A Sound of Thunder

The year is 2055. A hunter known simply as "Eckels" prepares to take the trip of a lifetime; going back in time to the Mesozoic to hunt the greatest predators that ever lived. However, when he goes back to the Late Cretaceous he panics when confronted with a Tyrannosaurus Rex, and falls off the path and crushes a butterfly, breaking some of the myriad of rules the time agency has to keep the time line from changing. When the party returns to the future, they find out that the world has changed for the worse. In the original time line, the presidential election was recently won by Keith, a moderate candidate, as opposed to Deutscher, a fascist extremist. However, in this changed time line, the reverse is true. A distraught Eckels pleads with Travis, the guide, to take him back in time and fix what he's done, but Travis, having previously warned him that it's impossible (the time machine skips over any moment in history that they've already visited), silently lifts and fires his rifle, presumably at Eckles.

First written by Ray Bradbury as a short story for Colliers magazine in 1952, A Sound of Thunder has become the most re-published science fiction story of all time. Its influence can be seen all over the fictional world, particularly due to its introduction of the Time Travel plot in which "small changes in the past snowball into the future". It is one of the Trope Namers for Butterfly of Doom, which is... well, exactly what it stated above. This story has also led to the creation of numerous other works, including a spin-off novel series and the short story series Rivers Of Time. Oh, and a movie, directed by Peter Hyams. But you'd better read about that one in other sources.

This story contains examples of:

 * As You Know
 * Butterfly of Doom: The Trope Namer
 * Close Enough Timeline: Travis actually theorizes about this before the hunt began.
 * For Want of a Nail
 * In Spite of a Nail
 * Ripple Effect Proof Memory
 * Science Marches On: Numerous facts about dinosaur biology, particularly about them having two brains.
 * Stay On the Path
 * Stock Dinosaurs: The only dinosaur that appears in the entire story is the infamous Tyrannosaurus Rex.
 * Temporal Paradox: Subverted when the safari guides explain that "time steps aside" to prevent such paradoxes from happening.
 * Title Drop: Twice in the narration.
 * Tyrannosaurus Rex
 * What Could Possibly Go Wrong: Who thought it was a good idea to make big-game time traveling, knowing full well what the risks and consequences were? What sort of monetary gain could be worth the risk of waking up one morning to have never existed?
 * Simple: Screw the Rules I Have Money.

This spin-off novel series contains examples of:

 * Abusive Alien Parents: The Mutata send their young off to be raised by other Mutata.
 * Always Chaotic Evil: The sentient Allosaurs.
 * Rule of Cool: Alternate universes filled with dinosaurs, samurai, sapient pterodactyls, cyborgs, and Aztecs. At one point it is hinted that there is even an entire universe filled with cat people.

This movie contains examples of:

 * Adaptation Expansion: Turning a short story into a feature film might be a good cause for the awfulness.
 * Delayed Ripple Effect: Taken to ridiculous extremes. Translucent blasts called timewaves come out of nowhere and start knocking people around. And each time they do more species become "devolved".
 * Dull Surprise: "Pierce Brosnan was originally slated to star. Unfortunately, he was replaced by a wooden marionette that looks a lot like Edward Burns." (it's a running gag on the recap seeing how his facial expressions are the same.)
 * Money Dear Boy: Ben Kingsley.
 * Sexy Man Instant Harem: Ryer bangs a client.
 * Shout Out: Haddon kiss-assingly compares his clients to "Brubaker landing on Mars". This is a reference to Capricorn One, Hyams' debut film, where Brubaker was the captain of a faked Mars landing.
 * Special Effect Failure: Apparently it was released when the FX weren't completely finished due to the production company's bankruptcy.
 * You Fail Biology Forever: Where do we start!
 * Baboonasaurs, that's where. Alternately "Baboonizards." There's also the flying "Batboonizards," and "miscellaneous underwater shark-eel-thing."
 * And we continue with the claim that lions are descended from Allosaurs. Congratulations.
 * You Get What You Pay For: The boss of the safari company shutting down a key component of the time machine to save power contributed to the catastrophe at hand.