"All around the world, hidden in museum storerooms, are the fossil bones of animals most people never knew existed." "They belong to a group of creatures that rivalled the dinosaurs in size and ferocity." "Now Walking with Beasts has brought these creatures back to life, and this programme will reveal the incredible story of how they came to dominate the Earth." "They are the mammals." "Surprisingly, the first very first mammals appeared on Earth at the same time as the dinosaurs." "(ROARING)" "But the dinosaurs quickly took over, and during their 160-million-year reign, the mammals made little impression." "The first mammals would have looked like shrews or mice." "They were tiny creatures, most of them." "If you find a fossil, they are minute compared to the dinosaurs." "If you look at this tiny jaw - this is a complete jaw of one of the early mammals - compared to the jaw size of this dinosaur, this would be about the size of one of T Rex's teeth." "The mammals looked destined for obscurity, but they were dealt an odd stroke of luck." "65 million years ago, the Earth encountered a few problems." "It was the end of the dinosaurs." "A few groups of animals struggled through this Armageddon, and the mammals were among them." "Today, the world is dominated by a magnificent variety of mammals." "But they owe their success to a remarkable set of characteristics that were there from the beginning - features that made them uniquely adaptable." "A warm-blooded metabolism helps maintain their body temperature and live life at high speed." "Their fur coat means they can withstand a range of temperatures and so live in an amazing variety of habitats." "They produce milk and care for their young, giving them a head start in a dog eat dog world." "And they come equipped with a variety of different shaped teeth, which means they can munch their way through almost anything." "They even have large brains, so they can learn as they grow, and are able to adapt as they face new challenges." "To recreate this remarkable story of evolution," "Walking with Beasts teamed up with scientists and special effects artists." "At every stage, the sculptors and model makers relied on studies of the fossils to put flesh on the bare bones." "They even took expert advice on where to take their animals to feed and drink." "On the computer, scientists advised animators on how to get the animals up on their feet." "Perhaps the biggest challenge was working out how they might have behaved, especially when all that was left of these creatures were a few bones and teeth." "Fortunately, palaentologists can tell a lot about a mammal from its teeth." "mammal teeth are hugely variable." "Whereas dinosaurs only had two or three kinds of teeth, mammals have dozens of different kinds and they're hugely different." "This is the tooth of a mammoth, just like the tooth of a living elephant." "Here's the root, here's the grinding surface, and it's ridged with these thickened structures across here." "Other kinds of mammals have different sorts of teeth." "This is a cave hyena, a giant hyena." "The teeth are different." "At the front here are the incisors, here are the canines for piercing flesh." "Towards the back, these extraordinary broad, sharp-edged teeth used for crushing and smashing bone." "If you look at the teeth of a mammal, you can tell very quickly what it ate." "This little chap has sharp pointed teeth." "They would have been used for piercing the outer carapace of insects." "An insect eater of some sort." "This one is obviously a flesh eater." "Look at these vast pointed teeth." "Here's the canine tooth, used for piercing through flesh." "The incisors at the front are just as fierce, for cutting up flesh and bone." "Towards the back are these massive cutting teeth for shredding flesh, cutting through bone, chewing and reducing it before they swallowed." "When you look at the teeth from this creature from South America, you can see the shape of the incisors." "They look human-Iike, not very sharp - a plant eater." "Towards the back, the molar teeth - the cheek teeth - are broad, grinding surfaces, rather like the teeth of horses or cattle." "The dinosaurs were lucky." "They lived through a period of stability in the Earth's history." "The weather forecast for 160 million years was warm and humid, but mammals have had to deal with a different kind of world - one that would keep the best forecasters guessing." "This unpredictable place saw huge fluctuations in climate." "Seasons arrived, forests came and went, whole habitats were created and destroyed... and the icecaps just kept on growing." "The last 65 million years of the Earth's history has been a roller coaster ride." "For the mammals, it was adapt or die." "Just how they seemed to like it." "Their first test after the Earth recovered from