A fascinating new study has uncovered a surprising feature of a plesiosaur, a marine reptile that lived alongside the dinosaurs more than 180 million years ago. A small team of archaeologists, geologists, paleontologists, and climate scientists has revealed that at least one type of plesiosaur had scales on its flippers, similar to modern-day sea turtles. This revelation comes from the study of a unique fossil that had been kept hidden away for decades, providing new insights into the plesiosaur’s physical appearance, behavior, and evolutionary history.
The Discovery of the Fossil
The fossil in question was first unearthed in 1940 during a quarry excavation near Holzmaden, Germany. Researchers immediately recognized it as a plesiosaur, a marine reptile known for its long neck, flippered body, and sharp teeth. However, due to the outbreak of World War II, the fossil was deemed too valuable to leave exposed. To protect it, the fossil was hidden in a museum garden during the war and then left in storage once the war ended. For 75 years, the specimen remained largely forgotten, safely stored away in a vault, untouched and unstudied.
It wasn’t until 2020 that researchers decided to revisit the specimen. At this point, advances in imaging technology and fossil preservation techniques had enabled scientists to examine the fossil in unprecedented detail. When they did, they were astounded by the remarkably preserved condition of the fossil. The Posidonia Shale, a sedimentary rock, had encased the plesiosaur fossil and helped preserve even the smallest details, including skin nuclei. This extraordinary preservation provided the team with an exceptional opportunity to study a creature that lived around 183 million years ago.
What Makes This Fossil Unique?
The Posidonia Shale in which the fossil was embedded is known for its ability to preserve fossils in exquisite detail. The remarkable condition of the plesiosaur specimen allowed the researchers to not only examine the fossil’s skeletal structure but also to observe the soft tissues, which are often lost in fossilization. Under microscopic examination, they discovered skin cells, which is a rare find for marine reptiles like plesiosaurs.
The unique preservation of this fossil also allowed scientists to observe features that had previously been unknown. For example, the team found that the plesiosaur’s flippers had scales on their surface, much like the flippers of modern sea turtles. This finding is groundbreaking, as it provides fresh insight into the evolutionary adaptations of plesiosaurs, revealing that their flippers were not just for swimming but also had a protective function. The scales may have helped reduce friction while swimming or served as a protective layer against predators and the environment.
The Plesiosaur’s Anatomy and Behavior
Plesiosaurs are well known in paleontology, and many fossils have been discovered over the years, but this new specimen adds previously unknown details to the understanding of these fascinating creatures. Typically, plesiosaurs are depicted with long, serpentine necks, large, powerful flippers, and sharp, conical teeth suited for catching fish. This fossil confirms many of these characteristics but also reveals much more.
The four flippers, two at the front and two at the back, are some of the most distinctive features of plesiosaurs. The scales on the flippers suggest that they were not only used for propulsion in the water but may have served an additional purpose in terms of hydrodynamics. The structure of these flippers likely allowed the plesiosaur to move gracefully through the water, using swimming strokes similar to modern aquatic animals like turtles or seals. The long neck, which could have been used to hunt prey, is another defining characteristic that has long intrigued scientists.
Researchers have been able to model the behavior and habitat of this particular plesiosaur with greater accuracy due to the exceptional preservation of the fossil. The fact that the specimen’s soft tissue is visible to the naked eye allowed scientists to gain a clearer understanding of its swimming technique and the possible depths at which it lived. The plesiosaur likely inhabited warm, shallow seas where it could easily catch fish and other marine life. The morphology of its teeth suggests it was a carnivorous reptile, likely feeding on smaller fish, squid, and other marine creatures.
Rewriting the Evolutionary History
The new findings regarding the scales on the plesiosaur’s flippers also force scientists to rethink some of their previous assumptions about the evolution of these ancient reptiles. Prior to this discovery, the appearance of plesiosaurs was largely understood based on fossilized bones, with less attention paid to the soft tissue preservation, which is rarer in fossils. This has led to the creation of theories about their behavior, movement, and even their role in the ecosystem based on incomplete data. The discovery of the scales on the flippers will likely prompt scientists to revise the evolutionary history of plesiosaurs, and it may even open up new discussions about their relationship to other marine reptiles, such as ichthyosaurs and marine crocodiles.
For years, it was assumed that plesiosaurs’ flippers were smooth and streamlined, optimized for swimming. But the scales present on the specimen’s flippers suggest a more complex evolutionary adaptation, one that may have been shaped by environmental pressures and the need to adapt to specific aquatic environments.
The discovery also highlights the importance of re-examining old specimens. In paleontology, fossils that have been in storage for decades can still hold the key to unlocking critical new knowledge. This fossil, in particular, demonstrates how advances in research methods can breathe new life into old specimens, providing fresh perspectives on well-known species.
Implications for Modern Research
The new findings about the plesiosaur’s anatomy and behavior extend beyond just our understanding of ancient marine reptiles. They have broader implications for the study of evolution, aquatic adaptation, and even modern marine biology. The discovery that plesiosaurs had scaled flippers similar to sea turtles could help scientists understand how different types of marine animals evolved to thrive in similar environments.
Moreover, the exceptional preservation of the fossil will likely serve as a model for how to study other fossils with soft tissue preservation in the future. Researchers will now be able to apply the same detailed techniques to other fossils to study soft tissues, possibly revealing new insights into the appearance, behavior, and biology of extinct species.
Conclusion
This discovery not only sheds light on a new aspect of plesiosaur biology but also underscores the importance of preserving and studying old fossils. The fact that a specimen hidden away for 75 years could provide such critical information about the evolutionary history of marine reptiles demonstrates the ongoing importance of paleontological research. As technology continues to advance, it is likely that more such findings will emerge, reshaping our understanding of the distant past.
In summary, the discovery of scales on the flippers of this 183-million-year-old plesiosaur fossil is an exciting revelation that pushes the boundaries of what we know about prehistoric marine reptiles. It challenges previous assumptions about their appearance and provides new clues about how they lived, swam, and interacted with their environment. This research not only rewrites a chapter of evolutionary history but also opens up new avenues for exploring the complex relationships between ancient creatures and their ecosystems.
Reference: Miguel Marx et al, Skin, scales, and cells in a Jurassic plesiosaur, Current Biology (2025). DOI: 10.1016/j.cub.2025.01.001