it's one of the most remote places on earth a harsh and unforgiving land the Australian outback a group of intrepid scientists have come here to unlock a mystery 50,000 years in the making they're searching for the mega beasts that once roamed these vast plains to discover how they lived and why they died we know a lot about the mass extinction of the dinosaurs but for the Australian Ice Age animals known as megafauna the case files are very thin it's an area of research with far more questions than answers nearly all of the megafauna that went extinct in Australia were truly unique in that they were not found anywhere else in the world they're being the largest plant a death in Australia was the predominant item this was a huge marsupial the largest that has ever lived they're bizarre the marsupial line for example Bhalla clear carnufex this was a lioness sized marsupial predator with flip blades four claws all colors four teeth but many are tender to protecting their young these super-sized creatures walk this land for millions of years battling climate change bush fires droughts and predation any one of these could have triggered their demise or maybe it was something even more devastating today scientific sleuths are racing to crack the case under the vast treeless null Arbor plain cavers make one of the greatest fossil discoveries of the century it sends shockwaves around the world McIver's found a complete skeleton of the marsupial lion Dada Kalia was in absolutely pristine condition the most complete skeleton that had ever been found or a remarkable set of circumstances paleontologist dr. Gavin Prideaux leads a special operation to recover the fossils it was a pretty unique feeling I don't expect I'll ever have it again it was amazement at the beautiful preservation of the specimen the animal was so completely virtual imagine it just taking its last breath dropping down dead phyla Kaleo means pouched lion like many Australian creatures today it's a marsupial a mammal that carries its young in a pouch [Music] in this subterranean treasure trove scientists find more remains undisturbed for hundreds of thousands of years they identify nearly all of them but eight skeletons are a mystery there are completely new species what I'm doing at the moment is putting together a skeleton one of the new remarkable species of extinct kangaroo from the clerical error case on the nullable claim we think they're aged at about half a million years and still remains undescribed over the last five hundred million years there have been other mass extinctions of large terrestrial animals but the death of the mega beasts is recent in natural history terms less than sixty thousand years ago and no one knows why they disappeared today scientists are on the verge of a major breakthrough at Colorado's Institute of Arctic and Alpine Research they're piecing together the puzzle they begin with the eggshells of one of the largest flightless birds ever to walk the earth the gigantic Jenny ortus the tiny pieces of eggshell contained clues about the types of plants the birds were eating when they went extinct Jenny honors was really a massive bird somewhere around 2 meters of 6 feet and it weighed something like 200 kilograms it was probably a forager it had a very large beak the Jenny orna sleeves alongside the Australian EMU one of the world's largest surviving Birds even though they're similar in height and neither can fly the Jenny onus was up to 6 times heavier to give some idea of how big and robust they are we can do a size comparison between the modern mu which this is a bone I picked up off the road from a a roadkill this is the femur or the the thigh bone from the EMU and this is the same bone but from the genuine it's a giant flightless extinct bird and you can see not only are they bigger but there's so much wider and much more robust there's a very heavy big animals the most widespread remains of this giant bird are it's fragile eggshells they provide valuable clues about what it ate [Music] [Music] we're heading now down towards Coral Bay in Western Australia and we're driving through a dune field on either side of us are the ridges of large dune field and it's in these dune fields where the wind has blown the sand away that were most likely to be able to find the eggshells of Jenny onus we should find some nice collections to pick them up here a little bit of secondary carbonate on professor gifford miller believes these ancient sand dunes hold the secret to the mega beasts mystery hi if I can say a few bits appearing here yeah and there should be something right up on top here I think go find some more this isn't an ordinary egg hunt there should be some up in here it's a place we found oh yeah there's a good collection here oh yeah yeah okay there they are yeah was it it looks like EMU and see EMU and genuine ascore existed and not only at the same time but they actually nest in the same area so it's very frequent that when you find genuine sake shells will also find emu egg shells at the same site using the eggshell samples they compared the diets of the two birds and the environment they share they also determine the age of the fossils because we find these eggshells with the same secondary carbonate which is like cement it's the same stuff like this that forms in the soil here and it's actually stuck onto the eggshell so that we know that this is old eggshell that actually comes out of these sediments and if it has dated eggshell from here to 25,000 the giant jenny or Ness is strictly a plant-eater Miller wonders if an environmental change might have disrupted its food supply and caused its extinction he turns to the eggshells of its neighbor the EMU for clues and so what we've done is we've taken the bird that does not go extinct the modern EMU and then we've looked back a hundred thousand years and we've reconstructed what the birds were eating during that period and then what they were eating after the big bird goes extinct using a method called amino acid Rasim ization he dates the eggshells when we collect eggshell in the field we often find that their sediment adhering to the eggshell that we can't remove by simply scraping so we need to grind that away because it has within it amino acids that are not from the eggshell itself he also analyzes the different kinds of carbons contained in each eggshell to better understand the birds died Miller