Sep 11, 2026 12:13 PM
A fossil feather preserved inside dinosaur poop could help explain why birds survived the mass extinction
https://www.eurekalert.org/news-releases/1142827
EXCERPTS: Birds are a specialized kind of dinosaur, and they've been around for a long time. The earliest known bird is Archaeopteryx, from 150 million years ago, and birds continued to evolve and co-exist alongside their fellow dinosaurs for nearly 100 million years. In the aftermath of the Earth’s collision with an asteroid 66 million years ago, nearly all the dinosaurs, including nearly all the birds, went extinct. But one group of birds, Neornithes, survived, and every living bird today is one of their descendants.
One of the biggest mysteries in paleontology is why this one small group of birds survived, when all the other birds and all the other dinosaurs died out. O’Connor has spent years studying fossil birds to try to answer this question. But this is the first time she’s studied feathers that were preserved inside fossilized droppings, or coprolites.
“As far as I know, no one has ever thought to look for feathers or to study feathers in coprolites, so this project was really exciting,” says O’Connor.
[...] The coprolite contained multiple feathers, tiny fish scales from a gar, and leg bones from a hesperonithiform bird. Since the bones and feathers, it stands to reason that the feathers came from that bird. “Hesperornithiforms were aquatic birds, ecologically similar to loons,” says O’Connor. “Most couldn’t fly, and instead, they used their specialized feet to dive down into the water to hunt for things like fish. The feathers showed adaptations for being underwater that we see in living aquatic birds.” The hesperornithiforms are close cousins of the Neornithes birds that survived the mass extinction and still live today, but they were not part of Neornithes themselves.
“The most common birds alive in the Cretaceous were part of a group called the enantiornithines. The modern Neornithes branch of birds were separate from that group, and so were the hesperornithiforms,” says O’Connor.
Some scientists have hypothesized that the Neornithes branch of the bird family survived because they lived near water, and something about this habitat helped buffer them from the effects of the mass extinction. However, the hesperornithiforms also lived by water, and they went extinct. So, there must be another reason to explain why Neornithes are the only birds that survived. O’Connor thinks one of the main reasons has to do with differences in their feathers.
“We think the types of feathers that these birds had, and/or the way they molted those feathers, may have been one of the underlying causes of the selectivity of the end-Cretaceous mass extinction—essentially, why some birds died out and why others survived,” she says.
The feathers found in the coprolite are the first hesperornithiform feathers ever found, and their features seem to represent a middle ground between the feathers of enantiornithines and modern birds. “Some of these diving birds’ feathers seem to have been modern-looking and water-proof, but they also had some smaller, fuzzy, primitive body feathers that we associate with dinosaurs and enantiornithines,” says O’Connor. The feathers on a bird’s body help insulate it from the cold. If the hesperornithiforms’ and enantiornithines’ feathers weren’t as good at keeping their bodies warm as Neornithes’ feathers, that could have been a major factor in these groups’ abilities to survive the impact winter following the asteroid strike 66 million years ago.
And since hesperornithiforms are neither neornithines or enantiornithines, the discovery of the feathers in the coprolite also help explain why these diving birds died out. “The hesperornithiforms retain primitive feather types that may not have been as efficient for insulation as modern plumaceous feathers, and that could explain why they went extinct along with the enantiornithines,” says O’Connor... (MORE - missing details, no ads)
PAPER: http://dx.doi.org/10.1016/j.cub.2026.08.054
https://www.eurekalert.org/news-releases/1142827
EXCERPTS: Birds are a specialized kind of dinosaur, and they've been around for a long time. The earliest known bird is Archaeopteryx, from 150 million years ago, and birds continued to evolve and co-exist alongside their fellow dinosaurs for nearly 100 million years. In the aftermath of the Earth’s collision with an asteroid 66 million years ago, nearly all the dinosaurs, including nearly all the birds, went extinct. But one group of birds, Neornithes, survived, and every living bird today is one of their descendants.
One of the biggest mysteries in paleontology is why this one small group of birds survived, when all the other birds and all the other dinosaurs died out. O’Connor has spent years studying fossil birds to try to answer this question. But this is the first time she’s studied feathers that were preserved inside fossilized droppings, or coprolites.
“As far as I know, no one has ever thought to look for feathers or to study feathers in coprolites, so this project was really exciting,” says O’Connor.
[...] The coprolite contained multiple feathers, tiny fish scales from a gar, and leg bones from a hesperonithiform bird. Since the bones and feathers, it stands to reason that the feathers came from that bird. “Hesperornithiforms were aquatic birds, ecologically similar to loons,” says O’Connor. “Most couldn’t fly, and instead, they used their specialized feet to dive down into the water to hunt for things like fish. The feathers showed adaptations for being underwater that we see in living aquatic birds.” The hesperornithiforms are close cousins of the Neornithes birds that survived the mass extinction and still live today, but they were not part of Neornithes themselves.
“The most common birds alive in the Cretaceous were part of a group called the enantiornithines. The modern Neornithes branch of birds were separate from that group, and so were the hesperornithiforms,” says O’Connor.
Some scientists have hypothesized that the Neornithes branch of the bird family survived because they lived near water, and something about this habitat helped buffer them from the effects of the mass extinction. However, the hesperornithiforms also lived by water, and they went extinct. So, there must be another reason to explain why Neornithes are the only birds that survived. O’Connor thinks one of the main reasons has to do with differences in their feathers.
“We think the types of feathers that these birds had, and/or the way they molted those feathers, may have been one of the underlying causes of the selectivity of the end-Cretaceous mass extinction—essentially, why some birds died out and why others survived,” she says.
The feathers found in the coprolite are the first hesperornithiform feathers ever found, and their features seem to represent a middle ground between the feathers of enantiornithines and modern birds. “Some of these diving birds’ feathers seem to have been modern-looking and water-proof, but they also had some smaller, fuzzy, primitive body feathers that we associate with dinosaurs and enantiornithines,” says O’Connor. The feathers on a bird’s body help insulate it from the cold. If the hesperornithiforms’ and enantiornithines’ feathers weren’t as good at keeping their bodies warm as Neornithes’ feathers, that could have been a major factor in these groups’ abilities to survive the impact winter following the asteroid strike 66 million years ago.
And since hesperornithiforms are neither neornithines or enantiornithines, the discovery of the feathers in the coprolite also help explain why these diving birds died out. “The hesperornithiforms retain primitive feather types that may not have been as efficient for insulation as modern plumaceous feathers, and that could explain why they went extinct along with the enantiornithines,” says O’Connor... (MORE - missing details, no ads)
PAPER: http://dx.doi.org/10.1016/j.cub.2026.08.054