In a quarry in southern Germany, encased in limestone, a nearly perfect fossil has been waiting patiently to rewrite the story of flight. The fossil, a pterosaur with a stiff, sword-like tail, is a new species described today in the journal Current Biology.

This remarkable discovery, made by an international team of scientists led by Dr. David Hone of Queen Mary University of London, sheds light on a longstanding mystery about how these enigmatic reptiles evolved into the airborne giants of the Mesozoic era.

A Missing Link Between Airborne Giants

The newly discovered species, named Skiphosoura bavarica, meaning “sword tail from Bavaria,” is a rare find. Measuring around two meters in wingspan — comparable to a golden eagle — the specimen is almost completely intact. Unlike most pterosaurs, which are often found flattened like pressed flowers in rock, this fossil was preserved in three dimensions. “This is an incredible find,” says Dr. Hone. “It really helps us piece together how these amazing flying animals lived and evolved.”

For over two centuries, scientists have struggled over the evolution of pterosaurs. These reptiles, which lived alongside the dinosaurs, fell into two main groups: the early, smaller non-pterodactyloids and the later, larger pterodactyloids. Early pterosaurs had short heads, long tails, and a distinctive fifth toe on their feet. Pterodactyloids, in contrast, boasted long necks, large heads, and reduced tails.

The differences between the two groups could be staggering. In the Late Cretaceous skies, the colossal Quetzalcoatlus northropi soared with wings spanning nearly 40 feet, making it one of the largest flying animals ever to exist. On the other end of the scale was the tiny Nemicolopterus crypticus, with a wingspan of just 10 inches, small enough to fit in the palm of a hand. While Quetzalcoatlus likely hunted from the skies like a prehistoric bomber, snatching up small prey, its sparrow-sized cousin likely darted through dense foliage, feasting on insects.

But pinpointing when and how these changes occurred has remained a mystery.

A Step Forward in Understanding the Evolution of Flight

The fossil of Skiphosoura provides a crucial piece of this evolutionary puzzle. In the 2010s, researchers discovered a group of intermediate species called darwinopterans, which showed that the head and neck evolved first. However, these fossils left other questions unanswered. Now, with Skiphosoura, scientists have found a link bridging the gap between these intermediate forms and the later, larger pterodactyloids.

Dr. Hone and his team’s analysis shows that Skiphosoura sits evolutionarily between the darwinopterans and the pterodactyloids. While it has a head and neck more typical of the larger pterodactyloids, it retains features like a slightly longer wrist and a shorter toe, suggesting a gradual evolutionary shift.

“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,” said Adam Fitch of the University of Wisconsin-Madison.

By reconstructing the pterosaur family tree, the team could place the recently discovered Dearc, a Scottish pterosaur, as another crucial link. Together, these fossils form a nearly complete evolutionary timeline: from early pterosaurs, to Dearc, to darwinopterans, and finally to Skiphosoura and the giant pterodactyloids.

Unlocking the Secrets of Stone

Uncovering this fossil was no small feat. René Lauer of the Lauer Foundation recounts the painstaking process. “The specimen was disarticulated with bones of varying quality often overlaid upon one another. Digital photography taken in both visible and UV light significantly aided in identifying these elements and analyzing finer details.”

Stefan Selzer, a preparator who has worked on over 60 pterosaur specimens, noted how this one stood out. “I recognized during the final prep that this specimen showed features combining characteristics of both major groups of pterosaurs,” he says, with the shortened tail serving as a defining feature.

While Skiphosoura‘s discovery answers many questions, it also opens new avenues of research. Scientists are now left wondering what other transitional species might still be hidden in the limestone quarries of Germany and elsewhere.

As Bruce Lauer of the Lauer Foundation puts it, “We are proud to bring this important specimen to science and further the understanding of pterosaur evolution.”