One of the most frequently asked questions at the Morrison Museum is, "Why did the dinosaurs become extinct?" The answer is that nobody knows for sure, but everybody seems to have their own favorite theory. People have proposed giant meteor or comet impacts, volcanic eruptions, radiation from a nearby supernova, changes in climate (it got too hot; it got too cold), diseases, predation of dinosaur eggs by early mammals, plus others too numerous to name. Except for the giant meteor impact, the currently 'fashionable' theory, none have gained a wide acceptance among the scientific community.
Eagles may be forever, but, Hollywood pictures notwithstanding, dinosaurs are most emphatically extinct (Note 1). After dominating the land for 130 million years, dinosaurs disappeared from the face of the Earth at the end of the Cretaceous Period, around 65 million years ago.
This series of articles will attempt to survey some of the more popular extinction theories, discussing pro's and con's of each. We will also discuss the problems of identifying and dating extinction events, and some of the requirements any successful extinction event must meet.
Another, more detailed discussion of extinction theories can be found on the University of California at Berkeley website, at <http://www.ucmp.berkeley.edu/diapsids/extinction.html>. Also see <http://www.ucmp.berkeley.edu/education/events/cowen1b.html>.
The Magnitude of the K/T Extinction
File created May 2001.