Amazing new discoveries in South America are revolutionising what we thought we knew about the dinosaur world. It now seems that South America was home to both the largest meat-eater - so new it's still without a name - and the largest herbivore - the enormous long-necked Argentinasaurus. And what's more, these dinosaurs lived at the same time in the same place. So it's possible that like in a science fiction movie, in this prehistoric world these two giants of their kind fought each other in a spectacular clash of the Titans. Horizon follows the scientists to Argentina as they unearth one of these giants - a brand new species of dinosaur; the biggest carnivore ever discovered. Not yet named, this new creature is even bigger than T. rex, the so-called 'king' of the carnivores. The new giant South American predator had a skull bigger than a man that was full of serrated, knife-like teeth and long powerful jaw muscles. They could dissect their prey with almost surgical precision. But even this formidable killing machine couldn't alone have taken on the massive long-neck, Argentinasaurus, which was the height of a five-storey building. It must have hunted in a pack. The problem is, the mega-meat-eaters have always been assumed to have been solitary creatures. The evidence shows that they lived and hunted alone. If they weren't pack hunters, then they would never have attacked Argentinasaurus. So it looked like the idea of a mighty battle between these two giants was simply science fiction. But extraordinary new clues are proving otherwise. Palaeontologist Phil Currie had long suspected that the giant carnivores might indeed have hunted in packs and he set out to find the proof. Only now after many years' work have Currie and his team unearthed the clues that are beginning to convince other palaeontologists that the huge carnivorous dinosaurs hunted in groups. With the help of his colleague Rodolfo Coria, Currie has discovered not one but two fossil bone-beds showing packs of massive carnivorous dinosaurs that have lain buried for millions of years. Each pack - one found in the badlands of Alberta, Canada and the other in Patagonia, Argentina - contains a whole range of individuals, from young through to fully mature adults indicating that they lived alongside in a herd. He's convinced that these dinosaurs were buried together because they were living together. These new finds are good evidence that these creatures really did hunt as a team. And that means a ferocious pack of enormous carnivorous dinosaurs roaming the lands of South America may indeed have taken on a huge Argentinasaurus in a fight to the death. So it may not just be science fiction - the Clash of the Titans could have happened after all.