When pterosaurs took to the skies, their physique apparently offered them an important advantage: Special muscles at the base of their wings formed the dinosaur body in such a way that it generated the least possible air resistance. This is shown by a new study that analyzed the soft tissues of a well-preserved pterosaur from southern Germany. According to the researchers, the corresponding muscle group could also have made the flapping of the wings stronger and easier to adjust.
Pterosaurs were the first vertebrates that could fly on their own. They ruled the skies for around 160 million years. How exactly the sometimes huge reptiles mastered this challenge is still largely unknown. Previous studies have already shown, for example, that the pterosaurs had particularly light and yet stable bones. Many studies that provide further information about the anatomy and evolution of the pterosaurs have only been made possible by modern techniques.
Aerodynamic shape
A team led by Michael Pittman from the University of Hong Kong has now made the muscles of a fossil pterosaur visible with the help of a special scanning process. The specimen they examined comes from a limestone formation in southern Germany, the Solnhofer Plattenkalk, and is kept in the Bavarian State Collection for Paleontology in Munich. To make the sensitive soft tissues visible, the researchers used a method called laser-stimulated fluorescence. They irradiated the fossil with a special type of laser light that stimulated the fossilized tissue to fluoresce in different colors.
A muscle structure was clearly evident, stretching from the neck of the pterosaur over the shoulders to the base of the wings. “These muscles give the animal a broad outline to smooth the flow of air over the wings and reduce drag,” write Pittman and his colleagues. In the pterosaur, the muscles apparently performed a similar function to the aerodynamic panels on airplanes today. “When manufacturing aircraft, engineers try to minimize drag by creating streamlined profiles,” the researchers explain. “To do this, among other things, they attach aerodynamic panels to the smooth shapes and edges of the aircraft. The claddings are usually curved sections that direct the air flow evenly over the structure, which reduces the profile resistance. “
Muscles with a threefold advantage
Similar shape optimizations are also known from today’s flying animals. Today’s birds have aerodynamically optimized plumage at the transition from the neck to the base of the wings, and bats have a particularly thick fur on the neck, which also improves the flow of air around their bodies. “In contrast to bats and birds, the pterosaurs’ wing-root lining was unique in that it consisted primarily of muscle rather than fur or feathers,” said Pittman and his colleagues.
“The fairing muscles could have contributed to wing lift and / or movement of the fore wing during flight,” they write. “That suggests an additional power generation function.” The muscle group could therefore have offered three advantages when flying: less air resistance, better control of the wing position and more power when flapping the wings. According to the authors, their result supports the assumption that the pterosaur they studied was an agile aviator who likely hunted insects. The study also underlines how new techniques can help to better understand the flight anatomy and evolution of pterosaurs.
Source: Michael Pittman (University of Hong Kong) et al., Proceedings of the National Academy of Sciences, doi: 10.1073 / pnas.2107631118