Credit: Andrey Atuchin A giant mosasaur from the end of the Cretaceous period in Morocco that could have reached up to eight metres long is the third new species to be described from the region in less than a year, bringing the total number of species up to at least 13. The high diversity of the fauna shows how mosasaurs, giant marine lizards related to snakes and Komodo dragons, thrived in the final million years of the Cretaceous period before they, and most of all species on Earth, were wiped out by the impact of a giant asteroid 66 million years ago.