National Geographic tells us: "Scientists tend to huddle around one of two hypotheses that may explain the Cretaceous extinction: an extraterrestrial impact, such as an asteroid or comet, or a massive bout of volcanism." Two key takeaways:
1) This sounds like the scientists are little cavemen, rubbing two hypotheses together and trying to start a fact!
2) If scientists are just huddling around two hypotheses, then they lack imagination.
Me? I have many more hypotheses re: why dinosaurs are extinct. (Ed. Note: The following photos may upset dinosaurs if they are not, in fact, extinct. My apologies to any such dinosaurs who, I hypothesize, would be very large and angry and "go all Jurassic Park" on me.)