During which era did the largest mass extinction occur, wiping out 90% of marine species?

The largest mass extinction event, known as the Permian-Triassic extinction, occurred at the end of the Paleozoic Era approximately 252 million years ago. This catastrophic event is highlighted by its significant impact, as it eliminated about 90% of marine species and around 70% of terrestrial vertebrate species. The causes of this mass extinction are believed to include massive volcanic eruptions, methane release, and changes in ocean chemistry and structure.

In contrast, the other eras listed—the Cenozoic, Mesozoic, and Proterozoic—do not host extinction events of similar scale or impact as the one in the Paleozoic. The Cenozoic Era, for instance, is often referred to as the "Age of Mammals" and is characterized by a different evolutionary trajectory rather than a mass extinction of such magnitude. The Mesozoic Era, while known for its own extinction events (most notably the one that led to the demise of the dinosaurs), did not experience the same catastrophic loss of marine biodiversity. The Proterozoic Era precedes the Paleozoic and does not feature this type of mass extinction when complex life began to flourish. Thus, the identification of the Paleozoic Era