Scientists have completed a post-mortem on the 150-million-year-old remains of two baby pterosaurs found in the Solnhofen Limestones fossil beds in southern Germany.
The study shows that these young winged reptiles – nicknamed Lucky and Lucky II – were struck down by fierce gusts of wind, causing them to plunge into a lagoon where they drowned.
Rapid burial in fine sediment preserved their tiny skeletons in remarkable detail, providing new insight into how these delicate creatures died and why so many fossils of juvenile animals are found in this part of Bavaria while adult remains are scarce. The findings of the study were published in Current Biology.
Baby pterosaurs – cause of death
“Pterosaurs had incredibly lightweight skeletons,” explains lead author Rab Smyth from the University of Leicester. “Hollow, thin-walled bones are ideal for flight but terrible for fossilisation. The odds of preserving one are already slim and finding a fossil that tells you how the animal died is even rarer.”
The juveniles, members of the genus Pterodactylus, were just days or weeks old when they died, with tiny wingspans measuring less than 20cm. Their skeletons were almost perfectly preserved. For Smyth and the team, one feature stood out: both showed a distinctive slanted fracture on the humerus.
Lucky’s left wing and Lucky II’s right wing were broken in a way that indicates a powerful twisting force, likely caused by violent winds, rather than a collision with a hard surface.
Once injured, researchers believe the young pterosaurs dropped out of the sky and into the lagoon below, where they quickly sank to the seabed. They were buried beneath layers of fine limestone mud, creating near-pristine fossils that remained unchanged for millions of years.
“When Rab spotted Lucky we were very excited but realised that it was a one-off: Was it representative in any way?” says co-author Dr David Unwin. “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.
“Later still, when we had a chance to light-up Lucky II with our UV torches, it literally leapt out of the rock at us – and our hearts stopped. Neither of us will ever forget that moment.”
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The findings challenge long-held assumptions about Solnhofen’s prehistoric ecosystem, say the researchers. Although hundreds of pterosaur fossils have been found there, most are juveniles. The team now believe this is due to storm-related deaths, not because small pterosaurs dominated the area.
“For centuries, scientists believed that the Solnhofen lagoon ecosystems were dominated by small pterosaurs,” Smyth explains. “But we now know this view is deeply biased. Many of these pterosaurs weren’t native to the lagoon at all. Most are inexperienced juveniles that were likely living on nearby islands that were unfortunately caught up in powerful storms.”
Top image: The hatchling Pterodactylus, nicknamed Lucky, illuminated in UV light. Credit: University of Leicester
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