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Feathers emerged 70 million years earlier than previously thought

A new study has extended the history of feathers by 70 million years. A team of palaeontologists led by the University of Bristol has discovered that flying reptiles known as pterosaurs had four different kinds of feathers.

Pterosaurs lived alongside the dinosaurs around 230 to 66 million years ago. While it was known that pterosaurs had a type of furry covering called “pycnofiber,” it was assumed to be fundamentally different to bird feathers.

The international team, which included experts from Nanjing, Bristol, Cork, Beijing, Dublin, and Hong Kong, has now demonstrated that pterosaurs had at least four types of feathers. These included simple filaments, bundles of filaments, down feathers, and filaments with a tuft halfway down.

The same types of feathers are now also associated with two major groups of dinosaurs: the ornithischians, which were plant-eaters, and the theropods, which include the ancestors of birds.

“We went to Inner Mongolia to do fieldwork in the Daohugou Formation,” said study lead author Baoyu Jiang of Nanjing University. “We already knew that the sites had produced excellent specimens of pterosaurs with their pycnofibres preserved and I was sure we could learn more by careful study.”

Study co-author Maria McNamara of University College Cork said, “Some critics have suggested that actually there is only one simple type of pycnofibre, but our studies show the different feather types are real.”

“We focused on clear areas where the feathers did not overlap and where we could see their structure clearly. They even show fine details of melanosomes, which may have given the fluffy feathers a ginger color.”

Professor Mike Benton from the University of Bristol’s School of Earth Sciences added, “We ran some evolutionary analyses and they showed clearly that the pterosaur pycnofibres are feathers, just like those seen in modern birds and across various dinosaur groups.”

“Despite careful searching, we couldn’t find any anatomical evidence that the four pycnofibre types are in any way different from the feathers of birds and dinosaurs. Therefore, because they are the same, they must share an evolutionary origin, and that was about 250 million years ago, long before the origin of birds.”

Professor Benton said that the discovery has amazing implications for our understanding of the origin of feathers, and also for a revolution of life on land.

“When feathers arose, about 250 million years ago, life was recovering from the devastating end-Permian mass extinction,” he  explained. ‘Independent evidence shows that land vertebrates, including the ancestors of mammals and dinosaurs, had switched gait from sprawling to upright, had acquired different degrees of warm-bloodedness, and were generally living life at a faster pace.”

‘The mammal ancestors by then had hair, so likely the pterosaurs, dinosaurs and relatives had also acquired feathers to help insulate them.”

“The hunt for feathers in fossils is heating up and finding their functions in such early forms is imperative. It can rewrite our understanding of a major revolution in life on Earth during the Triassic, and also our understanding of the genomic regulation of feathers, scales, and hairs in the skin.”

The study is published in the journal Nature Ecology & Evolution.

By Chrissy Sexton, Staff Writer
Image Credit: by Yuan Zhang

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