Causes of Mass Extinctions

Causes of Extinction

• Multiple factors contribute to mass extinctions, including:
  • Environmental stressors (e.g., climate change, sea-level changes)
  • Evolutionary factors (e.g., species competition, adaptation)
  • Random events (e.g., asteroid impacts, volcanic eruptions)
• Species vulnerability plays a crucial role in mass extinctions, with species that are:
  • Ecologically specialized
  • Geographically restricted
  • Having low population sizes
  • Being evolutionary novelties being more prone to extinction

Permian-Triassic Extinction (PT Extinction)

• Also known as the "Great Dying"
• Occurred around 252 million years ago
• Causes:
  • Massive volcanic eruptions in Siberia (Siberian Traps)
  • Climate change and associated ocean acidification
  • Possible asteroid impact
• Effects:
  • 96% of marine species and 70% of terrestrial species went extinct
  • Most families of life were severely impacted or went extinct
  • Recovery took millions of years

K-Pg Extinction (Cretaceous-Paleogene Extinction)

• Occurred around 65 million years ago
• Causes:
  • Asteroid impact (Chicxulub asteroid impact)
  • Global wildfires
  • Massive volcanic eruptions (Deccan Traps)
• Effects:
  • 75% of species, including non-avian dinosaurs, went extinct
  • Marks the end of the Cretaceous period and the beginning of the Paleogene period

Asteroid Impacts

• Large asteroid impacts can cause massive destruction and global cooling, leading to mass extinctions
• Examples:
  • Chicxulub asteroid impact (K-Pg Extinction)
  • Vredefort impact ( Possible contributor to the Permian-Triassic Extinction)
• Effects:
  • Shock waves and tsunamis
  • Global firestorms
  • Long-term climate disruption

Massive Volcanic Eruptions

• Large-scale volcanic eruptions can release massive amounts of toxic gases, causing global cooling and acid rain, which can lead to mass extinctions
• Examples:
  • Siberian Traps (Permian-Triassic Extinction)
  • Deccan Traps (K-Pg Extinction)
• Effects:
  • Global cooling
  • Acid rain
  • Reduced sunlight
  • Disruption of food chains

Causes of Extinction

• Multiple factors contribute to mass extinctions, including environmental stressors, evolutionary factors, and random events.
• Species vulnerability plays a crucial role in mass extinctions, especially for species that are ecologically specialized, geographically restricted, have low population sizes, or are evolutionary novelties.

Permian-Triassic Extinction (PT Extinction)

• Occurred around 252 million years ago and is also known as the "Great Dying".
• Massive volcanic eruptions in Siberia (Siberian Traps) and climate change with associated ocean acidification were the likely causes.
• Possible asteroid impact also contributed to the extinction.
• 96% of marine species and 70% of terrestrial species went extinct, with most families of life severely impacted or gone extinct.
• Recovery took millions of years.

K-Pg Extinction (Cretaceous-Paleogene Extinction)

• Occurred around 65 million years ago.
• The Chicxulub asteroid impact, global wildfires, and massive volcanic eruptions (Deccan Traps) were the likely causes.
• 75% of species, including non-avian dinosaurs, went extinct, marking the end of the Cretaceous period and the beginning of the Paleogene period.

Asteroid Impacts

• Large asteroid impacts can cause massive destruction and global cooling, leading to mass extinctions.
• Examples include the Chicxulub asteroid impact (K-Pg Extinction) and the Vredefort impact (possible contributor to the Permian-Triassic Extinction).
• Effects include shock waves and tsunamis, global firestorms, and long-term climate disruption.

Massive Volcanic Eruptions

• Large-scale volcanic eruptions can release massive amounts of toxic gases, causing global cooling and acid rain, which can lead to mass extinctions.
• Examples include the Siberian Traps (Permian-Triassic Extinction) and the Deccan Traps (K-Pg Extinction).
• Effects include global cooling, acid rain, reduced sunlight, and disruption of food chains.