The oldest fossil evidence of the red-orange hue of beta-keratin has been discovered in a 130-million-year-old basal bird.
International researchers are closing in on colour-coding the dinosaurs following the latest discovery of feather pigmentation from millions of years ago.
A team from the Chinese Academy of Sciences has reported the oldest fossil evidence of beta-keratin – a colour somewhere between red and orange – in feathers from a basal bird from the Early Cretaceous Jehol Biota.
The term ‘basal birds’ relates to species that are close to the base of the evolutionary chain, the earliest birds derived from dinosaurs named Paraves.
While not the first discovery of this kind, the team’s dating of the colour to a 130-million-year-old creature is quite the landmark.
Previous discoveries of feathers and feather-like epidermal structures saw researchers discuss associated microbodies as microbes.
Recently, these were reinterpreted as remnant melanosomes, common in animal cells and a site where synthesis occurs. From that, hypotheses of dinosaurian colour, behaviour, habitat, and physiology were proposed.
However, due to the similarity between melanosomes and microbes, both explanations were plausible.
So palaeontologists from the Nanjing Institute of Geology and Palaeontology (NIGPAS), the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Linyi University and North Carolina State University, got to work.
They adopted multiple molecular and chemical methods, applying immunogold to identify protein epitopes at high resolution. Their study reported fossil evidence of beta-keratin.
Through this they proved melanosomes as the true interpretation.
“This study represents a breakthrough in the study of ultrastructures of fossil feathers,” said Prof Zhou Zhonghe from IVPP, a co-author of the paper.
“[It] has provided the methods to apply to the controversial issue of whether the microbodies in many feathered dinosaurs and early birds are really melanosomes, and sheds new light on molecular preservation within normally labile tissues preserved in ancient fossils.”