It was the Chicxulub Impact 65 million years ago that killed the dinosaurs.
Actually, you are both wrong...
The dinosaurs were killed when ChubbyCheckersaurus introduced a new dance craze... the Twist. The new dance took the Cretacious World by storm. After two weeks of constant twisting, the apatosaurus was too dizzy to graze for food, the Allosauri were to spun out to hunt, and the velociraptors had tripped on their own claws. Within a week, they all died.