During the last 20 million years of the Cretaceous period (Turonian-Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators.
Durante os últimos 20 millóns de anos do período Cretáceo (Turoniense-Maastrichtiense), coa desaparición dos ictiosauros e os pliosauros, os mosasauros convertéronse nos depredadores mariños dominantes.