There were a great variety of fish present during the Cretaceous. Many of them are known only from tooth remains.

Among them was the bulldog tarpon, Xiphactinus. This species had a blunt head and jaws set with sharp teeth, reached a length of up to 20 feet, and weighed 500 to 600 pounds. It fed upon smaller fish and the young of marine reptiles. Another tarpon like fish was the smaller Gillicus, which has been found inside Xiphactinus specimens.