->''I, of course, used a time machine to "get the idea" of Unseen University from Hogwarts; I don't know what Paul [Kidby, the illustrator] used in this case. Obviously he must have used something.''
-->-- '''Creator/TerryPratchett''', on the similarities between ''Literature/{{Discworld}}'' and ''Literature/HarryPotter''

Simply defined, a fan thinks a trope, plot, or line was invented by a show he or she watches, when in truth its origins lie farther back in history.

Tropes tend to be much older than they appear, even if they aren't one of TheOldestOnesInTheBook, so it's increasingly likely that a viewer of a specific program won't be familiar with the original source of whatever is on display.

This can also be inverted by fans, who see a modern adaptation of some older classic they're unfamiliar with, and incorrectly assume some newly introduced trope was part of the original work. The ultimate expression of this is the UnbuiltTrope -- someone did it previously, examined it, deconstructed it, zig-zagged it, all spectacularly, finished the story's run, but is now remembered mostly nostalgically, not for its trope.

See also the more extreme FleetingDemographicRule. Compare with classical music CoveredUp, NamesTheSame, PopCulturalOsmosis, SeinfeldIsUnfunny, RevivalByCommercialization, SequelDisplacement, and the WeirdAlEffect. Somewhat related to AdaptationDisplacement. Contrast with NewerThanTheyThink. Do not confuse with OlderThanTheyLook. There will be a short quiz at the end of class.

For examples of people referencing this trope in fiction, see ItsBeenDone. See also FanMyopia for the same effect when it's over work knowledge rather than time knowledge.

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!!Examples:
[[index]]
* OlderThanTheyThink/AnimeAndManga
* OlderThanTheyThink/ComicBooks
* OlderThanTheyThink/{{Film}}
* OlderThanTheyThink/{{Literature}}
* OlderThanTheyThink/LiveActionTV
* OlderThanTheyThink/{{Music}}
* OlderThanTheyThink/TabletopGames
* OlderThanTheyThink/{{Technology}}
* OlderThanTheyThink/{{Theatre}}
* OlderThanTheyThink/VideoGames
* OlderThanTheyThink/WebComics
* OlderThanTheyThink/WebOriginal
* OlderThanTheyThink/WesternAnimation
* OlderThanTheyThink/{{Other}}
[[/index]]

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