6. Mammals survived the K/T Extinction because they were "more fit" than dinosaurs.
This is an example of the circular reasoning that continues to plague students of Darwinian evolution. There's no objective measure by which one creature can be considered "more fit" than another; it all depends on the environment they live in. Until the K/T Extinction Event, dinosaurs fit extremely well into their ecosystem, with herbivorous dinosaurs dining on lush vegetation and carnivorous dinosaurs dining on the herbivores. In the blasted landscape after the meteor impact, small, furry mammals suddenly became "more fit" because of the drastically changed circumstances (and drastically reduced amounts of food).
7. The dinosaurs died out because they became "too big."
This one has some truth to it, with an important qualification. The 20-ton titanosaurs living at the end of the Cretaceous period would have had to eat hundreds of pounds of vegetation every day, putting them at a distinct disadvantage when this vegetation withered and died from lack of sunlight (and also crimping the style of the multi-ton tyrannosaurs that preyed on the titanosaurs). But the dinosaurs weren't "punished" by some supernatural force for growing too big, too complacent and too self-satisfied, as some biblically minded moralists continue to claim.
8. The K/T meteor impact is just a theory, not a proven fact.
What makes the K/T Extinction such a powerful theory is that the idea of a meteor impact was broached (by the physicist Luis Alvarez) based on other strands of physical evidence. In 1980, Alvarez and his team discovered traces of the rare element iridium--which can be produced by impact events--scattered around the world in geological strata dating to 65 million years ago. Shortly afterward, the outline of a huge meteor crater in the Chicxulub region of Mexico's Yucatan Peninsula was discovered, which geologists also dated to the end of the Cretaceous period. This isn't to say that a meteor impact was the sole cause of the dinosaurs' demise (see below), but there's no question that there was a meteor impact in the first place!
9. The dinosaurs were killed by insects/bacteria/aliens.
Conspiracy theorists love to speculate about events that happened millions of years ago--it's not like there are any living witnesses who can contradict them. While it's true that disease-spreading insects may have hastened the demise of the dinosaurs, after they were already weakened by cold and hunger, no reputable scientist believes that the K/T meteor impact had a lesser effect on dinosaurs than million of pesky mosquitoes or new strains of bacteria. As for theories involving aliens, time travel or warps in the space-time continuum, that's grist for Hollywood producers, not serious, working scientists.
10. Humans can never go extinct the way the dinosaurs did.
Us homo sapiens do have one advantage that the dinosaurs lacked: our brains are big enough that we can plan ahead and prepare for worst-case contingencies. Today, scientists are hatching all sorts of schemes to intercept large meteors before they can plunge to earth and wreak another mass extinction. However, this has nothing to do with all the other ways humans can potentially render themselves extinct: nuclear war, genetically engineered viruses or nanotechnology run amok, to name just three. Ironically, if human beings do vanish off the face of the earth, it may be because of, rather than despite, our huge brains!
