Baby pterosaur fossils with broken wings solve Solnhofen Limestone preservation mystery

In a new study, scientists investigated two extraordinary baby pterosaur fossils with broken wings, as they died from a violent storm. These fossils are now helping to solve a mystery in paleontology.

Nicknamed Lucky and Lucky II, two baby pterosaurs who came to a tragic end. They could not escape a powerful storm 150 million years ago. The fossils prove that small, fragile creatures existed in the Mesozoic era. It's just, unfortunately, they rarely stand the test of time.

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"On rare occasions, however, nature conspires to preserve the delicate and the diminutive inhabitants of these lost worlds," according to a recent press release.

Solnhofen Limestone juvenile fossil pattern mystery

Intriguingly, if not mysteriously, the Solnhofen Limestones of southern Germany only hold young pterosaur fossils. Why is that? The pattern contradicts everything paleontologists thought they knew about preservation. The larger animals should have stood a better chance.

Lucky and Lucky II have helped to solve the mystery surrounding this fossil site.

University of Leicester research findings

In a new study in Current Biology, University of Leicester paleontologists cracked open a new window onto the ferocious past. The Mesozoic era was classically seen as a time when giant beasts ruled the skies, seas, and land.

However, at Solnhofen, nearly all the fossils belong to "very small, very young individuals, perfectly preserved," a press release continued.

Lead author Rab Smyth, from the University of Leicester's Centre for Paleobiology and Biosphere Evolution, explained that pterosaurs have incredibly lightweight skeletons. "The odds of preserving one are already slim, and finding a fossil that tells you how the animal died is even rarer."

Storm-related injuries in baby pterosaur fossils

Described as "catastrophically injured," these baby beasts belonged to a special group of pterosaurs, the Pterodactylus, the first scientifically named pterosaur. And with wingspans less than 8 inches wide, Lucky and Lucky II are the tiniest pterosaurs ever found from this historic group.

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They were so exquisitely preserved that scientists could see what happened to them. Their skeletons are complete, but they exhibit the same injury: a clean, slanted fracture to the humerus, as per the press release. Both of their right wings were broken, which suggested scientists that "a powerful twisting force" brought about this fatal injury, likely due to gusts of wind.

They got caught up in a storm and were too young to escape. They were only a few days or weeks old.

Fossil preservation explanation through storm evidence

Other young pterosaurs were found at the same location but showed no signs of skeletal trauma. They were flung into the lagoon. "This discovery explains why smaller fossils are so well preserved."

Though it brought the babes to a brutal end, the storm was the key to their preservation. Researchers could conclude that it was a common cause of death for pterosaurs in that region.

Reframing Solnhofen lagoon ecosystem understanding

Another clarification that the babes brought to the whole picture: Solnhofen lagoon ecosystems weren't dominated by small pterosaurs. The larger animals were able to weather the storms, but they died eventually, floating for days or weeks, on the now calm surfaces of the lagoon. Many of them weren't even from the lagoon. They were "inexperienced juveniles likely living on nearby islands that were unfortunately caught up in powerful storms."

In a press release, Co-author Dr David Unwin concluded that his heart stopped when he saw a match in Lucky I and Lucky II. They finally found evidence of how these animals had died.

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"Neither of us will ever forget that moment."

The study appears in Current Biology.