The creature's skull - broken into 350 fragments - was found by palaeontologists from the University of Chicago in a cliff face on the northern fringes of the Sahara Desert in Morocco. They made casts of the fragments and used them to work out the size of its head and to recreate a replica of its skull.
The dinosaur's head was 5ft 4in long - the largest dinosaur skull yet found - but examination of the brain case has revealed that the creature's actual brain was only the size of a tennis ball.
Not only was the dinosaur - Carcharodontosaurus saharicus (shark-toothed reptile from the Sahara) - longer than Trex, it may in some respects have been an even more formidable predator.
Unlike Trex its teeth were knife-shaped with razor sharp blades. It would have slashed and sliced, while the slightly later Trex would have grabbed, punctured and ripped its prey.
Carcharodontosaurus dominated what is now the Sahara, which was then lush river deltas and plains, between around 94 and 88 million years ago. Though 45ft long and 12 ft high at the hip, it was extremely agile, weighing about 8 tons and probably able to run at up to 20 miles per hour.
With its stocky neck it would have been able to gulp down huge chunks of meat. One of its major victims was the Sauropod, a vegetarian long- necked dinosaur that often exceeded 65ft in length. Carcharodontosaurus, also probably had a life expectancy of about 100 years.