New pterosaur from Skye reveals the hidden diversity of the Middle Jurassic

A well-preserved fossil uncovered on the Isle of Skye has been revealed as a new species of pterosaur.

With an estimated wingspan of 1.6 metres, Ceoptera evansae would have soared through the Jurassic skies over 165 million years ago. Its fossil gives scientists an insight into a poorly understood time during pterosaur history, when well-preserved remains are hard to come by.

Professor Paul Barrett led the expedition which discovered the fossil and has co-authored the description of the new species.

'This new species is the first of its particular group to have been found in Scotland, and is only the second flying reptile to be named from the country,' says Paul. 'It reveals that these animals were much more widespread than would otherwise be known from their generally patchy fossil record, and dates important events in pterosaur history to an earlier time.'

'It also adds another species to the growing fauna we have from the Scottish Middle Jurassic, where we already know of an ancient aquatic turtle, dinosaurs, fossil mammals, salamanders and another pterosaur.'

'As fossil vertebrates are poorly known in the Middle Jurassic, Skye is proving an important locality in increasing our knowledge of this period.'

The description of Ceoptera was published in the Journal of Vertebrate Paleontology. 

Pterosaurs and the mysterious Middle Jurassic

Pterosaurs first appeared in the fossil record in the Late Triassic and are believed to have evolved as close relatives of the lagerpetids, a group of small dinosaur-like animals. However, the lack of transitional forms in the evolution of pterosaurs makes it hard for scientists to be completely certain of their origin.

'Pterosaur fossils have a very poor fossil record in general, as their bones are quite fragile,' Paul explains. 'As flying animals, they're also not spending as much time on the ground near the rivers and lakes where fossils usually form.'

'Most of what we know about pterosaurs, especially in the Early and Middle Jurassic, comes from a handful of sites known as Lagerstätten where fossil preservation is exceptional. Almost everything we know about pterosaur biology and evolution comes from only eight or nine of these key areas around the world.'

Derived from the German word for deposits, Lagerstätten are rich fossil beds where important remains, such as Archaeopteryx, were first found. Other sites containing significant numbers of pterosaur fossils, such as China's Jehol Biota, are known for the Late Jurassic and Early Cretaceous, but not for other periods.

This gives the impression that pterosaur diversity peaked during these times but this is just a consequence of the otherwise poor preservation of these animals throughout the rest of their history.

One exception to this is Dearc sgiathanach, another pterosaur discovered on the Isle of Skye. Described in 2022, this species is incredibly well-preserved, and may represent one of largest pterosaurs in the Middle Jurassic skies.

Specimens like Dearc and Ceoptera suggest that the Jurassic was much richer in pterosaurs than previously known. Finding more new species will help palaeontologists to understand how the main types evolved.  

What does Ceoptera evansae reveal about pterosaurs?

The fossil was discovered in 2006 near Elgol on the southwest coast of the Isle of Skye during a Natural History Museum field trip.

'This area of Skye is a Site of Special Scientific Interest, so we could only collect specimens from rocks that had fallen naturally onto the beach,' Paul says. 'While crawling over these boulders to examine them for fossils, we noticed a few bones sticking out.'

'We collected the top of the boulder, and Lu Allington-Jones then spent over a year stabilising it at the Natural History Museum. She then used a variety of techniques, such as acid preparation and pneumatic pens, to expose the bones for study.'

In addition to physical preparation, the team also took CT scans to expose areas of the bone that were too fragile to be removed from the rocks. They revealed features such as a bony flange on the shoulder that set the specimen apart from other pterosaurs.

Lead author Dr Liz Martin-Silverstone, a palaeobiologist from the University of Bristol, says, ‘The time period that the fossil is from is one of the most important in pterosaur evolution, meaning it was already a significant find.’

‘However, to find that there were more bones embedded within the rock made this an even better find than initially thought. It brings us one step closer to understanding where and when the more advanced pterosaurs evolved.’

The team’s research has now culminated in the specimen being formally described as a new species. The genus name is derived from the Scottish Gaelic word for mist, 'ceò', in reference to the Isle of Skye sometimes being known as the Isle of Mist, combined with the Latin word for wing.

Meanwhile, its specific name recognises Professor Susan Evans of University College London for her research career as well as introducing the team to the area of Skye where the new species was found.

Comparisons of Ceoptera with other pterosaurs suggest that it belongs to a group known as the darwinopterans, which appear to represent the transition between early pterosaurs and the later pterodactyloids. However, it had been uncertain whether the darwinopterans were all descended from a single ancestor or are instead a group of similar looking but unrelated organisms.

Using Ceoptera, researchers have been able to identify features, such as a reduced toe on the foot, in many different species, which suggests that they do form a single group of related pterosaurs. 

'The new species fits very well within the darwinopterans and helps to extend the geographic range of the group from well-preserved material in China to the UK and Argentina,' Paul says. 'It also reveals that these reptiles originated in the Early Jurassic, which is much earlier than had previously been known.'

'We now think that the darwinopterans persisted for around 25 million years alongside a rich diversity of other pterosaurs, including Dearc. This overlap is very rarely found in the fossil record, with China and the UK currently the only places where this is known.'

The researchers hope that Ceoptera will be one of many new species of Middle Jurassic pterosaurs to be found, opening up new avenues to investigate how pterosaurs diversified during the Mesozoic era.