"We're living through the golden age of dinosaur discoveries." "All over the world, a whole new generation of dinosaurs has been revealed." "From the biggest giants and the deadliest killers to the weird and the wonderful." "From the Arctic to Africa, from South America to Asia." "In just the last few years, we have uncovered extraordinary fossils, exquisitely preserved and tantalisingly intact." "Combined with the latest imaging technology, we have been able to probe deeper and reveal more than ever before." "It gives us our first truly global view of these incredible animals." "In this programme we examine the new giants - the heavyweights of the dinosaur world." "It's only in recent years that we have unearthed the biggest dinosaurs that ever lived." "Animals on such a huge scale it is difficult to comprehend." "Just how and why did these titans grow so massive?" "And could any animal attack such a huge beast?" "One of these new giants has eclipsed all others." "At 35 metres, it was as long as Diplodocus." "Yet this dinosaur was seven times as heavy." "The first glimpse of this new giant was made in the 1990s during a dig in Argentina." "In Patagonia, a fossil was pulled from the ground." "It was a single vertebra, but it was as tall as a human being." "Other bones followed." "They belonged to the biggest dinosaur ever known to have walked the Earth." "It lived in South America 95 million years ago." "In a world very different from our own - a world that is only now giving up its secrets." "The start of a new life." "But on these plains, danger is never far away." "This is a chaoyangopterid pterosaur, attracted to the easy prey of a nest site." "Throughout the late 1990s, extraordinary dinosaurs were uncovered in Argentina." "At one location, a nest site was found, so full of dinosaur eggs that they could barely avoid crushing them underfoot." "Some eggs even contained exquisitely preserved dinosaur embryos." "Then, in 1999, at the same nest site, a complete adult dinosaur skeleton was uncovered." "It appeared they'd found the parent." "But first impressions can be deceptive." "This isn't the parent." "This is a Skorpiovenator - a predator." "The skeleton found at the nest site was almost certainly a nest raider, preying on the hatchlings." "The hatchlings' real parent, and the owner of the enormous vertebra is Argentinosaurus." "A plant-eating giant that dwarfs everything around it." "From the bones that were found, we've calculated that Argentinosaurus was a colossal 35 metres long, and weighed as much as 75 tonnes." "When born, the hatchlings themselves weigh a paltry 5kg and need to fend for themselves immediately." "From studying the embryos, and looking at the bones of the adults, we know that the growth of these giants was phenomenal." "Over 40 years, they grow from 5kg to an astonishing 75,000kg." "At their peak, it's been calculated they grow up to 40kg every day." "The dinosaur embryos are so well preserved we can see they already have their teeth, in preparation for a lifetime of eating." "But becoming a giant takes more than simply turning tonnes of food into muscle." "It's about the success and survival of a species over millions of years." "One way to increase the chances of survival is by having lots of offspring." "And the best way to do that is by laying eggs." "Lots of them." "The nest site in Patagonia stretches for an astonishing 15km and contains tens of thousands of eggs." "And the site was used continuously for hundreds of thousands of years." "For killers like Skorpiovenator, the nest site provides a feast." "But, with thousands of hatchlings, they have little impact on the success of the species." "And pose no threat to the adults." "But, wherever we find giant plant-eaters... ..there is always a giant killer lurking nearby." "And, sure enough, another startling discovery was made in Argentina." "In the same region, a nearly complete skeleton of an enormous predator was unearthed amazingly well preserved." "The skull alone was over 1.5 metres long." "And when a second, even larger, specimen was found, it became clear that this was bigger than any predator that had been found before." "Bigger than T Rex." "It was clear that giant predators roamed South America as well." "And it appeared that Argentinosaurus may have met its match." "In fact, wherever giant plant eaters have been discovered, it appears a giant predator lived alongside them." "From America, to Europe and Asia, we see the same relationship repeated." "But there was one place on earth that remained a mystery." "For decades, Africa was the forgotten continent, a huge gap in our understanding of planet dinosaur." "Then, in 2000, a cluster of bones was unearthed in North Africa." "The bones were huge - one single leg bone was as tall as a human." "It seemed this, too, was a land of giants." "And that could only mean one thing." "There must also be a giant killer." "95 million years ago, this was a dry and difficult place to survive." "Food and water were hard to come by and often only found in one place - along the banks of a river that has earned the name River of Giants." "This is Paralititan, a 45-tonne animal... ..and the undisputed heavyweight here." "For an animal this size, it's not easy to keep cool, so being near water is vital." "But rivers are dangerous places." "This is not a good place for a young animal to get stuck." "And it's not just because of these crocodiles." "This river holds much, much bigger threats." "It may look familiar... but this was no ordinary crocodile." "With a skull nearly two metres long, it's more than twice the size of any modern croc." "This was Sarcosuchus." "Weighing as much as eight tonnes, it's the undisputed king of crocodiles." "A cold-blooded killer." "And if it can drag its prey into