the great extinction was to adapt to a world completely covered by tropical forests." "South of Frankfurt in Germany there is a spectacular fossil site with evidence ofjust how different the world was 49 million years ago." "This is a unique glimpse into a time when mammals had just begun to take off." "Palaeontologists have discovered that this abandoned mine was once surrounded by lush tropical forest and full of an extraordinary collection of animals." "We have some of the weirdest animals I know of in the history of mammals at all." "extremely small horses, about 30cm high." "extremely large predacious birds, two metres high." "Leptictidium is one of the strangest animals which lived here." "Running or hopping on two legs - nothing today is like that." "These so-called Messle sediments gradually built up over millions of years, capturing an entire ecosystem." "The detail in these fossils is exquisite." "In some, the fur outline of the entire body is still visible." "In others, you can see the remains of the last meal inside their stomachs." "The rocks have revealed an extraordinary explosion in diversity." "Almost every group of modern mammal can trace its earliest members to this time." "It's an amazing time for the history of mammals because we have not only these weird mammals, but also a Iot of mammals which are part of the groups we know today." "Some, like the bats and anteaters, haven't changed much for millions of years, but others, like the early horse, were very different then." "If you compare the small MessIe horse with the horse today, you would not think that this is the same kind of animal, but it is." "This is why this site is so fascinating." "Although it was about the size of a cat," "Propalaeotherium is the forerunner of modern horses." "It has all the same features, but in miniature, though instead of one hoof it has several hoof-like toes." "OK." "Cut there." "Varied though they were, one thing the mammals had in common was their size." "early mammals were small, living in tropical forests." "They got bigger than in the age of the dinosaurs, but only pig size." "They lived below the trees;" "some could climb and adapt to new diets." "They couldn't get very big in those forests." "So, if mammals were small, who WERE top of the food chain?" "Looking at modern descendants, it might be hard to believe, but mammals once lived in mortal fear of birds." "Never underestimate the power of a beak." "I just gave riley a brazil nut." "It would be extraordinarily difficult for us to crack." "We can't do it with our teeth." "It takes tools for us to do it, whereas riley, with a skull this big, can actually crack that nut just using its skull." "Now imagine a very, very big Riley." "The first thing you see in this extinct bird is that it could have delivered an impressive bite." "The skull belonged to a gigantic two-metre-tall bird called Diatryma or Gastornis." "If we compare riley's skull - about this big - to the skull of these gigantic birds, we can see this animal is way overbuilt for cracking anything like nuts." "In fact, Gastornis was over-engineered in many ways, compared to modern birds." "Large, flightless birds are around today, Iike the ostrich." "It's obviously built along different lines." "It has a relatively tiny skull." "certainly not the massive skull," "large skull, that we see in extinct birds." "Gastornis was big and powerful, and specialised in one thing - eating mammals." "Gastornis or Diatryma, with such powerful jaws, was able to eat struggling prey, eat vertebrates;" "perhaps not just to eat the flesh but to crack open the bones and extract the highly nutritious marrow in the bones." "Gastornis was a gruesome reminder of something that had come before." "These birds were doing the same thing as a Tyrannosaurus or any other predatory dinosaurs." "These mammals may have viewed them much the same way." "If the world had stayed covered in tropical forest, it's possible birds, not mammals, would have remained in charge." "But while predatory birds ruled the roost on land, some mammals found escape in an unlikely place for a furry, four-legged creature - the water." "Here they started to grow very, very big indeed, eventually leading to the largest animals ever - the whales." "Whales are proof of the amazing adaptability of mammals." "But how these 150-tonne beasts evolved from small tree-dwelling creatures has been one of the greatest scientific mysteries." "For over a century, scientists have scoured the Earth for fossils of ancestors of whales on land." "In the 1920s, an intrepid American called Roy Chapman-Andrews led a huge expedition to Mongolia to discover fossils." "One of his most spectacular finds was the skull of a large hoofed carnivore." "Close examination of its teeth revealed surprising similarities to those of