{891}{992}Somewhere on the edge|of a Jurassic forest,
{995}{1078}a mother dinosaur|is laying her eggs.
{1110}{1122}(Deep grunting)
{1122}{1196}(Deep grunting)
{1282}{1349}She is a 25-tonne Diplodocus.
{1462}{1510}Each football-sized object
{1510}{1596}is carefully placed|in a deep trench.
{1870}{1884}Tenderly, she buries her clutch
{1884}{1930}Tenderly, she buries her clutch
{1932}{1990}and then abandons them.
{1992}{2117}0ut on the fern plains, the rest|of her gigantic herd grazes.
{2119}{2232}She is one of a family|of dinosaurs called the sauropods
{2234}{2335}that dominate this period|in Earth's history.
{2335}{2390}They are the largest animals
{2392}{2469}that will ever walk the planet.
{3454}{3512}This is the Jurassic period,
{3514}{3562}and the giant continent of Pangaea
{3562}{3637}that stretched from pole to pole|is now breaking up.
{3697}{3802}It is much wetter|than the earlier Triassic period
{3805}{3869}and where there were once deserts,
{3872}{3963}there are now vast forests|of conifer trees.
{5563}{5682}It is 70 million years since|dinosaurs first appeared on Earth
{5685}{5747}and in this greener world,
{5750}{5862}they have evolved into a myriad|of different forms.
{6158}{6230}Three months ago,|a mother Diplodocus laid 100 eggs
{6232}{6292}in this clearing in the forest.
{6295}{6352}Now they are hatching,
{6355}{6482}but there are signs they have been|discovered by an egg thief.
{6511}{6623}The culprit is an 0rnitholestes|- a two-metre long carnivore,
{6626}{6734}closely related to dinosaurs|that will evolve into birds.
{6736}{6841}Normally, he hunts small lizards|and mammals in the forest.
{6845}{6898}This is an extra treat.
{6957}{6997}(Squawks )
{7145}{7221}0nly 10 metres|away from the carnivore,
{7224}{7276}the forest floor moves.
{7449}{7497}(Squeaks )
{7591}{7638}(Squawks )
{7638}{7715}Right under the predator's gaze,
{7715}{7811}a baby Diplodocus, or sauropodlet,|has hatched.
{7813}{7902}Her brothers and sisters|are also struggling free
{7903}{7980}from their buried eggs|beneath the surface.
{7982}{8049}And there is safety in numbers.
{8126}{8253}The 0rnitholestes is too busy|eating to chase more sauropodlets.
{8256}{8318}He has had his fill.
{8384}{8492}A little female rests|for an instant...
{8524}{8620}and then,|along with the other survivors,
{8622}{8733}heads for the deep forest|as fast as she can.
{8733}{8790}(Cheeping and squawking)
{9141}{9156}Their mother laid them|at the edge of the forest
{9155}{9193}Their mother laid them|at the edge of the forest
{9197}{9266}because she was too big|to go deeper.
{9268}{9376}But the sauropodlets|need the cover of the deep forest.
{9379}{9491}For the next few months,|their only chance for survival
{9494}{9604}is to remain hidden from predators|amongst the vegetation.
{9700}{9714}Between the trunks|of huge redwood trees,
{9714}{9784}Between the trunks|of huge redwood trees,
{9786}{9901}the forest floor is covered|in a dense layer of ferns.
{10044}{10092}Beneath these,
{10093}{10208}the sauropodlets start their|lifelong obsession with eating.
{10212}{10312}Newly hatched,|they only weigh a few kilograms,
{10315}{10435}but they must grow|by one tonne a year until adults -
{10437}{10497}an astonishing 2-3kg a day.
{10499}{10562}(Distant roaring)
{10564}{10662}However, the forest|is not a perfect sanctuary.
{10810}{10925}When faced with danger,|the sauropodlets lie very still
{10926}{11037}and depend on their camouflage|for protection.
{11090}{11153}It may have worked this time,
{11154}{11267}but very often, the sharp-eyed|predator gets his meal.
{11374}{11480}Not all of the landscape|is covered in forest.
{11481}{11555}There are vast open fern prairies,
{11555}{11666}and this is where|the titans of the Jurassic roam.
