The Precambrian Eon

1st important event (Headen): The creation of the universe from a cloud of dust and gas.

The Precambrian Eon

2nd important event (Archean): Earth gained enough mass to hold an atmosphere.

The Precambrian Eon

3rd important event (Proterozoic): Atmosphere enriches with

oxygen due to bacteria—ozone layer forms

too . Supercontinent Rodinia forms. First multi-cell fossils.

“Snowball Earth”

Phanerozioc Eon

Paleozoic Era

1st important event: Cambrian Explosion aka "Explosion of life" Period went most major animal phyla appeared in fossil record. Lasted 20-25 million years

Paleozoic Era

2nd important event: Formation of Pangea.

Paleozoic Era

3rd important event: A event known as Permain-triassic extinction or the Great Dying happened, where many animal/plant life ended on earth after something struck.

Mesozoic Era

1st & 2nd important event: Massive floods of lava and and asteroid caused what is known as the Triassic- Jurassic extinction. This killed 20% of marine life and many amphibians as well as archosaurs went extinct.