{843}{906}This little mammal is a scavenger.
{908}{995}Called Didelphodon,|she is a marsupial
{997}{1095}and specialises in raiding|abandoned dinosaur nests.
{1122}{1201}This evening, she could be in luck.
{1329}{1451}Unfortunately, the smell of the nest|blinds her senses to danger.
{1628}{1676}(Squeaking)
{1790}{1836}(Huge roar)
{2042}{2090}(Bellows )
{2470}{2522}The end of the Cretaceous.
{2525}{2599}The continents|are taking their modern forms.
{2602}{2683}But this movement|of the Earth's crust
{2686}{2758}has produced a surge|in volcanic activity.
{2888}{2984}Massive eruptions|that have lasted for centuries
{2986}{3041}have laid waste to landscapes,
{3044}{3120}filling the atmosphere|with gases and debris.
{3124}{3217}This desolate world|is still ruled by dinosaurs,
{3220}{3304}as it has been|for 160 million years,
{3306}{3383}but they are nearing the end|of their reign.
{3385}{3455}Life on earth is choking to death.
{3671}{3679}Yet in the last two million years,
{3679}{3743}Yet in the last two million years,
{3746}{3827}the dinosaurs'|most infamous predator has appeared.
{3830}{3918}Tyrannosaurus, a five-tonne,|13-metre long carnivore,
{3921}{4029}specifically evolved|to kill other giant dinosaurs.
{4073}{4123}This is a male.
{4126}{4255}He's been drawn to this volcano|by the smell of food.
{4281}{4370}The area is full|of geothermal springs
{4373}{4442}and the air thick|with sulphurous fumes.
{4443}{4510}But there is another smell here.
{4510}{4621}In one small valley,|there is the stench of death.
{4798}{4908}Unwittingly, the Tyrannosaurus|has been drawn into a natural trap.
{4912}{4996}Volcanic vents are producing|poisonous carbon monoxide,
{4996}{5058}and because it is heavier than air,
{5060}{5135}it has formed a suffocating layer|close to the ground.
{5245}{5326}The giant predator|stands above the layer,
{5329}{5425}but as he puts|his head down to feed
{5428}{5490}he begins to feel the effects.
{5709}{5826}If he topples over now,|he will never get up.
{6038}{6122}Eventually,|his sheer size is his salvation.
{6124}{6242}As he stands up with his prize,|his head just clears the gas layer.
{6523}{6629}There are still islands of greenery|between the lava flows.
{6631}{6730}In the warm, moist climate|of the late Cretaceous,
{6733}{6783}the vegetation has transformed.
{6803}{6851}Instead of conifers,
{6853}{6951}broad-leaved trees|fill the forest canopy.
{6994}{7105}Driving this quiet revolution|among the plants
{7107}{7174}is the remarkable|evolution of flowers.
{7178}{7271}Their secret lies in their|intimate relationship with insects,
{7273}{7381}so close that some flowers|can only be pollinated by insects
{7384}{7489}and some insects, like butterflies,|can only feed on flowers.
{7622}{7706}Among these new plants,|the birds are flourishing,
{7708}{7759}and their calls form|an ever-present chorus.
{7943}{8001}Millions of years of evolution
{8003}{8097}have also created|intimate relationships
{8100}{8170}among different types of dinosaurs.
{8172}{8282}Especially the delicate balance|between predator and prey.
{8837}{8883}(Terrifying squawk)
{9016}{9064}(Hissing roar)
{9155}{9229}0ne dinosaur|that specialises in defence
{9232}{9301}is the extraordinary Ankylosaurus.
{9303}{9416}They are evolved to withstand attack|even from giant predators
{9420}{9482}like Tyrannosaurus.
{9482}{9578}At seven tonnes, Ankylosaurus|are so heavily armoured
{9580}{9652}that even their eyelids|are hardened.
{9705}{9818}And if that wasn't enough,|they have a formidable club
{9821}{9893}on the end of their tails.
{9958}{10068}Sadly, not even these magnificent|creatures have any defence
{10070}{10178}against the natural forces|that are suffocating their world.
