Why the dinosaurs subsequently became extinct?

Question

Why the dinosaurs subsequently became extinct?

Answer 1

The Alvarez impact hypothesis is one very touted cause. A body impacted the earth at approximately 65 million years ago; a very large body.

Answer 2

Here are two ideas.   I read just this week, that evidence of high toxic gases in the atmosphere at that time might be responsible.   Another idea is the rise of mammals.   Mammals that could attack small or baby dinosaurs or eat their eggs would be a factor, since mammals seem to dominate thngs today.