A process in which huge numbers of species on a Garden World die out suddenly. Divided into (from most severe to least):
The K-T extinction removed the dinosaurs; the P-Tr extinction eliminated 95% of all kinds of Terran life, the Fr-Fa (Devonian period) killed coral reefs and many types of invertebrates. Mass extinctions are caused by a variety of factors, but are often triggered or exacerbated by bolide impacts.
- Class 10 - all life destroyed
- Class 9 - all surface life (even microbial) destroyed; rare microbial life survives deep in the crust.
- Class 8 - most life destroyed; some microbial life survives in sheltered environments
- Class 7 - all higher life destroyed; hardy microbial life survives
- Class 6 - almost all complex life destroyed; microbial life survives
- Class 5 - most species and groups of organisms killed - P-Tr equivalent
- Class 4 - many species and groups of organisms killed; others survive - K-T or Fr-Fa equivalent.
- Class 3 - many species extinct, but most major groups survive - late Triassic, Mid Cretaceous, or End Eocene turnover
- Class 2 - some species extinct but many survive - minor extinction events
- Class 1 - susceptible and vulnerable species die out; all others survive - local forest clearing, medium climate change events
Generally, the highest extinction classes (anything higher than 6) result only from pernicious goo swarms or nearby supernova explosions. Class 10 is extremely rare; life is amazingly hardy. However, fragile, complex biospheres are easily disrupted, and any development automatically results in a class 1, even a class 2 extinction.
The great ecological crisis of the Industrial/Atomic/Information Age Old Earth was a Class 4.8 event, one of the most destructive on record (only actions like the deliberate "salting" during the Empires war, and again during the Sagittarius-Softbot war, are more thorough).
- K-T Extinction - Text by M. Alan Kazlev
Terragen mass extinction that occurred 65 million years ago, at the boundary of the Cretaceous and Tertiary periods. Caused by an asteroid or comet impact on the Yucatan Peninsula, resulting in prolonged darkness and rapid global temperature change. It resulted in the extinction of a number of important groups of animal life, including dinosaurs, plesiosaurs, mosasaurs, pterosaurs, ammonites, and several groups of plankton. Plants, small invertebrates, small reptiles and amphibians, small birds, and nocturnal mammals were not unduly affected, and large scavenging reptiles (crocodiles) also were able to survive. The K-T extinction event was a Level IV Mass Extinction.