The dinosaurs were wiped out solely by an asteroid impact with no other contributing factors.
The K-Pg extinction event (66 million years ago) resulted from a combination of factors, primarily the Chicxulub asteroid impact supplemented by massive volcanism. The Deccan Traps in India experienced intense eruptive activity contemporaneously with the asteroid strike, releasing greenhouse gases and causing atmospheric disruption. This dual catastrophe, impact winter from asteroid dust combined with volcanic effects, created a perfect storm of climate disruption, ocean acidification, and ecosystem collapse. Modern evidence suggests neither factor alone would have caused total extinction; the combined effect was catastrophic.