deduces the ratio of carbons that come from the different plants the birds ate such as grasses shrubs trees seeds and fruit and what we find is that prior to fifty thousand years ago the emu ate this wide range of food sources from purely grasses to trees and shrubs and then after extinction one whole suite of vegetation they used to eat simply disappears and after forty five thousand years ago their diet is irreversibly changed to a completely different type of food source this change of diet could be a critical factor in the extinction of the Jennie Horace [Music] when the mega beast roamed the Australian outback it was a lush Oasis full of plants and wildlife today it's a virtual Dust Bowl scientists are trying to figure out what went wrong the largest plant eating marsupial ever to walk the Australian outback is a giant wombat it's known as Diprotodon these huge herbivores live in open forests scrublands and grasslands and consume almost 300 pounds of vegetation a day the Diprotodon must constantly search for enough food and water to satisfy their huge appetites [Music] in 1893 a remarkable discovery at Lake Caliban in South Australia leads to the excavation and reconstruction of the very first complete skeleton of Diprotodon Australis since then hundreds of fossils have been found there including groups of Diprotodon trapped in a dry lakebed the evidence suggests a severe drought may have spelled the beginning of the end for these mega beasts the stomach contents of many of the Diprotodon fossils contain the remains of a drought resistant plant called salt bush it tolerates extreme temperatures and can grow in drought affected areas when the land grows parched Diprotodon feed on salt bush to survive in a drought being big does have its advantages large animals can dominate watering holes and dwindling food supplies if an area has become particularly drought affected and there is no food left obviously a larger animal has larger body reserves or fat reserves and is more able to travel the sort of long distances required to get to the next food source the huge Diprotodon czar well-suited for the long treks to find more food and survive the drought but their immense size could also be their Achilles heel the overwhelming influence on the way that this animal needs is its size so you've got to bear in mind dr. Stephen rug you know an expert in mega fauna biomechanics is working with computer animators to bring the creatures back to life so you've got to bear in mind and remember that you're talking about you know 2 to 3 tons of animal here you know we use draw no reference to get the walks the trots and so on you know right now is probably your closest looming for mechanical reference [Music] [Music] Diprotodon czar six feet tall 10 feet long and weigh almost three tons but size alone might not be enough to protect them from environmental peril and fierce predators [Music] an animal like Diprotodon would have been relatively slow moving and in a sense this could have made it a better target a potential predator but what they lack in speed they make up for in size being so large it could certainly abused its white to intimidate a potential predator so one of the ways that you can actually escape predation is to get too big for your predator given their massive size it seems unlikely that any animal predators force the Diprotodon into extinction but their size could also have been their weakness the key to the mystery of the Diprotodon disappearance may lie in the mass extinction of another huge animal with a voracious appetite but dinosaur the Australian ice age mega beasts are some of the biggest most powerful creatures ever to walk the earth there's thigh locally Oh a marsupial lion who keeps its cub in a pouch and the Jenny ortus four times larger than its cousin the email and then there's Meg Alenia the largest lizard that has ever lived but we aren't sure why it and other mega bees suddenly went extinct around 50,000 years ago it's not well-represented in terms of fossils we certainly do not have anything like a complete skeleton over millennia but there is certainly enough out there for us to be entirely sure that it was very big some people would argue well over a ton or so in weight so this is a potentially devastating animal it was definitely carnivorous it had very sharp teeth these teeth in fact was serrated so basically it had a mouthful of steak knives it was incredibly powerful and certainly theoretically quite capable of taking perhaps even the biggest of Australian megafauna but it's not powerful enough to evade extinction the answer to the mega beast mystery may lie millions of years earlier when doomsday struck another group of giants but dinosaurs here in the small town of Esperanza near the foothills of the Pyrenees Mountains is one of the greatest sites in global paleontology it's providing a new understanding of how large animals go extinct paleontologist Jean aloof oversees the excavations that have uncovered about ten different species of dinosaur fossils dating back 65 to 80 million years the most important is an herbivorous dinosaur named Eva hers is the most complete skeleton of its kind ever found in Europe the zoo does escalate avec suit was on TV do the cover Solomon Sita some countries some beaucoup PPT EK veit an agenda video ever measuring of your own limit for the long but was forgetful metro and designed the turn eligibility tabla not only beaucoup people even as a juvenile Eva eats as much as the largest mega beasts taking in hundreds of pounds of fresh vegetation each day this enormous appetite ultimately leads to her demise sixty-five million years ago a huge meteor over six miles in diameter hits earth in what is now southeastern Mexico the impact penetrates the Earth's crust causing huge fires triggering tsunamis and severe storms with high winds and acid rain temperatures plummet as dust and debris thrown into the atmosphere block out the sunlight the dinosaurs and at least half of all other species on the planet are wiped out the city of the double security prison a report on don't deputy new model J is for Simone the consequence damnit equal to it anywhere before it completely no soil before his noise say the countess's on to vessels of ginger also say you're not there as plant eating dinosaurs starved to death the carnivores that feed on them also begin to perish back in Australia there's no sign that