Permian-Triassic extinction

Definition

The Permian-Triassic extinction, also known as the Great Dying, was a massive extinction event that occurred approximately 252 million years ago, marking the boundary between the Permian and Triassic periods. This event is significant as it resulted in the loss of about 90% of marine species and 70% of terrestrial vertebrate species, making it the most severe biodiversity crisis in Earth's history.

5 Must Know Facts For Your Next Test

1. The Permian-Triassic extinction is believed to have been triggered by massive volcanic eruptions in what is now Siberia, known as the Siberian Traps, which released vast amounts of greenhouse gases into the atmosphere.
2. This extinction event caused significant changes in ocean chemistry, including anoxia (lack of oxygen), which contributed to widespread marine die-offs.
3. It took millions of years for ecosystems to recover fully after the Permian-Triassic extinction, highlighting its profound impact on Earth's biological history.
4. The event led to the dominance of reptiles and the eventual rise of dinosaurs in the Triassic period as ecological niches became available following the extinctions.
5. Fossil records indicate that certain groups, such as ammonites and certain corals, were heavily affected while others, like some species of plants and insects, showed resilience and adapted to new environments.

Review Questions

• What were some potential causes of the Permian-Triassic extinction, and how did they impact life on Earth?
  • The Permian-Triassic extinction was likely caused by a combination of factors, primarily extensive volcanic activity in Siberia that led to significant climate change. The release of greenhouse gases caused global temperatures to rise dramatically and disrupted ecosystems. Additionally, changes in ocean chemistry, particularly anoxia, devastated marine life. The resulting loss of biodiversity fundamentally reshaped life on Earth, paving the way for new dominant groups such as reptiles during the Triassic period.
• Analyze how the Permian-Triassic extinction influenced evolutionary pathways in subsequent geological periods.
  • Following the Permian-Triassic extinction, Earth's ecosystems underwent a significant restructuring. The massive loss of species opened up numerous ecological niches, allowing surviving groups to diversify and adapt. Notably, reptiles became more prominent during the Triassic period as they filled roles previously occupied by extinct species. This paved the way for the later dominance of dinosaurs in subsequent periods. Thus, this extinction event not only marked a dramatic reduction in biodiversity but also set the stage for new evolutionary trajectories.
• Evaluate the long-term consequences of the Permian-Triassic extinction on global biodiversity and geological processes.
  • The long-term consequences of the Permian-Triassic extinction were profound, influencing both global biodiversity and geological processes for millions of years. The massive reduction in species led to a decrease in ecological complexity, altering food webs and community structures. Recovery took a long time due to changed environmental conditions, which also influenced patterns of sedimentation and geochemical cycles. Ultimately, this extinction event serves as a critical reminder of how large-scale biological crises can reshape ecosystems and drive evolutionary change across geological timescales.

Related terms

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

Triassic period: The geological period following the Permian period, lasting from approximately 252 to 201 million years ago, characterized by the emergence of dinosaurs and the recovery of life after the mass extinction.

Volcanism: The eruption of molten rock from beneath the Earth's crust, often linked to major geological events and environmental changes that can lead to mass extinctions.