The ferocious Tylosaurus may have been the supreme predator in its domain, the Western Interior Seaway of the Cretaceous era. Tylosaurus was one of the mosasaurs, a group of marine lizards that returned to the sea in the Mesozoic era and lived there throughout the era of the dinosaurs. These formidable reptiles preyed on just about everything they encountered, including fish, birds, plesiosaurs, and even other mosasaurs. 100% cotton. Machine wash. Imported.