In a discovery that's catching the attention of scientists, researchers have found a remarkably well-preserved fossil of a marine reptile that’s challenging what we thought we knew about how these creatures lived. The fossil, identified as Plesiopterys wildi , is around 183 million years old and was uncovered in southern Germany. What makes it especially rare is the presence of preserved soft tissues, like skin, scales, and keratin, which are almost never found in marine reptiles from the Jurassic period.
The findings, published in Current Biology , offer a rare and detailed look at the texture, colouring, and movement of plesiosaurs– long-necked marine reptiles that lived during the Mesozoic era. Until now, scientists had to rely mostly on bones to imagine what these animals looked like, but this discovery gives a much clearer picture.
Fossil found in 1940, but only studied recently
The fossil specimen, labelled MH 7, was originally discovered in 1940 near Holzmaden, a region known for its fossil-rich Posidonia Shale. However, the specimen remained unprepared for decades. It was only in 2020 that researchers began to remove the surrounding limestone carefully and realised the fossil contained patches of soft tissue.
“Fossilized soft tissue, such as skin and internal organs, is exceptionally rare. We used a broad range of techniques to identify smooth skin in the tail region as well as scales along the rear edge of the flippers. This provided us with unparalleled insights into the appearance and biology of these long-extinct reptiles,” says Miguel Marx, a PhD student at Lund University and the study's lead author, as quoted by Lund University.
Flippers show signs of specialised movement
When researchers examined the fossil under a microscope, they found that the flippers were covered with tiny, triangular scales made of beta-keratin—a tough protein found in reptiles. These sturdy flippers likely helped the animal move with precision and control underwater.
On the other hand, the skin on the tail was smoother and made of alpha-keratin, suggesting it had a different function. This difference in texture shows that various parts of the body were specially adapted for different roles in swimming and steering.
“Apart from the mosaic of smooth skin and scales, it was an incredible moment to visualize the cells in thin sections of the fossilized plesiosaur’s skin. I was shocked when I saw skin cells that had been preserved for 183 million years. It was almost like looking at modern skin,” says Marx, as quoted by Lund University.
Traces of pigment suggest patterned colouring
One of the more unexpected findings was the discovery of melanosomes– tiny structures that carry pigment– in the skin of the tail. This suggests that the animal may have had patterns or variations in skin colour, instead of the plain or pale look that scientists usually imagine for marine reptiles.
The researchers noted that this pigmentation could have played a role in camouflage or communication, though further analysis would be needed to confirm such functions.
Discovery of a tail fin adds new clues
Along with the preserved skin and scales, researchers also found a soft-tissue tail fin– something rarely seen in plesiosaur fossils. This broad and flexible structure suggests the tail may have helped the animal steer more effectively or even boosted its speed while swimming.
Exceptional preservation thanks to Posidonia Shale
The exceptional condition of the fossil is thanks to the unique environment where it was preserved. The Posidonia Shale– an ancient seabed with very low oxygen levels– slows down the process of decay, sometimes allowing soft tissues to fossilise along with bones.
This kind of preservation is extremely rare in marine reptiles, which makes MH 7 a remarkable find and an important discovery for paleontologists.
Adding detail to the story of Plesiosaur evolution
Most studies on plesiosaurs have focused only on their bones, but this fossil gives a much fuller picture of the animal's biology. The preserved soft tissues offer new insights into how different parts of its body worked and how these features may have evolved over time.
According to the research team, these findings may also contribute to understanding how plesiosaurs adapted to specific environments over time.
“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. 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,” explains Marx, as quoted by Lund University.
After sitting untouched for nearly 80 years, this discovery is now offering one of the most detailed views yet into the biology of a creature that swam the Earth’s oceans almost 200 million years ago. The MH 7 fossil not only deepens our understanding of plesiosaurs but also highlights how valuable it can be to revisit and study old, forgotten specimens.
Thumb image credit: X/@JoschuaKnuppe (Illustration of "Skin, scales, and cells in a Jurassic plesiosaur")
The findings, published in Current Biology , offer a rare and detailed look at the texture, colouring, and movement of plesiosaurs– long-necked marine reptiles that lived during the Mesozoic era. Until now, scientists had to rely mostly on bones to imagine what these animals looked like, but this discovery gives a much clearer picture.
