Scientists have used a new technique to detect pigments in extinct animals, extending the timeframe that we can detect these compounds in fossils.
Biologists from the Chinese Academy of Sciences and North Carolina State University have recently reported the discovery of a 130-million-year-old bird fossil that contains biological compounds that confirm the presence of color.
The study was recently published in the Proceedings of the National Academy of Sciences.
The crow-sized Eoconfuciusornis bird was discovered in Early Cretaceous lake deposits in Hebei, Northern China. It’s one of the earliest known birds to have a keratinous beak and no teeth, just like modern birds. Using multiple molecular and chemical analysis techniques, they discovered pigment-containing organelles, called melanosomes, on the bird’s fossilized feathers.
Previously, there was a problem with looking for melanosomes in fossilized animals. That's because it was very difficult to tell if the structures were melanosomes that belong to the creature in question or just microbes that came along during the fossilization process. So, the researchers turned their searchlights to the presence of keratin.
"If these small bodies are melanosomes, they should be embedded in a keratinous matrix, since feathers contain beta-keratin," study author Mary Schweitzer, from the North Carolina Museum of Natural Sciences, said in a statement. "If we couldn't find the keratin, then those structures could as easily be microbes, or a mix of microbes and melanosomes – in either case, predictions of dinosaur shading would not be accurate."
By using an immunogold labeling technique, they found evidence of the structural protein beta-keratin – a sure sign that the coloring belonged to the bird. This is also the oldest example of beta-keratin compounds ever discovered, suggesting they can last much longer than previously thought.
Since it's now believed that many dinosaurs were feathered, the discovery could have big implications for the study of dinosaur coloration, as well as the evolution, habitat, and physiology of other prehistoric extinct creatures.
"This study is the first to demonstrate evidence for both keratin and melanosomes, using structural, chemical and molecular methods," added Yanhong Pan, associate research fellow at the Chinese Academy of Sciences. "These methods have the potential to help us understand – on the molecular level – how and why feathers evolved in these lineages."