A team of international researchers identified a 170-million-year-old marine reptile from the Age of Dinosaurs as the oldest-known mega-predatory pliosaur, according to a study published in the journal Scientific Reports. This group of reptiles is related to the famous long-neck plesiosaurs.
The fossils were found about 40 years ago in north-eastern France, but only now paleontologists from the Naturkunde-Museum Bielefeld in Germany, the Institute of Paleobiology of the Polish Academy of Sciences in Warsaw, Poland, the Natural History Museum in Luxembourg, and The Museum of Evolution at Uppsala University in Sweden have identified them as a new pliosaur genus: Lorrainosaurus.
The recovered bones and teeth of the Lorrainosaurus are the remnants of a skeleton that decomposed and was dispersed across the ancient sea floor. “The remains were unearthed in 1983 from a road cutting near Metz in Lorraine, north-eastern France. Paleontology enthusiasts from the Association minéralogique et paléontologique d’Hayange et des environs recognised the significance of their discovery and donated the fossils to the Natural History Museum in Luxembourg”, said co-author Ben Thuy, Curator at the Natural History Museum in Luxembourg.
Pliosaurs are plesiosaurs with large skulls and short necks. They appeared over 200 million years ago but stayed in the water for a long time until suddenly developing into massive apex predators. This study shows that this shift was triggered by feeding niche differentiation combined with a decline in other predators around 170 million years ago.
Lorrainosaurus is the oldest pliosaur with jaws over 1.3 m long, large conical teeth, and a bulky ‘torpedo-shaped’ body propelled by four flipper-like limbs. “Lorrainosaurus was one of the first truly huge pliosaurs. It gave rise to a dynasty of marine reptile mega-predators that ruled the oceans for around 80 million years,” explained Sven Sachs, a researcher at the Naturkunde-Museum Bielefeld.
“Our identification of Lorrainosaurus as one of the earliest mega-predatory pliosaurs demonstrates that these creatures emerged immediately after a landmark restructuring of marine predator ecosystems across the Early-to-Middle Jurassic boundary, some 175 to 171 million years ago. This event profoundly affected many marine reptile groups and brought mega-predatory pliosaurids to dominance over ‘fish-like’ ichthyosaurs, ancient marine crocodile relatives, and other large-bodied predatory plesiosaurs”, added Daniel Madzia from the Institute of Paleobiology of the Polish Academy of Sciences.
Other than a quick report published in 1994, these fossils have remained a mystery until this new study re-evaluated the finds. These bones suggest that the reign of gigantic mega-predatory pliosaurs might have started earlier than previously believed and was responsive to major changes affecting marine environments covering what is now western Europe during the early Middle Jurassic.
“Lorrainosaurus is thus a critical addition to our knowledge of ancient marine reptiles from a time in the Age of Dinosaurs that has as yet been incompletely understood,” concluded Benjamin Kear.
Sachs S, Madzia D, Thuy B, Kear BP. The rise of macropredatory pliosaurids near the Early-Middle Jurassic transition. Sci Rep. 2023 Oct 16;13(1):17558. 10.1038/s41598-023-43015-y.