MORPHOLOGY OF SHARK TEETH FROM TWO SPECIES OF MID-MIOCENE SHARKS: C. HASTALIS AND C. PLANUS, AND POSSIBLE ECOLOGICAL IMPLICATIONS

Bakersfield, California has long been known as one of the few places where an extinct rare species of fossil shark(Carcharodon planus) can readily be collected. The fossil rich Round Mountain Silt member of the Temblor Formation holds the remnants of a rich marine environment. The bone-bed layer, which is dated at 16 million years old, is littered with massive quantities of mammal bone material. This unique collecting area is between 10-100 cm in thickness, but most of the specimen material, including three apex predators: Otodus megalodon, Carcharodon hastalis and Carcharodon planus are found toward the lower 10-30 cm. This study concentrates on the latter two apex predators for which the fossil evidence shows were far more prevalent than the O. megalodon. ImageJ measurement studies on both the root and blade of individual teeth were made in order to look for distinct similarities and differences between the two species. A total of 80 teeth, forty from each of the two species, are being used in this study. It may be possible to draw both evolutionary and ecological hypotheses from a study of the two species. Further investigations can also center on regional differences in C. hastalis between Atlantic and Pacific populations. In compliance with the focus of this theme section, the presentation will be delivered for plain-talk understanding by students and the non-professional public.