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Terrifying mosasaur dominated the ocean 66 million years ago

In a new study from the University of Bath, researchers are describing a giant sea lizard that lived at the end of the Cretaceous period 66 million years ago. At this time, when dinosaurs were thriving on land, giant marine reptiles called mosasaurs dominated the ocean. Mosasaurs could grow up to 12 meters, or 40 feet, in length. They were distant relatives of modern iguanas.

The remains of the new mosasaur, named Thalassotitan atrox, were uncovered in Morocco about an hour outside Casablanca. According to the researchers, Thalassotitan had massive jaws and teeth like those of killer whales and hunted all other marine reptiles as an apex predator – at the very top of the food chain.

The huge skull of Thalassotitan measured five feet long, while its body grew to nearly 30 feet long, the size of a killer whale, noted the researchers. 

Unlike most mosasaurs which had slender teeth, Thalassotitan had conical teeth to rip apart huge prey. These experts report that possible remains of Thalassotitan’s victims have been discovered. 

These fossilized animals, including at least three different mosasaur species, were found with peculiar damage which suggests they were digested in Thalassotitan’s stomach before their bones were spit out.

“It’s circumstantial evidence,” said study lead author Dr. Nick Longrich. “We can’t say for certain which species of animal ate all these other mosasaurs. But we have the bones of marine reptiles killed and eaten by a large predator.

“And in the same location, we find Thalassotitan, a species that fits the profile of the killer – it’s a mosasaur specialized to prey on other marine reptiles. That’s probably not a coincidence.”

“Thalassotitan was an amazing, terrifying animal,” said Dr. Nick Longrich, who led the study. “Imagine a Komodo Dragon crossed with a great white shark crossed with a T. rex crossed with a killer whale.”

According to study co-author Professor Nour-Eddine Jalil, the phosphate fossils of Morocco “offer an unparalleled window on the paleobiodiversity at the end of Cretaceous.”

“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. Thalassotitan completes the picture by taking on the role of the megapredator at the top of the food chain.”

Dr. Longrich has written a blog about the research here:

The study is published in the journal Cretaceous Research.

By Chrissy Sexton, Staff Writer

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