Fossil reveals evolution of flying reptiles that lived alongside dinosaurs

By Stephen Beech

An "incredible" new fossil find has revealed the dramatic evolution of flying reptiles that lived alongside dinosaurs.

The complete specimen discovered in Germany finally shows how now extinct pterosaurs developed into flying giants, say scientists.

Early forms of the species were generally limited to a wingspan of around two meters (6.5 feet).

But the largest pterosaurs evolved to reach a wingspan of 10 meters (32.8 ft).

An international research team led by paleontologist Dr. David Hone, of Queen Mary University of London, say the new fossil discovery helps to explain the transition.

They named the animal Skiphosoura bavarica - meaning "swordtail from Bavaria" - because it comes from southern Germany and has a "very unusual" short, but stiff and pointed tail.

Dr. Hone explained that the specimen was complete with nearly every single bone preserved.

And, unusually, it was preserved in three dimensions, while most pterosaurs tend to be crushed flat.

Dr. Hone said that it would have been about two meters in wingspan, similar to that of large birds today such as the golden eagle.

For 200 years, paleontologists split the pterosaurs into two major groups, the early non-pterodactyloids and the later and much larger pterodactyloids.

The early pterosaurs had short heads on short necks, a short bone in the wrist of the wing, a long fifth toe on the foot and long tails.

The pterodactyloids had the opposite with large heads on long necks, long wrist, a short fifth toe and short tails.

But which parts of their bodies changed when between the groups was not known.

In the 2010s, a series of intermediate species, called darwinopterans, were found that revealed that the head and neck had changed first before the rest of the body.

The researchers explained that it was an example of an intermediate that bridged an evolutionary gap, but it also meant scientists did not really know what was going on before or after the changes.

Now, Skiphosoura reveals the changes.

The research team says that, evolutionarily, it sits between the earlier darwinopterans and the pterodactyloids.

It retains a very pterodactyloid-like head and neck, but also shows a longer wrist, and a shorter toe and tail than earlier darwinopterans - but not as extreme as those seen in the pterodactyloids.

The new study, published in the journal Current Biology, comes with a new reconstruction of the evolutionary family tree for pterosaurs.

As well as showing the intermediate position of Skiphosoura, it also shows a Scottish pterosaur, Dearc, as fitting in the "mirror position" between the early pterosaurs and the first darwinopterans.

Dr. Hone said: “This is an incredible find.

"It really helps us piece together how these amazing flying animals lived and evolved.

"Hopefully, this study will be the basis for more work in the future on this important evolutionary transition."

Research team member Adam Fitch, from the University of Wisconsin-Maddison, said: “Pterosaurs have long been symbols of the unique life of the past.

"Skiphosoura represents an important new form for working out pterosaur evolutionary relationships and by extension how this lineage arose and changed."

Fellow team member René Lauer, of the Lauer Foundation, said: “The specimen was disarticulated with bones of varying quality often overlaid upon one another.

"Digital photography of the specimen taken in both visible and UV light significantly aided in the process to identify these elements and to better analyze finer details that were not discernible in normal daylight alone.”

Stefan Selzer, a co-author of the project, helped prepare the specimen.

He said: “As a preparator, I have worked on more than 60 pterosaur specimens from Solnhofen limestone.

"I recognized during the final prep this specimen showed features that combined characteristics of both major groups of pterosaurs, with the shortened tail as the most important diagnostic feature.”