whales." "It turned out to be a distant relative." "It's extraordinary to look at a whale or dolphin and realise its ancestor was a Iand-Iiving creature which would have looked like a pig or a giant dog." "Over the years, the skeleton, skull and teeth of mammals can adapt, and has adapted rapidly." "No one knows what prompted hoofed carnivores to take the plunge and eventually become swift swimmers." "In fact, nearly all mammals can swim." "It's just that most would rather not." "By studying living animals, it is possible to work out how mammals could have made this remarkable transition." "As it happens, the world's expert on swimming mammals is Dr Frank Fish." "He believes he's uncovered how an ancient landlubber could become an expert swimmer." "If we look at this dog paddling, you see all four of the limbs stroking the water in an alternate fashion." "What a dog paddle really represents is sort of a trot that the animal's doing while it's in the water." "It isn't a very efficient gait." "A mammal equally at home in water and on land is the otter." "Otters seem to represent what a missing link between whales and land mammals might look like, making them a fascinating animal to study, even if they don't always cooperate." "Dr Fish is trying to record their unique swimming action on a slow-motion camera." "Great." "In the lab, he has discovered a few simple changes in swimming style that enable a land mammal to swim more like a seal, less like a dog." "What we find is, instead of using all four legs, the otter is instead using just its hind legs." "Its front legs are tucked up underneath it." "The hind legs paddle simultaneously." "The otters are not just running in the water." "They use their back feet together to act as a paddle, allowing their spine to flex up and down, driving them forward." "It's a much more efficient stroke." "Otters represent a transitional stage, something intermediate between both land and water." "Because of that, they're really of interest." "They probably represent, at Ieast in a modern form, what the ancestors of animals like dolphins may have been like." "But otters are modern animals." "No one had ever found an otter-like ancestor to the whales, a missing link between land and sea." "Then, in 1992, at a remote dig site in Pakistan, palaeontologists discovered a remarkable set of bones." "They seemed to assemble a creature made up of an assortment of parts - one that could live on land AND in the water." "Its discovery was a triumph for scientists." "It was the elusive missing link." "It was called Ambulocetus, which appropriately means "walking whale"." "When I first saw an AmbuIocetus skeleton, the bones were robust." "They remind you of semi-aquatic animals such as otters." "AmbuIocetus probably moved somewhat like otters today." "It had expanded limbs, in terms of its hands and feet, which were probably webbed so it could develop thrust in a paddling manner." "It also had a robust taiI, and probably was starting, Iike otters, to use the tail motion to produce thrust." "Ambulocetus was totally new to science." "Dr Fish's work helped the Walking with Beasts team to make it move, both on land and in the water." "But Ambulocetus wasn't the end of the whale's tale." "After all, it was an animal still tied to land." "It didn't explain how whales became larger and truly aquatic." "This was the next stage in the story." "It's the last place on Earth you'd expect to find anything to do with water." "But here in the Sahara Desert there is evidence that underwater creatures once lived here." "It's a place that intrigues marine palaeontologist Dr Mark D'Uhen." "40 million years ago, this was a vast ocean that we called the Tethys Sea." "It extended from the North atlantic across the Mediterranean, covering North Africa and northern India." "The water would have covered even the highest peaks." "The layers that you see here were once the ocean bottom." "You can see evidence for that here." "Here's an oyster shell." "Here's a snail." "I even found a shark tooth." "These are things you don't expect to find in the desert." "Something else you don't expect to find are giant whales." "When skeletons like these were discovered in the 19th century, they were thought to be huge sea serpents." "They were named Basilosaurus, which means "king lizard"." "But Basilosaurus was no giant lizard." "It has a mouthful of unmistakably mammalian teeth." "This is the snout and this is the roof of the mouth." "These are the incisors." "These are the front teeth, here, here and here." "As you get further back, the teeth have two roots." "You see two here, two here and two here." "BasiIosaurus has very few teeth compared to modern toothed whales." "It has the number of teeth more like primitive mammals." "They use their front teeth to grab onto prey." "They use their