Allosaurus("strange lizard") was a carnivorous Dinosaur, or theropod, that lived during the late Jurassic period, 150 to 140 million years ago. Its fossils have been found in the Morrison Formation, USA; the Tendaguru Beds, Tanzania; partial remains in Portugal, and a possible dwarf Allosaurus from Early Cretaceous Dinosaur Cove, Australia. It is not related to Tyrannosaurus, since T.rex evolved from small carnivores that first appearerd in the Jurassic period, the very time Allosaurus and it's relatives were in charge.
In Jurassic Park
Allosaurus has not yet been featured in a Jurassic Park movie, but rumors are spreading that it may be featured in the 2009/10 film, Jurassic Park IV.
In Operation Genesis
Allosaurus is in the video game Jurassic Park: Operation Genesis as a four-star large carnivore.