Ask the dinosaurs if you dont believe it.
THAT is, at best, hotly debated, with most saying they actually died off EARLIER or were killed by the event, but not surviving after.
Do you have source I can read?
I'm always interested in the Chicxulub Event and aftermath, and would love more to ponder!
I've actually met and spoke with Walt Alverez. Him and his Dad are/were brilliant.