Eustatic changes and the evolution of Palaeogene larger foraminifera - A numeric analysis

Abstract

Sea-level change is known to have influenced the evolution of marine life. It is examined here how faunal diversity and rates of taxic evolution are related to change in sea-level and stability of the sea-level cycles. Evolutionary metrics of Palaeogene larger foraminifera are calculated and stability of sea-level cycles are determined using number and average duration of third order cycles in each stratigraphic interval. Generic diversity and the rates of origin and extinction individually do not show one to one correspondence either with transgression-regression or with the stability of the sea-level cycles. The rate of extinction relative to the rate of origination, however, is found to be significantly affected by the stability of the sea-level cycles. The rate of extinction exceeds the rate of origin during the periods of low stability. Regression, assisted by unstable sealevel cycles and possibly sharp climatic deterioration caused extinction maxima of larger foraminifera in Late Eocene.