Allosaurus (A Sound of Thunder)

A Sound of Thunder is a 2005 science fiction thriller film 2005, Charles Hatton has made a fortune by founding 'Time safari', which offers rich 'big game hunters' short time travels to kill off dinosaurs just before their natural death. When Travis notices the weather and wildlife are not behaving as usual, he consults Dr. Rand, the contractually invisible inventor of the supercomputer which controls the time travel. They soon face 'time waves', each worsening the effects in 2055 of evolutionary distortions, lower lifeforms first. They attempt to identify and rectify the past alteration, but each attempt gets harder in their distorted present.

History
The film opens in the Cretaceous, on a prehistoric hunting safari. The expedition includes Time Safari employees Travis Ryer (Ryan Reynolds), Jenny Krase(Selena Gomez), Marcus Payne (Brandon T Jackson), Dr. Lucas, federal regulator Clay Derris and their wealthy guests Alicia and John Wallenbeck. The safari is set under very specific rules to avoid altering history: a volcano is observed to erupt five minutes after they arrive, their target is an Allosaurus (actually extinct in the Cretaceous) that would imminently get stuck in tar, frozen nitrogen bullets are used as ammunition to leave no trace, and the party wears self-contained suits and are told they must stay on a floating path and not touch anything. Furthermore, all the guns are tied to Travis's weapon, and will not fire until he does so.