1. Ordovician-Silurian Extinction: When the Earth’s crust shifted and the planet underwent a period of global cooling, much of the global ocean’s shallow life was extinguished. This mass extinction occurred approximately 443 million years ago and led to the extinction of nearly 80% of all species.
2. Late Devonian Extinction: A major extinction event that happened around 364 million years ago, this event is considered to be the second most important extinction event that occurred since the beginning of life on Earth. It is thought to have wiped out about two-thirds of marine species and left a lasting effect on evolution for the age.
3. Permian-Triassic Extinction: This mass extinction event was the most devastating extinction event to have happened in Earth’s history, wiping out 90-95% of all species at the time. Compared to the Ordovician-Silurian and Late Devonian Extinctions, this event has been exponentially more severe and had impacts on niche species that weren’t affected in earlier episodes.
4. Triassic-Jurassic Extinction: This event took place around 201 million years ago and falls in the top 5 most severe extinction events in Earth’s history. It wiped out more than half of all species on the planet which paved the way for the evolutionary novelty of the dinosaurs and modern mammals.
5. Cretaceous-Tertiary Extinction: Taking place around 65 million years ago, the fifth of the mass extinctions is known for the extinction of the dinosaurs. This event is thought to have been caused by a meteor impact and subsequent increase in global temperatures.
6. Holocene Extinctions: Also referred to as the sixth mass extinction, this ongoing event is not strictly a mass extinction event but rather a period of rapid extinction of thousands of species caused by human activities. It is estimated that from 1000-10,000 times more species are going extinct yearly than would be expected in a “normal” situation without human interference. This event is thought to be the most severe extinction event since the Permian-Triassic extinction around 252 million years ago.