Like their descendants, Kansas corals, bryozoans, and crinoids attached themselves to the sea floor or each other and rarely moved. Although they look more like plants, all of these are really animals. Shelled animals, such as brachiopods, clams, and snails also spent their lives deep underwater on the floors of the Kansas seas.
Besides stationary animals, the ancient Kansas seas also had active crawlers and swimmers. Trilobites were present in the Pennsylvanian seas in eastern Kansas. Several types existed at one time, but they are now all extinct. Another extinct sea dweller, the eurypterid, grew up to six feet long in the Kansas seas. Its living relative, the horseshoe crab, can still be found in many parts of the world today.
Several types of sharks and fish lived in the Pennsylvanian and Permian seas. An even greater variety of fish fossils have been found in rocks formed in the later Cretaceous sea that covered western Kansas. These fish shared the sea with the bottom dwellers and large swimming reptiles.
Two types of swimming reptiles, the mosasaur and the plesiosaur, have been found in Cretaceous sea deposits. From the looks of their large fossilized skeletons, they must have been a frightening and probably unwelcome sight to their smaller neighbors. Both reptiles had long bodies, sharp teeth, and paddlelike limbs. Although mosasaurs and plesiosaurs are extinct today, many of their smaller relatives, including snakes and lizards, are still common.
Figure 28. Mosasaurs, giant swimming reptiles, were up to 20 feet long. The mosasaur fossil above, which includes the head and part of the spine and ribs, was found in western Kansas.
