How do you know a meteor wiped outh the dinosaurs?

Well we're not completely sure if that was the cause of the extiction. This is however the most likely theory of extinction. The other theories are volcanoes which expeled carbon dioxide into the atmosphere that made it hard for the dinosaurs and other large animals to breath, a new poisonous plant species that wiped out the dinosaurs, disease and much more. But we do have a lot of evidence of a meteor hitting the Earth, for instance: There is a large crater like hole in the Gulf of Mexico, that hole has a samall gravitational pull (which is what they think the reason for the Bermuda Triangle is) and there are minerals and elements that are found in meteors in that area.