The prevailing scientific understanding is that the dinosaurs went extinct about 66 million years ago due to a combination of catastrophic events, with the primary cause being a massive asteroid impact. This impact created the Chicxulub crater on the Yucatán Peninsula in Mexico and led to immediate and widespread devastation, including massive fires, tsunamis, and a "nuclear winter" effect where dust and soot blocked sunlight, disrupting photosynthesis and collapsing ecosystems globally

. The asteroid, estimated to be 10 to 15 kilometers wide, struck Earth with such force that it caused a crater about 150 kilometers in diameter. The impact threw vast amounts of debris into the atmosphere, reducing sunlight and causing a significant drop in temperatures. This environmental upheaval severely affected plant life, which in turn caused a collapse in the food chain, leading to the extinction of many species, including non-avian dinosaurs, pterosaurs, large marine reptiles, and ammonites

. In addition to the asteroid impact, there were other contributing factors such as massive volcanic eruptions (notably the Deccan Traps in present-day India) that caused long-term climate changes. The Earth was already undergoing environmental stresses, including cooling trends and ecological competition, which made survival more difficult for dinosaurs and other species. These combined stresses likely made the ecosystems more vulnerable to collapse when the asteroid struck

. While the asteroid impact theory is the most widely accepted explanation, some debate remains among scientists about the exact sequence and interplay of events that led to the mass extinction. Some researchers argue that the timing of volcanic activity and other environmental changes might have played a more significant role or that the impact alone might not explain all the extinction patterns observed

. In summary, the dinosaurs were wiped out primarily by the catastrophic effects of a massive asteroid impact 66 million years ago, exacerbated by volcanic activity and gradual climate changes, which together caused one of the most severe mass extinctions in Earth's history