The leading explanation is that a giant asteroid hit Earth about 66 million years ago, triggering global darkness, cooling, wildfires, and food-chain collapse that wiped out non-avian dinosaurs. Many scientists also think massive volcanic eruptions in what is now India made the crisis worse, so the extinction may have been caused by a combination of events rather than one single disaster.

Quick Scoop

  • Main cause: asteroid impact at Chicxulub in Mexico.
  • Big effects: dust blocked sunlight, photosynthesis crashed, and ecosystems fell apart.
  • Possible added factor: Deccan Traps volcanism, which likely intensified climate stress.

What happened

The asteroid impact sent enormous amounts of dust and debris into the atmosphere, and that blocked sunlight long enough to disrupt plant growth and the entire food web. Once plants struggled, herbivores declined, and then carnivores followed, which helps explain why non-avian dinosaurs disappeared while birds survived.

Bottom line

If you want the shortest answer: dinosaurs went extinct mainly because of an asteroid impact, probably helped along by massive volcanic activity and climate disruption.