‘Merciless’ sea monster prowled the sea 66 million years ago
Agiant mosasaur with teeth like a killer whale ruled the oceans around Morocco towards the end of the Cretaceous period, a new study finds. The extinct predator, named Thalassotitan atrox, grew to about nine to ten metres long and likely fed on any other marine reptiles it came across, including fellow mosasaurs. The name Thalassotitan comes from the Greek words ‘thalassa’ and ‘titan’, meaning ‘sea giant’, and the species name atrox translates to ‘cruel’ or ‘merciless’. Researchers discovered fossilised skulls, jaws and other remains that they used to identify T. atrox near Casablanca in western Morocco, an area that was underwater during the Cretaceous period. The researchers found that the teeth of T. atrox were often chipped, broken or worn down, suggesting the species damaged them while violently attacking and biting the bones of prey.
Mosasaurs went extinct at the same time as the dinosaurs after a giant asteroid struck Earth 66 million years ago. The new finds add to a fossil record in Morocco that shows the ocean there was teeming with rich and diverse life before the asteroid hit.
“They tell us how life was rich and diversified just before the end of the ‘dinosaur era’, where animals had to specialise to have a place in their ecosystems,” said Nour-eddine Jalil, a collection manager at the Paleontology Research Center at the Museum of Natural History in Paris. “Thalassotitan completes the picture by taking on the role of the mega predator at the top of the food chain.”
Mosasaurs were a group of marine reptiles distantly related to modern lizards and snakes. They ruled the oceans for millions of years when dinosaurs dominated on land. A 2014 study estimated that one mosasaur specimen, from a different species in Russia called Mosasaurus hoffmanni, was about 17 metres long.
The new species wasn’t the biggest mosasaur, but it was still a top predator and filled a similar role in its ecosystem to killer whales (Orcinus orca) and great white sharks (Carcharodon carcharias) today. Most mosasaurs had long jaws and slender teeth, but T. atrox evolved a shorter, wider muzzle that increased its bite force and short, conical killer whale-like teeth that could endure the increased forces when biting large prey.
The researchers found fossilised bones of at least three other mosasaurs in the same rock beds as T. atrox that showed signs of acid damage, suggesting these mosasaurs were digested in the stomach of T. atrox and spat out again.