"is watching his prey." "Peering through the water, the carnivore fixes on his unwary victim, waiting for the perfect moment to strike." "Under these azure waters lies the future continent of Europe, but now, in the late Jurassic period, all that exists here are a few scattered islands." "The break-up of the old continents has pushed up the ocean floor and raised sea levels, flooding the lowlands and creating vast shallow seas." "Here, dinosaurs do N0T rule." "Instead, giant marine reptiles have evolved, perfectly adapted to life in these beautiful waters." "All of them are air-breathers, like this eight-tonne Cryptoclidus." "0n the land, they are cumbersome hulks, but in water, they are transformed." "All sea reptiles once lived on land, but 75 million years ago, their ancestors took to the water and their legs became flippers." "They share this shallow sea with other strange Jurassic creatures, like the ammonites, that snare small prey with their tentacles." "These rich, sunlit waters are on the northern edge of the ancient Tethys 0cean - the sea that separates the Earth's two continents, one in the north and one in the south." "0nce a year, they are the stage for a remarkable natural drama." "It starts with a single pregnant 0phthalmosaurus, followed by hundreds more of her kind." "All are gathering here from deeper water to give birth." "These are the oldest of marine reptiles and most completely adapted to aquatic life, with streamlined fish-like bodies." "Most other marine reptiles, like Cryptoclidus, use all four flippers to chase the blizzards of fish through the water." "Flapping like underwater wings, the flippers can be used separately to give them huge manoeuvrability, or together, for sudden bursts of speed." "This unique method of locomotion is destined to disappear from the ocean at the end of the age of the dinosaurs." "The animals on the small islands above also depend on the sea's bounty for their survival." "Among the jagged rocks live a colony of flying reptiles." "These sea pterosaurs are called Rhamphorhynchus." "They have evolved a way of catching fish without getting their wings wet." "Their beaks skim through the water, grabbing anything in their path." "The teeth of these flying reptiles may look bizarre, but they are ideal for snatching slippery fish from the water." "However, swallowing their catch is a different matter." "(Harsh squawking)" "(Low growling)" "The 0phthalmosaurus are starting to give birth." "Most sea reptiles lay eggs on land, but not 0phthalmosaurus." "They give birth to live young." "They give birth to live young." "This frees them from the need to crawl out of the water, and has allowed them to evolve their fish-like shapes." "A female has two to five pups, but since they are air-breathers, the young must be born tail first," "or they would drown before they escaped from the mother." "or they would drown before they escaped from the mother." "The newborn pups have just a few seconds to reach the surface and take their first breath." "As soon as they are born, the pups are vulnerable." "These waters are full of predators." "Even adult 0phthalmosaurus will eat the offspring of others to increase the chance of survival for their own pups." "The only real safety is amongst the crags of coral." "Birth is a dangerous time for the mothers, too." "This female is trying desperately to expel her unborn offspring." "Fighting for air, she stays near the surface." "Her struggles are a lure to sharks." "These predators have acute hearing, and the sound of splashing betrays an animal in distress." "As perfectly evolved killing machines, sharks patrolled the oceans long before marine reptiles appeared." "After 20 minutes, her exertions are exhausting her." "She is having to breathe more frequently." "The sharks start to move in closer." "Suddenly, something lurking in the gloom scatters the sharks." "Liopleurodon - at 150 tonnes," "Liopleurodon - at 150 tonnes, it is the largest and most powerful carnivore ever to live on the planet." "This male measures a colossal 25 metres, and is big even for his kind." "His size means he is probably over 100 years old." "He, too, detected the mother's distress from a distance." "Liopleurodon has a directional sense of smell - two chambers in his nose work in the same way as a pair of ears - pinpointing the source of a smell - a sophisticated tracking device, steering the largest carnivorous jaws ever known." "Each one of Liopleurodon's four flippers is over three metres long, giving him enough power to guide his huge bulk effortlessly through the water." "By now, the coral reefs around the islands are full of baby 0phthalmosaurus." "This intricate network of caves is their refuge, a safe haven from which they can start to learn about their world." "Baby 0phthalmosaurus have prominent teeth, allowing them to cope with the tough prey they find among the coral." "But this little male has yet to learn that ammonite shells are too tough for him." "Above the sea, food is less plentiful." "A lonely dinosaur has been forced to swim between the islands in search of a meal." "With huge marine predators in the water, this is a dangerous journey." "Large dinosaurs are rare here, and at five metres from nose to tail," "Eustreptospondylus is the biggest." "They are primarily scavengers, combing the beaches for dead animals, but on such small islands, they are always under pressure to find more carrion." "But another scavenger has got here first." "This Eustreptospondylus is picking the last rotten strips