The 二叠纪-三叠纪灭绝事件, also known as the Permian-Triassic extinction event, occurred around 252 million years ago. It is the most significant extinction event in Earth's history, with approximately 90% of marine species and 70% of terrestrial vertebrate species going extinct. This event marked the boundary between the 二叠纪 and the 三叠纪 periods. Several factors contributed to this mass extinction, including volcanic eruptions, climate change, and ocean anoxia. The 西伯利亚玄武岩 eruptions released vast amounts of carbon dioxide, leading to global warming and acidification of oceans. This catastrophic event reshaped ecosystems and paved the way for the rise of 恐龙 in the 三叠纪.