Fig. 2. Clumped isotope [Δ_47(abs)] value (calculated using the Gonfiantini parameters) versus temperature relationship of extant eggshell.

Data from this study, other biogenic carbonates analyzed between 2010 and 2018 at Yale University (8, 56–59), the calibration of laboratory precipitated carbonates from (8), and the extant eggshell carbonate calibration from (6). Error bars are SE for Δ₄₇ (smaller than the symbols) and the range of expected body temperatures. Calibration lines, solid line; 95% confidence error envelope, shaded line; and 95% prediction envelope, dashed-dotted lines.