Fig. S4.

Bispectra assessing phase coupling and energy transfers between frequencies in the δ¹⁸O data. Bispectral results over three 2-My-long intervals that correspond to (A) ∼2.4-My Eccentricity Cycle 9 (21.10 My to 19.10 My ago, (B) Cycle 10 (23.54 My to 21.54 My ago), and (C) Cycle 12 (28.30 My to 26.30 My ago; see SI Methods). Gray lines reflect the main astronomical frequencies of eccentricity, obliquity, and precession. The two panels of Fig. 2 are reproduced here (B and C) and expanded to include the interactions with the precession frequencies.