back teeth to chew, unlike modern toothed whales, which swallow their food whole." "This area in Egypt was named Valley of the Whales because the desert floor is littered with the remains of Basilosaurus." "These creatures were giant predators, but they were't quite like modern whales yet." "Their bodies were snake-like and they still had primitive characteristics that linked them back to their ancestors on land." "These are the back legs of BasiIosaurus." "You can see the pelvis, the femur, the kneecap, the lower leg, the foot with toes on it." "These tiny hind legs weren't attached to the backbone." "Their size shows they couldn't support their body weight on land." "If they didn't use them for walking, then what?" "One idea is they were used as sexual cIaspers, that the male and female used them to hook up during mating and hold on while they mated." "At 1 8 metres long," "Basilosaurus was probably the largest animal on Earth at that time." "It was a challenge for the scientists and special effects artists to make it work properly." "The scale model had to be shrunk to fit and it still took four people to control it." "Sort of sinister, spooky." "(BLOWHOLE SQUIRTS)" "And working out how to get an extinct animal to swim was a combination of artistic skill and scientific advice." "So, would you Iike to see those..." "What are these?" "Back legs or...?" "Hind, back legs." "Back legs, right." "I'd Iike to see if the joints will do it." "Just trailing, pointing absolutely straight back." " Like an otter's feet, for example." " Yeah, sure thing." "Now at last the story can be told of how hoofed carnivores evolved webbed feet and started to swim." "Eventually, their backbones loosened, their legs got smaller and their tails turned into flukes." "The mystery of how a group of mammals conquered water was complete." "Whales represented the mammals' first attempt to get truly enormous." "But land mammals were not far behind and they got their chance once the climate turned against the rainforests." "Life on Earth came under the influence of one continent" " Antarctica." "Over millions of years, other continents moved away, leaving it isolated over the South Pole." "Gradually the continent became colder and colder until a permanent icecap formed." "This triggered a change in the world's climate." "It meant a drop in global rainfall." "Rainforests shrank, making way for new habitats." "There were all sorts of changes going on." "climates worldwide were getting cooler." "There was the beginnings of the retreat of the forests as those climates changed, and animals were creeping out on to the plain." "All this change played into the hands of the land mammals." "Birds lost their place at the top of the food chain and mammals seized the opportunity to move into the open." "So that gave a big advantage to large size." "If you're out of the forest, out of protection, if you're big, you can escape predation." "You can run faster from predators." "The changing climate created a new breed of giants." "The age of the mammals had truly arrived, and it was ugly." "This is Entelodont, not the thing you'd want to meet, even in a nightmare... unless you happened to be a palaeontologist like Dr Scott Foss." "I've thought what it'd be like to meet an EnteIodont." "I always imagined these as creatures that would have an attitude." "They'd walk in and say, "I'm here!"" "No one would argue with such a mouthful of weapons." "The mouth of the EnteIodont is pretty incredible, and we know from these huge muscles here that would pull on the jaw that these animals had a strong, powerful bite." "They could grab onto things and twist and rip it away." "I'd say the words would be pulverised, mashing... crushing, grinding, grabbing things, twisting and pulling them." "They were scavengers, generalists." "They could do anything they wanted." "But even the biggest, nastiest creatures have their enemies." "Looking at EnteIodont skulls, we find bite marks, sometimes in the side of the face." "We find it right up here in the forehead." "We even find bite marks in the roof of the mouth." "If you can imagine that, bite marks into these creatures." "What creature could get its jaws round an EnteIodont?" "Another EnteIodont." "We know that because their teeth could have made those bite marks." "also, there's not a single other animal at the time that could have made such bite marks." "It was EnteIodonts doing this to each other." "The big question is why?" "Today animals will do battle with other animals of their species, mostly for mate competition or territory competition." "It's probably a form of competition - a very painful form of competition." "Entelodonts were the ultimate all-purpose animals, built like tanks and able to eat anything - a typical mammalian success story." "It's hard to say why we don't