AGE-DEPENDENT EXTINCTION IN RUMINANTS AT DIFFERENT TAXONOMICAL SCALES

In his seminal work Van Valen (1973) suggested that long and short-lived taxa have equal probabilities of going extinct. This “age-independent extinction”, has been mostly determined by the construction of higher taxa survivorship curves from a literal reading of the fossil record. Here we used a recently developed Bayesian framework, which accounts for several biases of the fossil record, to investigate Ruminantia (Artiodactyla, Mammalia) extinction regimes, both at the species and the genus level. We showed that Ruminantia present age-dependent extinction at the species level, with higher extinction probability for younger species, but age-independent extinction at the genus level. We also showed that the duration of genera is related to species richness. We discuss our results in the light of previous theory and suggest future developments on the subject.