Experts think the creatures adapted to river environments in the final million years before they became extinct.

Giant mosasaurs, once thought to be strictly ocean-dwelling predators, may have spent their final chapter prowling freshwater ...

Mosasaurs, giant marine reptiles that existed more than 66 million years ago, lived not only in the sea but also in rivers.

Prehistoric sea monster bigger than a killer whale may have terrorised rivers too - The mosasaur may have occupied a similar ...

A giant marine predator, once believed to roam only the seas, may have also inhabited ancient rivers 66 million years ago.

A giant ocean predator that terrorised the seas during the time of the dinosaurs may have also hunted in rivers, a tooth ...

Mosasaurs, giant marine reptiles that existed more than 66 million years ago, lived not only in the sea but also in rivers. This is shown by new ...

A 66-million-year-old tooth discovered in North Dakota, USA, suggests that some mosasaurs — extinct lizard-like reptiles that could grow up to 12 ...