6.4" Tylosaurus Jaw Section - Smoky Hill Chalk, Kansas

This is a beautifully preserved 6.4" jaw section of the giant Mosasaur, Tylosaurus. It comes from the Smoky Hill Chalk in Gove County, Kansas. This jaw section still has the root of two of the teeth still imbedded in the bone. Also if you look closely you can see part of a tooth imbedded in the bone. Each root section is about .5" in diameter, which can give a good idea how terrifying this creature was. A really cool feature worth mentioning is the mineral replacement that occurred within the organic portion (pulp) of the tooth. The interior of the teeth were replaced by a silica-rich mineralization during the fossilization process, that can be seen as the small translucent points that protrude through the center of the teeth.

There is minor repair and restoration around various portions of this jaw section.

Along with plesiosaurs, sharks, fish, and other genera of mosasaurs, Tylosaurus was a dominant predator of the Western Interior Seaway during the Late Cretaceous. Tylosaurus was among the largest of all the mosasaurs, reaching maximum lengths of 14 m (46 ft). A distinguishing characteristic of Tylosaurus 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 in intraspecific combat.

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, flying reptiles or pterosaurs (namely Pteranodon), flightless marine birds such as Hesperornis, and turtles. Many of the most well-known specimens of the marine reptiles were collected by dinosaur hunter Charles H. Sternberg and his son George.