Six mass extinctions are the catastrophic events that caused the wiping out the different species on the Earth. 5 Mass extinctions have already happened, we are on the verge of the 6th Mass Extinction. Before looking at the list, let’s understand what Mass Extinction is all about?
What is Mass Extinction?
Everyone has heard about Dinasoraus. Once they used to be the great rulers of this ecosystem. What happened to them is not a mystery anymore. Due to rigorous research, we came to know that they became extinct in one of the six mass extinctions events.
In any mass extinction event, more than 50% of the species becomes extinct. As of now, we know that the largest of the six mass extinctions event happened some 250 million years ago. in this event almost 95% of all the species present on the Earth Vanished. Many Scientists have estimated that almost 99.9% of the species on the Earth have become extinct in the last five mass extinctions.
List of Six Mass Extinctions are as follows.
- Ordovician-Silurian Extinction: In between 445.2-443.8 million years ago
- Devonian Extinction: In between 419.2 million to 359 million years ago.
- Permian-Triassic Extinction: In between 299 million to 252 million years ago.
- Triassic-Jurassic Extinction: Around, 210 million years ago
- Cretaceous-Tertiary Extinction: Approximately, 66 Million Years Ago
- Holocene Extinction Event- Ongoing
One: Ordovician-Silurian Extinction
This is the first mass extinction event in the six mass extinctions. It happened during the Hirnantian Age of the time period named Ordovician followed by the Silurian Age. This event happened to wipe out 85% of all the species during that time.
Causes of Ordovician-Silurian Extinction.
There are two major causes of Ordovician-Silurian Extinction. They are as follows.
- Cooling of Earth’s global temperature.
- Decrease in the sea levels.
This event impacted species living in warm and the shallow coastal waters.
Two: Devonian Extinction in the six mass extinctions.
The Devonian Extinction event is estimated to be happened between 419.2 million to 359 million years ago. It caused many tropical marine species to become extinct. This mass extinction event happened in the Devonian Period.
Causes of Devonian Mass Extinction.
There are no one cause or any perfectly identified causes but one can agree upon the following.
- Excessive sedimentation.
- Climate Change ( Either rapid cooling or rapid global warming)
- impact of the meteorite or a comet.
- Massive nutrient run-offs from different continents.
Three: Permian-Triassic Extinction
The Permian-Triassic mass extinction event happened between 299 million to 252 million years ago. This is the largest mass extinction event in the history of the Earth. It caused the extinction of many species including the vertebrates. Almost 95% of the species were wiped off from the Earth during the Permian and Triassic periods.
Causes of Permian-Triassic Extinction.
- Global Warming.
- Acid Rain.
Four: Triassic-Jurassic Extinction
The Triassic-Jurassic Extinction of the six mass extinctions event happed between 252 million to 201 million years ago. Due to this extinction event dinosaurs flourished. Major vertebrates were extinct during this event.
Causes of Triassic-Jurassic Extinction.
- Widespread volcanic eruptions.
- Acidification of the oceans.
Five: Cretaceous-Tertiary Extinction
The Cretaceous-Tertiary Extinction happened roughly 65-66 million years ago. It is also known as K-T extinction event that wiped out nonavian Dinosaur from the earth.
The possible causes of the K-T mass extinction in six mass extinction event is as follows.
- Impact of the Asteroid or Comet.
- Giant Volcanic Eruption.
Six: Holocene Mass Extinction, a human-induced extinction in the Six Mass Extinctions Event.
The Holocene mass extinction or commonly known as Anthropocene extinction is majorly induced by the human beings on the Earth. It has caused the disappearance of many species on Earth. One of the most famous being Dodo which we have lost recently. There are various other species that have become extinct.
The causes of the Holocene Mass Extinction is as follows.
- Habitat encroachment and hunting.
- Climate Change.
- Genetic Mutations.