Anapnoian Eon

The Anapnoian Eon is the fourth and longest eon in Espan History, it is commonly accepted to have begun close to 2940 million (about 2.940 billion) years ago when the Great Oxygenation event append, lasting 2.033 billion years

The Anapnoian Eon is named after the Greek word "Anapnoí" meaning breathing.

Events
The Anapnoian Eon started with the sudden appearance of atmospheric oxygen triggering the first mass extinction event on the planet during which 99% of Espan lifeforms died out. This event marked the end of the prKatagogian Eon and the start of the follow-up Anapnoian Eon.

Additionally to the oxygenation the higher oxygen levels had other effects on the planet, firstly the oxygen combined with Iron to start a new global phase of rusting, turning the Espan oceans brown red, but fore-mostly dropping the methane levels - The oxygen combined with the methane to form carbon dioxide and water, which do not retain heat as well as methane does - sending Espa deep into a vast ice age called the Kokkinoan Ice Age. For the planets climate to adapt to the new atmosphere 400 ma had to pass, and only by 2.5 BYA the ice would began to retreat.

After the ice age under the new oxygen atmosphere aerobic lifeforms soon developed into complex colonial and eventually multi-cellular lifeforms, drastically speeding up the process of evolution.

While this was happening somewhere around 2.1 BYA the first bacterial viruses appeared. At about 1.91 BYA the first bacteria with a nuclei formed thus separating the main domains of prokaryotic and Xenokaryotic Cells on Espa.

At around 1.84 BYA an aerobic protist enters the system of a larger protist and avoids digestion, becoming a source of energy instead. Eventually it becomes just another organelle inside the larger protist causing mitochondrial symbiosis. These symbiosis's happen again for phototrophes at 1.56 BYA, where a Photosynthetic Autotrophes became integrated into a larger Xenokaryota making the basis for all plants and algae. Resulting in the evolution of sexual reproduction opposed to Asexual reproduction by 1.5 BYA.

Its also around 1.5 BYA ago that Espa's solid inner core forms rapidly boosting the magnetic field of the planet.

As creatures become increasingly more elaborate by 907 MYA the eon ends being superseded by the Tskhovelian Eon.