What event caused the extinction of dinosaurs approximately 65 million years ago?

The event that is widely recognized as the primary cause of the extinction of dinosaurs approximately 65 million years ago is a large meteor impact. This impact is believed to have created the Chicxulub crater in what is now the Yucatán Peninsula in Mexico. The theory suggests that the meteor's collision released an enormous amount of energy, leading to catastrophic environmental changes.

These changes would have included widespread wildfires, a "nuclear winter" effect due to debris and soot obscuring sunlight, and a dramatic drop in temperatures. These alterations in the climate and environment would have severely disrupted ecosystems, leading to the extinction of numerous species, including the majority of the dinosaurs. The evidence supporting this theory includes the discovery of a layer of iridium-rich clay in the geological record, coinciding with the timeline of the dinosaurs' extinction, which is uncommon on Earth but found in meteoric materials.

While volcanic eruptions, climate change, and ice ages also contributed to environmental shifts during Earth's history, the large meteor impact provides a more direct and widely accepted explanation for the mass extinction event that wiped out the dinosaurs specifically at the end of the Cretaceous period.