Question: What causes mass extinctions?

Amy Birch answered on 19 Jun 2012:

Hi Meg,
In the earth’s history there has been 5 big mass extinctions and they are thought to have happened for a few different reasons. The dinosaurs were all wiped out because of an asteroid hitting earth causing lots of smoke & dust to cover the sky & preventing the sunlight from hitting earth. Global cooling (such as an ice age) and warming, and sea levels changing could have also caused others.
Hope this answers your question! 🙂