Amazing new discoveries down in South America are revolutionising what we thought we knew about the dinosaur world. Horizon follows the scientists as they unearth a brand new species of dinosaur; the biggest carnivore ever discovered. Not yet even named, this new creature is even bigger then T-Rex, the so-called 'king' of the carnivores.Finds like this have opened new questions about life in the age of the dinosaurs. It now seems that South America was home to both the largest meat-eater and the largest herbivore - the enormous long-necked Argentinasaurus. And what's more, these dinosaurs lived at the same time in the same place. Could it be that in this prehistoric world they fought each other in a spectacular clash of the titans?It seems like science fiction, but one team of palaeontologists has been studying this possibility, and has unearthed extraordinary clues that indicate that giant meat-eaters were not the solitary, lone predators, as was traditionally believed. The evidence now indicates that they may have been pack hunters. And that means a ferocious pack of enormous carnivorous dinosaurs roaming the lands of South America may indeed have taken on the huge long-necks in a fight to the death. So it may not just be science fiction - the Clash of the Titans may really have happened after all.