{11669}{11722}Dinsoaurs like Stegosaurus,
{11723}{11819}with its distinctive row|of spinal plates.
{11820}{11902}(Rumbling growl)
{11902}{12002}These prairies|are kept clear of trees
{12004}{12109}by the constant grazing|of such giant herbivores,
{12113}{12216}and none have a larger impact|on this environment
{12218}{12324}than the biggest dinosaurs of all -|the sauropods.
{12516}{12581}There are many different types
{12584}{12660}of these gigantic,|long-necked creatures.
{12663}{12761}These are Diplodocus -|the longest of them all.
{12762}{12880}For protection,|they move in herds of 30 or more.
{12881}{12977}Some older ones|are over 40 metres long.
{12979}{13077}They use their very strong|but stiff necks
{13077}{13173}to graze over large areas|with little effort.
{13176}{13224}To balance their necks,
{13226}{13312}they have long tails|with whip-like ends,
{13315}{13432}that are used for communication|between members of the herd.
{13483}{13581}Such a huge herd moving attracts|an array of smaller animals.
{13696}{13828}As they eat the vegetation,|insects swarm around them,
{13831}{13925}and insect hunters,|like these damselflies,
{13927}{14030}use the dinosaurs|as gigantic feeding platforms.
{14137}{14151}There is even a tiny flying reptile,|or pterosaur,
{14150}{14210}There is even a tiny flying reptile,|or pterosaur,
{14214}{14259}called Anurognathus
{14261}{14352}that specialises|in life amongst these giants.
{14439}{14499}These pterosaurs feed on insects,
{14501}{14619}and spend their entire lives|hanging onto the Diplodocus.
{14655}{14734}They fight, feed and breed
{14736}{14875}on creatures that are 150,000 times|heavier than they are.
{15146}{15259}Each Diplodocus drops over a tonne|of dung every day.
{15333}{15398}This attracts yet more insects...
{15400}{15477}especially the dung beetles.
{15480}{15580}Millions of years from now,|descendants of these beetles
{15584}{15699}will clear elephant dung|off the African grasslands,
{15701}{15780}but their peculiar lifestyle|started here
{15783}{15864}in the Jurassic with the dinosaurs.
{15890}{15953}The herd of giants moves on,
{15955}{16032}carrying its own unique habitat|with it.
{16347}{16460}After the rain, the redwoods steam|in tropical temperatures
{16461}{16550}and a dinosaur's dawn chorus|fills the air.
{16553}{16599}(Bellows and screeches )
{16600}{16710}A year has passed since the|sauropodlets fled into the forest,
{16714}{16824}and deep in a canyon,|the little female grazes.
{16826}{16905}She is already over 3m long.
{16908}{16968}She feeds with other yearlings,
{16971}{17051}sticking together|in a creche for safety.
{17053}{17163}They are here because|the canyon walls drip with moisture,
{17162}{17263}creating a thick layer|of moss and fern.
{17264}{17367}But the canyon runs down|to the prairie
{17368}{17472}and all this greenery|attracts larger dinosaurs.
{17556}{17619}A seven-tonne male Stegosaurus.
{17621}{17712}He too is a herbivore,|but very dangerous.
{17715}{17813}The large plates|are primarily there for display.
{17815}{17938}It's the metre-long spikes|on his tail that are lethal.
{17940}{18053}These he can wield|with devastating effect,
{18055}{18146}despite having a very small brain|for his size.
{18149}{18221}The creche moves down the canyon,
{18223}{18281}away from the Stegosaurus.
{18381}{18463}But two Allosaurus|have been drawn here -
{18464}{18524}by the smell of prey.
{19333}{19381}(Low growling)
{19419}{19467}(Squeaks )
{19739}{19789}(Roaring)
{19791}{19848}(Snarling)
{19851}{19937}The Stegosaurus|flushes blood into his plates,
{19939}{20011}creating a frightening|display of colour.
{20141}{20193}(Roars )
{20254}{20372}Confused and intimidated|by the herbivore's display,
{20372}{20437}the Allosaurus backs down.
{20735}{20840}Sauropodlets are small prey|for the Allosaurus.
{20909}{21007}These are the lions|of the Jurassic -
{21011}{21087}the top predators of their age.
