"We are living through the golden age of dinosaur discoveries." "From 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 wonderful." "From the Arctic to Africa." "From South America to Asia." "Using the latest evidence, for the first time we have a truly global view of these incredible animals." "This time, we journey back 150 million years to the Jurassic Period." "A time when the first giant killers stalked the earth." "But these giants weren't confined to the land." "Recent discoveries have revealed an astonishing new hunter in the oceans." "These new giant killers posed the greatest of threats." "With the smallest advantage tipping the balance between life and death, predator and prey were locked in a perpetual battle for survival." "To understand this world, we must travel back 150 million years to a time when much of Europe looked like the Bahamas." "A time when these warm tropical seas were home to giant predators." "Some of which, have left their mark etched in stone." "This cliff face in Switzerland is carved with a series of enormous gouges and grooves." "Many over nine metres long." "The entire rock face is actually one huge fossil, an upturned slab of Jurassic Ocean floor." "And the marks were left by a predator as it hunted for food." "Sharks like this squatina are similar to angel sharks which still exist today." "It's an ambush predator and lies in wait." "But in these seas there are bigger hunters." "This is Kimmerosaurus." "They belong to a group called plesiosaurs." "At six metres long, they're one of the Jurassic Ocean's most successful hunters." "And also one of the most common." "And it's this unusual hunting method that left its trace on the ocean floor." "We now know that the rock face in Switzerland is etched with the marks of hunting plesiosaurs." "But these giants were not the king of the seas." "Many of the fossils show evidence of having been violently ripped apart." "Clearly, there were much, much bigger predators lurking in these seas." "In 2008, in an island in the high Arctic, a fossil was dug out of the frozen earth." "Its skull alone was nearly twice that of T-rex." "This was an enormous killer." "A killer, the like of which had never been seen before." "More than 15 metres long, and weighing about 45 tonnes, this is the most powerful marine reptile ever discovered." "Twice as big as most Jurassic Ocean predators... this is Predator X, an animal that must go down in history as one of the ocean's most deadly hunters." "And it's prey like Kimmerosaurus that are in its sights." "Skull analysis of giant killers like Predator X, suggests that they hunted their prey by smell... channelling water through special internal nostrils, allowing them to silently hone in on their target." "By analysing their anatomy, we've calculated that Predator X could move up to five metres per second... fractionally faster than a Kimmerosaurus." "The kimmerosaurs only defence is to head for the refuge of shallow water." "This time, Predator X's size works against him." "Unable to hunt efficiently in shallow water... means that the Kimmerosaurus can use this as a refuge." "A subtle advantage that makes the difference between life and death." "Predator X and Kimmerosaurus are just one example of a predator-prey relationship locked in a fight for survival." "In the western states of North America is one of the richest sources of dinosaur fossils." "It's known as the Morrison Formation." "Recently, these rocks have given us a tantalising glimpse of how two dinosaurs adapted together to protect themselves against another deadly predator..." "Stegosaurus and Camptosaurus." "Fossils of these two species are almost always found in the same area." "In 2008, footprints of the two were recovered from the same site." "It seemed that they lived alongside one another." "But why would two unrelated plant-eaters live together?" "Stegosaurus... a heavily armoured tank with a deadly weapon at the end of its tail... known as a thagomizer." "Camptosaurus - a much smaller plant-eater with no obvious defences." "Skull analysis shows that Camptosaurus has bigger eyes... and relative to its body - a much bigger brain." "Camptosaurus appears to be a lookout." "While the armoured Stegosaurus provides the muscle." "It's likely Camptosaurus and Stegosaurus stuck close together for mutual protection... in a world where danger is ever-present." "Allosaurus... a one-and-a-half-tonne ambush hunter with a lethal bite." "The world had never known a predator like it." "But having lost the element of surprise, it's now faced with the prospect of either starving... or facing the most well-protected giant of the Jurassic." "Virtually impregnable from behind, a predator needs to try to attack the stegosaurs from the front." "The evidence for encounters such as these is incredible." "Fossil finds of 2005, directly link these two great animals in battle, revealing the unmistakeable signs