Mass extinctions

By: Mohamed Ahmed

Image taken from Tabletop Gaming

According to, to qualify to be a mass extinction, at least half of all species die out in a relatively short period of time. In this article we will be looking at the top 5 largest mass extinctions, the: Ordovician, Devonian, Permian, Triassic-Jurassic, and Cretaceous extinctions. 

The Ordovician-Silurian extinction was the second worst mass extinction, according to This extinction wasn’t even that far behind the worst mass extinction, which we will later look at. Jawless fish were the most advanced life forms during this time, and the majority of all beings lived in the ocean. The global temperature cooled and sea levels fell. Most species were adapted to shallow, warm water, and that was the reason why 85 percent of all organisms on earth became extinct. It was one of many extinctions that happened in a short period of time. 

The Devonian extinction happened 375-360 million years ago. According to, the cause of the Devonian extinction was never actually solved definitively. There are many theories about this, varying from global warming, to meteors, or even a lack of oxygen. No matter the cause, the marine animals where the ones that made up the majority of the casualties. 

The Permian extinction happened 252 million years ago. This was the worst mass extinction in the history of the world and is known as “The Great Dying”. Over ninety-six percent of all marine life, and 70 percent of land species. No direct cause was found, but according to an article on, it is speculated that a volcano in Russia was the main cause of the extinction. 

According to ‘History of Life’, the Triassic-Jurassic extinction has a lot of debate about the specific percent of the death. The speculated causes are: large impacts, prolonged volcanic activity, climate change, volcanic gases rising, and rain becoming toxic other theories.

Only 66 million years ago, the most well known extinction happened. Why was it the most well known? Dinosaurs! They went extinct with some plant and marine life.  Around seventy-five percent of the population of earth was wiped out. The main cause is speculated to be an asteroid and a virus. The mixing of two is what made mammals the new dominators of the earth. 

For more information, please visit: