Prehistoric sea monster bigger than a killer whale may have terrorised rivers too

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

The extinct lizard-like reptile grew up to 12 metres (40 ft) in length and may have occupied a similar niche to modern-day saltwater crocodiles, say researchers from Uppsala University in Sweden.