Scientists have discovered feathers appeared 70 million years earlier than first thought, and were found on flying reptiles called pterosaurs. The discovery pushes back the origin of feathers by at least 70 million years.
An international team of paleontologists, which includes the University of Bristol, has discovered that the flying reptiles, pterosaurs, actually had four kinds of feathers, and these are shared with dinosaurs.
Pterosaurs lived alongside dinosaurs 66 million to 230 million years ago. Scientists knew the flying reptiles were covered in a coat of so-called pycnofibers, but most thought the fibers were distinct from the feathers found on dinosaurs and birds.
New analysis of ancient pterosaur fossils revealed four types of features, the same four types found on feathered dinosaurs. The four feather types include: simple filaments, or hairs; bundles of filaments; tufted filaments; and down feathers.
Scientists have previously documented the four feather types on two types of dinosaurs, the ornithischians, which were plant-eaters, and the theropods, which include the ancestors of birds.
Fossilized filamentous structures from two pterosaur fossils. The drawing e represents the fur-like filaments, while h, k, and n are types of feathers found on different parts of the body. Baoyu Jiang, Michael Benton et al./Nature Ecology & Evolution
Using high-powered microscopes, scientists identified the same four feather types on ancient pterosaur specimens in Asia.
"We went to Inner Mongolia to do fieldwork in the Daohugou Formation," research leader Baoyu Jiang of Nanjing University said in a news release. "We already knew that the sites had produced excellent specimens of pterosaurs with their pycnofibers preserved and I was sure we could learn more by careful study."
Close inspection of the fossilized pycnofibers proved there are four types of fibers, not just one. The analysis also showed the four fiber types are the same four types of feathers found on dinosaurs and birds.
"We focused on clear areas where the feathers did not overlap and where we could see their structure clearly," said Maria McNamara of University College Cork. "They even show fine details of melanosomes, which may have given the fluffy feathers a ginger color."
Evolutionary models confirmed what the fossil analysis suggested, that the pycnofibers found on pterosaurs are the same as the feathers found on dinosaurs and birds.
"Despite careful searching, we couldn't find any anatomical evidence that the four pycnofiber types are in any way different from the feathers of birds and dinosaurs," said Mike Benton, professor at the School of Earth Sciences, University of Bristol. "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."
The new research, published this week in the journal Nature Ecology and Evolution, suggests feathers were one of many adaptations that emerged in the wake of the end-Permian mass extinction.
"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," Benton said. "The mammal ancestors by then had hair, so likely the pterosaurs, dinosaurs and relatives had also acquired feathers to help insulate them."
Study: ‘Pterosaur integumentary structures with complex feather-like branching’ by Z. Yang, B. Jiang, M. McNamara, S. Kearns, M. Pittman, T. Kaye, P. Orr, X. Xu and M. Benton in Nature Ecology and Evolution
