Geologic Time Scale

Formation of the Earth (4600 MYA)

4600 BCE

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

Formation of the Moon (4500 MYA)

4500 BCE

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

First signs of Animal Life (3700 MYA)

3700 BCE

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

First Photosynthetic bacteria (3500-3200 MYA)

3500 BCE

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!

Cambrian Explosion of Life (542 MYA)

542 BCE

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

First Plants on Land (470 MYA)

470 BCE

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

Ordovician-Silurian Extinction (440 MYA)

440 BCE

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

Late Devonian Extinction (365 MYA)

365 BCE

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

Permian-Triassic Extinction (252 MYA)

252 BCE

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.

Earliest Dinosaurs Appeared! (243-233 MYA)

243 BCE

The earliest dinosaurs were recorded in the rock record anywhere from 233 to 243 million years ago!

Cretaceous-Paleogene Extinction (66 MYA)

66 BCE

This extinction is the event that wiped out the dinosaurs and paved the way for the "Age of Mammals" which has shaped our modern world today.