Death by One Giant Space Rock?

Biology, astronomy, and geology collide when scientists try to figure out why dinosaurs went extinct. My favorite theory is the methane gas theory: dinosaurs farted themselves to death because their own fumes suffocated them. I don't know if that is a real theory but somehow I remember discussing this possibility back in sixth grade. Anyway, I just read an article that got me thinking. It cites a study which suggests dinosaur extinction was caused by a single asteroid, six miles in diameter, that crashed into earth. The impact not only resulted in a 110-mile wide crater in Mexico, but also fires, tsunamis, dust storms, and the demise of several animal and plant species. Can you imagine a giant rock shaking the earth and causing such colossal destruction? What's particularly fascinating is that while many species were devastated into extinction by this impact; birds, mammals, and presumably some plant species survived and adapted. Props to the scientists who devote their lives to getting to the bottom of these titanosaur-sized questions.