4.7" Mosasaur (Tylosaurus) Humerus - Lodged Shark Tooth!

This is a very interesting fossil, preserving feeding behavior in the fossil record. It's humerus of the Mosasaur, Tylosaurus from the Smoky Hill Chalk of Kansas. It has two deep gashes where it was bitten by a shark. The tip of a fossil shark tooth is still lodged (see arrows) in one of the deep gashes!

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 intra-species 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.