Five mass extinctions, known as the “Big 5,” have caused abrupt, drastic decreases in animal biodiversity over the last 540 million years. Each resulted from global-scale environmental perturbations and resulted in the extinction of a significant proportion of the world's biota in a geologically negligible period of time. Numerous studies have focused on the taxonomic changes and patterns that are the hallmark of these mass extinctions. However, mounting research indicates that the most significant results of mass extinctions actually may have been new ecological patterns that arose during their aftermath, rather than the extinctions themselves.