PRELIMINARY ANALYSIS OF TEETH OF THE EXTINCT REQUIEM SHARK PHYSOGALEUS CONTORTUS (ELASMOBRANCHII: CARCHARHINIFORMES) AS CUTTING TOOLS

Physogaleus contortus teeth are common in Pungo River Formation (Neogene: Miocene) float material from the Nutrien Phosphate mine of Aurora, North Carolina. These tiger-like shark teeth have a thick crown with cutting edges and a well-developed distal heel which are serrated, indicating cutting function. The crown is taller and narrower than true tiger sharks (Galeocerdo sp.), suggesting heightened grasping function. The mesial cutting edge is warped with serrations changing direction apically. While the evolutionary advantage of this curvature is not immediately apparent, comparison to the cutting edges of various knives and saws are instructive, especially when considering forces exerted on the tooth during prey processing in vertical motion (grasping), horizontal motion (head shaking – cutting/tearing) and rotational motion (cutting/tearing). Forces on the tooth during the bite cycle were assessed by examining feeding damage on collected teeth as well as enameloid ultrastructure using scanning electron microscopy.