"Permian–Triassic extinction event (""Great Dying"")."

The Permian-Triassic extinction event, informally known as the "Great Dying," was a catastrophic series of events that destroyed the majority of life on Earth about 251 million years ago. Scientists have suggested that the extinction event consisted of a combination of immense volcanic eruptions, extreme fluctuations in Earth's climate, and a lack of oxygen in the atmosphere and oceans. Entire populations of plants, reptiles, fish, insects, and mammal-like creatures died in the event. Even animals that survived the initial destruction and attempted to rebuild their ecosystems were later killed by resurgences of Earth's inhospitable atmospheric conditions.