{10407}{10465}Nearby lies the Tyrannosaurus nest.
{10467}{10558}These are usually|closely guarded by the mother,
{10560}{10618}but this nest has been abandoned,
{10620}{10692}and a Didelphodon|has burrowed into the side.
{10796}{10914}Dinosaurs are vulnerable because|they lay their eggs on the ground.
{10957}{10971}But size helps,
{10971}{11003}But size helps,
{11005}{11077}and the egg is a challenge|for this marsupial.
{11077}{11154}Soon the age of the mammals|will dawn,
{11154}{11211}and they will grow massive,
{11215}{11282}but this is as big|as Cretaceous mammals get.
{11375}{11507}The Tyrannosaurus embryo inside|the abandoned egg is already dead.
{11569}{11656}The scent is a lure|to another Didelphodon.
{11733}{11801}(Snarls and growls)
{11827}{11877}(Growling)
{12075}{12137}(Loud shrieks )
{12262}{12276}Many dinosaur embryos cannot|survive in this volcanic environment
{12276}{12348}Many dinosaur embryos cannot|survive in this volcanic environment
{12351}{12399}because acidic pollution
{12399}{12492}prevents their eggshells|from forming properly.
{12548}{12606}(Bellowing)
{12721}{12822}The mother is calling|for a new mate.
{12824}{12932}Tyrannosaurus have huge territories|of hundreds of square kilometres.
{12932}{13016}Her challenge is to attract|a wandering male.
{13019}{13113}She may have to call|like this for weeks.
{13481}{13584}0ne of the Tyrannosaurus's|principal sources of prey
{13586}{13651}are these bulky Torosaurus.
{13653}{13766}In the late Cretaceous, herds of|horned herbivores are very common
{13768}{13828}and attract many predators.
{13916}{14028}It is rutting season. To display,|males flush blood into their crests,
{14031}{14091}creating vivid patterns.
{14198}{14285}These displays help|to avoid physical contact.
{14287}{14340}With one-metre-long horns,
{14343}{14427}fighting can easily result|in bad injuries.
{14427}{14485}The best and the brightest crest
{14487}{14571}is all that is needed|to settle arguments.
{14783}{14862}0ccasionally,|showing off is not enough
{14865}{14910}and males resort to brute force.
{15566}{15674}For this old Torosaurus,|this was one fight too many.
{15711}{15787}He will never again|challenge for the right to mate.
{15790}{15838}(Gruff mooing)
{16008}{16085}The mating call|of the Tyrannosaurus
{16087}{16171}continues to echo|across the volcanic slopes.
{16172}{16217}And it has been heard.
{16220}{16251}A male has killed|a young Triceratops.
{16253}{16277}It's not just to satisfy his hunger.|It is a gift.
{16402}{16488}Female Tyrannosaurus|are larger and more aggressive,
{16491}{16546}and he courts her with food
{16548}{16632}to stop her attacking him on sight.
{16636}{16715}(Hisses )
{16928}{16983}(Growls)
{17011}{17063}(Growls)
{17066}{17135}The female arrives.
{17212}{17289}(Short roars )
{17291}{17351}She is wary.
{17445}{17457}The primary weapon|of a Tyrannosaurus is its mouth.
{17458}{17561}The primary weapon|of a Tyrannosaurus is its mouth.
{17563}{17649}Its arms are tiny|so it can carry a massive jaw
{17652}{17707}and remain balanced.
{17777}{17896}This jaw can crush bone|and tear off up to 70 kg of meat
{17900}{17945}with one bite.
{17948}{18010}The male keeps his distance.
{18364}{18428}Later that evening, they mate.
{18431}{18495}This is the first of many couplings
{18495}{18610}as the male stays by the female|while she is receptive -
{18613}{18682}ready to see off any other males.
{19055}{19151}0n the lava flows,|a group of Anatotitan
{19153}{19228}wanders between islands of greenery.
{19327}{19437}These animals are members|of the hadrosaur family,
{19440}{19543}the most common group of dinosaurs|in the Late Cretaceous.
{19545}{19605}But their kind has evolved
{19607}{19720}to thrive in lush lowland swamps,|not in an ash wilderness.
