Mass Extinctions
Mass Extinctions
This topic is an introduction to the mass extinctions that planet earth has experienced. You need to understand that a mass extinction is defined by a sharp decrease in the amount of plant and animal life. There have been five major mass extinction events in Earth's history.
Learn about the five major mass extinctions that occurred in Earth's history in this video below.
A mass extinction is a sharp decrease in the amount of plant and animal life. There have been five major mass extinction events in Earth's history. These are shown in the table given, along with the major events that characterised each.
| Major mass extinction event | Date of occurrence | Major events |
| Cretaceous-Paleogene extinction event | \(\text{65}\) million years ago | Approximately \(\text{75}\%\) of all species became extinct. Mammals and birds emerged as the dominant land vertebrates. |
| Triassic-Jurassic event | \(\text{205}\) million years ago | Most non-dinosaur species were eliminated, leaving land dinosaurs with no competition. |
| Permian-Triassic event | \(\text{250}\) million years ago | This was Earth's largest extinction event. It resulted in the loss of \(\text{96}\%\) of marine species and \(\text{70}\%\) of land species. The event had great evolutionary significance because it allowed the vacant habitats and ecosystems to be filled by new species through natural selection. |
| Late Devonian extinction | \(\text{375}\)–\(\text{360}\) million years ago | This was a prolonged period of extinction lasting up to \(\text{20}\) million years. During this period up to \(\text{70}\%\) of living species were eliminated. |
| Ordovician-Silurian extinction event | \(\text{450}\)–\(\text{440}\) million years ago | Over \(\text{50}\%\) of all genera were eliminated during this period and is ranked as the second largest mass extinction in Earth's history |
This lesson is part of:
History of Life on Earth
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