Contributed by alert reader Vince Rezula, who spotted it in Jurassic Park (Chapter: Third Iteration, The Tour).
Tim stood in front of one skeleton -- a Tyrannosaurus Rex, the mightiest predator the earth had ever known -- for a long time. Finally his father said, "What are you looking at?"
"I'm counting the vertebrae," Tim said.
"In the backbone."
"I know what vertebrae are," his father said, annoyed. He stood there a while longer and then he said, "Why are you counting them?"
"I think they're wrong. Tyrannosaurs should only have thirty-seven vertebrae in the tail. This has more."
I went looking for confirmation (searching on the web) and found nothing. But I sent email to a couple of people (owners of dinosaur-related web pages) who looked like they might be helpful, and both were. One person looked in a few books and found nothing specific, but did find one (Jack Horner, The Complete T. Rex) that said "Our T. rex specimen has only 17 of what would have been at least thirty-five tail vertebrae on T. rex." The other said: "Lessee here.. I have a skeletal drawing.... Yep, 37 tail vertebrae. One looks sort of intermediate between sacral and caudal, but if I had to choose I'd definitely call it caudal."