Paleontologists have analyzed 125-million-year-old feathers from a dinosaur species called Sinornithosaurus as well as feathers of the early bird Confuciusornis and a 50-million-year-old feather from the Green River biota of Wyoming, the United States. Their results show that the protein composition of modern-day feathers was also present in the feathers of dinosaurs and early birds, confirming that the chemistry of feathers originated much earlier than previously thought.
The 50-million-year-old feather from the Green River biota, Wyoming, the United States. Image credit: Slater et al., doi: 10.1038/s41559-023-02177-8.
Ancient biomolecules are a powerful source of information on the history of life on Earth.
They can inform on phylogenetic relationships, the origins of novel tissues and major evolutionary transitions in organismal physiology and ecology.
Despite evidence that proteinaceous biomolecules such as collagen can survive for several million years, preservation of fossil proteins — or their degraded remnants — on longer timescales is controversial.
“We developed a new method to detect traces of ancient feather proteins,” said University College Cork paleontologist Tiffany Slater.
“Using X-rays and infrared light, we found that feathers from Sinornithosaurus contained lots of beta-proteins, just like feathers of birds today.”
To help interpret the chemical signals preserved in the fossil feathers, the researchers ran experiments to help understand how feather proteins break down during the fossilization process.
“Modern bird feathers are rich in beta-proteins that help strengthen feathers for flight,” Dr. Slater said.
“Previous tests on dinosaur feathers, though, found mostly alpha-proteins.”
“Our experiments can now explain this weird chemistry as the result of protein degradation during the fossilization process.”
“So although some fossil feathers do preserve traces of the original beta-proteins, other fossil feathers are damaged and tell us a false narrative about feather evolution.”
The research helps answer a long-standing debate about whether feather proteins, and proteins in general, can preserve in deep time.
“Traces of ancient biomolecules can clearly survive for millions of years, but you can’t read the fossil record literally because even seemingly well-preserved fossil tissues have been cooked and squashed during fossilization,” said University College Cork’s Professor Maria McNamara.
“We’re developing new tools to understand what happens during fossilization and unlock the chemical secrets of fossils.”
“This will give us exciting new insights into the evolution of important tissues and their biomolecules.”
The study was published in the journal Nature Ecology and Evolution.
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T.S. Slater et al. Preservation of corneous β-proteins in Mesozoic feathers. Nat Ecol Evol, published online September 21, 2023; doi: 10.1038/s41559-023-02177-8
