mass extinction
The Permian Period ended with Earths second mass extinction. During this event, most of Earths species went extinct. It was the most massive extinction ever recorded. Its not clear why it happened. One possible reason is that a very large meteorite struck Earth. Another possibility is the eruption of enormous volcanoes. Either event could create a huge amount of dust. The dust might block out sunlight for months. This would cool the planet and prevent photosynthesis.