Discovery reveals how ancient reptiles ruled the skies

An evolutionary puzzle relating to how pterosaurs took flight and dominated the air, some 225 million years ago, has been solved.

Pterosaur flying through the air with use of tail vane.
Pterosaur flies with use of its tail vane. Illustration by Dr Natalia Jagielska.

Pterosaurs – commonly known as pterodactyls – were the first and largest vertebrates to achieve powered flight and did so with the aid of a lattice-like vane, attached to the tip of their tails, research reveals.

Stable flight

The diamond-shaped structure, made from interwoven membranes, prevented pterosaurs’ long tails from fluttering like flags in the wind and instead helped to guide and stabilise the creatures in flight.

Previous research revealed that maintaining stiffness in the tail vane was crucial to enable early pterosaur’s flight, but exactly how this was achieved remained a mystery, until now.

Mystery solved

The study, led by paleontologists from the University of Edinburgh discovered that that the tail vane most likely behaved like a sail on a ship, becoming tense as the wind blew through the cross-linked membranes to steer the ancient reptiles through the sky.

Studying prehistoric animals is usually restricted to examining fossilized bone but sometimes traces of delicate tissues such as skin and membranes can survive for millions of years, experts say.

Fresh techniques

The research team used a new technique called Laser Simulated Fluorescence – which causes organic tissues almost invisible to the naked eye to glow – on the fossils of a pterosaur known as Rhamphorhynchus.

Despite being 150 million years old, the delicate membrane of Rhamphorhynchus’ tail vane and its internal structures visibly popped up when scanned with the laser, providing the team with valuable insight into Pterosaurs’ anatomy and evolution.    

Total domination

Pterosaurs thrived in the skies for more than a hundred million years, before perishing with the dinosaurs in the end-Cretaceous extinction.

The research, published in the journal eLife, was led by scientists from the University of Edinburgh and the Chinese University of Hong Kong in collaboration with the National Museum of Scotland, Edinburgh and the Natural History Museum, London. It was funded by NERC.

It never ceases to astound me that, despite the passing of hundreds of millions of years, we can put skin on the bone of animals we will never see in our lifetimes.

"Pterosaurs were wholly unique animals with no modern equivalents, with a huge elastic membrane stretching from their ankle to the tip of the hyper-elongated fourth finger. For all we know, figuring out how pterosaur membranes worked, may inspire new aircraft technologies.

Without the researchers' vision to apply new technology to apparently well-understood fossils, this tail vane would have remained in the dark. It is exciting to now see a critical feature of the pterosaur's anatomy so beautifully displayed.

This study gives us an important glimpse into how early pterosaurs may have first taken to the skies and the importance of their tails while in the air. The study also raises intriguing possibilities for how pterosaurs may have used their tails to attract a mate; pterosaur tails may have been more colourful than we ever thought.

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