Mass Extinction: A mass extinction event is a period of time in Earth's history when a large percentage of the planet's species die out in a relatively short geological time frame, often due to catastrophic changes in the environment.
Background Extinction: Background extinction is the normal, ongoing rate of species loss that occurs naturally over long periods of time, as new species evolve and others become extinct due to natural selection and environmental changes.
Adaptive Radiation: Adaptive radiation is the process by which a single ancestral species diversifies into multiple new species that are adapted to different ecological niches, often following a mass extinction event.