The physiology of pterosaurs and other fossil flyers could provide ancient solutions to modern flight problems, such as aerial stability and the ability of drones to self-launch, according to a new paper published in the journal Trends in Ecology & Evolution.
A reconstruction of the giant pterosaur Hatzegopteryx launching into the air, just after the forelimbs have left the ground. Image credit: Mark Witton.
“There’s a lot of really cool stuff in the fossil record that goes unexplored because engineers generally don’t look to paleontology when thinking about inspiration for flight,” said Dr. Liz Martin-Silverstone, a postdoctoral researcher at the University of Bristol.
“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. They might not think to examine fossils which are often incomplete.
However, 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,” Dr. Martin-Silverstone said.
“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.”
Analyzing the morphology and predicted flight mechanics of these ancient creatures has revealed novel tactics that don’t exist in modern flyers.
Becoming 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.
Pterosaurs, on the other hand, may have developed a method to launch from a stationary position despite some specimens weighing nearly 300 kg.
One hypothesis suggests that the wing membrane and robust muscle attachments in the wings allowed pterosaurs to generate a high-powered leap off of 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,” Dr. Martin-Silverstone said.
“The unique launch physiology of pterosaurs might be able to help solve some of these problems.”
Pterosaurs can also provide insights on how to prevent flight instability once in the air.
Contrary to how 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. 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,” Dr. Martin-Silverstone said.
These unique physiological elements aren’t limited to just pterosaurs, either.
Other ancient flyers, such as Microraptor, had feathered wings on both their arms and legs, while a recently-discovered dinosaur, Yi qi, had wings that combined feathers with a bat-like membrane — a body plan that has never been repeated since their extinction.
As such, many flight strategies remain to be properly explored.
“If we combine our knowledge from flyers both living and extinct, we will have a much better chance of overcoming the hurdles still hindering manmade flight,” Dr. Martin-Silverstone said.
“We want biologists and engineers alike to reach out to paleontologists when they are looking to solving flight problems, as there might be something extinct that could help. If we limit ourselves to looking at the modern animals, then we’re missing out on a lot of diversity that might be useful.”
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Elizabeth Martin-Silverstone et al. Volant Fossil Vertebrates: Potential for Bioinspired Flight Technology. Trends in Ecology & Evolution, published online April 14, 2020; doi: 10.1016/j.tree.2020.03.005
