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Dinosaurs: The Final Day with David Attenborough (2022) is a captivating documentary that brings to life the dramatic final chapter of the dinosaurs’ existence. Guided by Sir David Attenborough, the film combines groundbreaking scientific discoveries with stunning visuals to reveal what happened on the last day of the dinosaurs. Informative and visually powerful, it offers a fascinating look at prehistoric life and one of the most important moments in Earth’s history.
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00:00:0066 million years ago, planet Earth was very different from today.
00:00:20Back then, one of our closest ancestors might have looked something like this little furry creature.
00:00:30The rulers of the land were giant reptiles.
00:01:00Dinosaurs.
00:01:07That's one of the most infamous, a carnivorous T-Rex.
00:01:13And just behind are the bison of their time, a common plant-eater, Edmontosaurus.
00:01:20But what happened to them all?
00:01:2266 million years ago, an asteroid hit the Earth.
00:01:28And scientists think that it was this collision that wiped out the dinosaurs.
00:01:35But no one has ever found direct evidence of that.
00:01:39In fact, no one has ever found the fossil of a dinosaur that died within a thousand years of the impact.
00:01:46However, a remarkable dig site promises to change that.
00:01:53It's in the Hell Creek Formation in the American Midwest.
00:02:01These badlands are rich in prehistoric remains.
00:02:08From Triceratops.
00:02:12To Pterosaurs.
00:02:18And here, one patch of land about the size of a football pitch is yielding a collection of astonishing fossils.
00:02:30The precise location is a closely guarded secret.
00:02:33Because this place may hold evidence of one of the most dramatic events in all the four-and-a-half-billion-year history of our planet.
00:02:49All right.
00:02:50We'll get down here between you.
00:02:52For ten years, a paleontologist and his team have been trying to find out exactly what happened here.
00:02:58You're at the edge of your seat every moment trying to dig this stuff up.
00:03:02It's like trying to defuse a nuclear weapon while you're in a rainstorm.
00:03:07He's named the site Tannis and believes it could be a mass graveyard of creatures that were killed in the catastrophic asteroid strike.
00:03:21A site that could reveal not only how the last dinosaurs lived, but how they died.
00:03:29If the dig team is right, Tannis could be a place where the remains of a long lost world are frozen in time.
00:03:38A place that gives us, for the first time, an unprecedented window into the lives of the very last dinosaurs.
00:03:52And a minute-by-minute picture of what happened on the day the asteroid hit.
00:04:01This landscape is full of fossils dating from the late Cretaceous, the period which began around a hundred million years ago,
00:04:08and ended 66 million years ago when the dinosaurs vanished.
00:04:15Paleontologist Robert De Palma wants to find out more.
00:04:24I think anybody who has ever liked dinosaurs in the past, or still does, has thought at one point or another,
00:04:31Well, what happened to them? Why are they not here anymore?
00:04:38So many different theories are out there, and nobody has a tight answer to that question.
00:04:44Judging from fossil evidence, this is what Hell Creek looked like in the late Cretaceous.
00:05:03There were low-lying marshy floodplains, intercut by river channels, and covered with horsetails, ferns, and trees.
00:05:23Back then, it was warm and wet here all year round.
00:05:28Tannis lies in the north-eastern corner of the Hell Creek Formation.
00:05:37Instead of today's dusty prairies, there were sandy riverbanks.
00:05:43Instead of rocky cliffs, there were forests.
00:05:49And instead of the life we know today...
00:05:54Well, Robert is hoping to find out more about what that was like.
00:06:09A sandbank lying between a river and a forest would one day become what Robert now calls Tannis.
00:06:17He and his team have been digging here since 2012.
00:06:26So somewhere from between there and down here is where that came from.
00:06:29Hey, look at that.
00:06:30What?
00:06:31Look.
00:06:32Oh, yeah, yeah, yeah. OK.
00:06:34And what they found is unexpected.
00:06:37Here we've got this freshwater environment of the Hell Creek Formation.
00:06:41And this shocking red-green color is coming from the shells of ammonites, a marine organism.
00:06:48Kind of like a coiled snail in appearance.
00:06:50So we've got this marine organism that's been thrown up into this freshwater environment.
00:06:56And they do not belong here.
00:06:58How they got here is a mystery.
00:07:01And there's more.