🚨 New plesiosaur paper 🚨
— Sven Sachs (@dinosven) March 31, 2025
I'm pleased to announce that our paper on the plesiosaur Plesiopterys wildi has been published today in PeerJ. In our study, led by @miguelpmarx, we describe a new and previously undescribed specimen. #science #paleontology #research
1/4 pic.twitter.com/xkaYHwWTQb
Fossil found in 1940, but only studied recently
The fossil specimen, labelled MH 7, was originally discovered in 1940 near Holzmaden, a region known for its fossil-rich Posidonia Shale. However, the specimen remained unprepared for decades. It was only in 2020 that researchers began to remove the surrounding limestone carefully and realised the fossil contained patches of soft tissue.
“Fossilized soft tissue, such as skin and internal organs, is exceptionally rare. We used a broad range of techniques to identify smooth skin in the tail region as well as scales along the rear edge of the flippers. This provided us with unparalleled insights into the appearance and biology of these long-extinct reptiles,” says Miguel Marx, a PhD student at Lund University and the study's lead author, as quoted by Lund University.
🚨 Big plesiosaur news 🚨
— Sven Sachs (@dinosven) February 6, 2025
Our study in @CurrentBiology, lead-authored by @miguelpmarx, may change the way we look at plesiosaurs as we describe for the first time pigment cells and details on scales in a Jurassic plesiosaur.#Science #News #nature
Reco by @JoschuaKnuppe
1/4 pic.twitter.com/qK1ZKagU0C
Flippers show signs of specialised movement
When researchers examined the fossil under a microscope, they found that the flippers were covered with tiny, triangular scales made of beta-keratin—a tough protein found in reptiles. These sturdy flippers likely helped the animal move with precision and control underwater.
On the other hand, the skin on the tail was smoother and made of alpha-keratin, suggesting it had a different function. This difference in texture shows that various parts of the body were specially adapted for different roles in swimming and steering.
“Apart from the mosaic of smooth skin and scales, it was an incredible moment to visualize the cells in thin sections of the fossilized plesiosaur’s skin. I was shocked when I saw skin cells that had been preserved for 183 million years. It was almost like looking at modern skin,” says Marx, as quoted by Lund University.
🚨 Big plesiosaur news🚨
— Joschua Knüppe (@JoschuaKnuppe) February 6, 2025
I'm delighted to finally reveal the illustration I produced for the paper "Skin, scales, and cells in a Jurassic plesiosaur"!
paper at the end of the🧵 pic.twitter.com/F77fGYgQ5c
Traces of pigment suggest patterned colouring
One of the more unexpected findings was the discovery of melanosomes– tiny structures that carry pigment– in the skin of the tail. This suggests that the animal may have had patterns or variations in skin colour, instead of the plain or pale look that scientists usually imagine for marine reptiles.
The researchers noted that this pigmentation could have played a role in camouflage or communication, though further analysis would be needed to confirm such functions.
Discovery of a tail fin adds new clues
Along with the preserved skin and scales, researchers also found a soft-tissue tail fin– something rarely seen in plesiosaur fossils. This broad and flexible structure suggests the tail may have helped the animal steer more effectively or even boosted its speed while swimming.
Exceptional preservation thanks to Posidonia Shale
The exceptional condition of the fossil is thanks to the unique environment where it was preserved. The Posidonia Shale– an ancient seabed with very low oxygen levels– slows down the process of decay, sometimes allowing soft tissues to fossilise along with bones.
This kind of preservation is extremely rare in marine reptiles, which makes MH 7 a remarkable find and an important discovery for paleontologists.
Adding detail to the story of Plesiosaur evolution
Most studies on plesiosaurs have focused only on their bones, but this fossil gives a much fuller picture of the animal's biology. The preserved soft tissues offer new insights into how different parts of its body worked and how these features may have evolved over time.
According to the research team, these findings may also contribute to understanding how plesiosaurs adapted to specific environments over time.
“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. 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,” explains Marx, as quoted by Lund University.
After sitting untouched for nearly 80 years, this discovery is now offering one of the most detailed views yet into the biology of a creature that swam the Earth’s oceans almost 200 million years ago. The MH 7 fossil not only deepens our understanding of plesiosaurs but also highlights how valuable it can be to revisit and study old, forgotten specimens.
Thumb image credit: X/@JoschuaKnuppe (Illustration of "Skin, scales, and cells in a Jurassic plesiosaur")
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