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Geologically rapid global warming occurred during the Paleocene–Eocene Thermal Maximum (PETM) ~56Ma. Several studies have argued that important changes occurred in the hydrological cycle during the PETM, but results have been inconsistent, ranging from global increases in humidity to drier conditions. Changes in paleosols during the PETM in the southeastern Bighorn Basin document major drying during the body of the event. Paleosol changes also suggest transitional episodes of climate change that both preceded and followed the PETM. Qualitative, semi-quantitative, and fully quantitative analyses of a ~70m thick interval of paleosols provide a high-resolution record of changes in soil moisture and precipitation. Those changes are compared to changes in temperature determined from δ¹⁸O values of tooth enamel from the mammal Coryphodon. A distinct shift to drier soils occurred just prior to the …