Turning into fossils distorted dino plumage

YALE (US) — Experiments suggest that fossil birds and dinosaurs may have had different colored feathers than scientists thought.

Geological processes can affect evidence of the original colors of fossil feathers, according to researchers, who say some previous reconstructions of fossil bird and dinosaur feather colors may be flawed.

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The discovery reveals how the evidence for the colors of feathers—especially melanin-based colors—can be altered during fossilization.

“Here we have concrete experimental evidence for how the colors of feathers are affected by pressure and temperature during burial,” says lead researcher Maria E. McNamara, a former Yale University postdoctoral researcher now based at the University of Bristol in the United Kingdom. The study is published online in the journal Biology Letters.

In modern birds, black, brown, and some reddish-brown colors are produced by tiny granules of the pigment melanin. These features—called melanosomes—are preserved in many fossil feathers, and their precise size and shape have been used to reconstruct the original colors of fossil feathers.

“The problem was that we had no idea whether melanosomes could survive the fossilization process intact,” says McNamara. “Our experiments show that this is not the case. Our results cast a cautionary light on studies of fossil feather color and suggest that some previous reconstructions of the original plumage colors of fossils may not be accurate.”

Using a novel experimental technique pioneered in the group’s recent study on the colors of fossil insects, McNamara’s interdisciplinary team simulated high pressures and temperatures that are found deep under the Earth’s surface. The team used feathers of different colors and from different species, but the geometry of the melanosomes in all feathers changed during the experiments.

“This study will lead to better interpretations of the original plumage colors of diverse feathered dinosaurs and fossil birds,” says co-author Derek E. G. Briggs, paleontologist and director of the Yale Peabody Museum of Natural History.
“Fossils that have experienced relatively mild burial conditions will yield the most accurate reconstructions.”

A Marie Curie International Mobility Fellowship through University College Dublin and the National Science Foundation supported the research.

Source: Yale University