When some long futuristic epoch comes to be and the next apex species forms on this planet...

[Fumesucker]

9. The first great extinction was when the oxygen released by plants killed off the anaerobic life..

http://www.slate.com/blogs/bad_astronomy/2014/07/28/the_great_oxygenation_event_the_earth_s_first_mass_extinction.html

Cyanobacteria are photosynthetic. They convert sunlight into energy and produce oxygen as a waste product. Back then, the Earth’s atmosphere didn’t have free oxygen in it as it does today. It was locked up in water molecules, or bonded to iron in minerals.

The cyanobacteria changed that. But not at first: For a while, as they produced free oxygen as their waste, iron would bond with it and the environment could keep up with the production.

At some point, though, as cyanobacteria flourished, the minerals and other sinks became saturated. They could no longer absorb the oxygen being produced. It built up in the water, in the air. To the other bacteria living in the ocean—anaerobic bacteria, remember—oxygen was toxic. The cyanobacteria were literally respiring poison.

A die-off began, a mass extinction killing countless species of bacteria. It was the Great Oxygenation Event. But there was worse to come.