a meteor destroyed the mega beasts habitat but the story of the dinosaurs offers a cautionary tale of what happens to large animals when their environment changes drastically the animals that did manage to survive the meteor all shared one critical characteristic they're small there's a clear cut off no creature over 55 pounds survives the larger animals require more food which is increasingly harder to find the mega beasts may have died from a similar scenario if their food source was suddenly wiped out the mega beasts with their enormous appetites would be in deep trouble scientists decide to investigate further by reconstructing the mega beasts environment they're one step closer to solving the mystery of the death of the mega beasts the date of the mega beasts extinction has been one of the longest-running and controversial debates in all of paleontology then at this secret location in southwestern Australia scientists make an amazing discovery they unearth the fossilized bones of what appears to be a super-sized kangaroo what we're looking at here is part of a skeleton of an extinct short-faced kangaroo these animals were quite widespread across Australia up until about 40 or 50,000 years ago and this species was common right across southern Australia and particularly abundant in the southwest at first paleontologists think it's just a really big kangaroo but at 9 feet tall the fully grown Pro Captagon is 3 times larger than the average kangaroo and there's another difference it has an unusually short face at a very simple level having a short face means that you can get more leverage to the front of the jaw being able to get more power more force through to the front of the jaw would mean that you don't for example bite off a larger branch having a longer face of course means that if you're a grazing animal you can have your teeth down in the grass or whatever it is that you're grazing on and still have your eyes a reasonable height from the ground so that you can be alert accreditors the pro copter Don doesn't need the benefit of a long snout it's too big for most predators to attack which also means it wasn't over predation that killed off these mega sized kangaroos scientists pour over the skeleton in the southwest cave searching for other explanations for their disappearance if we look at Liars here it seems to be this was the last level that we get a lot of megafauna material from there really very little megafauna about that but a lot of megafauna below it so it seems that this may capture the extinction interval of the megafauna in the southwest scientists will date the sand from this layer that was deposited as the mega beasts plunged to their deaths well here are some sand grains which he picked out from around the bones of megafauna might want to date these sand grains to work out when the animals which had died in these sands had last been alive before the quartz particles fell into the cave they were bleached by sunlight releasing the electrons trapped inside so I'm going to spray off any unwanted grains I'll load it onto the carousel when the particles were buried they began to absorb tiny amounts of radiation energy from the surrounding soil indicating when they were last exposed to sunlight by exposing the sand particles to lighten the stored radiation is released Roberts gauges its intensity and deduces the age of the particles with remarkable accuracy well we've now measured all of the grains and these are the results we're getting one of the grains produces a very nice amount of light and that's a very good grain from which we can work out when those sediments came into the cave and buried the remains of the megafauna that died in those sands we looked at several tens of sites now around the country in caves in open air sites in rock shelters and they all show very much the same thing when you do a statistical analysis of all the dates we got then the interval seems to be somewhere between about 51,000 and 40,000 years ago in that interval somewhere not in full-on megafauna went extinct the scientific investigators now have an approximate time of death but they need an even more precise date [Music] on the outskirts of Paris at the National Center for scientific research dr. Linda Alif is on a mission to employ a chemical technique known as uranium thorium dating to pinpoint a time of death for the mega beasts in the cave she turns to the caves ancient flow stones these flat slabs of calcite formed when water flows down the walls and along the cave floor over time the flow stones encase the remains of the creatures that have died there water filtering into the caves contains a tiny amount of uranium that builds up in the calcite formations this radioactive uranium decays over time allowing us to date the formations by dating the flow stones encasing the remains we can determine the precise age of the fossils inside this is part of the procedure for dating chasm carbonate formations and caves and we dissolved the somnolent acid the uranium and thorium get concentrated and all the calcium in the sample is stays in solution Alif uses a mass spectrometer to measure the weight of the molecules the amount of uranium and thorium present indicates the fossils age after years of research the scientists finally get the answer they've been looking for the mega beasts went extinct 46 thousand years ago it's within the time interval identified by professor Roberts and dating techniques the results verify that the mega beasts died off quickly in a relatively short period of time it's a stunning conclusion now there's a precise time of death but the extinction case is far from closed we still don't know what or who was at the scene of the crime around the time the mega beast vanish a new predator appears on the scene the humans who first walk the Australian outback come face-to-face with these strange and ferocious creatures but who are these early humans and what role if any do they play in the demise of the mega beasts during the ice ages Australia is joined with New Guinea and the islands surrounding the continent are bigger than they are today the sea passages between the land masses are narrow early humans use boats to travel from Asia to Australia they arrive on the northern shore of forty to seventy thousand years ago and quickly spread across the land [Music] what happens next will change the course of the continent and all who