End-triassic

Definition

The end-Triassic refers to a significant mass extinction event that occurred approximately 201 million years ago, marking the boundary between the Triassic and Jurassic periods. This event led to the extinction of about 76% of all species on Earth, profoundly impacting biodiversity and paving the way for the dominance of dinosaurs in the Jurassic period. The end-Triassic is notable not just for the number of species that vanished, but also for the dramatic shifts in ecosystems it prompted.

5 Must Know Facts For Your Next Test

1. The end-Triassic mass extinction is one of the 'Big Five' mass extinctions in Earth's history, alongside events like the Permian-Triassic extinction.
2. Major causes suggested for this extinction event include massive volcanic eruptions in what is now the Central Atlantic Magmatic Province, which released significant amounts of carbon dioxide and sulfur into the atmosphere.
3. The extinction led to a major turnover in marine and terrestrial life, significantly affecting both land-dwelling and marine ecosystems.
4. After the end-Triassic event, dinosaurs quickly rose to prominence, leading to their dominance in subsequent geological periods.
5. The recovery from the end-Triassic took millions of years, during which ecosystems gradually rebounded and diversified.

Review Questions

• How did the end-Triassic mass extinction affect biodiversity and ecosystem dynamics?
  • The end-Triassic mass extinction significantly reduced biodiversity by eliminating approximately 76% of all species on Earth. This loss resulted in major shifts within ecosystems as surviving species adapted to new environmental conditions. The extinction opened up ecological niches that allowed for the rapid diversification of certain groups, notably dinosaurs, which became dominant in terrestrial ecosystems during the Jurassic period.
• Discuss the potential causes behind the end-Triassic mass extinction and their impacts on global climate.
  • The end-Triassic mass extinction is believed to have been triggered primarily by extensive volcanic activity associated with the Central Atlantic Magmatic Province. This volcanic activity would have released large amounts of greenhouse gases like carbon dioxide, leading to significant climate change, including global warming and ocean acidification. The resultant environmental stress would have severely affected many species, contributing to widespread extinctions across various habitats.
• Evaluate the long-term consequences of the end-Triassic event on evolutionary trajectories and ecological relationships.
  • The end-Triassic mass extinction had profound long-term consequences for evolutionary trajectories, particularly as it paved the way for dinosaurs to become the dominant terrestrial vertebrates. With many ecological niches vacated due to extinctions, surviving lineages experienced rapid adaptive radiation. This event not only influenced species diversity during the Jurassic but also set up competitive relationships that shaped future ecosystems. The shift in dominance from synapsids to dinosaurs illustrates how mass extinctions can redirect evolutionary paths and alter ecological interactions for millions of years.

Related terms

Mass Extinction: A rapid and widespread decrease in the biodiversity on Earth, characterized by a significant loss of species across multiple taxa.

Triassic Period: The first period of the Mesozoic Era, occurring from about 252 to 201 million years ago, characterized by the emergence of dinosaurs and mammals.

Jurassic Period: The second period of the Mesozoic Era, following the Triassic, known for the rise and diversification of dinosaurs and significant geological changes.