New fossil, Skiphosoura bavarica, reveals evolution of flying reptiles

A new species of pterosaur whose fossil was recently discovered helps explain the evolution of flying reptiles, according to what was published in Current Biology by paleontologist David Hone, from Queen Mary University of London.

Pterosaurs are extinct flying reptiles that lived alongside their close relatives, the dinosaurs. The largest of them had a wingspan of up to 10 meters, but primitive forms generally reached only two meters.

The animal was named Skiphosoura bavaricawhich means Bavarian swordtailbecause it comes from southern Germany and has a very unusual short, stiff and pointed tail. The specimen is complete, retaining almost all bones, and unusually, it is preserved in three dimensions, even though most pterosaurs tend to be flattened. In life, it would have had a wingspan of about two meters, similar to that of large birds such as the golden eagle.

For 200 years, paleontologists divided pterosaurs into two main groups: the early non-pterodactyloids and the later, much larger ones. Early pterosaurs had short heads on short necks, a short wing wrist bone, a long fifth toe, and long tails, and pterodactyloids were the opposite: large heads on long necks, a long wrist, a fifth toe short and a short tail. But it was not known which parts of their bodies changed in each of these groups.

In the 2010s, a series of intermediate species called Darwinoptera were discovered, which revealed that the head and neck had changed before the rest of the body. It was a great example of an intermission that closed an evolutionary gap, but it also meant that we didn’t know what happened before and after these transformations.

Skiphosoura reveals these changes. Evolutionarily it is situated between these primitive Darwinoptera and the pterodactyloids. It retains a head and neck very similar to those of pterodactyloids, but also shows a longer wrist and a shorter toe and tail than early Darwinoptera, although these are not as extreme as those observed in pterodactyloids. With the study also comes a new reconstruction of the evolutionary family tree of pterosaurs. In addition to presenting the intermediate position of Skiphosourashows that a Scottish pterosaur, A berryfits in the mirror position between the primitive pterosaurs and the first Darwinoptera.

In other words, a complete sequence of evolution is now available, from the first pterosaurs to A berrythe first darwinoptera, Skiphosoura and pterodactyloids. While not all specimens are complete, we can now trace the increase in head and neck size, elongation of the wrist, shrinkage of the fingers and tail, and other characteristics step by step in various groups. It is an excellent illustration of the evolution of a group for which the transition has been far from clear until now.

Both A berry as Skiphosoura They are unusually large for their time, suggesting that the changes that allowed pterodactyls to reach enormous sizes occurred in these transitional species.

Hone concludes: It is an incredible find. It really helps us piece together how these amazing flying animals lived and evolved. We hope that this study will be the basis for more future work on this important evolutionary transition..