Dinilysia (meaning "terrible ilysia") is an extinct genus of snake from the Late Cretaceous (Coniacian) of South America. The snake reached a length of 6-10 feet (1.8-3 meters) and preyed on smaller animals. The shape of the animal's skull does not support the suggestion that snakes were burrowers during their ancestry; it is clear that Dinilysia was terrestrial.