A new study has revealed that a 183-million-year-old plesiosaur fossil featured both smooth and scaly skin. The specimen, which had been sitting in museum storage for decades, has helped scientists update their centuries-old reconstructions of these prehistoric creatures.
Plesiosaurs were long-necked reptiles that inhabited the world’s oceans between 66 million and 215 million years ago. While much has been learned about these animals through their fossilized skeletons, their skin and exterior features have largely remained a mystery. In a significant breakthrough, scientists have re-examined an old plesiosaur fossil.
A Rare Discovery of Fossilized Soft Tissue
The plesiosaur fossil, known as MH7, was discovered in 1940 in a quarry near Holzmaden, Germany. However, it wasn’t until 2020 that scientists revisited the specimen, which had been stored in the Urwelt-Museum Hauff for nearly 75 years.
The unique ocean conditions in the region where the fossil was found allowed some of the soft tissues, including skin, to be preserved for millions of years. Miguel Marx, a paleobiologist at Sweden’s Lund University, and his team analyzed fingernail-sized samples from MH7’s tail and flippers, finding astonishingly well-preserved skin cells.
“Also, the well-preserved German fossil really highlights the potential for soft tissue in providing valuable insights into the biology of these long-extinct animals,” in a statement from Lund University, he said.
Upon examining the skin under a microscope, the researchers discovered that the plesiosaur had both smooth skin on its tail and small scales on the rear edges of its flippers.
“Our findings help us create more accurate life reconstructions of plesiosaurs, something that has been extremely difficult since they were first studied over 200 years ago.”
Soft tissue preservation is an extraordinary occurrence in paleontology, especially for marine reptiles like plesiosaurs. While bone fossils are relatively common, the preservation of skin or muscle is rare due to their organic nature, which decays over time.
According to a study, published in Current Biology, only around eight plesiosaurs have been found with preserved soft tissues, making this particular fossil extremely valuable to scientists. The region’s unique ocean chemistry helped prevent the soft tissue from decomposing, allowing researchers to study it after millions of years.
Understanding the structure of soft tissues, something previously difficult to examine. It also allows for better reconstructions of how these animals functioned in their environments, moving beyond just their skeletal features.
The discovery of scaly skin on the plesiosaur’s flippers, in particular, provides intriguing clues about how it might have moved through the water. Scales on the rear edge of the flippers could have made swimming more efficient, similar to how sea turtles use their scales to stiffen their flippers for propulsion. Meanwhile, the smooth skin on the tail could have reduced drag, aiding in faster and more streamlined swimming.
Researchers speculate that these different textures may have helped the plesiosaur maneuver through water and along the seafloor while hunting for prey.
Though the findings remainà speculative, they offer an interesting hypothesis on how the plesiosaur adapted to its aquatic environment. F. Robin O’Keefe, a paleontologist at Marshall University, emphasized that:
“You don’t need to go to all the trouble of having a hyper-efficient wing if you’re going to be sitting on the bottom all the time,” he said.
He suggested it was likely an active predator, cruising through the water in search of food.
