If that was really the case.
How did other creatures manage to survive, including more delicate vulnerable ones like amphibians? How about tropical plants? It's not like they hibernated for a few thousand years and then popped up again. Also at least one species of Hadrosaur continue for at least 500,000 years after the extinction event, so......
Seems to be evidence of an impactful cataclysm, but that it was that thoroughly worldwide, or caused by the meteor itself.