PREDATORY BITE MARKS ON MARINE MAMMAL BONES FROM THE MIOCENE

It is commonly assumed that the megatooth shark Carcharocles megalodon consumed large prey, specifically marine mammals, during the Miocene. However, the evidence in the literature is depauperate. This may be because bones with bite marks tend to be broken and therefore often discarded since it is difficult to identify the taxonomy of such fossils. We seek evidence of bite marks on marine mammal bones from museum collections. In total, we have ~100 fossils with bite marks from three assemblages from both the east and west coast of the USA. We characterize the type of bite mark based off previously described bite types in the literature, identify the degree of diagenesis following Behrensmeyer (1978), and identify the anatomical placement of the bite on the marine mammal bone. Drawing upon methods from citizen science, we use quantitative approaches to classify types of bite marks using repeated measures. By replicating the scoring processes, we can calculate error associated with categorizing bite marks depending on the bite type and degree of diagenesis. We quantify the occurrence of bite marks and develop hypotheses about attack rates as well as inferences into attacking versus scavenging marks. We then draw cautionary conclusions about prey availability and the assertion that C. megalodon primarily consumed marine mammals.