EVIDENCE OF TOOTH SHAPE VARIATION IN CARCHAROCLES MEGALODON ACROSS OCEAN BASINS

The extinct Carcharocles megalodon maintained a cosmopolitan distribution during the middle to late Miocene. However, whether the presence of morphological variation in the total widespread population resulting has not been studied. We aimed to determine if variation in the tooth morphology related to differences in the geographic location (i.e. ocean basin). Our working hypothesis is that some differences in tooth morphology would be apparent and that these would result from genetic and environmental factors. Included specimens were representative of upper and lower anterior teeth from localities along North American Atlantic, Pacific and gulf coasts as well as the South American Pacific coast. Geometric morphometric methods were utilized to describe tooth morphology via relative warp analysis axes and subsequently tested for variation by applying MANOVA and ANOVA modeling techniques. With ocean basin of origin used as a grouping variable we found that the Atlantic and Pacific differed. Additionally, tooth size and interactions between basin and size were also found to influence morphology. Potential explanations could be similar to those found in modern Lamniformes, such as diet variability or mating trends that would be analogous with philopatry in adult individuals in the species. These results highlight the need to study geographic variation in extinct widespread populations to better infer and understand ecology of paleo systems.