New bizarre Triassic reptile with a feather-like crest discovered

The 247-million-year-old reptile is called Mirasaura grauvogeli, which means 'Grauvogel's Wonder
Reptile', in honour of the fossil collector who found it, Louis Grauvogel. The fossil was found in the 1930s in Alsace (France) and transferred to the State Museum of Natural History in Stuttgart in 2019.
The bizarre creature shows characteristics from reptiles but presents a dorsal crest with previously
unknown, structurally complex appendages growing from its skin, with some similarities to feathers.

The crest was probably used for display to other members of the same species. The finding shows that complex skin structures are not only found in birds and their closest relatives but may predate modern reptiles. This discovery changes our understanding of reptile evolution. “At first scientists were puzzled about the crest, but after preparation, a reptile skull was revealed. We can
now safely say that is a new species from a very strange group reptiles called drepanosaurs”, explains
palaeontologist Stephan Spiekman, first author of the study, from the State Museum of Natural History Stuttgart, Germany.

In order to analyse the specimen, which was a few centimetres in length and less than 0.5 millimetres in width, the team came to the ESRF’s new experimental station BM18. There, they scanned the skull using X-ray tomography, which revealed a bird-like shape with a narrow, mostly toothless snout, large forward-facing eye sockets and a large, domed skull. Kathleen Dollman, scientist at the ESRF and co-author of the publication, says: “The fossil is incredible and showed these feather-like structures beautifully. I knew that imaging such fine details was going to be challenging, but when we started to see the first images on BM18 I knew that we had found something special”.

Spiekman adds: “Without the ESRF we could not have been able to do the reconstruction of the skull,
because the fossil is so small that it is incredibly difficult to scan – it took me four months of working on the data to get the full reconstruction!”. This is the first Nature publication stemming from research carried out at the new BM18 beamline.

With the findings, the team hypothesized that the snout was probably used to extract insects from narrow tree holes, the big forward-facing eyes are typical of animal living in trees and the domed skull shows a fontanelle, which indicates that the specimen was very young when it died. It also had teeth in the roof of the mouth, as many different groups of extinct reptiles do.

Not hairs, not feathers, but something similar

Body coverings such as hair and feathers have played a central role in evolution. They enabled warm-
bloodedness by insulating the body, and were used for courtship, display, deterrence of enemies and, in the case of feathers, flight. Their structure in mammals and birds is characterised by longer and more complex skin outgrowths that differ significantly from the simple and flat scales of reptiles.

The crest of Mirasaura consists of individual, densely overlapping appendages that each possess a feather-like contour with a narrow central ridge. While real feathers consist of many delicate branched structures called barbs, there is no evidence of such branching in the appendages of Mirasaura. Because of this, the team believes that the structure of the complex, unique skin appendages of Mirasaura evolved largely independently of those of birds.

Dinosaurs and the origins of feathers

The study marks a turning point in a nearly 30-year trend in palaeontological research that began with the discovery of feathered dinosaurs in China in the late 1990s. Before this time, it was thought that reptiles, including dinosaurs that gave rise to birds, were covered with two scales and that only true birds had feathers. This changed when research started to show that many dinosaurs were much more bird-like than previously thought.

The discovery of feathered, non-avian dinosaurs in China caused a wave of new studies that began to blur the lines between scaly, 'cold-blooded' reptiles on the one hand and feathered, 'warm-blooded' birds on the other. Now, it is clear that the story is even more complex. "The fact that we have discovered such complex skin appendages in such an ancient group of reptiles sheds a new light on their evolution. Mirasaura is even older than the dinosaurs and not closely related to them.
Developmental biology studies show that the genetic basis for the growth of complex skin appendages, such as feathers, probably originated in the Carboniferous period more than 300 million years ago. Mirasaura provides the first direct evidence that such structures actually did form early on in reptile evolution, in groups not closely related to birds and extinct dinosaurs," says Spiekman.
"Mirasaura grauvogeli shows us how surprising evolution can be and what potential it holds. It repeatedly produces similar structures that are completely independent of each other but also structures that are so different that they can be distinguished. Mirasaura developed an alternative to feathers very early in Earth's history, long before the dinosaurs, which we did not expect and which will stimulate discussion and research," says Rainer Schoch, reptile expert and head of the Palaeontology Department at the State Museum of Natural History in Stuttgart and corresponding author of the publication. 

Reference:
Stephan N.F. Spiekman, et al.,  Nature. DOI: 10.1038/s41586-025-09167-9
 

Top image: Reconstruction and illustration of Mirasaura in its natural forested environment, hunting insects. Copyright: Gabriel Ugueto