Strange teeth of a prehistoric swimming predator puzzle paleontologists

Scientists discover a new species of mosasaur with unusual teeth, shedding light on the rapid evolution of marine reptiles.
Kavita Verma
A new species of mosasaur, a sea-dwelling lizard from the time of dinosaurs, has been unearthed in Morocco.
A new species of mosasaur, a sea-dwelling lizard from the time of dinosaurs, has been unearthed in Morocco.

Longrich et al 

A new species of mosasaur, a sea-dwelling lizard from the time of the dinosaurs, has been discovered by scientists. It has odd, ridged teeth that are unlike those of any other known reptile.

This shows that mosasaurs and other marine reptiles were evolving quickly up until 66 million years ago, when an asteroid wiped off the dinosaurs and around 90% of all species on Earth, coupled with other recent discoveries from Africa.

The new species, Stelladens mysteriosus, was roughly twice the size of a dolphin and originated in Morocco during the Late Cretaceous. Its unusual tooth configuration, which was placed in the shape of a star and resembled a cross-head screwdriver, included blade-like ridges that ran along the teeth. 

The front and back of the teeth of most mosasaurs featured two blade-like, serrated ridges to aid in cutting prey, but Stelladens had four to six of these ridges running along the tooth.

Evolutionary mysteries and unique feeding strategies

The distinctive teeth point to a specialized feeding method or diet, but it is still unknown exactly what Stelladens consumed. Small, sturdy, and worn-down at the points, the teeth ruled out soft-bodied prey. 

Additionally, they lacked the power to destroy organisms with thick armor, such as clams or sea urchins. This suggests that Stelladens might have developed a special feeding strategy or filled an ecological niche that no longer exists.

The investigation of Stelladens and other recent findings in Morocco provides information on the swift diversification and evolution of mosasaurs up until their extinction.

These results cast doubt on earlier theories on the contribution of environmental changes to the extinction event. The mosasaurs didn't disappear; they ended at the height of their power. The find also underscores the Late Cretaceous period's enormous biodiversity and ongoing discoveries.

A glimpse into Earth's prehistoric biodiversity

The study's researchers stress that there is still a lot to learn about the species that were there during this time and that many uncommon species may still be undiscovered. The Late Cretaceous ecosystem's rich diversity makes it likely that it will take decades to fully understand and catalog all of the different species that have ever lived on Earth.

An unmatched window into the tremendous biodiversity that existed just before the catastrophic events at the end of the Cretaceous epoch is provided by the fossils discovered in Morocco. 

These discoveries help us comprehend the complex evolutionary processes that molded our globe millions of years ago as well as ancient marine life.

Study Abstract: 

Mosasaurids, a clade of specialized marine squamates, saw a major adaptive radiation in the Late Cretaceous, evolving a wide range of body sizes, shapes, and specialized tooth morphologies. The most diverse known mosasaurid faunas come from the late Maastrichtian phosphates of Morocco. Here, we report an unusual new mosasaurid, Stelladens mysteriosus, based on a partial jaw and associated tooth crowns from lower Couche III phosphatic deposits at Sidi Chennane, Oulad Abdoun Basin, Morocco. Stelladens is characterized by short, triangular tooth crowns with a series of strong, elaborate, and serrated ridges on the lingual surface of the tooth, functioning as accessory carinae. Morphology of the teeth and associated jaw fragment suggest affinities with Mosasaurinae. No close analogues to the unique tooth morphology of Stelladens are known, either extant or extinct. It may have had an unusual and highly specialized diet, a specialized prey-capture strategy, or both. The diversity of mosasaurid teeth is much higher than that of plesiosaurs, ichthyosaurs, or extant marine mammals, and likely reflects both the ecological diversity of mosasaurids and complex developmental mechanisms responsible for tooth formation in mosasaurines. Mosasaurid diversity continued to increase up to the Cretaceous–Paleogene boundary.

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