mass extinction

noun

plural mass extinctions

: an event in which many living species on Earth experience rapid extinction rates during a relatively short period of geologic time

Unless climate change is curbed, Earth's oceans could see a mass extinction of marine life unlike anything the planet has seen for millions of years …

—Doyle Rice

[Paleobiologist Anthony] Barnosky calculates that humans are now creating a mass extinction. … As many as 30% of all species may be lost over the next four decades, conservationists estimate.

—Gaia Vince

specifically : a rare event in which seventy-five percent or more of all living species on Earth die out within a relatively short period of geologic time and that is usually associated with catastrophic natural phenomena (such as volcanic eruptions or asteroid impacts)

… the most recent of five events in Earth's history that scientists consider mass extinctions, defined by paleontologists as events where more than 75 percent of species vanish within a geologically short period of time, typically less than two million years.

—Katarina Zimmer

About 252 million years ago, the vast majority of species on Earth were killed off in the "Great Dying," the worst mass extinction in our planet's history. Up to 96% of all marine species and 70% of land animals were killed off during this event …

—Peter Kotecki

We are still far from meeting the requirements that paleontologists set for a "mass extinction event" (loss of 75 percent of species globally). However, in geologic time, we are moving towards that reality.

—Gabe Allen

The Triassic mass extinction event took place 200 million years ago, eliminating about 80% of Earth's species, including many types of dinosaurs.

—Tammana Begum

Examples of mass extinction in a Sentence

Recent Examples on the Web

But the change wasn’t a uniform mass extinction event. —Paul Smaglik, Discover Magazine, 2 May 2025

Paleontologists recognize five big mass extinctions in the fossil record, marked by the loss of a significant number of species in a (geologically speaking) short span of time. —David Bressan, Forbes, 17 Mar. 2025

After a meteor contributed to a mass extinction event that killed of all the dinosaurs, only the aquatic and semi-aquatic crocodylomorphs remained. —Paul Smaglik, Discover Magazine, 16 Apr. 2025

To find answers, a team of scientists studied North America’s fossil record, focusing on the 18 million years before the mass extinction at the end of the Cretaceous period. —Kimberly Richardson, CNN Money, 15 Apr. 2025

Word History

First Known Use

1943, in the meaning defined above

Rhymes for mass extinction

• contradistinction
• distinction
• tinction