Allosaurus

Long believed to be a medium sized predator new fossil finds suggest that this Jurrasic carnivore was at least as large as the T-Rex. What makes it an even more formidable hunter is the fact that it may have hunted in packs taking down the large plant eaters like Diplodocus and Apatosaurus. As a plant eater if you thought facing one T-Rex sized carnivore was bad try facing off against five of them.
Located in front of the eyes are 'horns' that scientist think may have helped tell the different Allosaur genders apart. Males having the taller horns and females the shorter. Also Scientists think these 'horns' were probably brightly colored to help the Allosaur in identifing its own species and/or the color may have been gender specific with males only having the bright colors. As the largest active carnivore during the Jurassic Period the Allosaurus was truely the Alpha Predator of its time.