Figure 1

Oxygen isotope compositions of phosphate (A) and carbonate fossils and microfossils (B) from tropical-subtropical (0–30°) and temperate (30–50°) latitudes. Carbonate δ¹⁸O values less than −8‰ (N = 139) are not shown. These are almost exclusively Paleozoic brachiopod shells that fail quality control (QC) standards (i.e., not “select”). Locfit regression lines (α = 0.05) for tropical and subtropical samples are shown with ± 95% confidence limits (CL). ForamP = planktonic foraminifera, Biv-gast = bivalves and gastropods, Belem = belemnites, Brach = brachiopods, and select = data that have passed QC standards. Belemnite values were adjusted by −1.5‰ to correct for ¹⁸O enrichment. Letters in the bar between figures refers to geologic periods Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Paleogene, and Neogene. Some symbols in key are enlarged for clarity.