A tiny skull, 247 million years old, upset our understanding of evolution. And it was in Grenoble, with a European synchrotron (ESRF), that the researchers raised the veil on this amazing fossil: Mirasaura Grauvogeli or “amazing reptile of Grauvogel”, in homage to the Alsatian collector who found him in the 1930s.
The fossil has been sleeping since at the Stuttgart Natural History Museum, before being scanned in the X -ray on the ESRF BM18 line. Result: a single back ridge, whose structure recalls that of the feathers, but whose evolutionary origin is quite different.
“Something exceptional”
“At the beginning, the crest left the scientists perplexed,” says Stephan Spiekman, paleontologist at the Stuttgart museum and first author of the study published in Nature. The 3D skull scan revealed a singular morphology: tapered muzzle, large orbits facing forward, teeth on the palace and a curved skull, typical of a very young individual. Characteristics common to arboreal animals.
But it is this famous ridge, made up of dense and complex appendages, which intrigues. Neither hairs nor real feathers, these growths may have been used for communication between individuals. An evolving alternative to feathers, developed long before the dinosaurs with feathers known since the 1990s. “Mirasaura provides the first direct proof that such structures emerged in the evolutionary history of reptiles”, marvels Stephan Spiekman.
A discovery made possible by the extreme finesse of the synchrotron light beams, capable of revealing the internal structure of a fossil less than 0.5 mm wide. “Without ESRF, it would have been impossible to achieve the reconstruction of the skull,” explains the researcher. Kathleen Dollman, scientist at ESRF and co -author of the study, adds: “From the first images, we understood that something exceptional was held. »»
