A fossil of Ichthyosaurus somersetensis was a pregnant female

Ichthyosaurus somersetensis (Image courtesy Dean Lomax)
Ichthyosaurus somersetensis (Image courtesy Dean Lomax)

An article published in the magazine “Acta Palaeontologica Polonica” describes the identification of a specimen of Ichthyosaurus somersetensis that was found to be a pregnant female. Paleontologists Dean Lomax of the British University of Manchester and Sven Sachs of the German Naturkundemuseum Bielefeld studied this almost 3.5-meter (11 feet) long ichthyosaur that was discovered in Somerset in the 1990s, where it lived about 200 million years ago then ended up in the collection of the Niedersächsisches Landesmuseum in Saxony, forgotten until recently.

Ichthyosaurs, order Ichthyosauria, have been known and studied for over two centuries, marine reptiles that evolved over time into a lot of different species, some of which could grow up to 20 meters in length. Ichthyosaurs are among the most commonly found fossils in the UK with thousands of specimens ranging from a few bones to complete skeletons.

Probably the remarkable amount of British ichthyosaurs is why the specimen examined in this research was practically forgotten in a museum in Hanover, Saxony, for about twenty years. During a routine visit in August 2016, Sven Sachs noticed it and informed his colleague Dean Lomax, a world-wide expert on ichthyosaurs.

The two paleontologists examined the specimen attributing it to the species Ichthyosaurus somersetensis, identified a few years ago by Lomax together with Professor Judy Massare. The study was made more complicated by the fact that the tail didn’t belong to the specimen but to another ichthyosaur. It was added to the skeleton to complete it and to give it a better look to be exhibited at the museum.

Sometimes fossils are somehow modified to improve a specimen’s appearance and give an idea of what the whole animal looked like, although in such cases the result isn’t accurate. However, when the information provided on these operations are for some reason incomplete, paleontologists must be careful not to be deceived during their studies.

A great surprise came when paleontologists realized that the specimen of Ichthyosaurus somersetensis they were studying was a pregnant female. It’s not the first case, indeed the most famous ichthyosaur fossil is a pregnant female, but it’s only the third case so it’s still very interesting. The embryo is incomplete but there are enough bones to give an idea of ​​its development.

This discovery confirms the importance of studying fossils that were sometimes discovered decades earlier but for some reason weren’t thoroughly examined. Dean Lomax himself identified the species Wahlisaurus massarae after seeing a specimen during a visit at the New Walk Museum in Leicester, describing it in an article published in the “Journal of Systematic Palaeontology” in June 2016. Now this specimen of Ichthyosaurus somersetensis and its embryo are providing new information on these marine reptiles.

Ichthyosaurus somersetensis reconstruction (Image courtesy Joschua Knuppe)
Ichthyosaurus somersetensis reconstruction (Image courtesy Joschua Knuppe)

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