Timeline: Geologic Time Scale

4600 BCE

Formation of the Earth (4600 MYA)

The Solar System forms and a collection of space dust forms the third planet from the Sun.

4500 BCE

Formation of the Moon (4500 MYA)

After colliding with a young planet Earth, space rock and debris form this satellite of the Earth.

3700 BCE

First signs of Animal Life (3700 MYA)

Ancient microbes (which are animals) were discovered and dated to be almost 3.7 billion years old!

3500 BCE

First Photosynthetic bacteria (3500-3200 MYA)

First evidence of photosynthetic microorganisms was discovered and dated to be 3.2-3.5 billion years old! They were known as stromatolites and were stationary in the oceans of the ancient Earth. Stromatolites still exist on Earth today!

542 BCE

Cambrian Explosion of Life (542 MYA)

The Cambrian explosion was a period of rapid evolution and the development of many new groups of multicellular organisms.

470 BCE

First Plants on Land (470 MYA)

Spores of ancient plants discovered to be habiting dry land rather than the usual water habitats.

440 BCE

Ordovician-Silurian Extinction (440 MYA)

Fluctuating temperatures on the earth destroyed life that was unable to withstand the changes.

365 BCE

Late Devonian Extinction (365 MYA)

Different theories exist for this one: maybe another global cooling event? Maybe excessive algae blooms stripped the oxygen out of ocean habitats.

252 BCE

Permian-Triassic Extinction (252 MYA)

This was the deadliest extinction event in the history of the Earth! Almost 96% of life on earth was wiped out through a combination of gas emissions from global events.