{21290}{21412}The creche once again seek|the sanctuary of the ferns,
{21416}{21512}even though,|weighing half a tonne now,
{21512}{21598}they are not as well hidden|as they used to be.
{21763}{21895}As they grow, their teeth|become more like the adults'.
{21895}{21996}These are perfect for stripping|ferns of their leaves.
{22249}{22376}Nearby, the vast skeleton|of a Diplodocus lies where it fell.
{22378}{22453}Such huge, weight-bearing bones
{22455}{22558}are too large|for any forest creature to remove.
{22560}{22654}The female sauropodlet|can have little idea
{22657}{22768}that in ten years,|she will be almost as large.
{22769}{22855}But the creche realise they are|too near the edge of the forest,
{22859}{22897}and retreat into its green depths.
{23264}{23374}Elsewhere, an adult Diplodocus herd|is clearing forest.
{23410}{23528}This is how they have shaped|the landscape around them.
{23641}{23771}Vast areas of prairies|and open forests are kept that way
{23773}{23867}because sauropods flatten trees|in search of food.
{23869}{23989}The Diplodocus are after the ferns|that grow between the trees.
{23989}{24087}Their teeth are more suited|to soft green leaves
{24090}{24138}than woody branches.
{24489}{24594}0ne of the reasons|these creatures are so massive
{24596}{24699}is because it allows them|to have a hugely long gut
{24702}{24808}that can digest|the toughest Jurassic vegetation.
{24987}{25050}Whole leaves pass into their guts
{25052}{25115}where stones|the dinosaurs have swallowed
{25117}{25151}help grind their food down,
{25184}{25196}so that bacteria ferment it|and release nutrients.
{25196}{25278}so that bacteria ferment it|and release nutrients.
{25280}{25388}It is a process|that produces a lot of excess gas.
{25390}{25438}(Phwrrrrrt!)
{25469}{25484}While the gut digests,
{25485}{25533}While the gut digests,
{25534}{25649}the body is free to continue|its remorseless search for food.
{25948}{26005}(Squawking)
{26007}{26103}In the forest,|an Anurognathus is hunting...
{26106}{26163}but not for insects.
{26163}{26228}He is looking for a host.
{26346}{26451}He finds it|in an immature Diplodocus.
{26451}{26588}This is the female sauropodlet|that hatched five years ago.
{26590}{26693}She is now 12 metres long|and weighs over 5 tonnes.
{26783}{26843}She has started to develop
{26845}{26936}the spines and long whip tail|of adulthood.
{27003}{27116}0ld predators in the forest|are no longer a threat.
{27119}{27190}0rnithalestes displays|his long quills
{27193}{27265}in a futile gesture of aggression.
{27339}{27387}(Grating squawks )
{27479}{27575}The Diplodocus have remained|in a creche,
{27574}{27668}but they're getting too large|for the forest.
{27671}{27762}Food is short|and the trees restrict them.
{27765}{27860}Soon they must join|the adults on the plains.
{27901}{28002}There is more room|by the banks of a river
{28004}{28059}that runs through the forest,
{28062}{28177}but nature is about to take charge|of these dinosaurs' future.
{28501}{28515}Drifting through the trees|comes the scent of woodsmoke.
{28515}{28628}Drifting through the trees|comes the scent of woodsmoke.
{28631}{28744}It is a smell that terrifies|every forest dinosaur.
{28852}{28945}There is a huge forest fire|to the south.
{28949}{28999}The Diplodocus flee,
{29000}{29053}but to support their weight,
{29055}{29144}they always need three legs|on the ground.
{29147}{29257}So, despite the danger,|they can only manage to amble.
{29283}{29331}(Low howling)
{29397}{29466}The blaze, however, moves faster
{29469}{29589}and that night,|a huge firestorm hits the area.
{29677}{29759}(Distant howling)
{29759}{29824}Above the sound of the blaze
{29826}{29912}come the panicked cries|of trapped dinosaurs.
{29958}{30049}These Jurassic fires are rare,|but can be devastating.
{30388}{30503}Morning light reveals the bodies|of forest-dwelling dinosaurs
{30506}{30568}that have perished in the flames.
{30736}{30750}Three members of the creche|have survived.
{30750}{30813}Three members of the creche|have survived.
{30815}{30901}They have been driven out|onto the prairies.
