Whether scales, hair or feathers: the skin of vertebrates has produced an amazing variety of forms in the course of evolution. But when and how these structures were created for the first time is still not fully clarified. A fossil reptile from the middle triad now provides new clues: Mirasaura Grauvogeli had striking skin processes along the back that neither real feathers nor hair, but still similarly resemble them.
Our hair is nothing more than cornifications of the extreme skin layer and also with bird feathers there are specialized skin structures. Such skin attachments bring many advantages: they protect against cold, serve camouflage and communication with fellow species and even enable flying for birds. But it was probably neither the birds nor the mammals that “invented” the skin hangers, but a common ancestor that lived over 300 million years ago and which these two groups share with the reptiles. There has been no direct fossils of this ancestor yet, but a find from France now provides concrete indications that complex skin slopes existed in early reptiles.
A miracle reptile with the backkamm
It is the small tree -inhabitant reptile “Mirasaura Grauvogeli”, which lived in the Middle Triassic in the area of today’s southern France 247 million years ago. His fossil remains were discovered in Alsace in the 1930s, but only now examined more precisely by paleontologists around Stephan Spiekman from the State Museum of Natural History in Stuttgart. It showed: Mirasaura, which translates as much as “miracle reptile”, surprisingly had a backkamm from spring -like structures.
These skin processes were finely structured and consisted of at least 16 densely overlapping elements, each with a spring -like contour with a narrow middle ridge. With a length of five to 50 millimeters, the “springs” also reached surprising dimensions. The largest of them made up more than a third of the body length of Mirasaura. But why did the reptile have this striking backkamm? As the team suspects, the skin processes could have served to impress fellow species or deter rivals. The back crest may even have colored and fulfilled a signal function in the Triaswald.
No bird, no dinosaurs – and still “springs”
As the paleontologists report, the early reptile belonged to the extinct group of the Drepanosaur. These were tree dwellers with gripping tail, large eyes and skillful hands with which they could hold on to branches like monkeys. Mirasaura also had a bird -like skull with a narrow, largely toothless snout, with which he could probably fish insects from narrow tree caves. Although Mirasaura is not related to the dinosaurs and therefore does not belong to the line of the birds, his skin processes show some surprising parallels to modern springs.
These similarities primarily affect the melanosomes – tiny cell organelles that store color pigments and are petrified by Mirasaura. “The melanosomes found in the soft tissues of Mirasaura are more like those who occur in existing and fossil feathers than the melanosomes that can be found in mammalian hair and reptile skin,” reports co-author Valentina Rossi from University College Cork. So although Mirasaura did not wear feathers, the similarities in the skin processes and the melanosomes contained indicate that early reptiles developed complex pigmented skin structures.
This could in turn mean that the evolutionary origins go back significantly from feather -like attachments than previously assumed – long before birds and dinosaurs express these characteristics. “The discovery shows that the ability to develop complex skin processes is much older and more widespread than previously assumed,” says Spiekman. “Mirasaura provides the first direct evidence of such structures in a group that is not part of birds or mammals.”
Source: Stephan Spiekman (State Museum of Natural History Stuttgart) et al.; Nature, DOI: 10.1038/S41586-025-09167-9
