Newly Discovered Marine Reptile Sawed Prey With Serrated Teeth

Researchers say the new species of mosasaur had teeth unlike those of any known reptile

Xenodens calminechari
An artist's rendering of a new species of mosasaur named Xenodens calminechari. The marine reptile was about the size of a porpoise and had serrated shark-like teeth. Andrey Atuchin

A newly unearthed species of dolphin-sized marine reptile had a mouth full of serrated blades for teeth, reports Jake Buehler for Science News. The 66-million-year-old saltwater terror’s saw-like teeth are a razor-sharp departure from the pointed or cone-shaped chompers of all other known reptiles, instead most closely resembling the flesh-shearing dentition of certain species of sharks.

Phosphate miners in Morocco’s Khouribga province first discovered the new mosasaur, and researchers were fascinated as soon as they laid eyes on its jaws, reports Laura Geggel of Live Science. The creature is aptly named Xenodens calminechari, which is Latin for “strange tooth” and Arabic for “like a saw,” respectively

“Those teeth are just unlike anything I’ve seen in a lizard before,” Nick Longrich, a paleontologist at the University of Bath and lead author of a paper describing the species that was published last month in the journal Cretaceous Research, tells Science News.

In a statement, co-author Nathalie Bardet, a paleontologist at the National Museum of Natural History in Paris, adds: “I have been working on mosasaurs for over 20 years...I must admit that among the 10 species that I know, this one has a so unusual and extraordinary dentition that at the beginning I thought it was a chimera reconstructed with different fossils!”

Mosasaurs first appeared some 120 million years ago and reached lengths of more than 40 feet—and exhibited a huge range of feeding habits with teeth to match. X. calminechari inhabited the warm seas that once covered North Africa, which Longrich says were teeming with deadly predators at the time.

"Sixty-six million years ago, the coasts of Africa were the most dangerous seas in the world,” says Longrich in the statement. “Predator diversity there was unlike anything seen anywhere else on the planet...A huge diversity of mosasaurs lived here. Some were giant, deep-diving predators like modern sperm whales, others with huge teeth and growing up to ten meters long, were top predators like orcas, still others ate shellfish like modern sea otters—and then there was the strange little Xenodens.”

Researchers say that despite its unimpressive size, X. calminechari’s formidable teeth might have allowed it to take bites out of larger prey. That added dietary flexibility would have been key to its survival in such perilous waters. The closest modern match for this mosasaur’s bite are the dogfish sharks, which use their serrated teeth to scavenge from large corpses and to slice up smaller prey.

The appearance of X. calminechari’s unique take on mosasaur life just before the dinosaurs met their end paints an interesting picture of the group’s evolution and suggests a thriving ecosystem, Longrich tells Science News. “The mosasaurs were still experimenting with new ways of feeding, new morphologies, new lifestyles just before that asteroid came down,” he says.

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