Fossils of small plesiosaurs, long-necked marine reptiles from the age of dinosaurs, first found in 1823, have been found in a 100-million-year-old river system that is now Morocco’s Sahara Desert. This discovery suggests some species of plesiosaur, traditionally thought to be sea creatures, may have lived in freshwater.
Now, scientists from the University of Bath and University of Portsmouth in the UK, and Université Hassan II in Morocco, have reported small plesiosaurs from a Cretaceous-aged River in Africa.
The fossils include bones and teeth from three-metre-long adults and an arm bone from a 1.5-metre-long baby. They hint that these creatures routinely lived and fed in freshwater.
The study by University of Bath and University of Portsmouth in the UK, and Université Hassan II in Morocco found that plesiosaurs were adapted to tolerate freshwater, possibly even spending their lives there, like today’s river dolphins.
Whilst bones provide information on where animals died, the teeth are interesting because they were lost while the animal was alive — so they show where the animals lived. The teeth show heavy wear, like those fish-eating dinosaurs Spinosaurus found in the same beds.
The scientists say that implies the plesiosaurs were eating the same food — chipping their teeth on the armoured fish that lived in the river. This hints that they spent a lot of time in the river, rather than being occasional visitors. While marine animals like whales and dolphins wander up rivers, either to feed or because they’re lost, the number of plesiosaur fossils in the river suggest that’s unlikely, says a release. A more likely possibility is that the plesiosaurs were able to tolerate fresh and salt water, like some whales, such as the beluga whale.
