Reports

Species Formation Through Punctuated Gradualism in Planktonic Foraminifera

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Science  20 Jul 1984:
Vol. 225, Issue 4659, pp. 317-319
DOI: 10.1126/science.225.4659.317

Abstract

Detailed analysis of evolutionary changes in a 10-million-year long Late Neogene lineage of planktonic foraminifera has revealed a pattern that is not consistent with either the gradualistic or the punctuational model of evolution. The lineage was in stasis over a considerable part of its total duration but underwent relatively rapid, but not geologically instantaneous, gradual morphologic change that did not lead to lineage splitting. The term punctuated gradualism is suggested for this evolutionary modality.