coextinction

noun

going extinct simultaneously

Wiktionary

noun

Etymology: Etymology tree Proto-Indo-European *ḱe? Proto-Indo-European *ḱóm Proto-Italic *kom Proto-Italic *kom- Latin con- Latin co-der. English co- English extinction English coextinction From co- + extinction.

The simultaneous extinction of two or more species (especially when one is dependent on the other)