Permian-Triassic extinction

Definition

The Permian-Triassic extinction, occurring around 252 million years ago, was the most severe biodiversity crisis in Earth's history, resulting in the loss of approximately 90-96% of marine species and 70% of terrestrial vertebrate species. This mass extinction event reshaped ecosystems and set the stage for the rise of new life forms, including the ancestors of modern amphibians and mammals.

5 Must Know Facts For Your Next Test

1. The Permian-Triassic extinction is known as 'The Great Dying' due to its unprecedented impact on biodiversity.
2. It is believed that volcanic activity, climate change, ocean anoxia, and possibly asteroid impacts contributed to this extinction event.
3. After the Permian-Triassic extinction, ecosystems underwent significant restructuring, allowing for new species to evolve and thrive.
4. The recovery from this extinction event took millions of years, paving the way for the dominance of reptiles during the Mesozoic era.
5. Amphibians evolved and diversified significantly during the Triassic period as they adapted to new ecological niches created by the mass extinction.

Review Questions

• How did the Permian-Triassic extinction influence the evolution of amphibians?
  • The Permian-Triassic extinction created a dramatic shift in ecological dynamics, leading to the decline of many existing species and leaving vacant niches. As a result, amphibians began to diversify in the newly available environments during the Triassic period. The changes in climate and habitat allowed amphibians to adapt and evolve new traits that helped them thrive in both aquatic and terrestrial ecosystems.
• Discuss the implications of the Permian-Triassic extinction for mammalian evolution in later periods.
  • The Permian-Triassic extinction set off a chain reaction that altered ecosystems globally, allowing for the rise of new species following the event. As ecosystems began to recover, mammals evolved from small synapsids that survived the extinction. This provided a foundation for mammals to adapt and fill various ecological roles that were previously occupied by other vertebrates before the extinction, ultimately leading to their dominance in later geological periods.
• Evaluate the causes of the Permian-Triassic extinction and their interconnected effects on marine and terrestrial life.
  • The causes of the Permian-Triassic extinction were multifaceted, involving massive volcanic eruptions that released greenhouse gases, leading to climate change, ocean acidification, and anoxic conditions in marine environments. These environmental stresses drastically affected both marine and terrestrial life, resulting in habitat loss and disrupted food chains. The interconnectedness of ecosystems meant that the collapse of marine species had a ripple effect on terrestrial ecosystems, significantly reducing biodiversity and altering evolutionary pathways for millions of years to come.

Related terms

Mass extinction: A widespread and rapid decrease in biodiversity on Earth, typically characterized by the loss of a significant percentage of species in a relatively short geological time frame.

Triassic period:

The geological period that followed the Permian, lasting from about 252 to 201 million years ago, during which new groups of reptiles and early mammals began to diversify.

Amphibians: A class of cold-blooded vertebrates that includes frogs, toads, salamanders, and caecilians, which emerged after the Permian-Triassic extinction and adapted to both aquatic and terrestrial environments.