Feeding ecology has shaped the evolution of modern sharks

Sharks are iconic predators in today’s oceans, but their modern diversity has ancient origins. In particular, current hypotheses suggest that a combination of mass extinction, global climate change, and competition between dominant Mackerel shark (Lamniformes) and Ground shark (Carcharhiniformes) clades has regulated their community structure over the last 66 million years. However, while these scenarios reflect an interplay of major biotic and abiotic events, the precise drivers remain obscure. Here, we focus on the role of feeding ecology using a morphometric dataset of 3,837 fossil and extant shark teeth. Our results reveal that morphological segregation rather than competitive overlap has characterized modern lamniform and carcharhiniform shark evolution. Moreover, although lamniforms suffered a long-term disparity decline, perhaps due to dietary ‘specialization’, their current disparity rivals that of ‘generalist’ carcharhiniforms. We posit that trophic partitioning and resource availability have shaped shark ecology, and represent critical determinants for future species survivorship.