The Solnhofen Limestone, a fossil hotspot in southern Germany, hosts a particularly rich array of baby pterosaur bones. That led paleontologists to believe that the animals flourished here—until an autopsy unveiled the broken, storm-tossed wings of two baby pterosaurs, painting a darker picture of how the bones got there.
In a Current Biology paper published September 5, paleontologists at the University of Leicester in the United Kingdom describe the tragic tale of Lucky and Lucky II, two baby Pterodactylus antiquus that appear to have been shredded to death by a violent tropical storm. Examining the “Luckies” under ultraviolet light revealed previously unknown skeletal trauma.
Surprisingly, Lucky’s left wing and Lucky II’s right wing each showed a clean, slanted fracture, hinting at some “twisting force” that snapped the little bones into pieces.
A lucky, fossilized irony
The findings are “lucky” for two reasons that run “counter to expectations,” the researchers say. Pterosaurs generally had lightweight, hollow skeletons ideal for flight, which makes it all the more remarkable that their brittle bones survived fossilization so pristinely, explained Rab Smyth, study lead author and a paleobiologist at the University of Leicester, in a statement. “The odds of preserving [a pterosaur] are already slim, and finding a fossil that tells you how the animal died is even rarer.”
Similarly, larger animals are a bit more likely to leave fossils behind. With a wingspan of about 8 inches (20 centimeters), Lucky and Lucky II are among the smallest, well-preserved pterosaur fossils ever found. In addition, their wounds remained clear enough for the researchers to conclude that, with reasonable confidence, a severe storm caused the injury.
If so, the young age of the pterosaurs further supports the hypothesis that the animals could fly soon after hatching, study senior author Dave Dunwin told Scientific American.
Freak accident or trend?
When the researchers first found Lucky, it seemed more reasonable to conclude that this was a “one-off,” said Unwin. Smyth added that for centuries, the consensus was that the “Solnhofen lagoon ecosystems were dominated by small pterosaurs.”
“A year later, when Rab noticed Lucky II, we knew that it was no longer a freak find but evidence of how these animals were dying,” Unwin said. “Later still, when we had a chance to light up Lucky II with our UV [flashlights], it literally leapt out of the rock at us—and our hearts stopped.”
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