Depth habitats of growth stages of pelagic foraminifera.

Oxygen isotopic analysis of different size groups of shells of pelagic foraminiferal species shows that some species deposit their shells at constant depths while others deposit them at increasing or decreasing depths. These patterns show regional variations. Globigerinoides rubra and Globigerinoides sacculifera remain the most convenient species for oxygen isotopic determination of the past surface temperatures of the ocean.