Vast new fossil record challenges story of Earth’s ‘big five’ mass extinctions

Palæontologists have trained a machine-learning model on a huge database of fossil records, then used it to reconstruct a timeline of changes in Earth’s biodiversity over hundreds of millions of years in unprecedented detail. The model, called OneStrata, hints at several possible challenges to big ideas about evolutionary history. For example, it suggests that three of the “Big Five” mass-extinction events were gradual declines in biodiversity, rather than the sudden cataclysms described by other reconstructions.