A 66-million-year-old feather found inside fossilised dinosaur poop may offer a clue to why some birds survived the asteroid impact that wiped out most dinosaurs.
uncertain
that → find → dinosaurs
Scientists say the feather belonged to a hesperornithiform, an extinct group of aquatic birds that lived alongside dinosaurs.
asserted
that → say → dinosaurs
The feather was preserved inside a coprolite, the scientific term for fossilised faeces.
asserted
feather → preserve → faeces
Researchers found several feathers, tiny fish scales and leg bones belonging to a hesperornithiform bird inside the fossil.
asserted
Researchers → find → fossil
The discovery, reported in the journal Current Biology and reported by Science Daily, suggests that feathers may have played a role in determining which birds survived the mass extinction.
uncertain
birds → report → extinction
Hesperornithiforms lived in aquatic environments but disappeared along with most other birds, while one branch, known as Neornithes, survived and eventually gave rise to every bird species alive today.
asserted
branch → live → species
About 66 million years ago, an asteroid struck Earth and caused a mass extinction at the end of the Cretaceous Period.
asserted
asteroid → strike → Period
Dust and debris entered the atmosphere, reducing sunlight and causing severe cooling known as an impact winter.
asserted
Dust → enter → winter
Most dinosaur groups disappeared, but some birds survived.
asserted
birds → disappear → ?
The unusual fossil was discovered in 2016 by David DeMar Jr, a research scientist and Hell Creek Project collections manager at the University of Washington Burke Museum.
asserted
fossil → discover → Museum
He was working in northeastern Montana when he spotted a small, dark reddish-brown rock.
asserted
he → work → rock
“I was crawling up a rocky outcrop collecting fish fossils when I came across a dark, reddish-brown nodule about half the size of a golf ball,” DeMar said.
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DeMar → crawl → ball
He examined it with a hand lens and noticed a tiny fossil feather on its surface.
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He → examine → surface
The discovery was unexpected because feathers had not previously been found in the Hell Creek Formation, despite more than 150 years of prospecting there.
asserted
feathers → find → years
Researchers later studied the specimen’s mineral composition and used CT imaging to examine its interior.
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Researchers → study → interior
CT scans combine thousands of X-rays to create detailed digital images without destroying the fossil.
asserted
scans → combine → fossil
Nate Carroll, a co-author and paleontologist at the Carter County Museum in Ekalaka, Montana, suspected the rock might be a coprolite.
uncertain
rock → suspect → Ekalaka
A micro-CT scan revealed what was preserved inside.
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what → reveal → ?
“Every hour processing the data revealed another feather, another scale, another bone, in stunning 3D,” Carroll said.
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Carroll → process → 3D
Inside the fossil
The coprolite contained several feathers, tiny scales from a gar fish and leg bones from a hesperornithiform bird.
asserted
coprolite → contain → bird
Since the feathers and bird bones were found together, researchers concluded that the feathers most likely came from the same bird.
asserted
feathers → find → bird
Most could not fly.
uncertain
Most → fly → ?
They used specialised feet to dive underwater and hunt fish.
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They → use → fish
The feathers also showed adaptations for life underwater.
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feathers → show → life
Some appeared modern and waterproof, while others were smaller and fuzzy.
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others → appear → ?
Jingmai O’Connor, the study’s lead author and associate curator of fossil reptiles at the Field Museum in Chicago, said scientists had not previously studied feathers preserved in coprolites.
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scientists → say → coprolites
“As far as I know, no one has ever thought to look for feathers or to study feathers in coprolites,” O’Connor said.
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O’Connor → know → coprolites
Why some birds survived
Scientists have long studied why Neornithes survived while most other birds disappeared.
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birds → survive → ?
One theory suggested that living around aquatic environments may have helped some birds survive the conditions after the asteroid impact.
uncertain
birds → suggest → impact
The newly studied fossil complicates that explanation.
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fossil → study → explanation
Hesperornithiforms also lived in aquatic environments but became extinct.
asserted
Hesperornithiforms → live → environments
O’Connor said the difference may instead have involved feathers and how birds replaced them.
uncertain
birds → say → them
“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 said.
uncertain
she → think → extinction
The feathers are the first ever identified from a hesperornithiform.
asserted
feathers → identify → hesperornithiform
Their structure falls between the plumage seen in enantiornithines, another extinct bird group, and modern birds.
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structure → fall → enantiornithines
Primitive feathers may have mattered
uncertain
feathers → matter → ?
The researchers found that some hesperornithiform feathers were waterproof and suited to diving.
asserted
feathers → find → diving
But the birds also had smaller, fuzzy body feathers that were more primitive.
asserted
that → have → feathers
Body feathers help birds retain heat.
asserted
birds → help → heat
During the impact winter, when sunlight was reduced and temperatures dropped, better insulation may have helped some birds survive.
uncertain
birds → reduce → winter
…and 14 more, not listed.
