Pterosaurs, winged reptiles that were among the closest relatives of dinosaurs, also had feather-like structures on their bodies, claims a new study. They likely combined functions such as temperature regulation and mate recognition, much like today’s birds.
The discovery was only possible thanks to the exceptional preservation of microscopic structures in the skin of a pterosaur found in what is now Northeast Brazil. The fossil, which corresponds to the partially preserved crest and skull of a specimen of the genus tupandactylusprobable species T. imperatoris about 115 million years old and was found in the Araripe Basin, between the states of Pernambuco, Ceará and Piauí.
The fossil likely left Brazil illegally, through international trafficking that plagues the region, but it was repatriated this year through 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 from the region, provided by geological conditions that favor the preservation of these structures.
The work on the fossil has just appeared in the scientific journal Nature. Two Brazilian researchers signed the study, Hebert Nascimento Campos, from the Maurício de Nassau University Center, and Edio-Ernst Kischlat, from the Geological Survey of Brazil, as well as European scientists led by Aude Cincotta, linked to the Belgian institute.
Although they are far from birds (a group that is essentially a branch of the carnivorous dinosaurs that has survived into our time), many pterosaurs display large crests and other adornments reminiscent of their distant modern relatives. This is the case of the Araripe animal, 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 by 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 preservation of the fossil of T. imperator allowed the team of the new study to examine the structure of the filaments present in regions of the animal’s skull, comparing it with fossilized feathers of dinosaurs, and also their interior. It turns out that, in other research carried out with fossils, paleontologists were able to observe the presence of so-called melanosomes (from the Greek, something like “black bodies”).
These tiny bags of pigment, with varying content and shape, are an important part of the range of colors and shimmers we see in today’s bird feathers. Their presence in the pterosaur specimen would therefore be another important clue about the similarity of their filaments to feathers themselves.
Paleontologist Hebert Campos says that although it is not exactly the same as bird feathers, the feather-like structures can help in understanding the origin of this morphology in animals. “The nomenclatural question is just to help with understanding, the fact is that it is a fossil with these structures extremely well preserved,” he said.
The analysis first revealed the presence of at least two different types of coverings on the skin of the Araripe flying reptile. One, the simplest, is a type of monofilament—basically “small strands” that arise in the animal’s epidermis. The other has a much more complex structure. It has a harder central axis, the thin tip of which would be inserted into the pterosaur’s dermis, and branches more or less regularly spaced on either side, resembling a small tree.
This design corresponds to some of the main parts of a bird’s feathers, such as the calamus (the “root” of the feather), the rachis (the central “stem”) and the side 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 dinos. The pigment bags 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 of branched feathers are oval. This strongly suggests a variation in type and color intensity in pterosaurs’ plumage, similar to what is seen in birds today.
If the conclusions of the study are correct, the hypothesis that the origin of feathers is a very old event should be strengthened. It was already imagined that the common ancestor of all dinosaurs could have been painful, considering the presence of this type of covering in all the main subgroups of dinos. With the new data, it is 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 master’s thesis at USP on the evolution of Brazilian tapejaridae, the fact that this specimen has an almost completely preserved crest sets it apart from the others of the genus. tupandactylus, which normally have only part of the crest and skull preserved. “We know that there are other specimens with preserved crests and pigmentation, and that is why it is important that these fossils return to Brazil and be studied by national researchers,” he says.
The work is also a victory for the movement of researchers from developing countries, such as Brazil, who have been asking for the return of relevant fossils to their countries of origin.
“I went to an academic meeting a few years ago and saw work describing these structures presented. At the time, the specimen was in a foreign collection. I am delighted to see that the policies of journals such as Nature are resulting in the repatriation of Brazilian fossils, as is the case of this tupandactylus“, said paleontologist Taissa Rodrigues, a specialist in pterosaurs at the Federal University of Espírito Santo.
