Life in the Fast Lane: Selective Survivorship of Mollusks withRapid Life Histories across a Pliocene Extinction BoundaryHerbert, Gregory S., Department of Geology and Center for Population Biology, UC Davis, CA 95616Stable isotope sclerochronology was used to trace the evolution of life history strategies and selectivity of survivorship in six lineages of the small predatory gastropod genus Urosalpinx across a late Pliocene (2.5 Ma) extinction boundary in Florida. The boundary coincides with an early, unusually intense glacial interval, but other changes, including a possible reduction in the intensity or predictability of upwelling, are also suspected.Serial isotopic sampling of entire fossil shells revealed consistent differences in rates of both sexual development and growth between extinction survivors and losers but not in season of hatching. Prior to the extinctions, the Urosalpinx group was composed primarily (83%) of species that matured late (2+ yrs) and grew slowly (30-85 mm in 1st yr spiral distance). In contrast, post-extinction survivors all matured
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yr spiral distance, Urosalpinx, Rapid Life Histories