Ray Bradbury wrote a short story where a time traveling safari hunter accidentally crushes a butterfly under his boot in the Cretaceous period, thereby changing the course of history millions of years later. He wrote the story two decades before the term Butterfly Effect first came into use
“The story begins in the future, in which the time machine has been invented but is still very temperamental. A hunter named Eckels pays to go traveling back into the past on a guided safari to kill a Tyrannosaurus Rex. As the party waits to depart they talk about the recent presidential elections in which an apparently fascist candidate, Deutscher, has just been defeated by the more moderate Keith, to the relief of many concerned. When the party arrives in the past, Travis (the hunting guide) and Lesperance (Travis’s assistant) warn Eckels and the two other hunters, Billings and Kramer, about the necessity of minimizing the events they change before they go back, since tiny alterations to the distant past could snowball into catastrophic changes in history. The hunters must stay on a levitating path to avoid disrupting the environment and only kill animals which were going to die within minutes anyway.
Despite his earlier eagerness to begin the hunt, Eckels loses his nerve at the sight of the Tyrannosaurus. Travis tells him he cannot leave, but Eckels panics and veers off the path. The two guides kill the dinosaur, and shortly afterward the tree that would have killed the dinosaur in the absence of human intervention falls on the corpse. Travis’s elation quickly changes to fury when they find Eckels and see by his muddy boots that he did in fact fall off the path. Travis threatens to leave Eckels in the past unless Eckels removes the bullets from the dinosaur’s body, as they cannot be left behind.
Upon returning to the present, Eckels notices subtle changes. English words are now spelled strangely, people behave differently, and, worst of all, Deutscher has won the election instead of Keith. Looking through the mud on his boots, Eckels finds a crushed butterfly, whose death was apparently the cause of many changes. He frantically pleads with Travis to take him back into the past to undo the damage, but in reply Travis deactivates his weapon’s safety, and there is only an ominous “”sound of thunder””, the same sound which had previously preceded the arrival of the Tyrannosaurus. It is ambiguous as to whether Travis shot Eckels or himself, but it makes undoing his actions impossible either way.”