In the early Cretaceous, a palm-sized bird made a fatal mistake. Its fossil shows a dense mass of tiny rocks lodged in its throat, a snapshot of a creature caught in its final moments. The accumulation includes more than 800 stones, far more than any known bird uses for digestion, and they are located so high in the throat that scientists say the animal likely choked.
Fossil belongs Chromornis funkya newly identified dinosaur species described in Paleontological electronics it opens a window into early evolution. CT scans showed that the throat stones were not used for digestion, suggesting the fossil preserves an unusual element that hints at the quirks and vulnerabilities of this now extinct lineage.
“It's quite rare to know what caused the death of a particular individual in the fossil record. But even though we don't know why this bird ate all those rocks, I'm pretty confident that the eruption of this mass caused it to suffocate, and that's what killed this little bird,” said Jingmai O'Connor, assistant curator of fossil reptiles at the Chicago Field Museum and lead author of the study, in his report. press release.
Recently identified species
It wasn't the fossil rocks that initially caught O'Connor's attention. bird itself was small – the size of a sparrow – but had teeth at the end of its beak, typical of larger early birds such as Longipteryx. The combination of features did not match any known specimen in enantiornithinesthe most famous group of birds of that time. This combination of features suggested that the fossil represented a new species.
It was only after identifying its distinctive anatomy that the strangeness of the throat became impossible to ignore. Modern birds such as chickens sometimes swallow small stones to grind up food in a muscular stomach called a gizzard; These stones, known as gastroliths, collect deep in the digestive tract.
But the stones in this fossil were located much higher, clustered near the neck bones. No other enantiornithine has been found with gastroliths of any type, not to mention the throat.
Read more: The smallest dinosaur was only 11 inches long and had beautiful feathers on its tail.
Scanning the last moments of a fossil's life
To get to the bottom of the rocks, the team used CT scanning to map every particle inside the rock. fossils throat. They compared these measurements to earlier work that quantified the number, volume and overall size of gizzard stones in other fossil birds known to use them. These birds had clear, repeatable patterns of small groups of stones being retained deep in the digestive system.
This fossil bird was found to contain 800 tiny stones, visible as a gray mass to the left of the neck bones.
(Image credit: Jingmai O'Connor)
Chromornis did not meet any of these criteria. The scans revealed hundreds of tightly packed rocks and clay granules accumulated high in the throat, forming a mass unlike anything seen in other fossil birds. The unusual size, composition and arrangement of the stones indicated behavior beyond normal feeding.
Linking the fate of one bird to a mass extinction
Having ruled out digestion, the team looked at the behaviors that might lead to such an overloaded cluster. The most likely explanation is related to stress or illness: modern birds, when unwell, sometimes swallow unusual objects.
“When birds get sick, they start doing strange things,” O'Connor said. “So we tentatively hypothesized that it was a sick bird that was eating rocks because it was sick. It swallowed too many and tried to regurgitate them in one big mass. But the mass of rocks was too big and it got stuck in its esophagus.”
The fossil's significance reflects the unusual behavior of a group that once dominated the planet. Cretaceous period but disappeared completely at the end of the era when an asteroid hit.
“During that environmental disaster enantiornithines went from being the most successful group of birds to being wiped out,” she added. “Understanding why they were successful, as well as why they were vulnerable, can help us predict the course of the mass extinction we are in now. Studying Chromornis and other extinct birds could eventually help in today's conservation efforts.”
Read more: Eggshells fill 30-million-year record gap in dinosaur migration
Article sources
Our authors in discovermagazine.com use peer-reviewed research and high-quality sources for our articles, and our editors review scientific accuracy and editorial standards. Review the sources used below for this article:
- This article refers to information from a recent study published in the journal PAleontological electronics: A new small-bodied longipterygid (Aves: Enantiornithes) from the Aptian Jiufotang Formation, preserving unusual gastroliths.
