Thagomizer

The thagomizer, or tail spikes, is an arrangement of four to ten spikes on the tails of particular dinosaurs of the clade Stegosauria, of which "Stegosaurus stenops" is the most familiar. The tail arrangement is believed to have been a defensive weapon against predators. [Holtz, T.R., (2000) "Classification and Evolution of the Dinosaur Groups" (pp140-168) in "The Scientific American Book of Dinosaurs", edited by Gregory S. Paul, New York: St Martin's Press ISBN 0-312-26226-4]

Etymology

The term "thagomizer" was coined by Gary Larson in a 1982 "Far Side" comic strip, in which a group of cavemen in a faux-modern lecture hall are taught by their caveman professor that the spikes were named for "the late Thag Simmons". The term was picked up initially by Ken Carpenter, a palaeontologist at the Denver Museum of Nature and Science, who used the term when describing a fossil at the Society of Vertebrate Paleontology in 1993. [http://www.newscientist.com/channel/life/mg19125592.200-the-word-thagomizer.html The word: Thagomizer] "New Scientist" 8 July 2006]

"Thagomizer" has since been adopted as an informal anatomical term,cite book |last=Holtz |first=Thomas R., Jr. |authorlink=Thomas R. Holtz, Jr. |year=2007 |title=Dinosaurs:the Most Complete, Up-To-Date Encyclopedia for Dinosaur Lovers of All Ages |publisher=Random House |location=New York |pages=p. 230 |isbn=978-0-375-82419-7] appearing, for example, on the website of the Smithsonian Institution. [cite web| url=waybackdate|site=http://web.archive.org/web/20041214142258/http://www.nmnh.si.edu/paleo/dino/stegdcvr.htm| title=Stegosaurus Changes| publisher=Smithsonian National Museum of Natural History, Department of Paleobiology| accessdate=2007-03-03] The term has been used in displays at Dinosaur National Monument in Utah, in the book "The Complete Dinosaur," and in the stegosaur display at the Smithsonian Institution.

The fate of Thag Simmons notwithstanding, stegosaurs and humans did not exist in the same era. In "The Prehistory of the Far Side", Gary Larson suggests that "there should be cartoon confessionals where we could go and say things like, 'Father, I have sinned – I have drawn dinosaurs and hominids together in the same cartoon.'" [Larson, G. (1992) "The Prehistory of the Far Side" p. 137. Warner Books.]

Paleobiology

There has been debate about whether the thagomizer was used for display only, as posited by Gilmore in 1914,cite journal|author=Gilmore CW|year=1914|title=Osteology of the armored Dinosauria in the United States National Museum, with special reference to the genus "Stegosaurus"|issue=89|journal= Series: Smithsonian Institution. United States National Museum. Bulletin 89 |publisher=Government Printing Office, Washington] or used as a weapon. Robert Bakker noted the tail was likely to have been much more flexible than those of other dinosaurs as it lacked ossified tendons, thus lending credence to the idea of the tail as a weapon. He also observed that "Stegosaurus" could have maneuvered its rear easily by keeping its large hindlimbs stationary and pushing off with its very powerfully muscled but short forelimbs, allowing it to swivel deftly to deal with attack.cite book|title=The Dinosaur Heresies |year=1986|author=Bakker RT|publisher=william Morrow, New York]

More recently, a study of tail spikes, by McWhinney et al., [cite book|title=The Armored Dinosaurs|year=2001|chapter=Posttraumatic Chronic Osteomyelitis in "Stegosaurus" dermal spikes|editor=Carpenter, Kenneth(ed)|author=McWhinney LA, Rothschild BM & Carpenter K|pages=141–156|publisher=Indiana University Press|isbn=0-253-33964-2] showed a high incidence of trauma-related damage. This supports the theory that the spikes were used in combat.

"Stegosaurus stenops" had four dermal spikes, each about 60-90 cm (2 to 3 feet) long. Discoveries of articulated stegosaur armor show that, at least in some species, these spikes protruded horizontally from the tail, not vertically as is often depicted. Initially, Marsh described "S. armatus" as having eight spikes in its tail, unlike "S. stenops". However, recent research re-examined this and concluded this species also had four.cite journal|author=Marsh OC|year=1877|title=A new order of extinct Reptilia (Stegosauria) from the Jurassic of the Rocky Mountains|journal=American Journal of Science|volume=3|issue=14|pages=513–514] cite book|title=The Armored Dinosaurs|year=2001|chapter=Othniel Charles Marsh and the Eight-Spiked "Stegosaurus"|editor=Carpenter, Kenneth(ed)|author=Carpenter K & Galton PM|pages=76–102|publisher=Indiana University Press|isbn=0-253-33964-2]

ee also

*"Stegosaurus", tail spikes
*"Strigiphilus garylarsoni"

Other scientific terms first used in comedy

*Horrendous Space Kablooie
*Flange of baboons

References