00:07:03I'm just going to go ahead and plane down some of this rock.
00:07:08Sitting just above the ammonites is something that many dinosaur hunters are desperate to find.
00:07:15So this orange layer right here is composed 100% of impact-related debris that is enriched in iridium.
00:07:23Iridium is an element that's rare in the Earth's crust.
00:07:28But it's common in asteroids.
00:07:31The layer it's in is called the K-P-G boundary.
00:07:37Here, Momo.
00:07:39Oh, dear.
00:07:41Really?
00:07:42It's made up of dust and debris from a huge asteroid impact.
00:07:48Look at that.
00:07:49That's me.
00:07:50Yeah, yeah, yeah, yeah, yeah.
00:07:51That's what we want.
00:07:52OK, so it's going from this area here.
00:07:53So somewhere within that region is where these pieces are coming from.
00:07:56The boundary separates the age of the dinosaurs from the age of mammals.
00:08:01So the rocks here come from about the time that the dinosaurs became extinct.
00:08:06No rattlesnakes.
00:08:08What makes the site even more exciting is the rock layer right beneath the boundary where Robert found the ammonites.
00:08:15The rock here is really not quite rocky as you would expect dinosaur bones and things to be encased.
00:08:21You expect really, really hard rocks and jackhammers and things like this.
00:08:25But it's very, very crumbly and it just falls apart in your hands.
00:08:30As well as being crumbly throughout, this layer of rock is also around a metre thick, which, along with other unusual features, makes Robert think that something very strange must have happened here.
00:08:45Maybe a flood or mud flow, burying anything within it in an instant.
00:08:55Oh, there's a beautiful. Look at that one. Beautiful.
00:08:58This could mean that anything he finds in this layer would have been quickly entombed, like the bodies in the volcanic ash of Pompeii.
00:09:11Robert knows from the geology that anything he finds at Tanis will be tantalizingly close to the end of the age of the dinosaurs and could be so well preserved that it could reveal new evidence that would bring this time period to life in a way no one has ever done before.
00:09:32Robert digs at Tanis each summer, the only time the weather allows him to do so.
00:09:42Come on down. Check out this lens over here.
00:09:45In order to understand how the impact affected life on Earth, you really need to get a very clear picture of what the world was like right before.
00:09:55That is a critical part of the story.
00:10:01Paleontologists Dr. David Burnham and Lauren Goerche have been digging with Robert for years.
00:10:11Oh, wow. See the brown?
00:10:14Yep.
00:10:15That might be a tubercle right there.
00:10:17And it seems today is their lucky day.
00:10:20Oh, my God. Look at that. Look, the scales are preserved.
00:10:24It's like doing a freaking dissection.
00:10:26Oh, my God.
00:10:28Biology of Tanis.
00:10:30Oh, the scale. Look, look, the wrinkles continue down that way.
00:10:33It's all nice and wet so far.
00:10:36The scales are getting smaller in that direction. How big are they there?
00:10:39I got one with the projection over here.
00:10:42What?
00:10:43Oh.
00:10:44Yeah, there's the protuberance right there.
00:10:46I've only seen that on one other specimen.
00:10:48I want life.
00:10:49Yeah.
00:10:50This is the closest thing to getting the touch of a living, breathing dinosaur.
00:10:53It is.
00:10:54They found something extraordinary.
00:10:58It is so exceedingly rare, a piece of Triceratops skin in the Hell Creek Formation.
00:11:06It may look like an impression in the rock, but this is skin that has been fossilized.
00:11:12And over millions of years has turned to stone.
00:11:18Triceratops bones are relatively common finds in Hell Creek.
00:11:23But skin in such condition as this is very rare indeed.
00:11:29The size and the patterning of the scales, together with the age and location of the rocks where it was found, strongly suggests that this is from a Triceratops.
00:11:42The brown colour contains traces of organic material.
00:11:46So it might even be possible from this to work out which pigments were in it.
00:11:52Finding and studying such well-preserved fossils as this helps paleontologists build a much more detailed picture of how these creatures lived.
00:12:01Combining this information with insights from scientists around the world makes it possible to speculate about what life in the late Cretaceous might have been like.
00:12:14We know from bones that adult Triceratops could reach 9 metres in length and 3 metres in height.
00:12:35Marks on the fossil also show us that this one was badly scarred.
