The six big mass extinctions

Through out history Earth has suffered a series of mass extinction events that saw the continuation of life on Earth threatened.  There has also been a number of lesser extinctions  but this work concentrates on the main mass extinction events. First, we will briefly define a mass extinction event and then look at the five most devastating mass extinction events in history. Then the discussion will look at the sixth and ongoing mass extinction event and conclude with thoughts for the future.

 

Artistic depiction  Devonian land and flora - Eduard Riou - Public Domain

What is a mass extinction event?

Each extinction varied in intensity and cause but each time life on Earth adapted, evolved and bounced back. A mass extinction event is a time in history where an extraordinary large number of different species die at the same time or within a limited time

The most well known of these events was the Cretaceous-Tertiary extinction which wiped out most of the dinosaurs. Nevertheless, there have been four other mass extinctions, some more devastating than this event, where half or more of all species were estimated to have died.

The most devastating of these events occurred at the end of the Permian period when 96% of species were wiped out.  This event and the Cretaceous-Tertiary extinction event are the two main mass extinctions so far.

There have also been a number of smaller scale mass extinctions.  For example human activity has caused the extinction of many animal and plant species throughout history and in modern times.  In time these will show in the fossil record as a mass extinction. In fact we are going through a sixth mass extinction of plants and animals caused by humans but how devastating that will prove to be only time can tell.  Read more