1.64" Cretaceous Cretoxyrhina Shark Tooth - Kansas
Cretoxyrhina mantelli was a large shark that lived about 100 to 82 million years ago, during the late Cretaceous period. It is nicknamed the Ginsu shark in reference to the Ginsu knife, since it fed by slicing into its victims with its knife-sharp teeth. Cretoxyrhina was the largest shark in its time and was among the oceans apex predators. Fossil records indicate that it preyed on a variety of marine animals including Mosasaurs, Plesiosaurs, bony fish like Xiphactinus, and large turtles like Archelon.
During the Late Cretaceous, much of the middle of the United States was covered by the Western Interior Seaway effectively splitting the continent in two. The Niobrara Formation in Kansas is one of the best known localities for marine fossils deposited during this time. These fossils include the remains of giant marine predators including Mosasaurs, Plesiosaurs, sharks like Cretoxyrhina and the giant predatory fish Xiphactinus.