have EnteIodonts today, why they didn't make it." "If we were to release them in North America, they might do very well." "They would eat anything." "I imagine they would especially like potato chips and hot dogs and things like that." "They'd probably do very well until they got into a populated area and that would be the end." "I don't think there would be room for people and an EnteIodont in suburbia." "(ALARM BLARES)" "The Entelodonts were a new breed of large mammal." "But it wasn't long before they were upstaged by the largest land mammals ever to live." "On Roy Chapman-Andrews' expedition in Mongolia, the dig diary records the discovery of a single bone," ""Big as a man's body"." "Some of those bones found their way to the Natural History Museum in London." "Bones over a metre long should be easy to find, but there are a lot of bones in the museum for Professor Mikael Fortelius to search through." "This is the bone of a very large animal." "If I found this, I would probably think that it was an elephant." "It's very, very large." "In some ways, it's like a giraffe and, in some ways, Iike a rhinoceros." "But it isn't like anything alive today and it's much much bigger than anything that lives today." "It took scientists a while to work out what sort of creature it was." "The only thing that was clear was that it was big." "This thing here is the neck vertebra of a medium-sized rhinoceros from the Ice Age." "It's a Iarge bone, but it's nothing compared to this, which is huge." "They had found an ancient type of rhino called an lndricothere." "When we think of large land animals, we always think of dinosaurs." "Dinosaurs WERE the largest animals we know about, but some land mammals also got large, such as this Indricothere." "It stands seven to eight metres tall." "It's about as long and would have weighed perhaps up to 15 tons." "And, as you can see, I don't even reach up to the top of its legs." "The lndricotheres were rhinos trying to be giraffes." "Long necks could reach the treetops, but they were massive and heavy like a rhino." "They were an extraordinary feat of engineering." "But these monsters were gentle giants, browsing only on tender young leaves." "In the case of the lndricotheres, that was a lot of leaves." "Why be big?" "It means you have nothing to hunt you, no predator big enough to eat you." "But, being big, you can be vulnerable, because population sizes are quite small and it doesn't take much to make a Iarge animal extinct." "The days of the lndricotheres were numbered as the Earth changed." "Antarctica's increasing isolation brought a shiver to the climate." "As ice spread at the South Pole, it shifted the weather patterns, bringing new seasonal extremes of drought and deluge." "Out of the turmoil, an astonishing new plant evolved, one that we couldn't imagine life without." "It was grass." "people think grass was always here, it's so common." "You'II see pictures of dinosaurs walking on grass." "That's not possible." "The first grasses appeared about 30 or 40 million years ago, and they took over." "climates became drier and inland areas became great savannahs." "As the savannahs grew, the grasslands expanded." "The woodlands, the early home of the mammal, disappeared." "mammals had to adapt." "They came out from under the trees, became bigger, longer legs, hooves, they ran faster and their teeth adapted." "Many of the animals that browsed on leaves went into decline." "In their place came a new breed of mammals, the grazers." "But grass is surprisingly difficult to survive on." "Luckily, mammals had the answer." "They developed a battery of teeth, complex stomachs and long legs to follow the grass wherever it sprouted." "But where there was meat on the hoof, predators quickly followed." "The competition for survival brought with it some of the most deadly animals on Earth." "If we look at the evolution of cats and of other predators, we can see that they've got faster, they've got bigger and better at what they do." "equally, the prey species have got faster, bigger and better at escaping." "There's what you may call an evolutionary arms race between them." "Prey want to get away, predators to catch them." "And so, over time, there has been a tendency to do the best they can, to reach the optimum solution." "The cat family are the ultimate predators." "No other mammal is such a finely-tuned assassin." "What makes a cat such an efficient killing mechanism?" "These tiger cubs are four months old and already they've got all the attributes that they'II need, just in a smaller form." "They've got large feet, very large paws," "long claws - very sharp." "They've got teeth that are able to slice off meat, able to bite into prey, to kill it." "They have whiskers to sense exactly where the item is, so it can bite precisely." "They're