live upon it [Music] amongst the strange landscapes of southwestern New South Wales lies evidence of these early peoples these are my ancestors footprint formal way back a long long time ago and that word God didn't you if they were telling us a story they always put that even we knew you know what they meant it was a long long time ago the footprints date back nearly 20 thousand years Lottie Williams is a member of one of three tribal groups who are the traditional custodians of the area the footprints were originally formed in mud as the water dried up they hardened and then remained hidden by layers of sand for thousands of years dr. Matt Cooper is part of the research team that discovers the prints the footprints that were found here at Lake Mungo are actually on the shoreline of and larger lake Lake GaN Punk and as we uncovered the layers of sound we've uncovered over 450 foot prints now and that makes them the largest collection of Ice Age footprints in the world and they tell us quite a few things about the social behavior of these early people in Ice Age Australia we think that perhaps a dozen or two dozen people were represented by the different prints on the surface and so we can see that Aboriginal society consisted of small bands of people we've got small children rising up to larger dive men so a whole family group or several families walking across the landscape now I think this one's just walking along casually that might look like a bit of a run some of the footprints are a stunning 12 inches long we think that they were made by quite tall people and by measuring the distance between the footprints we think that they are running quite fast some of them were perhaps running it up to 20 km/h and so this suggests that they were quite healthy fit individuals capable of quite high fits of exertion the ancient legends or Dreamtime stories of Aboriginal people tell of the Khadem acara animals that lived in forested areas with rich undergrowth and plenty of water it said their environment was destroyed and they were forced to roam the continent and that their bones can still be found today bones the giant kangaroo Madonna Mia a joint one but like critter it's been found out here fifty forty thousand year ago just to roam around here till these great lakes were full yeah it all fits in with their Dreamtime stories all the scientific evidence what's been passed down through generations generations the mega beasts and many other animals fed around this great lake Vera also leftovers from other great feasts piles of shellfish eaten by early humans so this sedimentary unit here is the lake mungo unit and dates back to about forty to sixty thousand years ago corresponding approximately to the timing of the extinction of the megafauna interestingly this also contains evidence of the first humans in the wall Andrew lakes we've got the bones of Mungo man and Mungo woman and stone artifacts eroding out at this unit dating back between about forty two and fifty thousand years ago so there's a window of perhaps four or five thousand years or so that we think that people and the megafauna were in the Australian landscape together it's a short overlap that closely coincides with the death of the mega beasts but it doesn't prove that prehistoric people are responsible for their mass extinction one of the major problems facing people who would argue for a human hand in the extinction of the megafauna in Australia is the lack of evidence so there's not in Australia for example a single kill site there's not even for a single individual megafauna any evidence that humans actually interacted with them but if humans aren't the culprits the scientific detectives must track down another suspect and this one has killed before [Music] here in the snowy mountains of New South Wales Australia scientists are investigating another possible culprit behind the mega beast extinctions climate change Ice Age glaciers carving their way through the landscape shape the mountains the climate is harsh the rugged scenery is frozen in time in solving the mystery behind why the Australian megafauna became extinct it's important to consider what the climate was like at the time and how it's changed before and since the megafauna became extinct throughout Earth's history the planet has endured several Ice Ages the earth cools and colossal ice sheets up to a mile thick spread from the polar icecaps to freeze vast regions of the continents eventually the planet reaches an apex known as the glacial maximum the snowy mountains are one of only a few places in Australia that are glaciated during the last ice age throughout the continent temperatures plunge 9 to 18 degrees Fahrenheit my work in the snowy mountains is centered around trying to work out when the last ice age occurred and how cold it got I've collected samples from surfaces created by glaciers either from where they eroded into the bedrock or where they've left rocks behind on debris ridges left behind by the glaciers barrows dates ice ages by determining when various rock surfaces were first unearthed by glaciers if an ice age occurred simultaneous with the extinction it's strong evidence that climate change killed the mega beasts when a glacier moves across the surface of the earth it scours out and it creates fresh new surfaces and these surfaces get exposed to radiation from outer space cosmic rays are continually bombarded the earth through the atmosphere and these caused nuclear reactions within the rock the reactions create new elements by measuring the amount of elements in the rock we can calculate how long ago the glacier moved in and exposed the rock surfaces this heavy ion particle accelerator measures the abundance of rare atoms and dates the rock surfaces once we get the sample back to the lab we need to extract these very rare elements out and we do this with very powerful asses and then we take this element and we make a very small target and then place this target into the accelerator 25% increase in beans well worth having yeah we found that the first ice age occurred at about 60,000 years ago and that there were two more after that one at about 30,000 years and another about 20 to 19 thousand years these findings confirm that the most extreme glacial maximum occurred long after the mega beast disappeared but it also means that the mega beasts did survive other Ice Age periods somehow adapting to the