Mass Extinction:

● Mass Extinction:

» A mass extinction event is when species vanish much faster than they are replaced.

 » This is usually defined as about 75% of the world’s species being lost in a ‘short’ amount of geological time - less than 2.8 million years.

● Mass Extinctions So Far:

1) First Mass Extinction: The Ordovician mass extinction that occurred about 445 million years ago killed about 85% of all species. 

2) Second Mass Extinction: The Devonian mass extinction (about 375 million years ago) wiped out about 75% of the world’s species.

3) Third Mass Extinction: The Permian mass extinction (about 250 million years ago) also known as the Great Dying caused the extinction of over 95% of all species.

 4) Fourth Mass Extinction: The Triassic mass extinction (about 200 million years ago) eliminated about 80% of Earth’s species, including some dinosaurs.

5) Fifth Mass Extinction: This Cretaceous mass extinction (about 65 million years ago) is known for wiping out non-avian dinosaurs.