strong, weII-muscIed and fast-moving." "altogether, this makes an animal that is superbly equipped for what it needs to do." "A full-grown Siberian tiger can weigh as much as 300kg and is the largest cat today." "But compared to some of its ancestors, it would look like a pussycat." "There was a creature that died out a few thousand years ago, with the most lethal weapons of any carnivore." "It was called Smilodon, the fabled sabre toothed cat, with its 20cm-long teeth." "The sabres were Smilodon's most dramatic feature, but the whole package made it such a lethal killing machine." "(SNARLING)" "If you look at the skeleton as a whole, it was a very, very strongIy-buiIt cat." "The forequarters, front legs, shoulders and neck are extremely heavily built." "Like many cats living today, it was fast over a short distance, probably an ambush predator, able to sprint out from cover, using its speed to close the distance very quickly, then its strength to seize the prey and pull it down." "As usual, it's the teeth that tell you how Smilodon went about its business." "If you look at the skull of a SmiIodon, your eye is immediately drawn to these sabre teeth." "But it's got teeth at the back equipped for slicing meat." "It's got teeth at the front that are equipped for pulling meat off, getting it into the mouth." "It has large upper canine teeth that are equipped for slicing into the prey once it's held immobiIised." "Everything about it shouts "predator" at us." "This is not an animal that can eat grass or vegetation." "It's a predator." "It's a killer." "The giant sabres were there for one gruesome purpose.:" "to be driven into the neck of the prey and, in one bite, to rip its throat out." "Although the mammals seemed to be on top of the world, conquering every habitat, the Earth was about to create the biggest challenge yet - life in the freezer." "Both the Earth's poles began to freeze over 2.5 million years ago." "The Ice Age had begun." "Ice sheets grew beyond the Arctic Circle, over much of the northern hemisphere, transforming all plant and animal life." "At the height of the ice Age, there were icebergs off the coast of Ireland, permafrost beneath London, and glaciers reached as far south as New York." "For most animals, it became an inhospitable place." "But some mammals took the cold in their stride." "Europe, North America and Siberia became filled with some of the most spectacular animals ever seen." "Don't drop it on the ground yet." "Exotic giants from the tropics evolved to suit the conditions further north." "elephants originally evolved as tropical animals, but mammoths developed a very specialised adaptation to extremely cold climates." "They had thick, woolly fur." "They had small ears, so they didn't lose heat." "They had a thick layer of subcutaneous fat, short back legs so they, again, did not lose heat." "The long tusks were used to clear away snow because they fed on grasses and other small plants." "One of their most specialised adaptations was the tip of their trunk... which had two large fingers that let them feed on the very small plants that were their main subsistence items." "All these magnificent creatures were around until so recently that instead ofjust bones, the remains of their skin and hair are preserved in the ice." "These finds provide unique information on what these extinct animals looked like." "Sometimes it has even been possible to recreate specific events in their lives." "Whole carcasses were found in the prime of life, having been trapped in frozen ponds." "In some cases, the flesh from their bodies could still be eaten." "(TRUMPETING)" "The Ice Age was a harsh environment, but mammals were tough enough to meet this challenge." "Their trademark fur and assortment of teeth kept them warm and well fed." "But having survived and thrived for so long, something mysterious was about to happen." "Giant mammals of the Ice Age, such as the mammoth, the woolly rhinoceros, MegaIoceros, the giant Irish elk, were all very successful animals that survived in a harsh climate." "Yet they disappeared relatively abruptly." "Why was that?" "Around 30,000 years ago, most of the giant mammals across the world started to become extinct." "By 10,000 years ago, as the ice Age came to an end, almost all had died out." "The mammals had flourished despite every change on the Earth." "They'd even survived an ice age." "So why did the large ones suddenly vanish?" "There is one group of mammals we haven't talked about - primates." "From the beginning, they kept pace as the Earth changed." "Then, only a few thousand years ago, one species became fantastically successful." "Could humans have had a hand in this catastrophe?" "Find out if we wiped out the ice Age giants in the next programme " "The Beasts Within." "And cut!" "Thanks, everyone." "That's a wrap."