Global extinction events and persistent age-dependency in sharks and rays over the past 145 million years

Understanding extinction mechanisms, including what traits make some species more vulnerable than others, is key in a changing world. It has been proposed that species' age predicts extinction risk. However, our understanding of age-dependent extinction (ADE) remains unresolved, with positive and negative trends being modelled only as mutually exclusive, and rarely across clade-specific diversification trajectories. Here, we reconstruct the global diversification trajectory of neoselachians (modern sharks and rays) over the past 145 Myr to assess ADE using a new model that allows positive and negative trends to co-occur. We recovered a dynamic diversification trajectory, including four previously undetected extinction events, the most significant in the Eocene-Oligocene. Negative ADE was consistently found over time, with young species, especially those younger than 4 Myr, being more vulnerable. Our results suggest that neoselachians have been more susceptible to extinction than previously recognized, with age being a consistent intrinsic predictor of their vulnerability through deep time.