Discover the Thalassotitan Atrox, a giant lizard, king of the seas 66 million years ago

A new species of mosasaur has been discovered thanks to very well-preserved fossils in Morocco. Named 

Thalassotitan Atrox, she was probably at the top of the food chain.

If we go back in time a few million years, the animal world did not look like much that we know today. Take, for example, the route for the Upper Cretaceous, a period between 60 million and 100 million years before our era. We then found, in the seas, the mosasaurs, a super-family of marine reptiles now extinct. But she never ceases to amaze us.

Paleontological work, published on August 24, 2022 , describes an entirely new species of mosasaurs. Its name is, to say the least, explicit: Thalassotitan Atrox. The fossils that have been found are numerous and of exceptional quality. They show with all the more precision how formidable the species was.

Skull of Thalassotitan Atrox. Source: University of Bath

“An awesome and terrifying animal”

Mosasaurs were not among the dinosaurs. But they were just as impressive. The Thalassotitan Atrox was particularly so: its skull alone measured 1.4 meters, and its body, from 9 to 12 meters.

Imagine a Komodo dragon crossed with a great white shark crossed with a T. rex crossed with an orca“: it is in these words that the biologist Nick Longrich describes this mosasaur on the site of the University of Bath (United Kingdom). “The Thalassotitan was a brilliant and terrifying animal“.

This species was probably, 66 million years ago – according to the dating of the fossils found – at the top of the food chain. It has many points in common with the killer whale, both in its large size and its dentition provided with teeth that are both massive and conical. British paleontologists explain that they allowed him to ” grab and tear huge prey“.

Size comparison between Thalassotitan, orca and adult human. 
Source: University of Bath

Moreover, the state in which the fossil teeth were found gives a clue about its prey. The teeth in question are often worn, broken. Some are so damaged that they seem almost crushed to the root. It is not a fish-based food that can generate this type of degradation. As a result, the authors believe that the Thalassotitan Atrox preyed on other large sea animals, including lizards, “chipping, breaking and grinding its teeth as it bit into their bones and tore them to pieces“.

The species was flourishing before the famous meteorite

In any case, the abundance of fossils — discovered in Morocco — demonstrates that the Thalassotitans Atrox were flourishing as contemporaries of the dinosaurs, still a million years before the Cretaceous-Paleogene extinction caused by a meteorite fall.

These fossils “tell us how life was rich and diverse just before the end of the ‘age of the dinosaurs’, when animals had to specialize to have a place in their ecosystems. Thalassotitan completes the picture by taking on the role of the megapredator at the top of the food chain,” explains Nour-Eddine Jalil, co-author of the study, on the university website.

And, this is only the beginning, according to the authors of this study, as to the understanding of this richness of life in the Cretaceous period: “Morocco has one of the richest and most diverse marine fauna known from the Cretaceous. We are only beginning to understand the diversity and biology of mosasaurs.”


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