Amino Acid Composition of Planktonic Foraminifera: A Paleobiochemical Approach to Evolution

Abstract

A unique, species-specific amino acid composition is identified with each of 16 species of planktonic Foraminifera isolated from the tops of deep-sea sediment cores. This amino acid pattern appears to directly reflect the genotype. The total amino acid content ranges from 2.0 to 4.2 micromoles per gram of calcified tissue or 0.02 to 0.04 percent by weight. Analyses of two Early Miocene species indicate that characteristic compositional differences are sufficiently well preserved over geologic time to determine phylogenetic affinities among extinct species living at least 18 million years ago.