This dataset contains the results of trace element analysis (Mg/Ca, Fe/Ca and Mn/Ca ratios in mmol/mol) of the benthic foraminifer Oridorsalis umbonatus from Ocean Discovery Program (ODP) Site 849 in the Equatorial East Pacific (0°11'N, 110°31'W). Trace element ratios were analyzed using a Agilent Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) 720. Mg/Ca data was normalised to the ECRM752-1 standard. Temperatures calculated using the O. umbonatus-specific calibration by Lear et al. (2002). For temperature calculation, raw Mg/Ca ratios were adjusted to account for past variation in seawater Mg/Ca using estimates of seawater Mg/Ca from Evans et al. (2016).