of injury." "A Stegosaurus back plate was discovered with a u-shaped bite taken out of it." "A bite mark that fitted the Allosaurus' jaws perfectly." "Even more amazing was an Allosaurus vertebra." "It had a massive impact wound." "The wound appeared to have been made by a Stegosaur's thagomizer." "The blow being so powerful it punched a hole in the bone of the Allosaurs' spine." "What's more incredible is that the injured bone shows signs of healing." "This Allosaurus survived." "The balance of power between predator and prey is a fine one." "Prey continually evolve different strategies to avoid predators." "Both with their bodies, like Stegosaurus, and their behaviour like Camptosaurus." "And in the Jurassic oceans, we have evidence to suggest that plesiosaurs protected their young... by finding sanctuary in shallow water nurseries." "But such lagoons won't always deter a hunter." "And a rising tide gives this predator a glimmer of hope." "But in this shallow water, the huge Predator X can't use its power." "The smaller, agile Kimmerosaurus can easily outmanoeuvre the lumbering killer." "However, the Kimmerosaurus can't permanently protect itself in this sanctuary." "They need to venture into deeper water to feed." "And that is where Predator X has the advantage." "Successful predators need to play a waiting game." "Allosaurus is the most common killer in these lands." "Nine metres long, with a battery of saw blade-like teeth and powerful, clawed forearms..." "Allosaurus is a formidable hunter." "It shares the plains with dozens of species of plant-eating dinosaurs." "A lone Camptosaurus, away from the protection of Stegosaurus... should be easy pickings for a hunting Allosaurus." "Allosaurus teeth were serrated front and back, perfectly evolved for tearing through flesh." "However, recent research has indicated that Allosaurus' bite was surprisingly weak." "Calculations suggested its bite was less powerful than a lion's... despite being seven times more massive." "So, just how did this Jurassic monster hunt and kill?" "The answer is with an element of surprise." "Camptosaurus relies on its keen senses to avoid predators." "Allosaurus on the other hand, is a fast and powerful ambush hunter." "Faster than Camptosaurus." "A one-and-a-half-tonne killer can't run fast for long." "It's a question of speed versus stamina." "Despite the apparent weakness of its bite," "Allosaurus did in fact have a deadly killing method." "Its skull could withstand a force more than 15 times as great as its bite." "This meant that Allosaurus used its head like an axe." "Its strong neck muscles driving its top jaw into its prey." "With every impact, the serrated teeth would tear through its prey's flesh." "The victim dying, through a combination of shock and blood loss." "It isn't pretty, it isn't clinical... but it's ruthlessly efficient." "However, making a kill never actually guarantees a meal." "Because here," "Allosaurus isn't the only killer in these parts." "Saurophaganax." "At 12 metres, it is the biggest carnivore in the region." "And one of the advantages of being so big is that stealing another's kill is that much easier." "Giant predators like Saurophaganax and Allosaurus used their power and size to dominate their domain and all those within it." "And the story was no different in the Jurassic oceans." "These are the bones of Plesiosaur." "They appear to have been broken into fragments." "And many of these show indications that they didn't die of natural causes." "It looks more like they were violently dismembered." "One particular fossil gives us a chilling idea of how these plesiosaurs might have been killed." "It consists of a skull with a few vertebrae still attached but nothing else." "All these dismembered fossils were found in deeper waters, where plesiosaurs need to feed but where they're in the greatest danger." "This animal is in the worst possible place... hunting alone at the surface, where it's most vulnerable to attack from below." "In deep water," "Predator X can use its full power." "Although, injured and stunned this plesiosaur is armed with a vicious bite." "So, Predator X still needs to be wary." "Severely wounded, now the only sanctuary is the shallow water of the nursery." "Predator X's bite is formidable, estimated to be four times that of T-rex." "Biting hard, it perforates the body, cutting through muscle and bone before shaking it to pieces." "It's almost certain that the bite marks on the fossil plesiosaur were made in this way." "And the position of the marks also indicated the attack came from below." "The never-ending battle between predators and their prey is a finely balanced one." "However, for the most successful and enduring predators, the struggle to survive is always tipped in their favour." "And predators like Predator X, a killer with one of the most powerful bites ever known... ruled the oceans for more than 100 million years."