Fossil find rewrites origins of feathers

Fossils unearthed in China belonging to two ancient reptiles with bat-like wings known as pterosaurs may provide proof that the first feathers evolved before dinosaurs and birds.

A team of paleontologists from the United Kingdom, Ireland and China analyzed the fossils of two pterosaurs that lived 160 million years ago and were surprised to find evidence of feathers.

The first feathered dinosaurs appear in the fossil record around 170 million years ago. While closely related, pterosaurs were not actually dinosaurs, so the discovery led the researchers to a startling realization.

Either dinosaurs and pterosaurs evolved feathers independently, or they both inherited the ability to grow feathers from a common ancestor that lived 250 million years ago - before the first dinosaurs and birds.

"This discovery has amazing implications for our understanding of the origin of feathers, and also for a major time of revolution of life on land," said Mike Benton, a paleontologist from the University of Bristol who worked on the study published in Nature.

Pterosaurs were winged reptiles that lived alongside the dinosaurs between 233 million and 66 million years ago. They were the first vertebrates capable of powered flight. Their wings were formed of a membrane of skin stretched along an elongated finger bone. Both pterodactyls and pteranodons - made famous by the movie Jurassic Park 3 - were types of pterosaur.

Previous fossil samples have shown the creatures were covered with hair-like insulation known as "pycnofibres", which were thought to be fundamentally different to the feathers found in dinosaurs.

However, after analyzing the two fossils found in Northern China, the research team discovered evidence of four types of insulation: simple filaments, bundles of filaments, filaments with a tuft halfway down, and down feathers.

"We went to Inner Mongolia to do fieldwork in the Daohugou Formation," said Baoyu Jiang, a paleontologist from Nanjing University, who led the research. "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."

Maria McNamara, a paleontologist from University College Cork in Ireland who worked on the study, said that she was able to view the remnants of feathers in great detail as the fossils are so well preserved.

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

Benton said that while it is possible that different of dinosaurs and their relatives evolved feathers independently of one another, the more probable explanation is that the ability to grow feathers was passed down to by a common ancestor.

He said that the pterosaur feathers were no different anatomically 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," Benton said.

"The hunt for feathers in fossils is heating up and finding their functions in such early forms is imperative," he added. "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."