Study of flying reptile sheds light on origin of feathers

Scientists from University College Cork (UCC) have discovered that pterosaurs had four kinds of feathers, shifting the origin of feathers back by 70 million years.

The new study, led by researchers from China's Nanjing University and UCC's Dr Maria McNamara, shows that pterosaurs, which were flying reptiles that lived side by side with dinosaurs from 230 to 66 million years ago, had at least four types of feathers.

These included simple filaments (hairs), bundles of filaments, filaments with a tuft halfway down, and down feathers.

It had long been known that pterosaurs had a furry covering, but these “pycnofibres” were thought to be fundamentally different to feathers of dinosaurs and birds.

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In fact, the new study published on Monday in Nature Ecology and Evolution shows that the pycnofibres are indeed feathers, and are similar to the feathers of dinosaurs, including the ancestors of birds.

Real feathers

Dr McNamara said some critics have suggested that there is only one simple hair-like type of pycnofibre, but their studies show different structures that we also see in dinosaurs – real feathers.

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

According to Dr McNamara, “this discovery has amazing implications for our understanding of the origin of feathers, but also for a major time of revolution of life on land. When feathers arose, about 250 million years ago, life was recovering from the devastating end-Permian mass extinction.”

Independent evidence shows that land vertebrates, including the ancestors of mammals and dinosaurs, were beginning to walk 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.

Independent evidence shows that land vertebrates, including the ancestors of mammals and dinosaurs, were beginning to walk 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, she explained.

Dr McNamara says the hunt for feathers in fossils is heating up and deciphering their functions in such early animals forms a critical part of the puzzle.

Major revolution

“It could rewrite our understanding of a major revolution in life on Earth during the Triassic, and our understanding of the genomic regulation of feathers, scales, and hairs in the skin. ”

Zixiao Yang and Baoyu Jiang, of Nanjing University, studied the rocks from the Daohugou fossil localities and the pterosaurs.

They said they were able to explore every corner of the specimens using high-powered microscopes, and found many examples of all four feathers.

UCD's professor Patrick Orr and professor Mike Benton from the University of Bristol were also involved in the study.

“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,” said professor Benton.

“Because the structures in the pterosaurs have the same anatomy as the feathers of birds and dinosaurs, they must share an evolutionary origin about 250 million years ago, long before the origin of birds.”