Mesozoic Predators

sharks and mosasaurs eat a dead plesiosaur
Smithsonian Institution

Before large mammals, reptiles ruled the ocean. During the Mesozoic, the time period when dinosaurs roamed on land, many of these large creatures were the top predators in the ocean food chain and fed on fish, cephalopods, bivalves, and even one another. Sharks scavenged on dead reptiles, like this plesiosaur. Mosasaurs could also be top predators.