Scientists from University College Cork 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 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 – 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. In fact, the new study shows that the pycnofibres are indeed feathers, and are similar to the feathers of dinosaurs, including the ancestors of birds.
Dr McNamara said “Some critics have suggested that there is only one simple hair-like type of pycnofibre, but our 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.”
The hunt for feathers in fossils is heating up and deciphering their functions in such early animals forms a critical part of the puzzle. 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 in China, studied the rocks from the Daohugou fossil localities and the pterosaurs. Mr Yang said “I was able to explore every corner of the specimens using high-powered microscopes, and we found many examples of all four feathers.”
UCD’s Prof. Patrick Orr and Prof. 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 Prof. 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.”
Birds have two types of advanced feathers used in flight and for body smoothing, the contour feathers with a hollow quill and barbs down both sides. These are found only in birds and the theropod dinosaurs close to bird origins. However, the other feather types of modern birds include monofilaments and down feathers, and these are seen much more widely across dinosaurs and pterosaurs.
Dr McNamara said “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.”
The study is published today in Nature Ecology and Evolution: Yang, Z.X., Jiang, B.Y., McNamara, M.E., Kearns, S.L., Pittman, M., Kaye, T.G., Orr, P.J., Xu, X., Benton, M.J. 2018. Pterosaur integumentary structures with complex feather-like branching. Nature Ecology and Evolution. DOI: 10.1038/s41559-018-0728-7.
See below for some news items on the study:
https://www.irishexaminer.com/breakingnews/ireland/not-just-splitting-hairs-ucc-study-pushes-origin-of-feathers-back-70m-years-892423.html (this was also on page 5 of the physical newspaper!:)