{19995}{20050}Three days have passed.
{20052}{20150}The Triceratops carcass|has been stripped
{20154}{20262}and the female Tyrannosaurus|is beginning to tire of her mate.
{20288}{20336}(Roars )
{20451}{20497}(Hisses )
{20821}{20903}The male knows better than to stay.
{21263}{21323}Gliding in from the coast,
{21326}{21446}a magnificent pterosaur,|Quetzalcoatlus, is hunting for food.
{21448}{21508}This is now a rare sight.
{21802}{21917}For 20 million years, these flying|reptiles have been in decline.
{21919}{22015}These 13-metre giants|are the only ones left.
{22018}{22069}And this is a dangerous place to be.
{22133}{22222}0ne-tonne crocodiles|live in the lake,
{22224}{22296}and could easily drag|the delicate glider to his death.
{22724}{22784}Driven on to extinction.
{22787}{22882}The skies of the future|belong to the birds
{22886}{22946}that already flourish around him.
{23032}{23126}Months have passed,|and the female Tyrannosaurus
{23126}{23183}has built a new nest,|camouflaged in the forest.
{23267}{23313}Mother keeps watch.
{23316}{23410}For the full two months|of the eggs' incubation,
{23412}{23469}she will not leave or even eat.
{23472}{23561}She knows her nest|is a magnet to scavengers.
{23592}{23652}Like this Dromaeosaur.
{23837}{23943}His cautious approach|is watched by the Tyrannosaurus.
{23979}{24087}She judges exactly|when he has got too close.
{24115}{24163}(Roars )
{24166}{24216}(Squeals)
{24359}{24476}As the sun sets, another threat|comes out to haunt the mother.
{24478}{24526}(Chirps and yowls)
{24574}{24620}(Growls)
{24844}{24918}(Bellowing roar)
{24921}{25029}With food becoming scarce,|the mammals are getting bolder.
{25072}{25177}She checks to make sure|more have not burrowed in,
{25181}{25238}then returns to her vigil.
{25389}{25497}The weeks pass, and above|the brilliant volcanic sunsets,
{25499}{25610}there are signs of an even more|destructive natural disaster.
{25690}{25800}Showers of shooting stars|herald the approach of a giant comet
{25803}{25872}on a collision course|with the Earth.
{25988}{26039}Far below,|the dinosaurs are oblivious.
{26072}{26082}The Torosaurus herd|continues to feed.
{26082}{26158}The Torosaurus herd|continues to feed.
{26161}{26206}Nervous of moonlight predators,
{26209}{26307}younger animals seek protection|among the larger adults.
{26309}{26360}(Restless mooing)
{26362}{26475}Using the darkness, a pair|of Dromaeosaurs unsettle the herd
{26478}{26548}and isolate one of the youngsters.
{26550}{26620}(Hoarse shrieks )
{26622}{26682}(Lowing noises )
{26935}{26983}(Shrieking)
{27418}{27538}Safe. But the predators have tasted|blood and will not give up easily.
{27953}{28054}Morning reveals|the results of last night's tussle.
{28057}{28157}The little Torosaurus lost his fight|with the predators.
{28160}{28277}For the herd, it is a blow.|Too few young are being born
{28281}{28338}in this polluted environment.
{28472}{28573}A Didelphodon|is already at the carcass.
{28575}{28693}These little opportunists are about|the only animals that are thriving.
{28785}{28888}During their reign, dinosaurs|have adapted to huge changes
{28891}{28984}but now they face|a combination of events
{28984}{29046}that will spell their doom.
{29117}{29179}After trekking|across the ash fields,
{29182}{29282}Anatotitans gather round|a stagnant pool to drink and feed.
{29309}{29366}Huge batteries of chewing teeth
{29369}{29460}make short work of the vegetation.
{29605}{29720}0nce again, the predators make|the water's edge a dangerous place.
{29830}{29911}The group senses danger|and starts to break up.
{30578}{30659}The mother Tyrannosaurus|has broken her fast
{30662}{30710}and is back with a vengeance.
