Dentition of the Late Cretaceous lamniform shark, Cretoxyrhina mantelli from the Niobrara Chalk of Kansas

ABSTRACT

Some specimens of the Late Cretaceous shark, Cretoxyrhina mantelli (Agassiz), from the Niobrara Chalk in Kansas have been found with partial or nearly complete sets of teeth. Analysis of these dentitions offers a better understanding of the shark's systematic position and tooth function. Cretoxyrhina mantelli has a lamnoid dentition with closely spaced tooth rows without any overlap, and with a tendency toward monognathic heterodonty. The best specimen shows four symphysial, two anterior, three intermediate, five lateral, and at least seven posterior teeth in the upper dental series, and one? symphysial, three anterior, five lateral, and at least ten posterior teeth in the lower. Some variation in individual tooth morphology is noted. Dental features support current taxonomic assignments of C. mantelli at ordinal, familial, and generic levels. Cretoxyrhina mantelli probably stabbed and anchored its food with large anterior teeth, and cut food primarily with its more distally located teeth.