the water and drown it, even better." "But, even for a deadly predator like this, the River of Giants holds dangers." "Across the world from Africa to Argentina, giant sauropods roamed far and wide." "This herd of Argentinosaurus are now on the move, travelling across a swamp covered with volcanic ash." "It's a dangerous place to be if you're living in the shadows." "These giants are so massive they've turned the sand beneath their feet into quicksand, creating death traps with every step." "It's a danger that was graphically revealed in 2010, when an astonishing set of footprints were unearthed." "Footprints that contained a deadly secret." "After months of painstaking examination, some of the fossil footprints were found to contain bones of other animals." "One exposed the bodies of two mammals, ten small dinosaurs, two crocodiles and a turtle." "In total, 18 animals were buried within a single step." "But becoming this big is not easy." "It requires some serious eating." "Argentinosaurus weighed around 75 tonnes." "A six-tonne African elephant eats for 18 hours a day to keep going." "Argentinosaurus weighs more than ten times as much." "So how did they get enough food?" "They turned themselves into the most efficient eating machines the world has ever known." "Everything about them is designed to get the most food in and the most calories out, with the least effort." "Their long necks give them access to more food without moving." "But the way they eat is the crucial bit." "These giants don't waste time chewing." "They rip and gulp down leaves whole, which are digested by bacteria in its massive gut." "Not chewing means it doesn't need a big, heavy head with big teeth and muscular jaws, which also means its neck can grow so long, able to reach food no other animal can reach." "Being so big means you're off the menu for most predators." "Here, there's a killer in a completely different league." "Over ten metres long and weighing around four tonnes, this is Mapusaurus." "A newly discovered killer on the block." "On its own, even it is not a match for a fully grown Argentinosaurus." "But this giant killer is not alone." "For years, it was thought that an adult Argentinosaurus would be too big for any predator to tackle." "But in 2006, a new discovery suddenly made even the biggest of dinosaurs a lot more vulnerable." "As they dug into the Argentinean dirt, they didn't just find one predator buried here." "The skeletons of at least seven Mapusaurus of different ages and sizes were found together." "It suggested that this was a group." "A giant killer that appears to hunt in gangs." "And more than capable of taking on the very biggest dinosaurs." "Not even a fully grown Argentinosaurus is safe from this group." "The best defence is their sheer size." "Mapusaurus's teeth are perfectly designed, like blades, to slice off chunks of flesh." "With prey so large, a single bite isn't always fatal." "It appears Mapusaurus could just snack, feeding from its victim without actually killing it." "The victim surviving to provide more food at a later date." "But even in a group, these giant killers are never far away from danger." "Attacking an animal more than ten times your weight carries grave risks." "Even with the threat of predators hunting in gangs, the phenomenal size of these giants would usually keep them safe." "But a giant needs to grow." "It's the younger, smaller animals that are in greatest danger from giant predators like Sarcosuchus." "And here in Africa there is nowhere to hide." "Things are about to get even worse for the young Paralititan." "Around the river of giants, there is another killer." "Carcharodontosaurus." "A predator always looks for the easiest kill, the weak, injured or young." "The Paralititan is all three." "In such a deadly game of tug of war there can only be one winner." "But the kill is still not certain." "Carcharodontosaurus can tackle this youngster, but a herd of 45-tonne adults is another matter." "Injured but alive, this youngster has a lucky escape." "Encounters like this have left tantalising clues behind." "Amongst the bones of a Paralititan, we have found a Carcharodontosaurus tooth suggesting a predator-prey relationship." "They complete a global picture, a pattern that is repeated across the world." "In Asia, we find Mamenchisaurus and Sinraptor." "In North America, Diplodocus and Allosaurus and now Africa." "For every giant plant eater we find a giant predator living side by side." "And it's in South America where we have the biggest of all." "Argentinosaurus and Mapusaurus." "Two giants whose fates appear to be inextricably linked." "This Argentinosaurus wounded by a gang of mapusaurs has succumbed to its wounds." "Out on the plain, other keen-eyed predators are quick to spot a stricken animal." "It's a prize worth waiting for." "And attracts carnivores from miles around." "Mapusaurus are not only hunters." "Like virtually every carnivore today, scavenged prey plays a huge part in their diet." "We know enough about the biology of giant sauropods to estimate of this 70-tonne animal, 11 tonnes is bone, three and a half tonnes blood, four tonnes is hide and skin," "15 tonnes fat and 39 tonnes is meat." "Enough to feed a whole ecosystem for days." "Mapusaurus was reliant on the giant sauropods in life and death." "When the Argentinosaurus disappeared from South America 93 million years ago, so did the giant predator Mapusaurus." "It was the same story in Africa - when Paralititan vanished," "Caracharodontosaurus followed." "It appears that these extinctions were linked, and this story is repeated time and again." "When the giant sauropods died out, the giant predators lost their main food supply and they too were doomed." "Subtitles by Red Bee Media Ltd" "Email subtitling@bbc.co.uk"