Pterosaurs coexisted with dinosaurs between 230 and 66 million years ago. They had broad wings formed by a series of membranes and some species were covered with down. The question of whether they had real feathers has long been debated among the paleontological community. From a fossilized pterosaur skull 115 million years discovered in northeastern Brazil, researchers are now providing new evidence to clarify the debate. The results of his study have just been published in the journal Nature.
Two types of feathers clearly identified
This fossil of Tupandactylus imperator it consists of a skull crowned by a huge crest made of soft tissue, at the base of which are feathers. The team identified two types of feathers: straight, dark feathers that look like hair, and shorter, branched, light-colored feathers. ” The proximal part of the occipital process is mainly associated with monofilaments (about 30 mm long and 60-90 μm wide. […] The distal part of the occipital process is associated with short branched integumentary structures (2-5 mm long). “, the researchers report.
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The discovery of branched feathers is especially remarkable: so far they have only been observed in certain theropods, bipedal carnivorous dinosaurs, ancestors of modern birds. ” For decades, paleontologists have debated whether pterosaurs had feathers. The feathers in our specimen definitely close this debate, because they are very clearly branched along their entire length, just like today’s birds. said Dr. Aude Cincotta, a paleontologist at University College Cork, Ireland, and the Royal Institute of Natural Sciences in Belgium.
The feathers, which today are the main character in the bird class, are made of β-keratin. They allow birds to fly, to protect themselves from cold and moisture (through a thermoregulatory mechanism) and sometimes to protect themselves from their predator (by mimicry or camouflage). Plumage also plays a vital role in visual communication throughout a bird’s life, especially when selecting a mate: colored feathers are usually used for visibility.
a) Incomplete skull showing a preserved soft tissue crest. bf) Detail of the integumentary structures associated with the back of the skull: b) monofilaments, c) branched feathers, d) detail of the curved branched feather in c), straight branched feather (e) with detail (f). gi) Soft tissue melanosomes: g) ovoid elongated crest fiber melanosomes, h) elongated monofilament melanosomes, i) ovoid branched feather melanosomes. Credits: A. Cincotta et al., Nature (2022)
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Looking closer at the pterosaur’s feathers using high-power electron microscopy, the team discovered melanosomes that were still intact. Melanosomes are intracellular organelles in which melanin is produced, the biological pigments responsible for the coloration of the skin of animals (skin, hair, scales, shell, feathers, etc.). The researchers were surprised to find that melanosomes in different types of feathers had different shapes (rather elongated for monofilaments, and rather ovoid for branched feathers), which had only been observed in theropods, including feathers. .
A characteristic inherited from a common ancestor
Previous analyzes of pterosaur feathers had revealed relatively homogeneous geometries of ovoid melanosomes, suggesting so far that these animals had limited color variation and therefore supported the hypothesis that early feathers played primarily a thermoregulatory role.
In modern birds, the color of the feathers is strongly related to the shape of the melanosomes. Therefore, from their observations, the researchers deduced that pterosaurs must also have all the necessary genetic machinery to control the color of their feathers. ” That feature it is essential for color modeling and demonstrates that color was a feature fundamental feathers primitivethey are “, emphasizes Maria McNamara, a professor at University College Cork and co-author of the study.
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Pterosaurs probably used these colorful attributes to communicate with each other or with other species. The fact that these pigmented feathers are present in both dinosaurs and pterosaurs suggests that their common ancestor, dating to the Middle or Late Triassic, about 250 to 200 million years ago, already had this form of pigmentation.
Note that after being examined in detail, the fossil of Tupandactylus imperator he was sent back to Brazil. ” It is very important that fossils of scientific interest such as Tupandactylus be repatriated to their country of origin and stored safely. said Edio-Ernst Kischlat, a paleontologist with the Geological Survey of Brazil and co-author of the publication.