Body coverings such as hair and feathers have played a central role in evolution, enabling warm-bloodedness by insulating the body and serving purposes such as courtship, display, and deterrence of enemies. An international team led by palaeontologists Dr. Stephan Spiekman and Prof. Dr. Rainer Schoch from the State Museum of Natural History Stuttgart, Germany, has unveiled a groundbreaking discovery that challenges our understanding of reptile evolution. The team has identified a previously unknown tree-dwelling reptile from the early Middle Triassic, named Mirasaura grauvogeli, or ‘Grauvogel’s Wonder Reptile’. This 247-million-year-old reptile boasted a dorsal crest with complex appendages similar to feathers, suggesting that such structures may predate modern reptiles.
The discovery, published in the prestigious journal Nature, reveals that complex skin structures are not exclusive to birds and their closest relatives. The crest of Mirasaura consists of individual, densely overlapping appendages with a feather-like contour. While lacking the delicate branching seen in true feathers, the structure of these appendages suggests an independent evolutionary path from that of birds.
Unique Skin Structures in Early Reptiles
The revelation of such complex skin appendages in an ancient group of reptiles provides new insights into their evolution. “The fact that we have discovered such complex skin appendages in such an ancient group of reptiles sheds a new light on their evolution,” says Dr. Stephan Spiekman, lead author of the study. He notes that Mirasaura is older than dinosaurs and not closely related to them. Developmental biology studies indicate that the genetic basis for complex skin appendages like feathers likely originated over 300 million years ago in the Carboniferous period. Mirasaura represents the first direct evidence of these structures forming early in reptile evolution.
Dinosaurs and the Origin of Feathers
This study marks a significant turning point in palaeontological research, which began with the discovery of feathered dinosaurs in China in the late 1990s. Prior to this, reptiles, including dinosaurs, were thought to be covered in scales, with feathers exclusive to true birds. The discovery of feathered, non-avian dinosaurs blurred the lines between scaly, ‘cold-blooded’ reptiles and feathered, ‘warm-blooded’ birds. Now, Mirasaura grauvogeli adds another layer of complexity to this evolutionary narrative.
“Mirasaura grauvogeli shows us how surprising evolution can be and what potential it holds,” says Prof. Dr. Rainer Schoch, reptile expert and head of the Palaeontology Department at the State Museum of Natural History in Stuttgart. He emphasizes that the independent development of structures similar to feathers long before the dinosaurs will stimulate further discussion and research.
Bizarre Tree-Climbers with Bird-Like Skulls and Claws
The latest technologies, including synchrotron imaging at the European Synchrotron (ESRF), have been employed to study Mirasaura. This revealed a bird-like skull with a narrow, mostly toothless snout, large forward-facing eye sockets, and a domed skull, likely used for extracting insects from tree holes. Belonging to the drepanosauromorphs, Mirasaura is part of a group known for bizarre features, such as grasping forelimbs and prehensile tails, allowing them to maneuver through trees like monkeys.
“Drepanosaurs have many ecological adaptations and have only been known to science for a few decades,” says Prof. Dr. Hans Sues from the National Museum of Natural History, Washington DC. He highlights that the dorsal crest with novel skin structures in Mirasaura adds to the remarkable adaptations of this unique reptile group.
Melanosomes and Skin Structures
Analyses of a thin, brown film partially preserved on the crest of Mirasaura confirmed the presence of melanosomes, tiny organelles containing melanin pigments. Dr. Valentina Rossi, an expert on fossil melanosome research, notes that the melanosomes in Mirasaura are more similar in shape to those found in extant and fossil feathers than those in mammalian hair and reptilian skin. This finding further supports the notion of independent evolution of feather-like structures.
Grauvogel’s ‘Wonder Reptile’
The discovery of Mirasaura grauvogeli is deeply rooted in the history of fossil collection. Louis Grauvogel, a local fossil collector, began excavating fossils from the Middle Triassic period in Alsace, France, in the 1930s. His extensive collection, which included the remains of Mirasaura, was transferred to the State Museum of Natural History Stuttgart in 2019. The fossils are now part of the museum’s palaeontological collection, available for research and public exhibition.
Dr. Léa Grauvogel-Stamm, a palaeobotanist and daughter of Louis Grauvogel, played a crucial role in researching and maintaining the collection. An interdisciplinary team of palaeontologists plans to further investigate the site where Mirasaura grauvogeli was found, aiming to understand why the skin outgrowths are so well preserved. Future research will also explore the ecology, biology, and environment of Mirasaura, as well as its interactions with other animals.
The State Museum of Natural History Stuttgart, a forward-looking research and communication institute, houses over 12 million objects. It researches the evolution of life and biodiversity, communicating findings to the public. The research was funded by the DFG – Deutsche Forschungsgemeinschaft and the European Research Council, with support from various cultural and scientific organizations.
