Geek Trivia: Quite a tail to tell

What famous comic strip is responsible for coining the word <em>thagomizer</em>, which has since become the accepted scientific term for the spikes at the end of a Stegosaurus' tail?

Editor's note: The Trivia Geek decided to take off Presidents' Day, so he's used his executive authority to resurrect this Classic Geek, which originally ran on Aug. 15, 2006, from the archives. Look for fresh Geek Trivia on Feb. 26, 2008.

If someone were to compile a list of the most recognizable species of dinosaurs, it's a fair bet that the Stegosaurus would make the top five. Even though the original Jurassic Park film snubbed the mighty Stegosaurus -- a scenery-chewing CGI Triceratops supplanted its role in the Michael Crichton novel -- there are still plenty of closet dino-philes who could readily identify this thunder lizard by virtue of its distinctive dorsal plates.

Ask the average Jane or Joe what those dorsal plates were for, however, and it's unlikely you'll get a coherent or correct answer. Of course, a paleontologist probably couldn't do much better -- that's because the exact form and function of the Stegosaurus' most distinctive physical feature is still a topic of passionately unsettled scientific debate.

Unlike what untold number of Godzilla movies may have led you to believe, a Stegosaurus' plates were not exposed bits of razor-sharp bone designed to fend off the predations of the nearest Tyrannosaurus Rex -- several million years actually separated the two species. While possessing a bone core that survives in the fossil records, stegosaur plates were actually much more similar to the spines and ridges found on the backs of contemporary crocodiles -- covered in scaly hide and containing circulatory vessels.

Given these characteristics, the plates would have been far too sensitive and fragile to serve any serious defensive purposes. Instead, paleontologists are left to wonder whether the Stegosaurus employed these rather specialized physical features for one of the following purposes:

  • Regulating body temperatures by cooling the blood along the exposed area of the thin plates
  • Increasing the apparent size of the Stegosaurus -- thus intimidating predators -- without a significant increase in body mass
  • Serving as a means of identification -- either between species, herds, or prospective mates

Dorsal plates aren't the only part of the Stegosaurus anatomy that have troubled paleontologists. The spikes on the end of the Stegosaurus' tail -- known as the thagomizer -- also serve an uncertain function. Of course, the general public makes many of the same assumptions about the tail spikes as they do the dorsal fins -- that they existed for some martial purpose.

That assumption goes a long way toward explaining where the thagomizer got its name -- from a famous comic strip that riffed on the "deadly" nature of the Stegosaurus' tail spikes and thus coined the accepted scientific term for the dinosaur's anatomical feature.


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By Jay Garmon

Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...