Although the evolution of feathers is associated with new skin ultrastructures, the fossil record of these changes is poor, and thus the critical transition from scaly to feathered skin is poorly understood. A new study led by palaeontologists from University College Cork sheds light on this issue using preserved skin. Psittacosaurus, a non-avian feathered dinosaur from the Early Cretaceous period (135-120 million years ago), when dinosaurs were evolving into birds. Fossil evidence supports the division of skin development. Psittacosaurus: A reptilian state in featherless areas, and an avian state in feathered areas.
studied Psittacosaurus Specimens under natural light (top half) and ultraviolet light (bottom half). It shows the orange-yellow fluorescence of fossilized skin. Image credit: Zixiao Yang.
Feathers are associated with complex skin adaptations to facilitate feather growth, flight, and thermoregulation, which distinguish feathered skin from scaly reptilian skin.
However, the details of the transition between these two skin types in early feathered animals are unknown.
University College Cork palaeontologist Jixiao Yang and his colleagues investigated the evolution of skin using fossil specimens of Psittacosaurus from the Early Cretaceous Takahe fauna of China. Psittacosaurus is a feathered dinosaur that lived approximately 130 million years ago, with feathers remaining only on its tail.
The researchers were then able to use ultraviolet (UV) fluorescence and electron microscopy to study the structure of the skin cells.
“This fossil is truly a hidden gem,” Dr. Yang said.
“The fossil skin is not visible to the naked eye and remained hidden when the specimen was donated to Nanjing University in 2021.”
“It’s only under ultraviolet light that the skin appears to glow with an orange-yellow color.”
“What’s really surprising is the chemistry of the fossil skin. It’s composed of silica, the same as glass.”
“This kind of preservation has never been found in a vertebrate fossil before. There may be many more fossils with hidden soft tissues waiting to be discovered.”
But the most interesting part of this discovery is what it tells us about the evolution of dinosaur feathers.
“The evolution of reptile scales to feathers is one of the most significant and least understood events in vertebrate evolution,” Professor McNamara said.
“While many feather fossils have been studied, skin fossils are much rarer.”
“Our findings suggest that soft, bird-like skin initially developed only on the feathered parts of the body, and the rest of the skin was still scaly, similar to modern reptiles. .”
“This zoned development would have preserved essential skin functions such as protection from abrasions, dehydration, and parasites.”
“Thus, the first dinosaurs to experiment with feathers survived and were able to pass on the feather genes to their descendants.”
of study Published in today’s diary nature communications.
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Z. Yang others2024. The cellular structure of dinosaur scales reveals retention of reptilian-style skin during the evolutionary transition to feathers. Nat Commune 15, 4063; doi: 10.1038/s41467-024-48400-3
Source: www.sci.news
