Before the Cretaceous mass extinction known for wiping out non-avian dinosaurs, the Earth had witnessed four other great mass extinctions.
- A paper published last week in the journal, Nature Geoscience, has come up with a new reason behind the first mass extinction, also known as the Late Ordovician mass extinction.
- The article notes that the cooling climate likely changed the ocean circulation pattern.
- This caused a disruption in the flow of oxygen-rich water from the shallow seas to deeper oceans, leading to a mass extinction of marine creatures.
- The Ordovician mass extinction that occurred about 445 million years ago killed about 85% of all species.
- The other big extinction events were:
- The Devonian mass extinction (about 375 million years ago) wiped out about 75% of the world’s species.
- The Permian mass extinction(about 250 million years ago) also known as the Great Dying caused the extinction of over 95% of all species.
- The Triassic mass extinction (200 million years ago) eliminated about 80% of Earth’s species, including some dinosaurs.
- Some researchers have pointed out that we are currently experiencing a sixth mass extinction as the result of human-induced climate change.