Pterosaurs, the largest animals ever to fly, soared the skies for 160 million years – much longer than any species of modern bird. That ought to be enough to think about how they did it, and what we can learn from them.
But despite their aeronautic excellence, these ancient flyers have largely been overlooked in the pursuit of bio-inspired flight technologies.
Now, in a review just published in the journal Trends in Ecology and Evolution, researchers outline why and how the physiology of fossil flyers could provide ancient solutions to modern flight problems, such as aerial stability and the ability of drones to self-launch.
“There’s a lot of really cool stuff in the fossil record that goes unexplored because engineers generally don’t look to palaeontology when thinking about inspiration for flight,” says lead author Liz Martin-Silverstone, from the University of Bristol, UK.
“If we’re only looking at modern animals for inspiration, we’re really missing a large degree of the morphology out there and ignoring a lot of options that I think could be useful.”
Previously, engineers have largely focused on the physiology of modern birds and insects when designing aeronautic technology like drones and planes; fossils are often incomplete.
But Martin-Silverstone says there are a select few pterosaur fossils that provide extraordinarily deep insight into the anatomy of their wings, which is essential for understanding their flight capabilities.
“There are two or three absolutely amazingly preserved pterosaur fossils that let you see the different layers within the wing membrane, giving us insight into its fibrous components,” she says.
“Also, some fossils are preserved enough to show the wing attachments beneath the hip. While you don’t know exactly the shape of the wing, by knowing the membrane attachments you can model the effectiveness of different wing shapes and determine which would have performed best in natural conditions.”
Analysis of the shape and predicted flight mechanics of these ancient creatures has revealed novel tactics that don’t exist in modern flyers.
Getting airborne is one example.
Launching into the air through a leap or jump, also known as ballistic launch, is standard throughout the animal kingdom. However, larger birds require a running start to gain enough momentum for lift-off.
Incredibly, pterosaurs may have developed a method to launch from a stationary position, despite some specimens weighing nearly 300 kilograms.
One hypothesis, proposed by co-author Mike Habib, of the Dinosaur Institute at the Natural History Museum of Los Angeles County, US, suggests that the wing membrane and the robust muscle attachments in the wings allowed pterosaurs to generate a high-powered leap off their elbows and wrists, giving them enough height to become airborne.
“Today, something like a drone requires a flat surface to launch and is quite restricted on how it actually gets into the air,” says Martin-Silverstone.
“The unique launch physiology of pterosaurs might be able to help solve some of these problems.”
Pterosaurs can also provide insights on preventing instability in flight.
Contrary to the way sails can become unstable in a strong wind, pterosaurs evolved strategies to resist flutter of their broad wings.
“So far we’ve struggled to design things like flight suits that can resist the pressures of flight,” says Martin-Silverstone.
“If we can understand how pterosaurs did it, for instance by understanding how their wing membrane was actually structured, then that’s something we can use to answer modern engineering questions.”
Martin-Silverstone suggests that if we combine our knowledge from flyers both living and extinct, we’ll have a much better chance of overcoming the hurdles still hindering man-made flight. She wants biologists and engineers to reach out to palaeontologists when they’re looking to solve flight problems.
“If we limit ourselves to looking at the modern animals, then we’re missing out on a lot of diversity that might be useful.”
Ian Connellan is editor-in-chief of the Royal Institution of Australia.
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