Pterosaur Study Pushes Back the Origin of Feathers by 70 Million Years
Advances in scientific technology are upending what we know about pterosaurs, the reptilian close cousins to dinosaurs who were the first of Earth’s vertebrates to achieve flapping-powered flight. They’ve long been described as covered in close-cropped fur — think Petrie in The Land Before Time. A study released Monday, however, describes pterosaurs with a twist — instead of a fur-like coat alone, they also sported multiple types of feathers.
This finding, published online Monday in Nature Ecology & Evolution, arguably pushes back the origin of feathers by about 70 million years and equips pterosaurs with feather types that scientists previously thought belonged singularly to theropod dinosaurs and modern birds. Theropods, two-legged carnivorous dinosaurs, evolved to become the 13,000 species of birds alive today.
“We knew pterosaurs had fluff or fur for some time, and it was a fair chance they might share some features with dinosaurs because the two groups originated from a common ancestor,” co-author and University of Bristol professor of vertebrate paleontology Michael Benton, Ph.D., tells Inverse. “We believe, then, we have evidence that shifts the origin of simple feathers way back in time.”
Scientists have known about pterosaurs’ fur-like covering, technically known as pycnofibres. The idea, which still holds strong, with some critics, was that the lizards were adorned with one type of pycnofibre, and these were fundamentally different than the feathers we see covering birds today. However, Benton and his colleagues provide evidence that pterosaurs had at least four types of feathers: simple filaments (the fur-like hairs), bundles of filaments, filaments with a tuft halfway down, and down feathers.
These examples of four feather types were seen once the team applied high-powered microscopes on two specimens of two short-tailed anurognathid pterosaurs who lived between 165 and 160 million years ago in China. Apart from the fur-like hairs, the three types of filaments appeared to be branched under the lens of microscopic and spectroscopic imaging techniques — a distinctive morphological feature of feathers, and the main argument for these being classified as such. The scientists were also able to pick up on the melanosomes inside the feathers, which suggest that these two pterosaurs were red-heads.
The team argues that these different coverings likely helped play a role in heat regulation, sensing, signaling, and aerodynamics. Branching features, Benton explains, can be fluffed up more than single-string feathers. Pterosaurs, much like birds, probably relied on that fluff to stay warm.
It’s actually not that difficult to imagine how these different feather combinations worked — Benton explains that that we just need to take a peek at birds alive today.
“If you look at a chicken, it has fluffy down feathers on its breast and complex flight feathers on its wings,” Benton says. “So, it’s more a point that pterosaurs didn’t just have simple single-strand structures, but many showed branching. Modern birds have a variety of feather types too.”
What future research will illuminate is whether feathers are ancestral to both dinosaurs and pterosaurs, or evolved independently in both lineages. Because these four pycnofibre types aren’t anatomically different in bird and dinosaur feathers, this team places its bet on the former. It could be that there’s an evolutionary origin point for feathers, and the trait was suppressed among other types of ancient creatures like armored dinosaurs and sauropods. Regardless, it means that all the pop culture pterosaurs are inaccurate in looks — and need a dash of feathery-fluff.