Five Mass Extinction Events In Earth's History That Wiped Off Most Life

Mass extinction events or biotic crises occur when Earth undergoes sharp changes in terms of diversity of species on the planet.

It is estimated that Earth has undergone at least five mass extinction events in the last 440 million years whereby life on the planet was diluted, if not erased. This may be due to the fact that most life on Earth is microbial, but our understanding of extinction events is highly rooted in visible species.

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[Also Read: Is Humanity Doomed? Science Says We Are In Middle Of A 'Mass Extinction Event']

Here are the five mass extinction events that happened on Earth:

1. The first mass extinction event

The Ordovician-Silurian extinction took place roughly 440 million years ago, according to LiveScience. In this event, at least 85 per cent of all species on the planet were wiped away.

This extinction event is generally called the first mass extinction event on Earth and is largely attributed to the change in water temperatures on Earth, which killed most oceanic life.

It's unclear what caused this change. With lower sea levels, habitats died, according to a study published in Oceanology. Nat Geo claims that chemicals that seeped into the ocean after depletion of oxygen may have killed life on Earth.

[Also Read: Human Actions Made 68% Flightless Bird Species Extinct, Claims Study]

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2. "The age of fish" extinction event

During the Devonian period, which is also called "the age of fish" extinction, many ancient marine species were killed 365 million years ago.

You won't believe this, but it appears that the evolution of vascular plants like flowers and trees may have caused this particular extinction event, or at least according to a 1995 study published in GSA Today.

[Also Read: Over 30 Percent Shark Species Now Face Extinction, As Per Marine Experts]

The development of plants also meant changes in Earth's land - turning rock into soil. These soils permeated through water, which introduced bacteria and algae to our oceans. When they overgrew as blooms in oceans, the water essentially turned into toxic soup, killing off 75 per cent of all species.

3. The Great Dying

Known as the worst extinction event to hit Earth, the "Great Dying" meant the end many species on our planet about 253 million years ago.

This extinction event wiped out at least 90 per cent of all species on Earth, including 96 per cent marine life and 70 per cent terrestrial life, according to Live Science.

Volcanoes were aplenty on Earth during this period. In the aftermath of volcanic eruptions, Earth was covered in greenhouse gases causing changes in weather and erratic climate.

[Also Read: About 30 Percent Of All Wild Trees On Earth Will Soon Be Lost Forever, Says Study]

This effect trickled down into the oceans, where oxygen was being depleted. At that point, a supercontinent called Pangaea existed on Earth, which could have limited the movement of oceanic waters - allowing carbon dioxide pooling to take place.

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4. Killer volcanoes

About 201 million years ago, volcanoes on Earth remained extremely active, contributing to carbon dioxide levels on the planet.

In turn, these accentuated changes in climate that killed all at least 80 per cent life on Earth, according to Live Science. The pattern during this period is eerily similar to what Earth is experiencing right now.

Here's what happened: sea levels rose, global temperatures increased, ice melted, causing the demise of many species - eerily similar to what Earth is undergoing at the moment.

5. Goodbye dinosaurs!

The fifth known mass extinction event, known as K-T extinction market the end of dinosaur life on Earth when an asteroid struck present day Mexico, making 75 per cent species extinct.

Not much later, Earth would have been covered in dark skies owing to the debris from the asteroid. When this happened, there was no sunlight in place for plants to thrive. In effect, food chains were broken. This essentially meant the death of most life on Earth.

These were the most recent five extinction events known to science. Many scientists have started calling the ongoing changes in Earth the sixth mass extinction event.

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Earlier, Indiatimes reported how toxic algae and bacterial blooms are turning our fresh water bodies inhabitable. In addition, Earth is currently witnessing erratic weather, rising oceans, and increasing temperatures - all telltale signs of impending doom, according to scientific reports.

We should worry and do our best to limit ways in which we could be hurting the climate. Did you enjoy reading this list? Don't forget to check out Indiatimes.com daily for the best and freshest in the world of technology and science.