00:12:44Triceratops were plant-eaters.
00:12:57Other fossils tell us that they had sharp beaks and hundreds of teeth that enabled them to shred tough plants such as these cycads.
00:13:14Almost all adult Triceratops, including Roberts, have been found on their own.
00:13:23So it's possible that the adults were solitary, like modern-day male rhinos.
00:13:31So they were probably territorial, chasing rivals away.
00:13:35And perhaps marking their territories.
00:13:45If you weigh more than an African elephant, there's not much that can bother you.
00:13:50Except perhaps a little mammal.
00:14:01Robert found these jaw bones in the fossilised burrow at Tannis.
00:14:19The shape of this tiny bone and tooth means it's most likely come from what's known as a paediomide, an early mammal.
00:14:35And a type of marsupial.
00:14:36Robert also discovered fossilised nuts and seeds in the burrow.
00:14:46So we have an idea about what it might have eaten.
00:14:49Robert's finds are adding to our knowledge of the complex world at the very end of the late Cretaceous.
00:15:05And it's not just the fossilised creatures.
00:15:09If you walk on damp sand, you'll leave a trace behind.
00:15:13A footprint.
00:15:17A footprint.
00:15:19The same was true 66 million years ago.
00:15:24And very, very occasionally, such traces were preserved.
00:15:29And that's exactly what happened here at Tannis.
00:15:34You know, we won't foil a backside.
00:15:37Right, we'll just put plaster right on.
00:15:39Robert has discovered a number of footprints.
00:15:42Yeah, let's see.
00:15:44Looks like a good print.
00:15:45Yeah.
00:15:51Their shape gives him a clue as to what might have made them.
00:16:01If he's right, they were made by a winged creature that might well have liked a small mammal.
00:16:07For lunch.
00:16:08The footprints are long and narrow with four toe prints.
00:16:24Two are slightly longer than the others.
00:16:28And that suggests they were made by...
00:16:33A pterosaur.
00:16:44Pterosaurs are not dinosaurs, but flying reptiles on a different branch of the evolutionary tree.
00:16:50Male pterosaurs usually had crests, while females didn't.
00:16:54So crests may have been used in courtship displays.
00:16:56A pterosaur.
00:16:57They're wearing binder going to be another view.
00:16:59John falter.
00:17:01Ptermarp
00:17:10Small pterosaurs usually had crests, while females didn't.
00:17:12So crests may have been used in courtship displays.
00:17:14and we have an indication of where females laid their eggs
00:17:26because evidence suggests one pterosaur laid hers
00:17:30in the soft sandy banks of the river at Tannis.
00:17:44And this is a fossilised egg of a pterosaur that Robert found there.
00:17:57The only one ever discovered in North America.
00:18:01If you look at it with the naked eye, all you see is a jumble of lines.
00:18:07But if you examine it with the latest technology,
00:18:11you can find out a wealth of information,
00:18:14from the chemistry of the bones to the composition of the shell.
00:18:18And that, in turn, can tell us a lot about how these incredible creatures lived.
00:18:30Robert has been given access to the Diamond Light Source Synchrotron in Oxfordshire.
00:18:38It's a very powerful research tool that acts like a giant microscope.
00:18:45By accelerating electrons in this huge ring,
00:18:49the synchrotron creates beams of light many times brighter than the sun.
00:18:56Robert and paleobiologist Dr. Victoria Edgerton now want to turn that beam onto the egg fossil
00:19:07to discover more about its chemical make-up.
00:19:10We're pretty much lined up on the skeleton,
00:19:13but we might have to move the stage a little bit to get to the right part.
00:19:16Sure.
00:19:17Meanwhile, Robert can reveal the creature inside.
00:19:22And this...
00:19:24Who made this wonderful thing?
00:19:27I got replicas of the bones from inside that egg,
00:19:31and I restored the remainder and put together what the skeleton would have looked like when it hatched.
00:19:37That's how big the creature would have been outside the egg, if it had hatched.
00:19:41So, this is the baby. How big was it going to grow?
00:19:46These very long neck vertebrae here are what really gave part of the story away to us,
00:19:51because those long bones match very, very closely with the Asdarkid pterosaurs.
00:19:56That is the giant pterosaurs.
00:19:58Oh, they were the whoppers, weren't they? I mean...
