What is believed to have contributed to the extinction of the dinosaurs?

The belief that an asteroid impact contributed significantly to the extinction of the dinosaurs is supported by substantial geological evidence. Specifically, the impact hypothesis is often linked to the discovery of a layer of iridium-rich clay in the geologic record, which corresponds to the boundary between the Cretaceous and Paleogene periods. This layer suggests that a massive asteroid struck Earth about 66 million years ago, causing dramatic environmental changes, including wildfires, a "nuclear winter" effect that blocked sunlight, and subsequent disruptions in food chains.

The impact theory is further reinforced by the identification of the Chicxulub crater in the Yucatán Peninsula, which aligns with the timing of the mass extinction event. This forceful encounter would have immediately and significantly altered the climate, habitats, and ecosystems where dinosaurs thrived, ultimately leading to their extinction.

Other options, while they may have contributed to various extinction events over Earth's history, are less directly relevant to the specific event that led to the disappearance of the dinosaurs. For instance, volcanic activity could have contributed to environmental changes, and climate change may have played a role in other extinction events. However, the asteroid impact stands out as a compelling and well-documented cause for this particular mass extinction.