Answer: True
A Sound of Thunder is a short story by Ray Bradbury, published in 1952. It deals with the paradoxes of time travel.
In the story, a man named Eckels joins a safari that allows people to travel back to the past and kill extinct species, such as dinosaurs. The victim has been carefully targeted as the animal was about to die and hunting him is unlikely to have serious consequences in the future. Eckels, however, ends up panicking when the Tyrannosaurus rex appears, and cannot kill him (other members of the hunting party do). However, he accidentally steps on a butterfly. This small but unplanned action changes the future forever.