10" Fossil Mosasaur (Tylosaurus) Jaw Section - Kansas

Along with plesiosaurs, sharks, fish, and other genera of mosasaurs, Tylosaurus was a primary predator of the Western Interior Seaway during the Late Cretaceous. Among the largest of all the mosasaurs, Tylosaurus reached a maximum lengths of 14 meters (46 feet). A distinguishing characteristic is its elongated, cylindrical premaxilla (snout) from which it takes its name, and which may have been used to ram and stun prey and also for intraspecific combat. Tylosaurus was designated as one of two official Kansas state fossils in 2014.

The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil-rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. It outcrops in parts of northwest Kansas--its most famous localities for fossils--and in southeastern Nebraska. Large, well-known fossils excavated from the Smoky Hill Chalk include marine reptiles such as plesiosaurs, large bony fish such as Xiphactinus, mosasaurs, pterosaurs, and turtles.