Amazing Fossil Find Shows That Pterosaurs Had Something In Common With Dinosaurs And Birds

China is a land of spectacular fossil finds that included some of the first feathered dinosaurs ever discovered. Now, paleontologists have unearthed fascinating a pair of fossils showing feathers on creatures that we never knew had them: pterosaurs.

And it looks for all practical purposes that pterosaurs, like their dinosaur counterparts, had feathers to help provide warmth, NewScientist reports. But scientists are especially excited about this because it means feathers evolved much earlier than previously thought — some 70 million years earlier, in fact.

A sampling of the fossil pterosaur feathers. Image courtesy of NewScientist via the Journal of Nature Ecology & Evolution

Pterosaurs already had wings made of skin, muscles, and fibers, so they really didn’t need flight feathers. Instead, their feathers were small and tufted.

“They are almost certainly just for insulation,” notes Mike Benton at the University of Bristol, UK, and a member of the team that discovered the fossils two years ago.

The second fossil was discovered a few years before, but its significance in science has gained a new understanding.

But even as early as the 1840s, fossil finds of these enigmatic winged reptiles showed they had hair-like filaments on their heads and bodies. Paleontologists coined the term “pycnofibres” to set the filaments apart from the fur of mammals and the feathers of birds. And the pycnofibers in the two pterosaur specimens are beautifully preserved.

The research team, whose members are from Nanjing, Bristol, Cork, Dublin, and Hong Kong, found four types of branched filaments, thus confirming these are indeed feathers.

“If your dermal fluff branches, that’s a feather,” Benton says.

This illustration by Zixiao Yang shows the four feather types: filaments, filament bunches, tufted filament, down feather. Scale bars for photos are a-d: 100µm, 200µm, 500µm, and 1mm). Image via the Journal of Nature Ecology & Evolution via ScienceDaily

They described the feathers as simple filaments (hairs), bundles of filaments, down feathers, and filaments that are tufted in the middle. These four types of feathers are also found on two groups of dinosaurs — the herbivorous ornithischian dinosaurs like the stegosaurs, for instance, and the theropods, which include the tyrannosaurs. And it’s the theropods who are the ancestors of birds.

The two fossil specimens, which date from 165 million to 160 million years ago are so complete even their soft tissues have been preserved, said lead study author Baoyu Jiang, a professor of paleontology at the School of Earth Sciences and Engineering at Nanjing University in China, in an email to LiveScience.

One of the fossils was discovered in China’s Yanliao Biota in 2015 by Jiang and his fellow researchers. The site, located north of Beijing, is known for spectacular fossil finds from the Jurassic period. The researchers also decided to study another pterosaur fossil found a few years earlier from this site.

He added that researchers don’t yet know if the two fossils are from the same species, but are working to find out.

Quetzalcoatlus northropi, the largest known pterosaur, would quite obviously need a lot of feathers. Image license Public Domain by Big Bend National Park (U.S. Park Service) U.S. Department of The Interior via Wikimedia Commons

The researchers have several ideas about the purposes the feathers served. They may have served as insulation to provide warmth, or they could have been used in the same way a cat uses its’ whiskers — to provide a sense of touch. There’s also the possibility they helped streamline flight. And melanosomes (melanin-filled organelles) found within the feathers show they were likely reddish-brown, which means they may have been used for camouflage or for signaling to other pterosaurs.

Paleontologists have long thought that the heads, bodies, and limbs of pterosaurs were covered in pycnofibers and these fossils provide evidence that this is true. The heads of these two pterosaurs were covered in branching filaments, while those on the neck were brush-like on the ends. Downy filaments on the wing membranes complete this picture.

“If all I had was a photo of the fluffy stuff on these fossils, and I didn’t know they were attached to a pterosaur, I would probably think they were the feathers of a feathered raptor dinosaur,” said paleontologist Steve Brusatte, with the University of Edinburgh in the UK, who was not part of the research team. “I think it’s now case closed, pterosaurs had feathers.”

Across millions of years, evolution has taken remarkable twists and turns, creating marvelous species, seemingly to fill every niche. The order Pterosauria are one such clade. Some evolved magnificent crests, like Tupandactylus imperator below:

Tupandactylus in flight. Image license CC SA 3.0 by Dmitry Bogdanov via Wikimedia Commons

And some, like Anurognathus ammoni, were tiny (we’re talking about a 20-inch wingspan):

Anurognathus ammoni takes off after a lacewing. Image license CC Attribution 3.0 by Dmitry Bogdanov via Wikimedia Commons

And all of them are fascinating. The video below offers some facts about these remarkable creatures.

Featured illustration by Yuan Zhang via The Journal of Nature Ecology & Evolution

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