"Anne Elk's Theory on Brontosauruses" is a sketch from Episode 31 of Monty Python's Flying Circus, 'The All-England Summarize Proust Competition'.
This sketch features Graham Chapman as a television interviewer and John Cleese in drag as a palaeontologist, Anne Elk, appearing in a television talk show titled Thrust. The plot of the sketch is that the interviewee, Anne Elk, can hardly describe the basis of her supposed new paleontological theory on dinosaurs, specifically Brontosauruses. After several false starts during which she repeatedly and noisily attempts to clear her throat, Miss Elk spends most of the interview circuitously leading up to the 'theory by A. Elk. Brackets Miss, brackets.' It turns out that in the end Miss Elk's new theory on brontosauruses is rather shallow: 'All brontosauruses are thin at one end, much much thicker in the middle and then thin again at the far end.' Her true concern is that she receive full credit for devising this new theory: 'That is my theory, it is mine and belongs to me, and I own it and what it is, too.'
This sketch was also performed on the album Monty Python's Previous Record, under the title 'Miss Anne Elk'. On the album, before beginning her second theory, the interviewer shoots her.
Anne Elk's roundabout speech pattern was based on Graham Chapman's companion David Sherlock, who evidently spoke in such a manner, amusing the other Pythons.
The sketch inspired the concept of "Elk Theories" to describe scientific observations that are not theories but merely minimal accounts.
The character A. Elk and her 'Theory of Brontosauruses' is used in the American Psychological Association Style Guide to illustrate how to reference a periodical article in a learned journal.