Modern and early birds, plus feathered dinosaurs, have all sported feathers made of the same material, according to a new study.

The researchers investigated 125-million-year-old feathers from a dinosaur and an early bird to identify the proteins present. Both lived in China during the Early Cretaceous Period, about 25 million years after the first birds evolved.

Established science holds that they should have found spiral-shaped alpha proteins, which set ancient feathers apart from modern ones.

“Modern feathers are rich in beta-proteins that help strengthen [them] for flight,” said paleontologist Tiffany Slater, who led the project along with fellow paleontologist Maria McNamara, in a statement.

But the two researchers from University College Cork examined the old feathers using a new method that combines X-ray and infrared spectroscopy. “We found that feathers from the dinosaur Sinornithosaurus contained lots of beta-proteins, just like feathers of birds today,” Slater said.

Explaining Alpha-Proteins in Ancient Feathers

Meanwhile, other, older techniques have found alpha-proteins on the surfaces of ancient feathers. But the team argues that those are merely artifacts from the fossilization process, as they have attempted to demonstrate experimentally. The researchers used a sped-up fossilization process using heat to show how the beta proteins unraveled to become alpha ones.

“Our experiments can now explain this weird chemistry as the result of protein degradation during the fossilization process,” said Slater. “Although some fossil feathers do preserve traces of the original beta-proteins, others are damaged and tell us a false narrative about feather evolution.”

The new study speaks to the long-running debate over whether ancient proteins can be analyzed in a meaningful way after many millennia.

“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 McNamara in a statement. “We’re developing new tools to understand what happens during fossilization and unlock the chemical secrets of fossils.”

Read More: Did All Dinosaurs Have Feathers?

Early Feathered Creatures

One of the first feathered dinosaurs ever discovered, Sinornithosaurus is believed to have hunted in groups using an odd leaping attack. Scientists have disagreed over whether the animal wielded poisonous fangs, an idea based in part on the wide grooves found on its teeth. Nevertheless, Sinornithosaurus was an especially capable predator that may even have jumped between tree branches while in pursuit of prey.

Confuciusornis was an early, crow-sized bird that left behind an extensive fossil record, including many specimens replete with feather details. Due to its wing shape, Confuciusornis was likely a fast, yet rigid flyer and not a slow, agile one adept at maneuvering through the forest.

Read More: What Species Today Are Descendants of Dinosaurs?