The Permian-Triassic period marks a significant transition in Earth's history, occurring around 252 million years ago. It is known for the largest mass extinction event, where approximately 90% of marine species and 70% of terrestrial vertebrates went extinct. This event is often referred to as the Great Dying and drastically altered the planet's biodiversity. Following the extinction, the Triassic period began, leading to the rise of new species and ecosystems. This era saw the emergence of the first dinosaurs and mammals, setting the stage for the evolution of life in the Mesozoic era. The recovery from the extinction took millions of years, reshaping the course of evolution.