extreme climate change fossilized footprints at Lake Caliban in South Australia confirm that the Diprotodon has a thick fur coat it may well be that the fur of animals locked up loaded on actually got thinner or thicker depending on the climate at the time but Australia's ice ages aren't just cold they're dry to see levels drop by more than 300 feet and the island of Tasmania becomes a part of the Australian mainland the Ice Ages were associated with our great drying out of the Australian continent the deserts expanded and the vegetation the treeline retreated back into the mountains and it certainly would have been a hostile time for a bigger for changing something like fur leaf is a relatively minor adaptive challenge changing your your actual physiology to withstand more arid conditions is another thing the theory is simple the Ice Age brought on an extreme drought that decimated the mega beast population but proving it is difficult [Music] the calcite formations in these spectacular caves provide important clues about the impact of aridity on the mega beasts it's also one of the few sites on the planet with a nearly continuous fossil record of vertebrate life spanning the last half million years this extensive timeframe allows scientists to study how dramatic decreases in rainfall affect mega beast populations dr. Linda Alif and her team are looking for fluctuating patterns of growth in the calcite formations indicating wet and dry periods we take samples of stalactites stalagmites from a lot of different places in the cave and we date when they grew they match the data with the ages of different fossils in the cave the results revealed that although the populations declined during drier periods most eventually did bounce back what we did was essentially demonstrate that the megafauna did indeed make it through a number of successive wetter times and drier times but the only time that megafauna didn't bounce back based on our studies of the last five hundred thousand years was just at the time that humans were in Australia the climate change theory leads investigators back to prehistoric apologies fresh evidence may provide the proof that these early humans unleashed a systematic assault that wiped out the mega beasts in remote caves around Australia are ancient intricate aboriginal paintings the rock art portrays the daily practices and lifestyles of the earliest people to inhabit the continent and the creatures they encountered aboriginal paintings around australia are done in in wide variety of different styles depict a huge range of different kinds of activities abstract concepts animals plants and they're done in many different ways there are a lot of caves and rock shelters throughout australia that show an extremely wide variety of motifs styles and of course represent many different ages [Music] in 1984 paleontologist dr. Peter Marie encounters an extraordinary painting in Arnhem Land in remote northern Australia it was an incredibly ancient painting older than I'd seen anywhere else in Arnhem Land what I began to realize what this painting was depicting I was of course stunned really he sees an unidentified animal from the aboriginal Dreamtime stories with a small trunk short robust limbs and a well-developed tail to Murray it bears a startling resemblance to pallor kes teased an extinct mega beast using the literature that was available to us in the specimens that were currently in museums most of which were very fragmentary it was one fervent hope that we might eventually find a very complete specimen to help us refine our reconstructions of it to compare with this painting it takes years of searching to find the right specimen I actually was not the one who discovered it however it was one of my colleagues and we were very surprised and delighted to see that everything was intact the skull verifies that the creature depicted in the rock art was indeed real it's a major discovery for the team the painting confirms that humans and mega beasts shared a time and a place in the Australian outback the arrival of humans to North America and to Madagascar also coincides with a mass extinction of animals it's a coincidence that has led to the Blitzkrieg theory a lightning war so swift it annihilated the mega beasts it's based on the assumption that humans will always exploit a food source the theory claims that the Aborigines hunted the mega beasts to extinction through efficient and systematic persecution when humans arrived in Australia it essentially increased almost by 50% the number of big predators on the landscape so just by virtue of their presence and their need to eat and sustain their own populations it would have impacted on the megafauna any evidence that humans hunted mega beasts has only been in direct then at Cuddy Springs in north-central New South Wales scientists make an explosive discovery the critical evidence that Cuddy Springs provides is it's the only site on continental Australia that has secure evidence of human artifacts and megafauna bones in association dr. Judith field is investigating some of the most important mega beast bones in Australia in about 5 1 meter squares I think we've counted about 141 individual bones that indicate that the whole animals were there and had died there beneath the surface of the ancient lake she uncovers distinct layers of fossil sediments known as horizons each layer corresponds to a different chapter of natural history the lowest horizon that this is a swamp people aren't gonna be camping out there but in the overlying horizon at 30,000 this is definitely a camp site we've got lots of big complete pieces of charcoal we do have burnt bone and in fact we have a burnt femur or the upper limb bone from one of the extinct kangaroos from its horizon it does suggest that this was burnt in a fire and fire in the middle of that clay pen can only have been made by humans among the many fossils at Cuddy Springs is a complete jawbone of a Diprotodon but in a dramatic twist lodged between its bones is a stone tool this is probably the most exciting discovery and as always it's the first discovery and spend the rest of your life looking for something equivalent but the first thing we actually found was the lower jaw of a young Diprotodon wedged between it and a limb bone was what we call a core tool core tools are used to make other tools like blades and stone knives the people that I learned