/ Mass extinction Content for UC Davis en /blog/how-earths-greatest-extinction-really-happened <p><span lang="EN-US">Around 252 million years ago, the Earth experienced its largest mass extinction. Known as the “Great Dying,” this cataclysmic event wiped out more than 81% of marine species and 70% of life on land.&nbsp;</span></p> November 21, 2025 - 1:18pm Andy Fell /blog/how-earths-greatest-extinction-really-happened