The pterosaur with traces of color reveals the origin of the feathers – 20/04/2022 – Science / Brazil

The pterosaur with traces of color reveals the origin of the feathers – 20/04/2022 – Science / Brazil

According to a new study, pterosaurs, winged reptiles that were among the dinosaurs’ closest relatives, also had feather-like structures on their bodies. They likely combined functions such as temperature regulation and mate recognition, just like today’s birds.

The discovery was made possible only by the exceptional preservation of microscopic structures in the skin of a pterosaur found in present-day northeastern Brazil. The fossil, which corresponds to the partially preserved crest and skull of such a specimen tupandattiloprobable species T emperorIt is about 115 million years old and has been found in the Araripe basin, between the states of Pernambuco, Ceará and Piauí.

The fossil probably left Brazil illegally, due to international trafficking affecting the region, but was repatriated this year thanks to an agreement between the Royal Institute of Natural Sciences of Belgium, where it was housed, and the Brazilian government.

The greed for this and other Araripe fossils is explained precisely by the presence of soft tissue details (muscles, skin, blood vessels and even feathers) in specimens of the region, provided by geological conditions that favor the conservation of these structures.

The work on the fossil just appeared in the scientific journal Nature. The study was signed by two Brazilian researchers, Hebert Nascimento Campos, of the Maurício de Nassau University Center, and Edio-Ernst Kischlat, of the Geological Survey of Brazil, as well as European scientists led by Aude Cincotta, linked to the Belgian institute.

Although remote from birds (a group that is essentially an offshoot of the carnivorous dinosaurs that have survived to the present day), many pterosaurs display large crests and other adornments that are reminiscent of their distant modern relatives. This is the case of the animal Araripe, owner of a showy crest and with a wingspan that could reach 3 meters. It was also already known that the body of flying reptiles could be covered with mysterious filaments. These structures are sometimes compared to fur, but in recent years some researchers have argued that they are closer to the feathers of birds and dinosaurs.

The excellent conservation of the fossil of T emperor It allowed the new study group to examine the structure of the filaments present in the regions of the animal’s skull, comparing it to the fossilized dinosaur feathers, as well as its interior. It turns out that, in another investigation conducted on fossils, paleontologists were able to observe the presence of so-called melanosomes (from the Greek, something like “black bodies”).

These little pigment pouches, with varying content and shapes, are an important part of the range of colors and brightness we see in today’s bird feathers. Its presence in the pterosaur specimen would therefore be another important clue to the similarity of its filaments to the feathers themselves.

Paleontologist Hebert Campos says that while not quite the same as bird feathers, the feather-like structures can help understand the origin of this morphology in animals. “The problem with the nomenclature is just to help understand, the fact is that it’s a fossil with these extremely well-preserved structures,” he said.

The analysis first revealed the presence of at least two different types of coverings on the skin of the flying reptile Araripe. One, the simplest, is a type of monofilament, basically the “filippi” that arise in the epidermis of the animal. The other has a much more complex structure. It has a harder central axis, the fine tip of which would be inserted into the pterosaur’s dermis, and more or less regularly spaced branches on either side, resembling a small tree.

This design corresponds to some of the main parts of a bird’s feathers, such as the quill (the “root” of the feather), the rachis (the central “stem”) and the lateral branches. And both types of filaments can be found in dinosaurs with fossilized feathers.

The shape and distribution of melanosomes complete the picture of great similarities with the feathers of birds and dinosaurs. The pigment pockets have different shapes (elongated, oval and spherical), which are distributed in a specific way in the different structures of the skin. Monofilaments contain only elongated melanosomes, for example, while those with branched feathers are oval. This strongly suggests a variation in the type and intensity of color in the pterosaur’s plumage, similar to that seen in birds today.

If the conclusions of the study are correct, the hypothesis that the origin of feathers is a very ancient fact must be strengthened. He already imagined that the common ancestor of all dinosaurs could be painful, given the presence of this type of cover in all major dinosaur subgroups. With the new data, it’s possible that the common ancestor of dinosaurs and pterosaurs was also covered in feathers to some extent.

For the biologist Lucas Piazentin, who defended a thesis at the USP on the evolution of the Brazilian tapejaridae, the fact that this specimen has an almost completely preserved crest differentiates it from the rest of the genus. tupandattilo, which normally retain only part of the crest and skull. “We know there are other specimens with preserved ridges and pigmentation, which is why it is important that these fossils return to Brazil and be studied by national researchers,” he says.

The work is also a win for the movement of researchers from developing countries, such as Brazil, who have called for the return of relevant fossils to their countries of origin.

“I went to an academic meeting a few years ago and saw a document describing these structures being presented. At the time, the specimen was in a foreign collection. I am pleased to see that the policies of journals such as Nature are leading to the repatriation of Brazilian fossils, as is the case with this one. tupandattilosaid paleontologist Taissa Rodrigues, a pterosaur specialist at the Federal University of Espírito Santo.