An artist's rendition of an Allosaurus fragilis with its jaws open fully, based on the research of paleontologist Robert T. Bakker. Allosaurus were active predators of large animals, and probably had the ability to open their jaws extremely wide. Studies suggest that they attacked prey open-mouthed, slashing flesh with their teeth, and tearing it away without splintering bones. Allosaurus was a genus of theropod dinosaurs that lived in the upper Jurassic period.Image: Steveoc 86