Fish-like marine reptile buried in its own blubber in southern Germany 150 million years ago

A new study published in PeerJ uses modern techniques to understand the conservation of unique ichthyosaur fossils. The complete animal and tail are the first to retain the outward form of the body in the last major group of ichthyosaurs.

A new peer-reviewed paper describes two ichthyosaur* specimens from the Solnhofen** region that are approximately 150 million years old. They are housed in the Jura Museum, which belongs to the episcopal seminary of Eichstätt. Ichthyosaurus is a complete specimen with an internal skeleton and soft tissue outlines around the body. The other is a complete tail fin. It was preserved along with the tail vertebrae and soft tissues around it, confirming that ichthyosaurs also in this group had moon-shaped tails, like their ancestors.

The study was conducted by an interdisciplinary team of scientists. Lene Liebe Delsette, lead author, and Jorn Hurum have worked with marine reptiles for several years at the Natural History Museum in Oslo, Norway. Martina Kölbl-Ebert is an expert on the Solnhofen region and its fauna. They worked with mineralogist Henrik Friis, who analyzed soft tissue samples to see what they contained.

“The full sample is what makes this project unique because it tells the full story. Ichthyosaurs are not common as fossils in Solnhofen, which at that time was a relatively shallow area with many islands, while ichthyosaurs were inhabitants of the open ocean. We do not know. I don’t know why this one ended up in the lagoons, but maybe that’s why it died. Observing the specimen is impressive because it is apparently a completely dead body of an animal, where we can see its shape due to the unique preservation,” said Delsett. said.

At or after death, the ichthyosaur landed on its back and side on the seafloor and was covered in fine sediment. Little oxygen and a lot of luck kept it alive until it was discovered and excavated in 2009. In the article, scientists give the first description of the specimen and begin the process of studying its soft tissues. To do this, they took small samples of the soft tissues of the tail and examined them using X-ray crystallography and a scanning electron microscope. Since the skeletons and the rock in which they are preserved are almost the same color, ultraviolet light was used to study the shape of the bones in order to understand what type of ichthyosaur it was. They found that the phosphate found in the tissues of ichthyosaurs likely contributed to the preservation. It is not yet possible to identify all types of fossilized tissue in an ichthyosaur, but a new study strongly supports the preservation of skin and possibly connective tissue. However, most of the material surrounding and covering the specimen is likely to be decomposed fat.

“We know from previous research that ichthyosaurs probably had blubber, like whales do today. Our study confirms this for a group of ichthyosaurs, where it was not accurate. Fat is another strong similarity between whales and ichthyosaurs, besides theirs. I hope that in the future these two ichthyosaurs from Solnhofen can be used to improve our understanding of swimming as they retain their tail and body shape,” says Delsett.

Notes

* Ichthyosaurs were marine reptiles that lived during the age of the dinosaurs. Their fossils are found all over the world and they are known for having a fish-like shape compared to today’s dolphins.

** The Solnhofen region in southern Germany is famous for its Late Jurassic fossils, including the Archeopteryx, generally recognized as the first bird, and many other animals, many of which are preserved with soft tissues, as well as skeletons and teeth, which are rare in the fossil record.

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