TAXON AGE SELECTIVITY IN MODERN EXTINCTIONS

Previous work has found that in the fossil record, older taxa (i.e., those having older origination times) are less likely to go extinct during background extinctions, but this relationship largely disappears during mass extinction events. Here we explore the relationship between the age of a taxon and its extinction risk for modern taxa in the current global extinction. We use fossil data from the Paleobiology Database, and modern data from the International Union for Conservation of Nature (IUCN) Red List, which evaluates species conservation status. We limit our analysis to genera with both a fossil record as well as substantial evaluation by the IUCN. Genera were assigned values that represented the extinction risk of their constituent species, and these values were plotted against genus age. We find no significant relationship between genus age and extinction risk for multiple taxa at different taxonomic levels. This pattern does not match what has been observed throughout the Phanerozoic in background intervals, but is instead consistent with dynamics observed in the Big Five mass extinctions.