In the state of Nuevo Leon in northern Mexico, mountains and rocks form an arid landscape where urban development has replaced the desert plains for several decades. A few million years ago, however, this limestone landscape gave way to a uniform blue, that of the sea. Towards the end of the Late Cretaceous (-140 million years ago to -60 million years ago), certain species were more feared than others in these oceans. One of them was recently revealed by researchers.
In a study published in the Journal of South American Earth Sciences, paleontologists discovered a new species of marine reptile, Yaguarasaurus regiomontanus, a mosasaur that was considered “one of the most feared predators of its time,” according to the study’s scientist and lead author, Hector Rivera-Sylva , interviewed by Newsweek. It is believed to have lived off the coast of what is now Mexico 90 million years ago.
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Ultra strong jaw
The fossil was exhumed from a quarry by a worker in 2021 and entrusted to the Desert Museum (MUDE). Researchers from the facility then conducted excavations on a hill southwest of Vallecillo, a village in Nuevo León. Thanks to reconstruction work, they were able to determine the dimensions of the animal. The almost five meter long specimen had a slim silhouette, webbed feet and toes and a broad tail. The most striking feature, however, is the jaw.
The opening revealed dozens of sharp teeth, giving the mosasaur enormous striking power. A significant advantage for animals that already have a disproportionate size (up to 15 meters long). This also allowed it to hunt very large prey in the ancient waters of the Western Interior Seaway, a closed sea that divided the North American continent in two.
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A fossil in France
The appearance of mosasaurs coincides with that of dinosaurs in the heart of the Mesozoic Era, 100 million years ago. As victims of a sudden change in time caused by the impact of gigantic meteorites, the two families died out around 66 million years ago, as did numerous land and marine species.
At the end of the 18th century, the mosasaur was given the name “Meuse lizard” after the French discovered a fossil skull in the river of the same name near Maastricht. The latter had brought the specimen to the Natural History Museum in Paris.
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