Scientists Suspect Newly Discovered Mosasaur Fossil Is a Forgery

In 2021, scientists identified a new mosasaur species upon the discovery of a Cretaceous-period jaw with unusual teeth in a Moroccan mine. There’s only one problem—the remains may have been forged.

Researchers in Canada have raised doubts about the authenticity of the fossil used to identify and describe a new species of extinct marine reptile, Xenodens calminechari, in 2021. Their analysis, detailed in a December 16 study published in The Anatomical Record, highlights inconsistencies within the previous research and calls for new CT scans of the jaw to confirm its validity.

If their doubts prove to be true, it “should be established in the published literature that this is a fake,” Henry Sharpe of the University of Alberta, who led the recent study, told Live Science.

Our rebuttal to “Xenodens” is now published open-access in The Anatomical Record: this bizarre “shark-toothed” mosasaur is likely both a forgery and nondiagnostic (🧵) pic.twitter.com/9s1UWMYJaw

— Hank Sharpe (@Paleoartologist) December 17, 2024

Mosasaurs were large marine lizards and one of the oceans’ top predators during the Cretaceous period (145.5 million to 66 million years ago), with some individuals reaching up to 56 feet (17 meters) long. The researchers from the 2021 study partly based their identification of the new mosasaur species on four sharp teeth found on an incomplete jawbone, dated to between 72.1 and 66 million years ago, and unearthed in a Moroccan phosphate mine.

“The new mosasaurid exhibits a dental battery [dental arrangement] with numerous small, short, bladelike teeth packed together to form a saw-like cutting edge,” the researchers, led by Nicholas R. Longrich from the University of Bath, wrote in the 2021 study. They claimed that it was the first such arrangement of teeth discovered in tetrapods (four-limbed vertebrates), and it was this hypothesis that prompted Sharpe and his colleagues to take a closer look.

Two of the surviving teeth on the alleged X. calminechari jaw sit within a single tooth socket—a feature at odds with most other known mosasaur teeth and jaw arrangements, in which each tooth grows in its own socket. Mosasaur tooth sockets are developed from the bone of the individual teeth, as opposed to the bone of the jaw, explained Michael Caldwell of the University of Alberta, who also contributed to the new study. That means each tooth should have its own socket.

“Every time one of these teeth is resorbed and falls out, there’s a huge pit left over. And that’s because the next tooth is coming into that hole to build all that tissue back up again so that it’s firmly anchored in the jaw,” he told Live Science. Additionally, Sharpe’s team suggests the presence of “possible adhesive material” and argue that the particular overlap of a kind of tissue over two teeth is unusual and could indicate forgery, according to the study.

Besides the teeth themselves, the discovery of the jaw in Morocco’s Khouribga province took place under potentially suspicious circumstances, since the fossil was “obtained nonscientifically (without technical supervision) from an area in Morocco that yields many manipulated or forged specimens,” they wrote in the study.

The researchers ultimately suggest that the teeth and jaw may belong to two different creatures, though CT scans of the remains could settle any doubts. It remains to be seen whether the researchers will be able to apply this technique to the X. calminechari fossil—or convince others to do so—in the near future. For now, proceed with caution if you come across citations of a new mosasaur with strange teeth!