00:20:01What, 25 feet?
00:20:03Some of them.
00:20:05This probably had a wingspan, maybe 15 feet, 5 meters.
00:20:10Well, it looks as though it could take off, really.
00:20:12It's easy to picture something like that, just hatching out of the egg and fluttering out,
00:20:16almost like a little bat.
00:20:23They've scanned the egg, here and in America.
00:20:30Victoria has the results.
00:20:33So, what have you learnt from the cyclotron image?
00:20:37What we have here is a chemical map of calcium directly within the bones of this animal.
00:20:43That tells us that these bones were already hardened,
00:20:46so it might be ready to fly not long after it hatches.
00:20:51OK.
00:20:52Can you see any sign of the shell? And what sort of shell was it?
00:20:55We can.
00:20:56What I can show you...
00:20:59Ah!
00:20:59We can see the rim of the egg in sulphur.
00:21:02Does that tell you whether it was a hard shell or a soft shell?
00:21:07We have been looking at this.
00:21:09We can see folding occurring and this unusual undulation.
00:21:14If it were a hard egg, we would expect splintered bits and broken bits, just like a chicken egg.
00:21:21This helps to tell us that it was soft.
00:21:23So it was perhaps like a turtle?
00:21:25Absolutely.
00:21:26That's not the case, is it, with dinosaurs?
00:21:29Many dinosaurs had hard-shelled eggs.
00:21:31Yes.
00:21:32This is a new discovery about those dark-heated pterosaurs.
00:21:35Absolutely.
00:21:37This is something that we are confirming for the first time.
00:21:40Ah!
00:21:41That flying pterosaurs had eggs like turtles.
00:21:45Yes.
00:21:46Much more reptilian-like than bird-like.
00:21:49And that can potentially tell us more about the environment in which these eggs were laid.
00:21:54How interesting.
00:21:55Yeah.
00:21:56Creatures that lay soft eggs tend to bury them in order to protect them.
00:22:15So, female pterosaurs probably look for places like Tannis to lay their eggs.
00:22:21Because the sandy soil here is just soft enough for the hatchling to dig itself out.
00:22:33Now the pterosaur just has to make sure that the hole is perfect.
00:22:44So, female pterosaurs had two ovaries and they laid their eggs in pairs.
00:23:01But it's not over yet.
00:23:03Pterosaurs had two ovaries and they laid their eggs in pairs.
00:23:09Here, on the sandbank, sandwiched between the river and these glorious trees, life at Tannis
00:23:26seemed to be thriving.
00:23:28Whoops!
00:23:30Never a dull moment.
00:23:32But all that was about to change.
00:23:35The chain of events that led to the extinction of the dinosaurs began in the distant past,
00:23:48deep in space.
00:23:55Most scientists think it all started in a ring of dust, rocks and debris known as the asteroid belt.
00:24:03It's usually an uneventful place, but it's thought that many, many millions of years ago,
00:24:16a rock was bumped into a new orbit, and diverted onto a collision course with planet Earth.
00:24:27Robert is building a vivid picture of late Cretaceous life at Tannis.
00:24:48And the team have found some more well-preserved footprints.
00:24:51So these are animals that were actually walking in the water?
00:24:56These guys would have been essentially on a mushy river bank going down to drink at some point.
00:25:01You know, animals tend to congregate around the rivers.
00:25:05This print is 30 centimeters long.
00:25:09So I think this is from a type of dinosaur that we call a duck-billed dinosaur.
00:25:13And they would have been very common in the Cretaceous.
00:25:16They ate the plants in the area, and they got very large, 30 feet long.
00:25:23And there are more.
00:25:25This track, you see all the toes are very well-preserved.
00:25:28You even see a nail print at the tips of the toes.
00:25:31So the little toenails dug into the mud.
00:25:34I love this one.
00:25:35This is Robert's prize footprint.
00:25:43It has three toes.
00:25:46And it's longer than it is wide.
00:25:49So it's very likely to be a carnivorous dinosaur.
00:25:54It's so well-preserved that you can see the mark left by its sharp claw there.
00:26:00Hell Creek is well-known for one carnivore in particular, T-Rex.
00:26:08This footprint is too small for an adult T-Rex.
00:26:13But it's possible that it was made by a young one.
00:26:16Robert also found this at Tannis.
