Cretoxyrhina was one of the largest sharks and a formidable predator in the Late Cretaceous seas. Nicknamed the Ginsu shark after the kitchen knife that slices and dices, Cretoxyrhina ripped apart prey with a mouth full of razor-sharp, bone-shearing teeth. Evidence suggests Cretoxyrhina fed on mosasaurs, plesiosaurs, and even the giant bony fish Xiphactinus, a fierce predator itself.
Sharks are made of cartilage, which does not fossilize well. Much of what is known about them comes from their abundant—and harder—teeth. Cretoxyrhina's were smooth, curved, and grew more than two inches (five centimeters) long. Bite marks and teeth embedded in the bones of its prey suggest Cretoxyrhina chomped with brutal force.
Estimates from a few calcified remains of cartilaginous Ginsu sharks suggest they grew upwards of 24 feet (7 meters) long, similar in size to modern great white sharks. Though fierce and feared, Cretoxyrhina was preyed upon by the giant mosasaur Tylosaurus, and Ginsu remains were scavenged by the smaller shark of its time, Squalicorax.