BREAKING NEWS – Popular Science Magazine – What caused the dinosaurs to become extinct? There are two popular theories. The first one is, the earth was hit by a meteor or comet, which caused a global climate change. The second one is, there was a flood that covered the entire planet that simply drowned the gigantic prehistoric animals. Recently paleontologists are considering a third possibility that could have gradually wiped them all out. Because more often than not, when a site is discovered that has a high concentration of dinosaur bones, in the area there are usually fossilized empty packs of cigarettes.