The 1st north american occurrence of the late cretaceous elasmobranch ptychodus rugosus with comments on the functional morphology of the dentition and dermal denticles
Journal of Paleontology 56(2): 403-409
Fossil material identified as belonging to the Late Cretaceous elasmobranch, P. rugosus, was recovered from the Austin Chalk in Dallas County, Texas [USA]. The material, consisting of 11 vertebral centra, 553 teeth representing upper and lower dentitions, and microscopic dermal denticles, is the 1st occurrence of this ptychodontid in North America. Many of the teeth were articulated in life position within the chalk matrix, allowing for reconstruction of the dentition. Close inspection reveals that these teeth bear a series of structures that served to articulate them with adjacent teeth, locking the dentition as a whole into a rigid structure. Analysis of the dermal denticles shows that they are morphologically similar to those of modern elasmobranchs.