How has the Earth changed over time?

Approximately what percentage of marine animals were lost in the Earth’s greatest extinction period?

The Permian-Triassic extinction or the “Great Dying” happened about 252 million years ago. In addition to 96% of marine species, 70% of terrestrial vertebrate (organisms with a spinal column or vertebra and that live mainly on land) became extinct. It’s been a challenge for scientists to work out the cause of this event as much of the evidence has been destroyed – imagine trying to solve a crime that happened over 250 million years ago!