to make these tools from they were full-blood Aborigines and of course I'm going back 70 years but they were still making these tools at that particular time this is a type of course church stone that we used and it's a very good stone as you can see I used all the modern tools today to make these stones so what I'll do I'll strike a piece of beautiful and these guys it's very sharp as you can see you can strike big cutting noise off this piece of stone as big as you want it and indeed if those megafauna us were like cattle today big as that they'd have no trouble watching those particular animals up with these ancient stones forensic tests on the stone tools detect minut traces of blood and bone fragments tens of thousands of years old [Music] when we examine the stone tools that are associated with the big bones we did find blood we did find where trace is consistent with working bone and with working soft tissue and these can only come about by impacting on the bone or defleshing so if you're filling an animal then the impacts of filling will be reflected at a microscopic level on the surface of the stone tool anything that moved in the Australian bush more people they had them on the coals and eat them and so megafauna animals wouldn't have been any different to the smaller animals that existed at that particular time the evidence is clear early humans ate mega beasts but the fossilized animals were trapped in mud as they died and the ancient tools that were found resemble kitchen utensils more than weapons cuddy Springs could simply be a massive scavenging site where humans feed on the already dead or dying but it's hard to ignore the clues that put early man squarely at the scene of the crime no fines suggest that the Aborigines had surprising skills and sophisticated technologies that made them lethal killers [Music] [Music] early humans are hunter-gatherers their most effective weapons are the large stone spear points found in northern Europe and America these are typically associated with big mammal hunting [Music] stone cutting tools in Australia date back tens of thousands of years but stone spear heads aren't used until six thousand years ago long after the mega beasts disappeared the reason that early Australians didn't hunt with stone tip Spears is that the really fine stone that you need to make very thin kinds of highly refined stone points was not widely available in Australia there are lots of silk REITs and stuff which are very good to make implements for shaving wood and cutting and things like that but very difficult to make perfectly shaped spear points there is no evidence for any specialized hunting technology from this period and it is well acknowledged by archeologists but what people were making from this period is very simple it suggests the tools of prehistoric humans in Australia aren't sophisticated enough to effectively hunt mega beasts but at Cuddy Springs scientists uncover thirty thousand year old grinding stones technology remarkably advanced for its time these stones won't appear elsewhere in the world for another twenty thousand years dr. field traces their origins to a quarry 75 miles away from Cuddy Springs to the west of Teddy Springs there's a quarry on a hill which is completely covered with pits that have been humanely made as they've taken out all that sandstone and brought it around dr. field and her team discover many ancient stone tools that gives edge is the usage looks like video them bang the anyway early humans used the rocks for carving tools and grinding stones but they weren't suitable for more deadly weapons with the start of being too brittle for axis yeah that was my knee grinding stones these other ceremonial okay the early Australians turned to other materials to make more effective weapons Australia has an abundance of hardwoods that can be shaped using these other kinds of perhaps harder to work flint tools and they're every bit as effective as even the most sophisticated stone tips the argument that Aboriginal people didn't have sophisticated enough equipment to kill big game as coarse nonsense at least what we know from the modern toolkits Aboriginal people made they were perfectly adequate for dispatching any of this sort of prey [Music] [Music] they're hard wooded spear points inflict substantial damage their most effective in killing the youngest mega beasts and that alone could lead to extinction to wipe out the megafauna actually doesn't take much effort in a sense they're very slow breeding animals so if just one kill is made per person per decade that would be enough if you're picking off the juveniles not the adults the juveniles that's enough to drive that species to extinction because you're picking them off more quickly than they can actually replace their population it is a form of blitzkrieg it is a form of overkill but it's not the sensationally type we have lots of blood on the landscape that wasn't happening it was just small-time barbecues really every year by small family groups and after a few thousand years maybe only a thousand years these species would have disappeared completely from the record even if early humans did have the weapons to kill juvenile mega beasts not all scientists believed they were easy targets a major part of the argument for human hunting as a the primary cause of megafauna extinction is the idea that the Australian megafauna were naive that they were unused to predation and because of that they were easily killed the reality is that Australia's megafauna almost certainly had predators so these animals would have had at least some anti predator responses and defenses some mega beasts are ferocious well-armed to attack or defend [Music] especially the terrifying marsupial lion the massive young lion Thalia was right at the top of the food chain in ice age Australia this was an animal with remarkable specializations in some ways it was the most specialized mammalian carnivore of all time it was well armed with retractable claws on both its hands and its feet it's bum claws were particularly well developed some people think of these as actual killing weapons but the marsupial iron actually went in and sliced and diced its prey open it up with the claws and that they might then have bled to death I think that's pretty unlikely in reality these massive thumb claws I think would have been used as grappling but not everyone agrees that thigh