Simple version
A mass extinction is when a large percentage of species disappear across the planet in a relatively short geological time.
Extinction is always happening in the background, but mass extinctions are different. They are global crises where whole ecosystems break down.
The big five
Scientists often talk about five major mass extinction events. These include the Ordovician Silurian, Late Devonian, Permian Triassic, Triassic Jurassic and Cretaceous Paleogene extinctions.
The Permian Triassic extinction was the most severe, wiping out most marine species and many land species. The Cretaceous Paleogene extinction is the one famous for ending the non bird dinosaurs.
What caused them
Different mass extinctions had different causes. Some involved massive volcanic eruptions, climate change, ocean chemistry shifts, falling oxygen levels, asteroid impact or combinations of pressures.
Usually it is not just one simple problem. Earth systems are connected, so one major disruption can trigger many others.
What survived
Survival depends on size, habitat, diet, reproduction, flexibility and luck.
Small animals that could hide, eat varied food or survive harsh conditions often had an advantage. But there is no guarantee. Whole branches of life disappeared.
Common mistake
A common mistake is thinking extinction means life failed. Life did not fail. It changed direction.
Mass extinctions are tragedies for lost species, but they also open space for surviving groups to diversify. Mammals expanded after the non bird dinosaurs disappeared.
AwareSTEM link
This page connects deep time to modern ecology. It helps learners understand that biodiversity matters because ecosystems can collapse.
It also teaches humility. Earth has recovered before, but recovery can take millions of years.
What learners should notice
Earth's history has repeated crisis points. Life survives, but not all life survives.
Recovery can take millions of years, which is far beyond human timescales.
Build the understanding
Introduce the big five extinctions as separate events with different causes. Then compare them for patterns: climate, ocean change, volcanism, impact and food chain disruption.
AwareSTEM activity idea
Create a table: extinction, likely cause, percentage lost, survivors, what changed next. This turns deep time into a pattern exercise.
Quick recap
Mass Extinction Events sits inside the The Great Extinction part of The Story of Everything. The main point is this: the big five, what caused each, and what survived.
By the end of this page, the learner should be able to explain the idea in plain English, connect it back to the timeline, and say why it matters beyond a school-style fact.
Key words to know
Use these as anchor words while learning this topic: Mass Extinction Events, The Great Extinction, evidence, time, change, system, signal, scale and connection.
The aim is not to memorise every word. The aim is to build a small vocabulary that helps the learner explain the idea clearly to someone else.
Question to ask
Ask: what does mass extinction events change in the bigger story?
A good answer should not stop at one fact. It should explain what came before, what changed, and how that change affected the next part of the timeline.