00:26:30The crown of a tooth.
00:26:33Its shape and its serrated edge are indications that it comes from an adult T-Rex.
00:26:44The crown of a tooth.
00:27:06Bite marks found on T-Rex bones show that they ate other T-Rexes.
00:27:12And a youngster would make an easy catch.
00:27:22But not this time.
00:27:33Very few footprints are preserved as fossils in Hell Creek.
00:27:37So if you find several in one place, as Robert has done,
00:27:42it's a reasonable assumption that there would have been many more nearby.
00:27:50And that supports the idea that dinosaurs and pterosaurs were thriving at Tannis shortly before the impact.
00:27:59And if they were thriving, they must have been reproducing.
00:28:14Fossils from dinosaurs similar to T-Rex show they may have laid around 20 eggs in a circular nest.
00:28:29It's possible that, like crocodiles, they partly covered their eggs to keep them warm.
00:28:41For one T-Rex, a misfortune.
00:28:57For one T-Rex, a misfortune.
00:28:59But for all dinosaurs, a disaster was looming.
00:29:13Deep in space, the asteroid was approaching.
00:29:31It's journey would take it through the orbit of our neighboring planet, Mars.
00:29:47Had the two collided, a catastrophe on Earth would have been avoided.
00:29:51But it was not to be.
00:30:04And Earth's fate was sealed.
00:30:06As Robert's dig continues, his vision of what happened at Tannis is finally starting to come together.
00:30:29It seems the sandbank was full of life.
00:30:32T-Rex, Triceratops, little mammals, alongside the footprints of other dinosaurs and pterosaurs,
00:30:40all in a very small area.
00:30:44See the scales?
00:30:45I do.
00:30:46Oh my god.
00:30:47That excites me just looking at it.
00:30:52Then Robert finds something truly remarkable.
00:30:59See the cracks already forming?
00:31:00Look at that.
00:31:01So we're going to have to really monitor that before we glue it.
00:31:04Because this is getting vulnerable now.
00:31:07An almost complete creature.
00:31:12To get this block out, we're freezing it.
00:31:21Robert is about to attempt something tricky.
00:31:26Steady?
00:31:26Let's go.
00:31:30To get the fossil out in one piece, they're trying to freeze it using liquid nitrogen at almost 200 degrees below zero.
00:31:38Watch the footing.
00:31:47Lauren, I'm worried about brittleness here.
00:31:50Get that hammer.
00:31:51Yeah.
00:31:51Give this a couple of whacks with the hammer.
00:31:52Okay, move over five centimeters.
00:31:57Good.
00:32:00It's cracked loose.
00:32:03Yep.
00:32:03Okay, it's loose.
00:32:04So we have to get this out in one piece.
00:32:07One, two, three.
00:32:12Yee-haw.
00:32:14Total success.
00:32:15Total success.
00:32:16This is a technique used in archaeology for digging up human remains.
00:32:23We've got enough time to work with the fossil and not damage it.
00:32:27And I couldn't be happier.
00:32:29And the creature Robert found.
00:32:36A turtle.
00:32:40This is the fossil.
00:32:42Now it's been cleaned up.
00:32:43It's lying on its side.
00:32:46Here's the outline of its shell.
00:32:49The shape of the shell and the scorched edges here tell us that this was a binid turtle.
00:33:01Robert's binid turtle looks very similar to modern cooter turtles and lived in the same sort of
00:33:07freshwater environment.
00:33:08For a turtle, tennis would have been ideal.
00:33:23Warm, shallow water.
00:33:28Plenty to eat.
00:33:34And lots of safe places in which to warm up
00:33:36in the late Cretaceous sunshine.
00:33:43The turtle fossil Robert found is almost complete.
00:33:47This is the underside.
00:33:50And this brown material up here is fossilized wood.
00:33:55It's the end of a stick that passes right through its body and comes out just here.
00:34:02So the evidence points towards this turtle having been impaled.
00:34:06A violent end to one of the many creatures found in the crumbly rock layer at Tannis.
00:34:16When I look at the animals and plants preserved in the sediments of Tannis and the footprints beneath
00:34:21it, I see a picture of a vibrant ecosystem, many different dinosaurs and a thriving, thriving place.
00:34:28After ten years of digging, there is now enough evidence to piece together much of the story of Tannis and the creatures which lived here.
