Mighty predators: Uncovering the dietary secrets of mosasaurs 

Researchers have revealed new insights into the dietary habits of mosasaurs, giant marine reptiles from the Cretaceous period. The study reveals that these ancient creatures were surprisingly selective in their feeding habits.

The study was conducted by researchers from Utrecht University and the Natural History Museum Maastricht, along with colleagues from the University of Leicester.

Focusing on the wear marks on mosasaur teeth, the experts uncovered intriguing details about the food preferences of mosasaurs.

Geological background

The Maastricht limestones, renowned as the cradle of palaeontology, have been a focal point of research since the discovery of the first Mosasaurus in 1766. 

This area, straddling the Dutch-Belgian border near the Limburg capital, offers a rich window into the Cretaceous period, which ended 66 million years ago.

Focus of the study 

“We were curious whether different species of mosasaurs around Maastricht were really getting in each other’s way in their choice of food, or whether this was not so much of a problem,” explained Dr. Femke Holwerda, a palaeontologist at the Utrecht University Faculty of Geosciences. 

With a lack of stomach content data, the researchers analyzed minute scratches on mosasaur teeth from southern Limburg and near Eben-Emael, Belgium.

The experts used a novel approach, first making silicone rubber casts of the teeth, followed by 3D scanning. “This technique had already been used in dinosaurs, but we were the first to look at the teeth of mosasaurs in the same way,” explained study co-author Anne Schulp.

What the researchers learned 

“It seems that the various species of mosasaur reveal differences in diet. We noted these differences mainly between the smaller species – by mosasaur standards – of about three to seven meters in overall size, and the larger ones, eight to fifteen meters in length,” said Dr. Holwerda.

There were also some dietary differences among the larger species. “Prognathodon in particular, with its large cone-shaped teeth, appears to have had a surprising amount of shellfish in its diet, so it apparently loved its seafood buffet.”

“Another species, Plioplatecarpus, with narrow pointed teeth, showed a striking number of signs of wear. Perhaps this species was also fond of fish with strongly scaled bodies.”

Study significance 

This research adds crucial pieces to the puzzle of the Cretaceous world’s ecosystem. “We wish to understand diversity better,” said Schulp. “And that is made easier for us because the animals studied all come from the same rocks, and therefore the same period. So instead of describing just one species, we look at the ecosystem as a whole.”

Maastricht limestones

The soft limestone deposits around Maastricht are particularly valuable for paleontologists. 

“Nowhere else in the world is the habitat of mosasaurus as well preserved as here. You can find them in very soft limestone, so wear and tear of the teeth from other causes may be ruled out,” said Schulp.

Amateur paleontologists 

John Jagt, curator at the Natural History Museum Maastricht, emphasized the positive role of amateur paleontologists.

“Amateur literally means ‘enthusiast’ and thanks to 250 years of intensive research by these enthusiasts, we have learnt a lot about mosasaurs and other extinct life forms,” said Jagt. “A museum like ours benefits greatly from this. What also helps is that this kind of amateur science is stimulated in the Netherlands: it is simply allowed by law. That’s not the case everywhere.”

Mosasaurs

Mosasaurs were a group of large, marine reptiles that thrived during the Late Cretaceous period, approximately 82 to 66 million years ago. They were among the dominant marine predators of their time, filling a role similar to that of modern-day killer whales. 

Evolution and diversity

Mosasaurs are believed to have evolved from semi-aquatic squamates, a group that includes snakes and lizards. Over 40 species have been identified, ranging in size from about 1 meter to over 17 meters in length.

There was significant diversity in their body shapes and adaptations, reflecting a range of habitats and dietary preferences.

Physical characteristics

They had elongated bodies, large heads with powerful jaws, and paddle-like limbs adapted for swimming. 

Mosasaur teeth varied among species, with some adapted for crushing shellfish, while others were more suited for slicing through flesh.

Many species had a bi-lobed tail, similar to sharks, which suggests they were powerful swimmers.

Habitat and diet

Mosasaurs inhabited a wide range of marine environments, from nearshore to open ocean.

Their diet was diverse, including fish, ammonites, smaller reptiles, and mollusks. As apex predators, they played a crucial role in their ecosystems.

Reproduction 

Mosasaurs were viviparous, giving birth to live young in water, which is a trait shared with some modern lizards and snakes.

Little is known about their growth rates and lifespan, but it’s likely that they grew rapidly to reach their large sizes.

Extinction

Mosasaurs, along with many other marine reptiles, went extinct during the Cretaceous-Paleogene extinction event about 66 million years ago, which also wiped out the dinosaurs.

Scientific significance

Fossils of mosasaurs, including complete skeletons, have been found on every continent, including Antarctica. Studying these fossils can provide valuable insights into the marine ecosystems of the Cretaceous period.

The study is published in the journal Scientific Reports.

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