Paleontologists from the University College Cork (UCC) in Ireland have discovered 125 million-year-old scales that are preserved under the plumage of feathered dinosaurs and early birds, revealing the first evidence of how dinosaurs cut their skin.
UCCs Maria McNamara and her team studied the fossil cells and scales of modern birds with powerful electron microscopes for the study, which was published today in the journal Nature Communications .
"The fossil cells are preserved down to the nanoscale keratin fibrils, and it is noteworthy that the fossil scales are almost identical to those of modern birds ̵
The study suggests that this modern skin feature evolved sometime in the late Middle Jurassic period, at the same time as a host of other skin features developed. "At that time, there was an outbreak of feathered dinosaurs and birds, and it's exciting to find evidence that the skin of early birds and dinosaurs developed rapidly in response to supporting feathers," Dr. McNamara.
Dr. McNamara led the study, in collaboration with her postdoctoral fellow. Chris Rogers; Dr. Andre Toulouse and Tara Foley, also from UCC; Dr. Paddy Orr of UCD, Ireland; and an international team of paleontologists from the UK and China
The scales are the first evidence of how dinosaurs shed their skin. The feathered dinosaurs studied – Microraptor, Beipiaosaurus and Sinornithosaurus – clearly flattened their skin like the early bird Confuciusornis studied the team and even modern birds and mammals, and not as a piece or several large pieces, as in many modern reptiles
Co-author Professor Mike Benton of the School of Earth Sciences of the University of Bristol said: "It's uncommon to be able to examine the skin of a dinosaur, and the fact that these are dandruff proves that the dinosaur his not lost whole skin like a modern lizard or snake, but lost skin fragments between her feathers. "
Modern birds have very oily corneocytes with loosely packed keratin, which allows them to cool quickly if they fly for extended periods of time. However, the corneocytes in the fossil dinosaurs and birds were packed with keratin, suggesting that the fossils did not get as warm as modern birds, presumably because they could not fly at all or for so long.
Ornithomimus dinosaur with preserved tail feathers and skin tightens connections between dinosaurs and birds
Maria E. McNamara et al. Fossilized Skin Shows Coevolution with Feathers and Metabolism in Feathered Dinosaurs and Early Birds, Nature Communications (2018). DOI: 10.1038 / s41467-018-04443-x