Skiphosoura bavarica, a species of pterosaur that lived around 149 million years ago in what is now southern Germany, bridges the gaps between the early monofenestratan pterosaurs and the later pterodactyloids.
Life restoration of two Skiphosoura bavarica in flight. Image credit: Gabriel Ugueto.
For two hundred 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 5th toe on the foot and long tails, and the pterodactyloids had the opposite: large heads on long necks, a long wrist, short 5th toe and short tail.
But which parts of their body changed when between these 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.
It was a great example of an intermediate that bridged an evolutionary gap.
But it also meant we did not really know what was going on before or after these changes.
Skiphosoura bavarica sits between these 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 these are not as extreme as those seen in the pterodactyloids.
“This is an incredible find,” said lead author Dr. David Hone, a paleontologist with Queen Mary University of London.
“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.”
“Pterosaurs have long been symbols of the unique life of the past,” said co-author Dr. Adam Fitch, a paleontologist with the University of Wisconsin-Maddison.
“Skiphosoura bavarica represents an important new form for working out pterosaur evolutionary relationships and by extension how this lineage arose and changed.”
A near-complete but disarticulated specimen of Skiphosoura bavarica was found in 2015 in the Schaudiberg Quarry near Mühlheim, Bavaria, Germany.
The specimen is preserved in three dimensions, where most pterosaurs tend to be crushed flat. In life it would have been about 2 m (6.6 feet) in wingspan, similar to that of large birds like the golden eagle.
“The specimen was disarticulated with bones of varying quality often overlaid upon one another,” said co-author Dr. René Lauer of the Lauer Foundation.
“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.”
“The Lauer Foundation is proud to have the opportunity to bring this important specimen to science and further the understanding of pterosaur evolution,” added co-author Dr. Bruce Lauer of the Lauer Foundation.
In addition to showing the intermediate position of Skiphosoura bavarica, it also shows that a Scottish pterosaur species, Dearc, as fitting in the mirror position between the early pterosaurs and the first darwinopterans.
“In other words, we now have a complete sequence of evolution from early pterosaurs to Dearc, to the first darwinopterans to Skiphosoura, to the pterodactyloids,” the paleontologists said.
“While not every specimen is complete, we can now trace the increase in size of the head and neck, the elongating wrist, shrinking toe and tail and other features step-by-step across multiple groups.”
“It’s a superb illustration of the evolution of a group for which the transition has been far from clear before.”
“Both Dearc and Skiphosoura are unusually large for their time also suggesting that the changes that enabled the pterodactlyoids to reach enormous sizes were appearing even in these transitional species.”
The study was published today in the journal Current Biology.
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David William Elliott Hone et al. A new and large monofenestratan reveals the evolutionary transition to the pterodactyloid pterosaurs. Current Biology, published online November 18, 2024; doi: 10.1016/j.cub.2024.10.023
Source : Breaking Science News