Paleontologists at University College Cork (UCC) in Ireland have discovered X-ray evidence of proteins in fossil feathers, providing new clues into the evolution of feathers. Previous research has shown that the composition of ancient feathers was different from that of today's birds. However, new research reveals that protein components of modern feathers are also present in the feathers of dinosaurs and early birds, confirming that feather chemistry originated much earlier than previously thought.

Fossilized feathers from the Green River Formation (ca. 50 million years ago, United States). The specimen is housed at Yale University's Peabody Museum of Natural History. New method reveals similarities between dinosaurs and birds. The scale indicates 100 millimeters. Source: Dr. Tiffany Slater

Graphical abstract based on Slater et al.'s 2003 paper. Image source: Scientific Graphic Design

The research published today in Nature Ecology and Evolution was led by paleontologist Dr. Tiffany Slater and Professor Maria McNamara of the School of Biological, Earth and Environmental Sciences at the University of California, Berkeley, in collaboration with scientists from Linyi University in China and the Stanford Synchrotron Radiation Lightsource in the United States.

The team analyzed 125-million-year-old feathers from the genus Sinornithosaurus and the early bird Confuciusornis, as well as a 50-million-year-old feather from the United States.

Pictured here is Dr Tiffany Slater in the School of Biological, Earth and Environmental Sciences at University College Cork. Photo credit: DaraghMcSweeney/Provision

Dr Slater said: "It is really exciting to discover new similarities between dinosaurs and birds. To do this, we have developed a new method to detect traces of proteins in ancient feathers. Using X-rays and infrared light, we found that the nylon feathers in dinosaurs contained large amounts of beta protein, just like the feathers of birds today."

To help interpret the chemical signals preserved in fossilized feathers, the team also conducted experiments to help understand how feather proteins break down during fossilization. The feathers of modern birds are rich in beta protein, which helps enhance their flight capabilities.

Scanning electron microscope image of zebra finch feathers. Graduation lines indicate 200 microns. Photo credit: Dr. Tiffany Slater

"However, previous tests on dinosaur feathers found that most of them were alpha proteins. Our experiments can now explain this strange chemical reaction as the result of protein degradation during fossilization. So while some fossil feathers do retain traces of the original beta proteins, others are damaged, telling us a false story about feather evolution."

The study helps answer a long-standing debate about whether feather proteins, and proteins in general, are preserved deep in time.

Pictured here is Dr Tiffany Slater and Professor Maria McNamara in the Experimental Fossil Laboratory in the School of Biological, Earth and Environmental Sciences at University College Cork. Photo credit: DaraghMcSweeney/Provision

Professor Maria McNamara, senior author of the study, said: "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. We are developing new tools to understand what happened during fossilization and to uncover the chemical secrets of fossils. This will give us exciting new insights into the evolution of important tissues and their biomolecules."