Body coverings such as hair and feathers play a central role in evolution. As complex skin appendages, they not only enable warm-bloodedness by forming an insulating body coverage but often serve a range of other functions such as perception, camouflage, display, or, in the case of birds, flight. Likely developed from the primitive scales of their reptile-like ancestors, such complex skin appendages have until now only been known in mammals, birds, and their closest fossil relatives—dinosaurs and pterosaurs.
An international team led by palaeontologists Dr. Stephan Spiekman and Prof. Dr. Rainer Schoch from the State Museum of Natural History Stuttgart has now described an early Triassic reptile from around 247 million years ago that likely developed another type of complex skin outgrowth, distinct from feathers and hair. The small reptile had a crest consisting of densely overlapping appendages that show a feather-like contour with a narrow central ridge. However, while “modern” feathers consist of many delicate, branched structures called barbs, no evidence of branching was found in the newly described animal. For this reason, the research team infers that the structure of the skin appendages evolved largely independently from the feathers of dinosaurs and birds.
The wondrous reptile was named Mirasaura grauvogeli by the researchers, meaning “Grauvogel’s wonder reptile,” honoring Louis Grauvogel, a French fossil collector and the discoverer of the fossil.
The investigation revealed that Mirasaura belongs to the drepanosaurs, a rather unusual group of early reptiles that existed exclusively during the Triassic period. Like most other known drepanosaurs, Mirasaura was arboreal and lived in the first forests emerging after the greatest mass extinction event in Earth’s history, which occurred 252 million years ago at the end of the Permian, also known as ‘the Great Dying’. The skull of the “wonder reptile” was bird-like, with a domed skull, forward-facing eyes, and a narrow, almost toothless snout. The small reptile hunted insects among the branches of trees and other plants.
The crest on Mirasaura’s back is long, relatively narrow, and probably served either to impress potential mates or to deter predators. A closer examination of the skin outgrowths showed that they contained melanosomes. Melanosomes are cell structures that contain pigments. Thus, it can be assumed that the fan was possibly brightly coloured—or at least patterned. Interestingly, Mirasaura probably could not “fold” its crest onto its back, so it would have always been held upright.
The discovery of Mirasaura’s 247-million-year-old “feather alternative” fundamentally expands our understanding of reptile evolution and once again demonstrates how flexible and continually surprising evolution can be.
The scientific article was published in the scientific journal “Nature”.