Simplify the following text for a Grade 11 native English-speaking person.
Original: Since then , the debate about the extinction of the dinosaurs and other mass extinction events has centered on whether the extinction mechanism was the asteroid impact , widespread volcanism ( which occurred about the same time ) , or some other mechanism or combination .
Simplified: The only debate now is whether the main extinction mechanism was the asteroid impact or widespread flood volcanism from the Deccan Traps ( which occurred about the same time ) .