The Discovery
A fortunate crack in a piece of fossilized dung, or coprolite, led researchers to an extraordinary ancient find. Originally recovered from Montana's Hell Creek Formation in 2016, the specimen initially revealed its secrets when scientists noticed a single feather exposed on its exterior. To examine the interior without damaging the fossil, researchers used micro-CT scans to create a detailed three-dimensional map of its contents. Their findings were formally published on September 10 in the journal Current Biology.
What Scientists Found
The scan revealed leg bones, fish scales, and additional bird feathers preserved inside the fossilized droppings. Scientists determined the remains belonged to an ancient aquatic bird known as a hesperonithiform. Analysis of the plumage showed a unique combination of advanced and primitive traits:
- Dense bristles capable of shedding water, similar to features found on modern pelicans.
- A central feather shaft filled with air pockets, a lightweight adaptation for flight seen for the first time in a specimen from the Age of the Dinosaurs.
- Primitive, stringy feathers that provided inferior thermal protection compared to modern plumage.
Why It Matters
The structural flaws in these ancient feathers may help solve a long-standing mystery regarding why certain bird lineages went extinct while others endured. Roughly 66 million years ago, a massive asteroid impact triggered a mass extinction that brought on a deep global freeze. While the direct ancestors of modern birds managed to live through the severe shift in climate, hesperonithiforms and their close relatives died out.
Vertebrate paleontologist Jingmai O’Connor of the Field Museum of Natural History in Chicago noted that poor insulation from these primitive feathers likely made it difficult for the aquatic birds to retain body heat during the cold spell. Because fossilized feathers are exceptionally rare, scientists note that this insulation theory will require further testing as more discoveries are made.
Source: dinosaur fossil discovery - BingNews · Published September 29, 2026