Five articulated abdominal vertebrae from a marine lizard (Mosasauridae) with three embedded teeth attributed to the shark Cretoxyrhina mantelli were recovered recently from the Smoky Hill Chalk member of the Niobrara Chalk (Upper Cretaceous) in Gove County, Kansas. The specimen occurred below stratigraphic Marker Unit 4 (Hattin, 1982) within the Zone of Protosphyraena perniciosa (Stewart, 1990), and is considered to be of late Coniacian age. Both the anterior and posterior vertebra of the series appear to have been severed and eroded prior to fossilization, indicating partial digestion and subsequent regurgitation by a carnivore. Comparison of the specimen with other mosasaur vertebrae suggests that the mosasaur was about 6 m in total body length. Although it is difficult to estimate the size of the shark from the fragmentary teeth in the remains, it is apparent that the shark was a relatively large individual. Shimada (unpub. M.S. thesis, 1994) reported that specimens of C. mantelli from the Smoky Hill Chalk reached lengths of 4.5 to 5.5 m and fed upon bony fish, mosasaurs, and possibly other marine reptiles. This new specimen provides additional information regarding the paleoecology of the Niobrara seas.
The following photos show the locations of several broken Cretoxyrhina mantelli teeth that were left embedded in the mosasaur's severed abdominal vertebrae as the result of a tremendously powerful bite. The fragment on the left of the first photograph is the remains of a vertebra that was bitten completely through.