luckily Oh has the ability to be a lethal killer or to defend itself against human predators one of its features is especially puzzling it's teeth at first look phylla Koleos teeth don't resemble those of a typical carnivore so dr. Roe is putting the creature to the ultimate test he scans a complete skull of a small Tyler Kaleo from the South Australian Museum then he sends the data to his colleagues at the University of Western Australia using a technique known as rapid prototyping they build a full-size cast of the skull and jaw prototyping uses computer modeling to create paper-thin cross-sections of the skull a high-powered co2 laser beam then melts metal powder into each of the thousands of layers until it finally builds a bronze cast [Music] in collaboration with the University of Newcastle in New South Wales Doctorow designs a method to estimate the bite force of the marsupial lion they conduct a series of experiments using computer modeling and a sheep's head good first of all we've had these large incisors at the front penetrate the flesh between those upper and lower incisors it's pulled the neck of the animal back into those massive slicing teeth at the back and this is a relatively small marsupial on skull the bite of even a small phyla Kaleo generates 1,000 pounds of force close to that of a female lion an animal double in size pound for pound the thigh locally owes bite is nearly twice as powerful as any big cat today there is no doubt in my mind that a large marsupial lion could have easily killed him [Music] the marsupial lion is indeed one of the animal kingdom's most ferocious creatures when it comes face-to-face with prehistoric humans chances are it's the humans who turn and run for investigators the mystery of the mega beasts extinction is still far from solved but the smallest piece of evidence from one species just may hold the key [Music] professor Gifford Miller is searching these sand dunes for tiny fragments of eggshell from one of the largest flightless birds ever to inhabit the earth [Music] there's some pits around good yeah I got some here a couple of them Miller's research is unearthing new possibilities in the case of the mega beasts extinction [Music] [Music] using the eggshells of the generous he concludes that the bird goes extinct 45,000 years ago the giant bird lives alongside emus and both are herbivores around the same time the Jeni onus goes extinct the emus diet changes and a whole array of vegetation simply disappears the changes we observe in the diet after 45,000 years tells us that there was a complete revolution of ecosystems across semi-arid Australia and that after forty five thousand years the ecosystems were fundamentally different than previously and they remained in that different state all the way through to the present day they they never returned to the condition they were before the change in vegetation spells doom for the Jenny earnest because it's a picky eater that eats only a few plants it doesn't have the varied diet of the more successful emus the evidence that we've compiled from the dietary reconstructions can explain why a picky eater Jenny or nests that had a very specific dietary strategy was more vulnerable than the EMU which is a bird that has a very eat anything kind of feeding strategy when the vegetation changes and its usual sources of food vanish the Jenny onus isn't able to adopt a new diet but it doesn't end there the change of vegetation causes a domino effect throughout the entire food chain as the herbivores die off the animals that depend on them for food also become vulnerable carnivorous mega beasts must compete for the little food that is left [Music] and that's not their only problem Miller and his team discover another link in the deadly chain of events they find several Jenny or nest egg shells that are burnt this cluster of eight shells obviously from a group of eggs have been put together by people coming in here the broken eggs show itself that the burnt eggshell suggests it's been in somebody's fire and they've been cooking them up some of them are burnt completely and it's possible that could be by wildfires but many of them exhibit this what we call point burning where part of the shell is quite burnt and the rest of it isn't is here's another example here and the only real way that this can happen is if somebody has cooked the egg and after they've sucked it and eaten it they toss the eggshells back in and some of them land against the hot coals of the fire on which they've been cooked and and so you get this partial burning of very small portions all right this looks like a collection off this area he put down the slug I got some nice ones over there Miller also discovers a campsite of the coast where early humans cooked at least two other Jenny Ornish eggs he collects over two pounds of eggshells all with clear evidence of point burning and the genuineness we've actually dated from the site near here that's once we found our somewhere between 50 and 55 thousand just before the bird goes extinct these findings confirm once again that early humans coexisted with mega beasts they readily used jenny or nest eggs as a source of food further threatening the survival of these huge birds interestingly Jenny onus had more predators than just humans and you can see here in this puncture the predation by the canine tooth of an unknown animal that was taking the eggs of genuineness as a food source puncturing them with their canine teeth and then eating the the poor young inside Jenny or nazar threatened from all sides skilled predators changing climate vanishing food supplies and fierce competition from other animals but in the past as far back as we can look the animals had have been able to adjust to those stresses so we think that the main difference in this window of time 50 to 45,000 is that humans appear on the landscape and something in human activity pushed these animals through that threshold beyond which they could not recover it investigators have narrowed their long search down to one critical question could humans have altered the ecology of the mega beasts the extinction of the dinosaurs shows that being big can be a death sentence we know that around the time of the mega beast extinction Australian vegetation changes and the Outback becomes much more arid if food sources dried up the effect would have been catastrophic large animals require more