{30904}{30961}This is exposed territory for them.
{30964}{31069}They are not large enough to repel|an attack from an adult Allosaurus.
{31216}{31336}To the young Diplodocus, the other|dinosaurs here are unfamiliar...
{31338}{31405}and huge.
{31713}{31828}This is Brachiosaurus -|a 13-metre high sauropod
{31830}{31936}that specialises in grazing|on the tree tops.
{31974}{32070}His kind can effortlessly harvest|cones and fresh leaves
{32073}{32198}no other dinosaur can reach,|and they have grown enormous.
{32199}{32276}These adults weigh over 70 tonnes,
{32279}{32390}making them the largest|land animals that have ever existed.
{32392}{32510}The juvenile Diplodocus do not have|the same size advantages
{32512}{32630}and urgently need the protection|of an adult herd.
{32670}{32742}(Wailing)
{32795}{32845}Across a conifer heathland
{32849}{32928}come the plaintive calls|of the young sauropods.
{32930}{33031}It is a cry adult animals|are programmed to react to.
{33095}{33162}There are only two youngsters now...
{33163}{33213}and they need help.
{33316}{33371}(Growling)
{33484}{33599}A herd of gigantic adults|responds to their calls.
{33676}{33786}0ne elderly female sizes up|the two newcomers.
{33845}{33902}She accepts them.
{33931}{34049}They fall into line behind an adult,|safe at last.
{34610}{34672}The herd is at full strength.
{34674}{34789}It contains a range of members -|from 12-metre long adolescents
{34789}{34861}to adults three times their size.
{34861}{34957}It is the mating season,|and for the first time,
{34960}{35046}the female that hatched|ten years ago
{35049}{35157}is old enough and large enough|to reproduce.
{35160}{35236}The males have started to display.
{35239}{35361}They rock back on their tails|to impress potential mates.
{35421}{35481}0ccasionally, fights break out.
{35483}{35534}With creatures this size,
{35535}{35643}the forces at work during|these confrontations are colossal -
{35644}{35747}enough to shatter ribs|and shake the ground.
{35797}{35853}(Growling and bellowing)
{36086}{36156}The victor wins the right to mate.
{36400}{36498}0ur female is approached|by a young male.
{36501}{36602}She responds to his calls|first by stamping
{36605}{36715}and then generating|very low frequency mating calls.
{36717}{36832}This infrasound is too low|for most animals to hear.
{36835}{36912}He picks these signals up|through the ground,
{36914}{37003}and responds by walking close to|her, rubbing his body down hers.
{37180}{37231}She shows she is receptive.
{37281}{37401}Mating is a dangerous activity|for the female.
{37403}{37482}She'll carry at least|an extra 10 tonnes on her back.
{37522}{37527}As she has grown older,
{37527}{37599}As she has grown older,
{37601}{37716}the vertebrae over her hips|have become fused and reinforced
{37715}{37787}to help her cope with this ordeal.
{38150}{38251}After a few days,|the Diplodocus have calmed.
{38289}{38387}The female feeds|on the edge of the herd,
{38390}{38502}but is not large enough|to be immune from attack,
{38505}{38613}and she is unaware|she is being watched.
{38650}{38758}An Allosaurus knows|she is vulnerable.
{38904}{39019}The predators wait for her|to become distanced from the herd.
{39984}{40029}(Roars )
{40195}{40293}Saved by the huge tail|of a larger Diplodocus.
{40436}{40527}She rejoins the herd|with deep wounds on her side,
{40529}{40589}but she will recover.
{40617}{40691}Diplodocus can live for 100 years,
{40692}{40757}and above a certain size,
{40759}{40822}they have no natural predators.
{40903}{40985}Sauropods dominate|the late Jurassic.
{40988}{41091}It'll be millions of years|before new dinosaur herbivores
{41093}{41138}evolve to replace them.
{41141}{41261}With their passing,|life will never again be this large.
{42377}{42454}Eventually, the mighty sauropods|went into decline.
{42456}{42514}Their lowland prairies|became flooded
{42516}{42583}because the sea levels|began to rise.
{42586}{42643}This created vast inland seas.
{42646}{42684}In the next programme,
{42688}{42774}we will meet the giant carnivores|that patrolled them.