High tropical and low polar biodiversity is one of the most fundamental patterns characterizing marine ecosystems, and the influence of temperature on such marine latitudinal diversity gradients is increasingly well documented. However, the temporal stability of quantitative relationships among diversity, latitude and temperature is largely unknown. Here we document marine zooplankton species diversity patterns at four time slices [modern, Last Glacial Maximum (18,000 years ago), last interglacial (120,000 years ago), and Pliocene (~3.3-3.0 million years ago)] and show that, although the diversity-latitude relationship has been dynamic, diversity-temperature relationships are remarkably constant over the past three million years. These results suggest that species diversity is rapidly reorganized as species’ ranges respond to temperature change on ecological time scales, and that the ecological impact of future human-induced temperature change may be partly predictable from fossil and paleoclimatological records.