food and larger areas of food so the large animals will actually or could theoretically be the first animals to go vegetation change is the most compelling theory in the mega beast extinction debate but there's still one piece of the puzzle that's missing scientists are searching for what could have destroyed the mega beasts habitat and where there's smoke there's fire [Music] [Music] the mega beast investigation now has a prime suspect early humans they have the opportunity but do they have the motive and the means to destroy the mega beasts environment and drive them to extinction at the time of the mega beast disappearance vegetation in Australia changes dramatically and since then other types of plants have taken their place the present-day landscape is dominated today by fire promoting grasses mostly spinifex and cane grass that has very low nutrient value and it promotes fire so it's a highly flammable landscape with very few trees and shrubs in it today scientists have unearthed new layers of incinerated remains of ancient vegetation [Music] bushfire has been a natural part of the Australian landscape for a long period of time initiated largely by lightning strikes but what we see beyond about fifty to forty five thousand years just that around about the time humans arrived in Australia a much greater increase in charcoal frequency the charcoal deposits correspond with the arrival of humans and the period of the mega beast extinctions they also correspond with the disappearance of several varieties of rainforests together they point to a substantial increase in wide-scale burning that transformed the environment it seems very likely that that is related to the arrival of people and not just a coincidence coexisting with such large and threatening creatures early humans think of an ingenious method of trapping their prey fire [Music] but they also burn the land for other reasons humans burnt the landscape to hunt across the fire front they're burned to promote vegetation that's edible they burn to clear the landscape for mobility this method known as firestick farming most likely wiped out the vegetation in many parts of prehistoric Australia before humans arrived bushfires aren't as frequent or as intense the mega beasts grades on the many bountiful plants but the regular burning has devastating side effects it destroys the plants with palatable leaves and fleshy fruits that are eaten by herbivores mega beasts the more burnings the less food for plant eaters I think it's very likely those increases in fire frequency and fire intensity did put unprecedented pressure on the megafauna populations and probably combined with hunting factors that they their population simply could not recover from in a few thousand years early humans changed the ecology of an entire continent and wiped the mega beasts off the face of the earth [Music] [Music] [Music] for over a million years Australian mega bees live through ice ages droughts and wildfires but it's humans who deliver the deadly blow I believe if humans had not arrived in Australia the megafauna would still be here today so we played the decisive role we push them over the edge we were that extra stress they didn't want recent discoveries on the island of Tasmania support this claim here mega beasts survived 5,000 years longer than on the mainland but they also go extinct soon after humans arrived we were the decisive factor in the extinction of the megafauna all the dating evidence points to Waldo being a close conjunction of the arrival of people in the extinction of the megafauna we have a mechanism to explain it the mechanism is firestick farming the systematic and regular burning of vegetation it dramatically alters the landscape and destroys most of the mega beasts sources of food driving them to extinction we've argued that changed firing of the landscape is the simplest explanation landscapes clearly have a sensitivity to disturbances that eventually might be on a continental scale but there's still one lingering question for thousands of years Australian Aboriginals have had a highly sophisticated system of managing the food they hunt and collect from the land these sustainable practices are still in use today so why would their ancestors have destroyed the mega beasts habitats to the point of extinction when humans came to Australia originally it was a new landscape to them completely different to the Southeast Asia they came from and there was a period of adjustment over time early humans became familiar with the nature of Australian ecosystems and learn to better manage their natural resources and live in a more sustainable way today humans are still dramatically altering landscapes but this time it's on a global scale we know much more about Earth's ecosystems and the impact of large-scale environmental destruction and yet we continue down the same perilous path within 30 years our continued destruction of the biosphere could cause the extinction of up to one-fifth of all living species what we don't know is whether as we convert forests to cropland as we modify landscapes with building cities whether there are feedbacks in the climate system that will produce unexpected unanticipated dramatic changes to which we're not prepared pollution the destruction of rainforests and global warming greatly overshadow the effect our ancestors had on their environment human activity now threatens the very existence of the human race a gun type that affect their predisposed extinction he see a destruction Denorfia unmarked and you can assume like to know suppose we especially men probably under any other we have we only space an email service ARPANET in a scalper supposedly the history shortly the mighty megafauna no longer roamed the earth but their legacy endures these great creatures have allowed us to glimpse a wondrous and little-known world that is no more they've reminded us that all things are connected the earth does not belong to us we belong to it [Music]
Generally accepted as people arrived, killed them all.
Not sure about that one myself, and if it happend, I'd say it had a lot more to do with early arrivals to Australia setting fire to the forests rather than stabbing them all.
I also don't know how people would have gone against the Marsupial Lion, aka. Thylacoleo carnifex aka Pouch Lion Executioner.
Of course it was people. Same thing happened when people came to the americas.