Why Dinosaurs Died: A Look at the Leading Theories

Introduction

• Dinosaurs dominated Earth for over 160 million years.
• The Cretaceous-Paleogene (K-Pg) extinction event occurred around 66 million years ago, leading to the extinction of 75% of all species, including non-avian dinosaurs.
• Scientists have proposed several theories to explain this extinction.

Leading Theories

Impact Hypothesis

• A massive asteroid, approximately 6 miles wide, struck Earth at the Yucatán Peninsula, Mexico.
• Impact created the Chicxulub crater and released enormous energy.
  • Energy release was over a billion times that of an atomic bomb.
  • Immediate effects included:
    • Massive wildfires
    • Mega-tsunamis
    • Earthquakes
  • Long-term effects due to atmospheric dust and debris:
    • Blocked sunlight for months or years
    • Global temperature drop
    • Photosynthesis halted, collapsing food chains
    • Resulted in the death of herbivorous dinosaurs, followed by carnivores.

Volcanic Activity

• Intense volcanic eruptions occurred in the Deccan Traps, present-day India.
• Eruptions persisted for hundreds of thousands of years.
  • Released lava and gases like sulfur dioxide and carbon dioxide.
  • Potential effects:
    • Acid rain
    • Atmospheric cooling
    • Long-term climate shifts
• Volcanic activity may have weakened ecosystems prior to the asteroid impact.

Climate Change

• Late Cretaceous period experienced fluctuating sea levels and changing temperatures.
• Environmental pressures stressed dinosaur populations and altered habitats.
• Gradual environmental changes made adaptation and survival difficult for dinosaurs.

Combined Effects

• Asteroid impact is the most widely accepted single cause.
• Likely a combination of:
  • Asteroid strike
  • Volcanic activity
  • Climate change
• These events collectively led to the mass extinction.
• Opened ecological niches for mammals and humans.

Conclusion

• Dinosaur extinction resulted from a combination of catastrophic events.
• The asteroid impact was the final catalyst, exacerbated by volcanic and climate conditions.
• Studying this extinction provides insights into Earth's resilience and the impact of global disasters.