Researchers discover a hidden step in the evolution of dinosaur feathers

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Examine dinosaur specimen NJUES-10 under natural (top half) and UV light (bottom half), showing the orange-yellow fluorescence of the fossil skin. Credit: Dr. Zixiao Yang

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Examine dinosaur specimen NJUES-10 under natural (top half) and UV light (bottom half), showing the orange-yellow fluorescence of the fossil skin. Credit: Dr. Zixiao Yang

Paleontologists from University College Cork (UCC) in Ireland have discovered that some feathered dinosaurs had scaly skin like modern-day reptiles, shedding new light on the evolutionary transition from scales to feathers.

The researchers studied a new specimen of the feathered dinosaur Psittacosaurus from the early Cretaceous period (135-120 million years ago), a time when dinosaurs evolved into birds. The research shows for the first time that the Psittacosaurus had reptilian skin in places where it had no feathers.

The study, published in Nature communicationwas led by UCC paleontologists Dr. Zixiao Yang and Prof. Maria McNamara from UCC’s School of Biological, Earth and Environmental Sciences, who collaborated with scientists based at Nanjing University (China).

The team used ultraviolet (UV) light to identify spots on preserved skin, which are invisible in natural light. Further examination of the fossil skin using X-rays and infrared light revealed spectacular details of the preserved cell structure.

Dr. Yang says: “The fossil is truly a hidden gem. The fossil skin is not visible to the naked eye, and remained hidden when the specimen was donated to Nanjing University in 2021. The skin is only visible under UV light, with a striking orange-yellow glow.

“What is really surprising is the chemistry of fossil skin. It is composed of silica, the same as glass. This kind of preservation has never been found in vertebrate fossils. There may be many more fossils with hidden soft tissues waiting exploring.”


The fossil skin under an electron microscope, showing mineralized cell layers. Credit: Dr. Zixiao Yang

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The fossil skin under an electron microscope, showing mineralized cell layers. Credit: Dr. Zixiao Yang


Dr. Zixiao Yang of University College Cork, who discovered that some feathered dinosaurs had scaly skin like modern-day reptiles, shedding new light on the evolutionary transition from scales to feathers. (Image credit: Ruben Tapia/UCC TV). Credit: Ruben Tapia/UCC TV.

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Dr. Zixiao Yang of University College Cork, who discovered that some feathered dinosaurs had scaly skin like modern-day reptiles, shedding new light on the evolutionary transition from scales to feathers. (Image credit: Ruben Tapia/UCC TV). Credit: Ruben Tapia/UCC TV.







The most exciting aspect of the discovery, however, is what it tells us about the evolution of feathers in dinosaurs. Prof. McNamara, senior author of the study, said: “The evolution of reptilian scale feathers is one of the most profound but poorly understood events in vertebrate evolution. Although numerous feather fossils have been studied, fossil skin is much rarer.

“Our discovery suggests that soft, bird-like skin initially developed only in the feathered parts of the body, while the rest of the skin was still scaly, like in modern reptiles. This zoned development would have maintained essential skin functions, such as protection against wear, dehydration and parasites. The first dinosaur to experiment with feathers could therefore survive and pass on the genes for feathers to their offspring.

The Psittacosaurus specimen NJUES-10 is currently housed at Nanjing University.

More information:
Zixiao Yang, Cellular structure of dinosaur scales reveals the maintenance of reptilian skin during the evolutionary transition to feathers, Nature communication (2024). DOI: 10.1038/s41467-024-48400-3. www.nature.com/articles/s41467-024-48400-3

Magazine information:
Nature communication

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