Vertebrate fossils in Kansas

Vertebrate fossils—of gliding reptiles that dominated the sky, of sharks and swimming reptiles that ruled the sea, of dinosaurs and mammoths that roamed the land—are embedded in Kansas rocks and sediments. Some are common in specific locations. Others, such as dinosaurs, are rare.

Several types of sharks and fish lived in the Pennsylvanian and Permian seas in Kansas. An even greater variety of fish fossils have been found in rocks formed in later seas that covered western Kansas during much of the Cretaceous Period (145 to 66 million years ago). Two types of swimming reptiles, the mosasaur and the plesiosaur, have been found in Cretaceous sea deposits. Both had long bodies, sharp teeth, and paddle-like limbs. A large gliding reptile, the pterosaur, soared over the seas.

Fossil evidence suggests that dinosaurs appeared during the Mesozoic Era (252 to 66 million years ago) and disappeared at the end of that era. Though few dinosaur fossils have been found in Kansas, three types of dinosaurs did live along the shoreline of the Cretaceous seas that covered much of the state. Silvisaurus and Niobrarasaurus were built more like tanks while the duck-billed Claosaurus stood on its hind legs, though not fully upright. Although these were all land animals, most of the dinosaur remains found in Kansas came from rocks formed in sea sediment deposits. That indicates the animals died on shore, floated out to sea, and sank.

Dinosaurs, mosasaurs, and a lot of other vertebrates, especially large ones, died off in a mass extinction at the end of the Mesozoic Era. In the following Cenozoic Era, many mammal species grew significantly larger in size and spread through Kansas after the last Cretaceous sea receded. Fossil records show that mastodon, mammoth, rhinoceros, camels, saber-toothed cats, peccary (wild pig), and an extinct species of large bison roamed the state at one time or other between 23 million and 11,700 years ago.