Xenodens calminechari: Cretaceous Mosasaur Had Shark-Like Cutting Teeth

Thursday, January 21, 2021

Life reconstruction of Xenodens calminechari. Image credit: Andrey Atuchin.

A bizarre new genus and species of mosasaur with teeth unlike those of any known reptile has been identified from fossils found in Morocco.

The mosasaurs were a group of lizards that became highly specialized for marine life in the mid-Cretaceous period.

By the end of the Cretaceous, these creatures had undergone an adaptive diversification, and showed a wide range of body sizes, movement styles, and diets. Their ranks included fish eaters, apex predators, and ‘hard eaters.’

The new mosasaur species lived during the Maastrichtian stage of the Creataceous, approximately 69 million years ago.

Scientifically named Xenodens calminechari, it was about the size of a small porpoise.

“About 66 million years ago, the coasts of Africa were the most dangerous seas in the world,” said Dr. Nick Longrich, a paleontologist at the Milner Centre for Evolution at the University of Bath.

“Predator diversity there was unlike anything seen anywhere else on the planet.”

“The new mosasaur adds to a rapidly growing list of marine reptiles known from the latest Cretaceous of Morocco, which at the time was submerged beneath a tropical sea.”

“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 10 m long, were top predators like orcas, still others ate shellfish like modern sea otters — and then there was the strange little Xenodens calminechari.”

“They coexisted with long-necked plesiosaurs, giant sea turtles, and saber-toothed fish. The new mosasaur adds another dangerous predator to the mix.”

The jaws of Xenodens calminechari. Image credit: Nick Longrich, University of Bath.

Xenodens calminechari had knifelike teeth that were packed edge to edge to make a serrated blade and resemble those of certain sharks.

The cutting teeth let the ancient animal punch above its weight, cutting fish in half and taking large bites from bigger animals.

“Similar to living sleeper sharks and related dogfish sharks, the unusual jaws allowed Xenodens calminechari to punch above its weight, cutting small fish in half, carving pieces out of larger prey, and perhaps even scavenging on the carcasses of large marine reptiles,” the researchers said.

“But rather than being an extreme specialist, the teeth probably let Xenodens calminechari eat a huge range of prey.”

“A mosasaur with shark teeth is a novel adaptation of mosasaurs so surprising that it looked like a fantastic creature out of an artist’s imagination,” said Dr. Nour-Eddine Jalil, a paleontologist at the National Museum of Natural History in Paris and the Universite Cadi Ayyad.

Xenodens calminechari is further evidence of the extraordinary paleobiodiversity of the Phosphate Sea.”

The discovery of Xenodens calminechari is reported in a paper published in the journal Cretaceous Research.


Nicholas R. Longrich et alXenodens calminechari gen. et sp. nov., a bizarre mosasaurid (Mosasauridae, Squamata) with shark-like cutting teeth from the upper Maastrichtian of Morocco, North Africa. Cretaceous Research, published online January 16, 2021; doi: 10.1016/j.cretres.2021.104764

Source: www.sci-news.com/