[N] 2006 New specimen of mososaurid Prognathodon, Bearpaw Fm, Alberta
Massare, J. A. (2006) New specimen of Prognathodon (Reptilia: Mososauridae) from the Bearpaw Formation of Alberta. JVP 26(3) Abstracts pp.96
An exceptionally complete mosasaur was recovered from a mining operation on the Blood Nation Reservation near Lethbridge, Alberta. The Prognathodon specimen is from the lower Bearpaw Formation, approximately equivalent to the DeGrey Member of the Pierre Shale. It may be one of the best specimens of the genus from North America. The pectoral region and forelimbs were damaged by the mining operation, but the remainder of the skeleton was recovered. It includes a flattened skull that is missing parts of the posterior region, but has well preserved preorbital skull region, jaws, and teeth. The articulated vertebral column is nearly complete, missing only a few anterior vertebrae, and extending beyond the region of elongated neural arches, usually interpreted as a tail fluke. The hind limbs are fairly complete, as is the pelvis. The specimen is tentatively assigned to P. rapax on the basis of the shape of the quadrate, the dentary not projecting anterior to the first tooth, and the lack of a medial ridge on the frontal. If the tentative identification is correct, it expands the geographic range of P. rapax into the Western Interior Seaway. Moreover, this discovery provides new details about the morphology of this poorly known species.