The extinction of the dinosaurs was caused by a catastrophic event that occurred around 66 million years ago. The most widely accepted theory is that a large asteroid, approximately 6 miles wide, collided with Earth, causing a massive impact that threw huge amounts of debris into the air and caused massive tidal waves to wash over parts of the American continents. The impact also caused substantial fires and filled the sky with material that plunged the planet into a species-dooming winter. The asteroid impact was so devastating that it caused the extinction of around 75% of Earths animals, including dinosaurs, in a relatively short period of time.

While the asteroid impact is the most widely accepted theory, there is also evidence to suggest that volcanic eruptions that caused large-scale climate change may have played a role in the extinction of the dinosaurs. The Deccan Traps in India, for example, were a site of huge, relentless volcanism that may have been causing climatic chaos before the asteroid impact. However, the exact nature of the catastrophic event that caused the extinction of the dinosaurs is still open to scientific debate.

In summary, the extinction of the dinosaurs was caused by a catastrophic event, most likely an asteroid impact, that occurred around 66 million years ago. While there is evidence to suggest that volcanic eruptions may have played a role in the extinction, the asteroid impact is the most widely accepted theory.