Extinction level event
An extinction level event or mass extinction was an event that occurred over a widespread area which led to a severe decrease in life and possibly the extinction of species.

Around 65 million years before 2154, a comet caused a mass extinction on Earth. Most of the reptiles died out and mammals became the dominant species. ()

On Talos IV, nuclear war caused a near-extinction level event, but a small population of the indiginous species remained. ()

On Terralysium, an extinction level event was narrowly avoided in the late 2250s. A disruption in the gravitational stability of the planet's outermost ring sent radioactive particles on its way to the upper atmosphere, and eventually the planet's surface. Had this not been avoided, it would have caused nuclear winter. ()

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Events