Permian-Triassic Extinction Event

Definition

The Permian-Triassic extinction event, occurring around 252 million years ago, is recognized as the most severe mass extinction in Earth's history, eliminating approximately 90-96% of marine species and about 70% of terrestrial vertebrate species. This catastrophic event marked the boundary between the Permian and Triassic periods, leading to significant ecological and evolutionary changes that shaped the future of life on Earth.

5 Must Know Facts For Your Next Test

1. The Permian-Triassic extinction event lasted for millions of years, with evidence suggesting that it unfolded in multiple phases rather than being a single, sudden event.
2. It is believed that volcanic eruptions in what is now Siberia released vast amounts of carbon dioxide and other gases, contributing to climate change and ocean acidification that drove many species to extinction.
3. The aftermath of this extinction event saw the rise of new groups of organisms, including the ancestors of modern reptiles and mammals, which began to diversify during the Triassic period.
4. Fossil evidence indicates that life in marine environments was hit hardest, with many coral reefs disappearing and significant losses among ammonites and trilobites.
5. This event significantly reshaped ecosystems, allowing for the emergence of dinosaurs later in the Mesozoic Era as the planet began to recover and evolve new life forms.

Review Questions

• What were some potential causes of the Permian-Triassic extinction event, and how did they impact marine and terrestrial life?
  • Potential causes of the Permian-Triassic extinction event include massive volcanic eruptions in Siberia that released large amounts of greenhouse gases into the atmosphere, leading to severe climate change. This change resulted in ocean anoxia and acidification, which devastated marine ecosystems. Terrestrial life was also severely impacted as habitats changed and food sources diminished, causing a dramatic decline in biodiversity across various groups of organisms.
• How did the Permian-Triassic extinction event influence the evolutionary trajectory of life on Earth during the Triassic period?
  • The Permian-Triassic extinction event created an ecological vacuum that allowed for new groups of organisms to emerge and evolve during the Triassic period. With many dominant species gone, new adaptive radiations occurred, particularly among archosaurs and early mammals. This led to significant evolutionary changes and paved the way for the eventual dominance of dinosaurs in later Mesozoic eras.
• Evaluate the long-term effects of the Permian-Triassic extinction event on Earth's biodiversity and its relevance to current biodiversity crises.
  • The long-term effects of the Permian-Triassic extinction event fundamentally reshaped Earth's biodiversity by eliminating vast numbers of species while allowing new ones to flourish. This event serves as a critical example for understanding current biodiversity crises, highlighting how human-induced changes such as climate change, habitat destruction, and pollution can lead to severe declines in species diversity. The historical context provides valuable insights into resilience and recovery patterns within ecosystems following mass extinctions.

Related terms

Mass Extinction: A widespread and rapid decrease in the biodiversity on Earth, where a significant proportion of species are lost in a relatively short geological timeframe.

Geological Time Scale: A system of chronological dating that relates geological strata to time, providing a framework for understanding Earth's history and major events, including extinction events.

Triassic Period: The geological period following the Permian, lasting from about 252 to 201 million years ago, characterized by the recovery of life forms after the Permian-Triassic extinction.