Creataceous animals. Computer artwork of three Enchodus swimming in an estuary in the Western Interior Seaway of North America. On the shore (upper right) are duck-billed Hadrosaurs in front of a flock of feathered Ichthyornis. On the left are a pair of ostrich-like Struthiomimus. Enchodus were six-foot-long predatory fish that lived during the late Cretaceous period about 75 million years ago. During this period, North America was divided by waters from the Arctic Ocean and the Gulf of Mexico known as the Western Interior Seaway, Cretaceous Seaway, the Niobraran Sea, or the North American Inland Sea.