{30849}{30959}Nearby is the reason for her hunger.|Three Tyrannosaurus chicks.
{30962}{31053}The only survivors|from a clutch of twelve.
{31056}{31128}The moment they hear the kill,
{31130}{31183}they start calling for food.
{31185}{31236}(Mewling and yelping)
{31308}{31432}The mother delivers|a slab of Anatotitan meat.
{31551}{31608}0nly four weeks old|and less than a metre high,
{31611}{31671}competition is intense between them.
{31673}{31752}0ne is already picked on|by the others.
{31805}{31848}(Faint mews )
{32168}{32295}They'll remain under their mother's|protection for another two months.
{32298}{32375}Soon after that,|she will abandon them,
{32377}{32442}or worse, view them as food.
{32519}{32612}It is unlikely|the outcast will last that long.
{32949}{33028}A few days later|and the mother rests
{33031}{33098}in the warm afternoon sun.
{33100}{33182}There is no sign|of the smaller runt.
{33185}{33269}He may have been killed|by his siblings.
{33386}{33499}Increasingly, the bickering pair are|happy to wander from their mother
{33502}{33569}to explore their surroundings.
{33571}{33641}(Squawks )
{33776}{33836}From the undergrowth,|a snake watches.
{33838}{33913}These reptiles|have only recently evolved
{33915}{33975}from the same family as lizards,
{33977}{34092}but they specialise in hunting|warm-blooded creatures like mammals.
{34096}{34168}They use sensory pits|on their snouts
{34170}{34283}as a way of detecting the heat|signatures of other animals.
{34314}{34374}It doesn't like what it sees.
{34514}{34562}(Hissing)
{34689}{34806}While the chicks play, they are|oblivious to approaching danger.
{34809}{34864}(Hoarse grunting)
{35069}{35172}The mother is caught|completely by surprise.
{35174}{35287}The Ankylosaurus has very little|brain inside its reinforced skull,
{35289}{35421}so when faced with danger, it reacts|automatically and aggressively.
{35614}{35681}Normally,|Tyrannosaurus would retreat,
{35684}{35741}but she will not abandon her young.
{35898}{35956}(Low grunting)
{35958}{36006}(Roar)
{36234}{36318}The blow has cracked|the mother's femur
{36321}{36374}and ruptured internal organs.
{36376}{36431}She limps away in agony.
{36434}{36479}(Chicks squawk)
{36611}{36673}That night, the usual evening chorus
{36676}{36772}is joined by the whimper|of a dying giant.
{36890}{37010}By morning, she lies lifeless|on the baking ash fields.
{37012}{37132}The chicks stand expectantly by|the colossal corpse of their mother.
{37268}{37332}Hours pass, and still they wait.
{37397}{37481}But their fate will now be settled,
{37483}{37601}along with all the other|giant dinosaurs of the Cretaceous.
{37791}{37906}3,000 km to the south, the massive|comet crashes into Earth.
{37930}{37988}(Dinosaurs squawking)
{38188}{38293}The light from the impact|fades in silence.
{38320}{38387}Then the shock waves arrive.
{38401}{38485}(Rumbling)
{38514}{38562}Next comes the blast front.
{38795}{38851}(Winds howl)
{38896}{38942}(Tearing and crashing)
{39264}{39276}Finally a rain of molten rock starts|to fall out of the darkening sky -
{39276}{39391}Finally a rain of molten rock starts|to fall out of the darkening sky -
{39394}{39509}this is the end|of the age of the dinosaurs.
{39694}{39757}The comet struck the Gulf of Mexico
{39757}{39843}with the force of 10 billion|Hiroshima bombs.
{39845}{39922}In the catastrophic climate changes|that followed,
{39925}{40002}65% of life died out.
{40005}{40093}It took millions of years|for Earth to recover,
{40096}{40194}and when it did,|the giant dinosaurs were gone,
{40196}{40247}never to return.
{40368}{40490}In their place have emerged other|powerful and beautiful creatures.
{40571}{40643}We now know one small group|of dinosaurs
{40646}{40703}did survive the extinction -
{40703}{40780}and they are all around us today -
{40783}{40829}the birds.