Small pterosaurs ‘pole vaulted’ to flight from water, study suggests

An analysis of a small pterosaur fossil has provided more evidence that the Jurassic-era flying reptiles used their long arms to rock back and forth to “pole vault” themselves into the air.

The research, recently published in the journal Scientific Reports, assessed a tiny pterosaur fossil from rocks dated to the late Jurassic era about 163 million years to 146 million years ago unearthed in Germany.

Scientists studying fossils of pterosaurs since they were first discovered over two centuries ago have reasoned that the physical features of the flying reptiles, including a “forward centre of gravity”, prevented them from a bird-like running launch.

Researchers have theorised a launch from water bodies for pterosaurs, similar to a method seen in modern-day water-feeding birds and bats.

However, direct physical evidence of such mechanism has been elusive, until now.

In the new study, scientists, including Michael Pittman from the Department of Earth Sciences and University College London, analysed the fossil remains of a pterosaur type called aurorazhdarchid unearthed from the Jurassic rocks of Germany with well-preserved soft tissues, including a wing membrane and webbed feet.

Their analysis suggests the soft tissues were primary propulsive contact surfaces needed for the pterosaur’s water launch with a four-legged pole-vaulting mechanism.

With previous studies indicating that pterosaurs were not strong swimmers, scientists say the soft tissues likely aided in launching from water rather than being swimming adaptations.

When folded, the pterosaur’s wings may have helped the reptile push off from the water’s surface.

The findings “reveal that quadrupedal water launch was theoretically feasible and that webbed feet significantly impacted launch performance”, according to the researchers.

They could also identify key factors limiting water launch performance in all pterosaurs, including “available propulsive contact area, forelimb extension range and forelimb extension power about the shoulder”.

Scientists believe the new findings also offer comparative context for further investigations of water launch potential and evolution in pterosaurs.

“While many small pterosaurs likely had enough contact area, range of motion, and power to escape the water surface, it is quite plausible that more terrestrial taxa may have been unable to water launch, especially if a lack of pedal webbing limited propulsive contact area,” they wrote in the study.

The new findings follow a collection of studies published last year, in which researchers assessed the fossil of a giant pterosaur Quetzalcoatlus that weighed over 250kg and had a wingspan of nearly 12 metres.

The 2021 research suggested giant pterosaurs likely leaped, jumping at least 2.5m into the air, before lifting off.

Scientists have called for further analysis of additional specimens in the future to decode the evolution of flight across pterosaur species.