Meeting Abstract
Serrasalmid fishes, such as carnivorous piranhas and their herbivorous pacu relatives, possess an extensive range of cranial morphologies that are believed to bear strong correlations to diet. Most notably, the morphology of their teeth ranges drastically across Serrasalmid species, from sharp piscivorous-like teeth which are well-equipped for consuming flesh, to incisiform teeth more closely associated with herbivory. However, tooth morphology is not the only contributor to the diversity of cranial forms found within the family. Across the taxon, Serrasalmid fishes display various degrees of occlusal offsets, wherein the teeth of the upper jaw or lower jaw will extend past their opposing counterpart. By creating and manipulating 3D-printed physical models to test bite performance, our study sought to answer the question of whether this degree of occlusal offset has any influence on biting ability with different types of prey. Eight representative species, five piranhas and three pacus, were chosen and evaluated for occlusal ability in order to determine the natural degree of occlusion for each species. We also tested whether specific degrees of occlusion can be attributed to certain diets, and how biting ability is affected when species are taken out of their natural occlusal positions. Our study found that underbites, which are generally associated with the piranha clade, performed better on the flesh-like experimental material than overbites, which are more typically associated with the pacu clade; in contrast, overbites outperformed underbites on the brittle material. This implies that Serrasalmid fishes have evolved to possess degrees of occlusion which best suit their dietary niches.