of flesh off a dead turtle." "But even these decaying remains are enough to trigger a confrontation." "(Growling)" "Neither will risk an injury and in the end, it is the loudest roar that wins." "(Fierce roar)" "The only food supply here that is not from the sea is the insects." "Bark beetles infest the trees here." "They represent a tantalising feast of protein just under the surface." "This tempts a young Rhamphorhynchus to probe for insect larvae, but this is not really a job his beak is evolved to cope with." "Now two weeks old, the young 0phthalmosaurus are growing fast on a seafood diet, but they are still at risk... especially from shark attack." "A head of coral provides a temporary refuge for this pup." "His pursuer has a deadly advantage - he does not have to return to the surface to breathe and has only to wait until the pup needs air." "But the little reptile has one thing on his side... ..speed." "Safe..." "until he needs to breathe again." "Having a lungful of air presents marine reptiles with a buoyancy problem." "Cryptoclidus has found one solution." "He is not searching for food in the sand." "He is after pebbles and grit." "Sieving off the fine grains, he retains the larger stones in his stomach for ballast, which weighs him down and counteracts the air in his lungs." "The land represents safety for the Cryptoclidus - they have come up onto the rock ledges to rest, and also to be out of reach of Liopleurodon." "Darkness does not bring peace in the restless sea." "Billions of microscopic creatures rise up from the depths as the light fails, and shoals of fish surge into life to pursue them." "0phthalmosaurus adults are masters of hunting at night." "Most have left for deeper waters, but a few remain to take advantage of the plenty here." "With their enormous light-sensitive eyes, they pick out squid in the gloom." "Their long toothless snouts are streamlined weapons, making it easy for them to snap up fast-moving prey." "With the approaching full moon, strange-looking visitors gather on the shoreline in their thousands." "These are horseshoe crabs - ancient creatures who originated 150 million years before the Jurassic." "0n a high tide, the females struggle up the beach and each lay as many as 18,000 eggs, which the males compete to fertilise." "This strategy has served them well since before the dinosaurs appeared, and will do so for at least another 150 million years to come." "Early morning, and the horseshoe crabs cause a feeding frenzy." "Every year, the Rhamphorhynchus come to this beach to gather up the eggs, while the last few crabs struggle back into the water." "The nutritious eggs are an easy meal for these reptiles." "But nature seldom offers anything free of risk." "(Low growling)" "(Squawking)" "A month later." "Tiny horseshoe crabs start to work their way out of the eggs." "The high tide that brought the females up the beach now sweeps their offspring back into the sea." "For the pups, their secure life around the reef is coming to an end." "In a few weeks, they'll be big enough for life in the open oceans." "The first signs are when, like adults, they show the skills to hunt fish in open waters." "This is not without risk." "The sharks are still a danger." "0ne day, these will be the most feared predators in the sea, but in these Jurassic waters, they themselves are prey." "The Liopleurodon is an expert at ambush." "He takes one giant gulp of air, then descends to hide in the depths." "There, he can hold his breath for over an hour." "And Liopleurodon is a shark-eater." "Unexpectedly, a female Liopleurodon arrives on the scene." "This, the bull will not tolerate." "Liopleurodon are fiercely territorial" "Liopleurodon are fiercely territorial and confrontations almost always end in violence." "The female is forced to leave the area." "Her flipper has been badly ripped by the male's tusk-like teeth, attracting sharks that follow her trail of blood." "It is four months since the pups were born" "It is four months since the pups were born and they're ready to leave, but they are facing one of the greatest hazards of this cruel sea." "These islands are regularly ravaged by violent tropical storms that are strong enough to tear up the shallow sea beds, smash corals and kill thousands of marine animals." "The storm has had its victims." "It was not just these delicate-boned Rhamphorhynchus that were broken in the 100-mph winds..." "..the old Liopleurodon, disorientated in the murky waters, has ended up stranded on an island beach." "As the beachcombers start to gather, they are wary." "While the giant is still alive, his enormous jaws are lethal." "But they can afford to bide their time." "The carnivore's own 150-tonne body is slowly suffocating him." "The Liopleurodon's life has now ebbed away." "The mightiest carnivore the world has ever seen is no more than a banquet for a group of lucky scavengers." "The Jurassic is a golden period for giant marine reptiles." "It will be another 90 million years before they vanish from the oceans, along with the extinction of the dinosaurs on land." "Most of the 0phthalmosaurus pups have survived the storm and now face life in the open sea." "0ne day, the females will return, and when they do, they will be carrying the next generation." "Marine reptiles were one of the glories of this ancient time - even though turtles are the only ones left today." "Another group of reptiles shared the dinosaurs' world - the pterosaurs." "As we shall see in the next episode, they were just as spectacular."