Rare 183-Million-Year-Old Plesiosaur Fossil Found with Skin and Scales Intact
Millions of years ago, a long-necked marine predator with flippers dominated the seas. Plesiosaurs were marine reptiles that lived alongside dinosaurs and went extinct at the same time as them.
For the first time ever, scientists have gotten a detailed look at its soft tissue, revealing a surprising secret about its skin.
This plesiosaur fossil was unearthed from a quarry near Holzmaden in Germany way back in 1940. But its journey to scientific discovery was a long one.
To shield it from the ravages of World War II, it was interred in a museum garden. After this, it spent decades in storage. The fossil finally emerged for study in 2020.
Interestingly, this 4.5-meter-long fossil specimen, dubbed MH7, dates back to 183 million years. Soft tissues barely survive this long period, which makes the fossil particularly valuable find for paleontologists.
“We report a virtually complete plesiosaur from the Lower Jurassic (∼183 Ma)3 Posidonia Shale of Germany that preserves skin traces from around the tail and front flipper,” a team of researchers, led by Miguel Marx from Lund University in Sweden, wrote in the study paper.
Microscopic analysis of the soft tissues
Plesiosaurs were Mesozoic marine reptiles with a 140-million-year evolutionary history. These creatures dominated the world’s oceans. Like the dinosaurs, plesiosaurs went extinct during the mass extinction event at the end of the Cretaceous period, about 66 million years ago.
These extinct creatures are primarily known from skeletal remains. The fossils have been found across various locations of the globe, showing they had a global distribution.
For this study, researchers prepared and treated thin sections of the fossil. They dissolved the sections in the minerals to isolate the organic remains and enable the microscopic study of the preserved tissue structure.
This provided a microscopic glimpse into the plesiosaur’s skin and found it wasn’t entirely smooth-skinned, as previously thought.
The examination indicates that some plesiosaurs possessed both smooth skin on their bodies and small scales on their flippers — like those found on modern sea turtles.
“The flipper integument otherwise integrates small, sub-triangular structures reminiscent of modern reptilian scales,” the study noted.
The team’s expectation that the plesiosaur would be scaleless originated from the fact that ichthyosaurs — another group of marine reptiles that lived alongside plesiosaurs — were known to have smooth skin.
First comprehensive analysis
The plesiosaur‘s scaled flippers likely provided stiffness for swimming or traction for seafloor movement. This allowed them to simultaneously look for food. The smooth skin on the rest of its body would have minimized drag which likely improved swimming efficiency.
The fossil has provided fresh insights into the appearance of these ancient marine reptiles.
“The actual external appearance of long-necked plesiosaurs is really anyone’s guess, but now we have a better idea thanks to this new fossil,” Marx told New Scientist.
The team highlights that soft tissue preservation has been observed in other plesiosaur fossils, but their status as “historically significant museum pieces” has prevented in-depth analysis due to destructive sampling methods.
This study, therefore, represents the first comprehensive examination of preserved plesiosaur soft tissue.
Source: Interesting Engineering
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