by Patrick J. Kiger
New research sheds light on how reptiles flew like glider pilots and parachutists some 50 million years before the first birds.
The study, by scientists from the University of Bristol in the U.K., who published their findings in the journal Paleontology, shows that the reptiles, members of the family Kuehneosauridae, which existed 225 million years ago, used membrane-covered extensions of their ribs to form large gliding surfaces on the sides of their bodies.
Fossilized remains of the 2-foot-long ancient creatures were first found in the 1950s in a cave system near Bristol. Their lateral wings were always assumed to be some sort of adaptation that enabled flight, but this is the first study of their aerodynamic capability.
Chief researcher Koen Stein, who did the work while studying for a masters in paleobiology, found that two genera of the reptiles had slightly different structures and different methods of flying. Kuehneosuchus was a glider with elongated wings, while kuehneosaurus, with much shorter wings, was a parachutist. As the two forms are so alike in other respects, it is possible that they are males and females of the same animal.
Stein and colleagues built models of the creatures and tested them in a wind tunnel belonging to Bristol’s aerospace engineering department.
“Surprisingly, we found that Kuehneosuchus was aerodynamically very stable,” Stein explained in a Bristol press release. “Jumping from a five-metre tree, it could easily have crossed nine metres distance before landing on the ground. The other form, Kuehneosaurus, was more of a parachutist than a glider.”
So that Stein and his colleagues could work out how these creatures controlled their flight, they had to model different skin flaps over the wing area. “We also built webbed hands and feet and had an extra skin membrane between the legs on the models, but these made the flight of the animals unstable, suggesting that they probably did not have such features.”
“This is a fantastic example of interdisciplinary research,” said professor Michael Benton, a member of the research team. “Palaeontologists are keen to understand how all the amazing animals of the past operated, and by collaborating with aerospace engineers we can be sure that model-making and calculations are more realistic.”
The study found that keuhneosaurus’ parachuting speed, descending at a 45-degree angle, would be between 10 and 12 meters per second.
The researchers also tried to figure out how the creatures controlled their flights.
"We also built webbed hands and feet and had an extra skin membrane between the legs on the models, but these made the flight of the animals unstable, suggesting that they probably did not have such features," Stein said.
