The latitudinal biodiversity gradient through deep time

•The latitudinal biodiversity gradient has not been a persistent feature through time.•The modern pattern might only have originated 30 million years ago.•A temperate diversity peak is recorded during warmer intervals.•A tropical diversity peak might characterise icehouse worlds. Today, biodiversity decreases from equatorial to polar regions. This is a fundamental pattern governing the distribution of extant organisms, the understanding of which...