The classic paleotemperature record based on delta (super 18) O data from pelagic foraminiferal calcite suggests that equatorial sea-surface temperatures during the Maastrichtian ( approximately 12 - 20 degrees C) were much cooler than today ( approximately 27 - 29 degrees C). Such cool equatorial temperatures contradict basic theories of tropical atmospheric and ocean dynamics. We report delta (super 18) O data from remarkably well preserved rudist aragonite and magnesian calcite cements of Maastrichtian age ( approximately 69 + or - 1 Ma) from the carbonate platform of Wodejebato guyot in the western Pacific. These data suggest that equatorial sea-surface temperatures in the Maastrichtian (best estimate approximately 27 - 32 degrees C) were at least as warm as today. This finding helps reconcile the geologic delta (super 18) O record with ocean-atmospheric dynamic theory and implies a reduction in the poleward heat flux required by global climate simulations of greenhouse conditions.