Thalassotitan is an extinct genus of mosasaur (a group of extinct marine lizards) that lived in Morocco during the late Maastrichtian of the Cretaceous period, around 66 million years ago. The mosasaur's remains were found in the Ouled Abdoun Basin, where many other mosasaurs have been found. This mosasaur was described in 2022 and was assigned to the tribe Prognathodontini alongside other mosasaurs like Prognathodon and Gnathomortis. The prognathodontine mosasaurs are separated from other mosasaurs based on their massive jaws and robust teeth. This genus shows definitely that mosasaurs evolved to take over the apex predator niche in the oceans of the late Cretaceous which is now filled by sharks and orcas. Heavy wear on its teeth and fossils found in the vicinity of the holotype etched by