Planktonic foraminiferal ontogeny and new perspectives for micropalaeontology

Abstract

Planktonic foraminifers are some of the most widely used micro-fossils for dating marine sedimentary rocks and the calcareous test has been used to reconstruct their depositional history over the past 120 million years¹. By tracing the successive growth stages of extant representatives of this group, we have obtained criteria which identify pre-adult forms that, traditionally, have been disregarded in foraminiferal research. Thus, large quantities of “… unidentifiable miscellaneous juveniles …”² have become available to help decipher the fossil record of marine environments. Comparative studies of growth series at species and supraspecific levels allowed the identification of three major species groups, each showing three different developmental stages. Their recognition introduces new possibilities for establishing a natural classification of planktonic foraminifers, for disclosing their evolutionary history and for testing evolutionary models in general.