Pterosaurs could have brightly colored feathers, exquisite fossils

Long before the first birds took off and fluttered, pterosaurs soared into the sky. These leathery winged reptiles, bodies covered with thin filaments, which paleontologists call pycnibers, were the first vertebrates to truly fly. Now experts are beginning to think that pterosaurs and birds have more in common than previously thought: exquisitely preserved fossils from Brazil not only hint that the peculiar threads of pterosaurs could be real feathers, but also suggests that this plumage could be just as large like that of any modern toucan or tanogra.

The fossil described Wednesday in a new study in nature, it is a pterosaur is called Tupandactylus emperor which was found in the Early Cretaceous limestone of the Brazilian formation of Krato. “What’s characteristic of this sample – and it’s very obvious when you look at it – is the fact that it retains extensive soft tissues,” says study co-author Maria McNamara, a paleobiologist at Cork University College in Ireland.

This pattern has a vague and complex history. It is unclear who found the fossil and when they did, but it ended up in the hands of a private collector and was later transferred to the Royal Belgian Institute of Natural Sciences. At the time, paleontologist Edia-Ernst Kishlat “was in contact with Brazilian authorities and the Brazilian embassy in Brussels,” said lead author Od Sincata, who now works at the Belgian Institute. In October 2021, the institute signed an agreement with the Brazilian Embassy on the repatriation of the fossil, and it arrived at the Museum of Earth Sciences in Rio de Janeiro in February this year.

Unauthorized fossil excavations in Brazil and private possession of such fossils have been illegal since 1942, and the Krato Formation was only mined sometime after that year, says a paleontologist. student Rodrigo Pegasus of the Federal University of ABC in Brazil, who was not involved in the new study. Similar problems have recently arisen in the paleontology community in connection with other fossils: a study of a feathered dinosaur from the same formation in 2020 was withdrawn after it emerged that the specimen may have been exported from Brazil. The authors of the new Tupandactyl the study noted the unclear origins of the fossil in a summary report for the newspaper.

Regardless of the history of the pterosaur fossil, the transfer of personal hands to a safe place in the museum has finally made it possible to describe it. Initially, McNamara says, she and her colleagues studied the sample with a view to identifying details of its extremely clean soft tissues. Researchers were not necessarily looking for clues to color, she notes, but she says they were “thrilled” when they found such evidence in the form of microscopic structures called melanosomes.

Since 2008, paleontologists have been turning to melanosomes for study the color of fossil dinosaurs, pterosaurs and other organisms. The shape and density of melanosomes, as well as their distribution in skin, feathers and other tissues, help create what biologists know as structural colors: shades that range from rusty red to iridescent oil spots and that are created by light interacting with feathers. (However, these structures can only give a partial picture of animal coloration because many shades are created chemically.) McNamara and co-authors found different forms of melanosomes in Tupandactylskin and two types of fluffy, feather-like threads along the skull, meaning that the colors of each were different.

Paleontologists have recently challenged earlier hypotheses about which forms of melanosomes create which specific shades. “In the pterosaur we studied, we didn’t try to infer the color,” McNamara said. However, she notes, forms of melanosomes differ in two different types of filaments – whether they are interpreted as pycnofilaments or feathers – indicating different shades, with branched filaments probably lighter than unbranched.

Although this area of ​​paleontology is still new, previous studies of pterosaurs have found only homogeneous forms of melanosomes in their tissues. This suggests that these pterosaurs were either uniformly stained or relied on chemically generated staining for additional shades. Finding that Tupandactyl had different forms of melanosome among skin types and filaments is evidence that this pterosaur wore a palette of different colors in the early Cretaceous, a rice shared by birds and other feathered dinosaurs. As pterosaurs evolved, they had the ability to adjust the color of their feathers by changing the shape of their melanosomes, just like theropod dinosaurs and birds, McNamara says.

Coloring is extremely important for animals that perform a variety of roles from camouflage to communication. McNamara and her co-authors suggest that different shades of Cretaceous pterosaurs played a role in social signaling that can convey health, age, sex, mating readiness, and other vital aspects of their biology. “If some pterosaurs had intricate and colorful specimens, then, yes, this is strong evidence that they played a role in social cues.” Pegasus says, adding that they are looking forward to other researchers conducting and confirming the results of the new work.

There has also been some scientific debate as to whether pterosaur down represents true feathers or feathery pycnofilaments. McNamara, for his part, says there is no doubt that these threads are in Tupandactyl and other pterosaurs were feathers. The main evidence that she and her co-authors cite is that fossils from Brazil have both simple filaments and pinnate structures that are branched along their length, a feature visible only in dinosaur feathers.

If both pterosaurs and dinosaurs had feathers, and if these feathers had different shades for visual communication, then either these traits developed independently in each branch, or they date back to the common ancestors of both groups – reptiles that lived in the early Triassic period more than 243 millions of years ago. “We feel that the overall structure of dinosaurs and pterosaurs reflects a common origin,” McNamara says. In addition, the findings add support the hypothesis that some pen or the predecessor of a pen was present among these Triassic reptiles, suggesting that far more pterosaurs and dinosaurs wore feathery veils than paleontologists had expected. Pegasus shows that no skin prints, feathers or other body coverings of Triassic dinosaurs and pterosaurs have yet been found to test this hypothesis. Paleontologists are just beginning to uncover a deep history of colorful down and down, a line of investigation in which experts will dig into the very first days of the reptile era.