, the sheer number of stones, 800 in total, would have been too many for a bird of this size to use in digestion.
Researchers speculate that the bird may have been ill. Some birds swallow stones to rid themselves of parasites or to compensate for nutrient deficiencies. The exact reason why Chromeornis funkyi ingested so many stones remains a mystery.
