The ‘Big Five’

250 years ago life on earth almost vanished. Throughout time many people only think of one incident when you hear the word mass extinction, the meteor that wiped out the dinosaurs. Did you know there have been five major extinctions? Over time there have been many mass extinctions but the ‘big five’ have almost wiped out all life on earth.

The End of the Ordovician Period

The first mass extinction was 444 million years ago. Massive global cooling caused the sea levels to dramatically change. Paleontologists estimate 86% of life died out, causing the first mass extinction in Earth’s history. During the Ordovician period much of life only existed in the sea, so the drastic drop in the sea level caused many species to die out. However it gave way to a new era, the Silurian period where biodiversity skyrocketed. This new space in the sea allowed many other species to branch out and many new species to form and evolve.

The Late Devonian Period

The second mass extinction in Earth was caused by the rapid growth of plant life. This accelerated spread of plants caused a major drop in CO2 levels. CO2 forms the atmosphere and keeps rays from the sun to heat the planet. The lack of CO2 caused another massive global cooling killing off about 75% of life. Even though the last mass extinction that happened was a global cooling this mass species dying this happened 360 million years ago 84 million years after the last one.

The End of the Permian Period

The third of the ‘big five’ was caused by elevated volcanic activity near modern day Siberia. This was known as the great dying that almost killed off all life, 250 million years ago. Paleontologists estimate 96% percent of life died off. Due to the elevated volcanic activity the levels of CO2 and sulfur in the atmosphere skyrocketed. Acid rain caused the ocean to become acidic. Along with that the chemical composition of the yard and oceans changed. 

The End of the Jurassic Period

During the time of the dinosaurs people think of one main extinction, the asteroid. But did you know there was a mass extinction before it? At the end of the Jurassic Period volcanic activity in the oceans caused mass global warming 200 million years ago. This volcanic activity changed the chemical composition of the ocean. It caused 80% of life to die out, as paleontologists estimate, which is a larger estimated percentage for the later on asteroid. 

The End of the Cretaceous Period

The final extinction of the ‘big five’ is the classic meteor that everyone thinks of. 65 million years ago a giant meteor hit what is now the Gulf of Mexico. This killed off about 80% of life on earth. This caused a cataclysmic quick global cooling. As well as volcanic activity that caused what is known as volcanic winter that killed off most of plants and other sunlight relying life. On top of that, the asteroid caused tectonic shifting and activity, widening the gaps between the continents jumpstarting the formation of the world today.