One issue that gives archaeologists (and scientists in general) fits is the impossibility of proving a negative. For example, no one can demonstrate, with 100 percent certainty, that every single T. Rex vanished off the face of the earth 65 million years ago; there's an exceedingly slim chance that some specimens managed to survive, and are happily breeding on a remote, and still undiscovered, version of Skull Island.
This isn't simply a rhetorical issue. In 1938, a living coelacanth--a primitive fish believed to have gone extinct at the end of the Cretaceous epoch—was found off the coast of Africa. To evolutionary scientists, this was as shocking as if a live Brontosaurus had been discovered in Siberia, and caused some quick rethinking about the casual use of the word "extinct." (The coelacanth isn’t technically a dinosaur, of course, but the same general principle applies.)
"Living Dinos" and Cryptozoology
Unfortunately, the coelacanth sensation has bolstered the confidence of modern-day "cryptozoologists," investigators (not all of them scientists) who believe that the so-called Loch Ness Monster may actually be a supposedly long-extinct plesiosaur, among other odd theories. Creationists are especially eager to prove the existence of living dinosaurs, since they believe this will somehow invalidate evolutionary theory (which it won't, even if that mythical Brontosaurus is ever found).
The fact is, every time reputable scientists have investigated rumors or sightings of living dinosaurs, they’ve come up completely dry. Once again, this doesn’t establish anything--that old "proving a negative" bugaboo--but it is persuasive evidence in favor of the total- extinction theory.
Are Birds Living Dinosaurs?
In any case, a question like "Did the dinosaurs really go extinct?" may be missing the point. Any group of creatures as numerous and diverse as dinosaurs will pass off a huge chunk of genetic material to its descendants, no matter what form those descendants take. Some biologists even make the case that dinos never really became extinct at all; they merely evolved into birds, which are sometimes described as "living dinosaurs."
