Thagomizer n. Stegosaurus tail spikes named in memory of caveman Thag Simmons.
The thagomizer originated in a 1982 Gary Larson comic The Far Side and has become an adopted term in scientific circles, education, and research despite the fact that dinosaurs and hominids did not coexist.
It is a rare example of a humorous coined term crossing into serious use, where paleontology teachers and museum interpreters use it as a practical label for the tail spike array of stegosaurs.
"Now this end is called the thagomizer ... after the late Thag Simmons."
- Gary Larson, The Far Side (1982)
An Allosaurus vertebra has a puncture wound that matches a Stegosaurus tail spike, with bone remodeling around the injury. It is one of the clearest fossil clues that a thagomizer strike was a real defensive weapon, not just display armor.
A stegosaur's build can make you wiser,
Its plated back is a primeval visor;
But woe to any beast that dares surprise her—
She’ll answer with her thagomizer.