View Full Profile. Learn about our Editorial Policies. Most scientists agree that five events in Earth’s history qualify as “mass extinctions”—defined as events where more than three-quarters of ...

This can be seen also in the geological record. Five big mass extinction events are recognized by paleontologists. At the end of the Ordovician some 443 million years ago, when an estimated 86% of ...

The researchers compared their model to the magnitude of Earth’s “Big Five” mass extinctions. The illustration above indicates the percentage of biodiversity lost during each event (left).

today’s crisis “does not yet qualify as a mass extinction in the paleontological sense of the Big Five.” But holding such a high standard for an event to qualify as a mass extinction doesn’t allow a ...

Life on Earth is anything but predictable. For evidence, look no further than the five mass extinctions that have occurred over the past 500 million years: Even in the midst of widespread ...