Key Extinction Events to Know for Paleontology

Extinction events have dramatically shaped life on Earth, marking significant turning points in evolution. From the Great Dying to the demise of the dinosaurs, these events reveal the complex interplay between environmental changes and the survival of species throughout history.

1. End-Permian Extinction (The Great Dying)

   • Occurred approximately 252 million years ago, marking the boundary between the Paleozoic and Mesozoic eras.
   • Estimated to have wiped out about 90-96% of all marine species and 70% of terrestrial vertebrate species.
   • Likely caused by massive volcanic eruptions in the Siberian Traps, leading to climate change, ocean acidification, and anoxia.
   • Resulted in the loss of biodiversity and a prolonged recovery period for ecosystems, shaping the evolution of future life forms.
   • Considered the most severe extinction event in Earth's history, profoundly impacting the course of evolution.

2. End-Cretaceous Extinction (K-Pg Extinction)

   • Occurred around 66 million years ago, marking the boundary between the Mesozoic and Cenozoic eras.
   • Famous for the extinction of the non-avian dinosaurs, along with approximately 75% of all species on Earth.
   • Primarily attributed to a combination of a massive asteroid impact (Chicxulub crater) and extensive volcanic activity (Deccan Traps).
   • Led to significant changes in terrestrial and marine ecosystems, paving the way for the rise of mammals and birds.
   • This event is crucial for understanding the dynamics of extinction and recovery in evolutionary history.

3. Late Devonian Extinction

   • Spanning from about 375 to 360 million years ago, this extinction event occurred over several million years.
   • It is characterized by a series of extinction pulses, with an estimated 70-80% of species lost, particularly affecting marine life.
   • Likely caused by a combination of factors, including climate change, anoxia in oceans, and possibly asteroid impacts.
   • Significantly impacted reef ecosystems and led to the decline of many fish groups, altering the trajectory of vertebrate evolution.
   • Highlights the complexity of extinction events and their potential for prolonged effects on biodiversity.

4. End-Triassic Extinction

   • Occurred approximately 201 million years ago, marking the transition from the Triassic to the Jurassic period.
   • Responsible for the extinction of about 70-75% of species, including many reptiles and marine organisms.
   • Likely driven by volcanic activity associated with the breakup of Pangaea, leading to climate change and ocean acidification.
   • Set the stage for the dominance of dinosaurs in the Jurassic period, reshaping terrestrial ecosystems.
   • Important for understanding the relationship between geological events and biological responses in Earth's history.

5. Ordovician-Silurian Extinction

   • Occurred around 443 million years ago, marking one of the first major extinction events in the Phanerozoic eon.
   • Estimated to have caused the extinction of about 85% of marine species, particularly affecting brachiopods and trilobites.
   • Likely triggered by a combination of glaciation, sea-level changes, and anoxic conditions in the oceans.
   • This event emphasizes the vulnerability of marine ecosystems to environmental changes and the interconnectedness of life.
   • Provides insights into the early dynamics of extinction and recovery in the history of life on Earth.