ASPECTS OF THE POST-CRETACEOUS RECOVERY OF THE CENOZOIC PLANKTIC FORAMINIFERA

Survivorship analysis was used to extract unbiased (censorship-correct ed) estimates of the species longevity distribution of the Cenozoic pl anktic Foraminifera. These estimated distributions provide the basis f or monte carlo simulations of the post Cretaceous recovery in the grou p. Using the achievement of a stable longevity distribution as a crite rion for recovery yields a predicted recovery time of approximately 15 Myr. This prediction agrees well with the observed recovery time, but significant patterns of deviation from simulations suggest that extin ction and origination rates covary and that rapid turnover during the Paleocene recovery period may have significantly reduced mean longevit y during that time. A significant fit to a Weibull survivorship model suggests that there is an longevity-dependent increase in extinction p robability which may be explained by temporal inhomogeneity in the ori gination rates of short-lived species. The scale of the inhomogeneity suggests it is unlikely to be an artifact of taxonomic practice or sam pling error. Censorship-corrected mean longevity is reported to be 9.1 7 Myr.