Stability and change in Tethyan planktic foraminifera across the Paleocene-Eocene transition

Examination of planktic foraminifera in the Tethys basin during the Paleocene-Eocene transition reveals two stasis intervals that are separated by a major saltation event coincident with the P-E short-term perturbation in global climate and oceanography. Changes occurred at many spatial and temporal scales as well as many taxonomic and ecologic hierarchical levels, though with various rates and magnitudes. The stasis intervals are marked by slow changes at the species level and account for 50% of the observed first and last appearances during a 2.5 Myr interval. The saltation event is marked by rapid changes at the species and morpho-guild levels and accounts for the remaining 50% of first and last appearances during an interval of about 100-200 kyr. Despite these changes, many taxonomic and ecologic units, such as the depth assemblages and genera, and faunal parameters, such as species richness and turnover rates, are stable with respect to the P-E perturbation. This coexistence of change and stability marks the crisis of Tethyan planktic foraminifera across the P-E transition and reveals the possible dynamics of ecological evolution.