2023-10-25 20:00:00
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The Jurassic seas witnessed a struggle for dominance between two large groups of marine reptiles: the dolphin-like ichthyosaurs; and the plesiosaurs, with enormous necks. But within this second group there was a family that evolved contrary to the others, reducing the length of the neck, strengthening its fins and achieving a compact and robust body: It was about pliosaurs.
Pliosaurs appeared at the end of the Triassic period, but it was during the Jurassic when they became the top predators of the seas, displacing the ichthyosaurs. Now, a team of researchers has identified the oldest known species of pliosaurwhich they have called Lorrainosaurus keileni. The study has been published in the journal Scientific Reports.
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A terrible super predator
Lorrainosaurus keileni It lived between 175 and 171 million years ago, during the transition from the Early to the Middle Jurassic. “These creatures emerged immediately after a historical restructuring of marine predator ecosystems,” explains Daniel Madzia, co-leader of the study and paleobiologist at the Polish Academy of Sciences. “This event profoundly affected many groups of marine reptiles and led megapredatory pliosaurs to predominate over ichthyosaurs”.
The reason is that, unlike long-necked plesiosaurs, pliosaurs had a body and way of hunting similar to ichthyosaurs, so they were direct competitors of them. However, pliosaurs’ fins were more robust, which gave them greater mobility and speed in the water; and their jaws larger and stronger with sharp teeth that allowed them to capture prey larger than ichthyosaurs. During the Middle Jurassic they surpassed them in size and displaced them, occupying a position that they would maintain until the end of the Cretaceous, with the appearance of the enormous mosasaurs.
Study authors
Reconstruction of Lorrainosaurus keileni with the bones found.
He Lorrainosaurus keileni, In particular, it reached 6 meters in total length and its jaws alone measured 1.3 meters long. According to the reconstruction proposed by the authors, its body was compact and hydrodynamic, and its fins would have allowed it to propel itself at high speed. Sven Sachs, the other director of the study and researcher at the Nature Museum of Bielefeld (Germany), states that it was “one of the first truly huge pliosaurs” and “gave rise to a dynasty of megapredatory marine reptiles that dominated the oceans for about 80 million years.”
Unfortunately, little remains of this specimen: part of the jaw, a fragment of the coracoid (a bone that connects the scapula to the sternum) and a pair of fin bones. The dimensions and appearance attributed to the Lorrainosaurus keileni They are based on other pliosaurs close to it. The fossils They were found about 40 years ago in the French region of Lorraine – from which it takes its name – but until now they had not been described as belonging to a new species.
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