00:34:41Robert has found so many fossils, it looks as if even at the very end of the late Cretaceous, Tannis was bursting with life.
00:34:53Full of the giant reptiles that had dominated the planet for more than 150 million years.
00:35:02It's impossible to know how much longer their reign would have continued.
00:35:13Because all this was about to end.
00:35:25The asteroid hit in what is now the Yocatan Peninsula in Mexico.
00:35:38It's called the Chicxulub Asteroid after the town nearest to the center of its crater.
00:35:58Any living thing within 900 miles of the impact was destroyed by the blast.
00:36:28But what effect did the impact have on Tannis nearly 2,000 miles away?
00:36:48To find out, Robert is looking for clues that might link Tannis to the actual day the asteroid hit.
00:36:58We've got some wood and pressed up against this and all intertangled, we've got the carcasses of fish.
00:37:09Okay.
00:37:10That's a beautifully preserved tail. So that fish is going to be absolutely gorgeous.
00:37:16So part of the detail work that we're doing right now is going in and checking out all the individual elements in this mass death layer.
00:37:23Some of the evidence he's found so far has been hidden inside the fish themselves.
00:37:34In more ways than one, it literally is an operation of a Cretaceous fish.
00:37:37So we're performing surgery on this thing.
00:37:40Robert needs to open this fish's skull.
00:37:45And very carefully, we want to separate this from the rest of the fish.
00:37:49We've got a nice ant that made a home in there.
00:38:04And beautiful, look at that.
00:38:06Okay, here we have the gill bars of the fish.
00:38:08Those are the bars that hold the filaments of the gills.
00:38:11Between the gill bars, all of these clusters of round objects, those are the ejectospherules.
00:38:19Ejectospherules are tiny balls that were once molten rock.
00:38:23They could be evidence of what Robert suspects, that creatures here died on the day of the asteroid strike.
00:38:32Those ejectospherules last saw the light of day when they were flying through the air 66 billion years ago.
00:38:41After a large asteroid impact, a mix of vaporized and molten rock is propelled into space.
00:38:59There it cools, solidifying into tiny glass droplets.
00:39:06Some carry on deeper into space.
00:39:11But most are pulled back to Earth by gravity.
00:39:22After a major asteroid hit, trillions of ejectospherules would fall from the sky.
00:39:30Then, over millions of years, pressure and chemical reactions in the ground would turn most of them to clay.
00:39:37They'd look something like this.
00:39:42So, finding spherules in the gills of a fish, as Robert has done at Tannis,
00:39:48suggests the fish sucked them in while the spherules were still fawning.
00:39:52So, these creatures could have died at the time of an asteroid impact.
00:40:03Once Robert begins to look for ejectospherules, he finds more and more,
00:40:09and realizes the thick, crumbly layer of rocket Tannis is full of them.
00:40:17I mean, this stuff is... Oh my God, look at that one.
00:40:20These things are just gorgeous.
00:40:23Ejectospherules like this give us a fingerprint of where they came from.
00:40:27If these spherules were connected to the Chicxulub impact, then the whole crumbly layer could be full of evidence of what happened on the day the asteroid hit.
00:40:39That's a good one.
00:40:41Oh, is that a droplet right there?
00:40:43To see if that's the case, Robert needs to find a spherule that hasn't turned to clay.
00:40:50Oh my God, that's a beautiful droplet.
00:40:53Okay.
00:40:53The small pieces of orange material that Robert and Lauren are digging up may be able to help.
00:41:02They're amber.
00:41:05If there was anything flying through the air at that time, this is where it's going to get caught.
00:41:11The amber they're collecting was once sticky resin oozing out of a late Cretaceous tree trunk.
00:41:17It's a way for the tree to protect itself like a scab forming on a cut.
00:41:33Anything covered by the resin would be frozen in an amber thyme capsule.
00:41:37If they find a spherule preserved in amber, it could be analyzed to see if it comes from the Chicxulub asteroid impact.
00:41:55So during this batch, we were incredibly lucky that we came across two completely unaltered spherules.
00:42:03This spherule could be something amazing, evidence preserved well enough to analyze for chemical clues.
00:42:15If so, it could link Tannis directly with the Chicxulub impact and the last day of the dinosaurs.
00:42:23To investigate, Robert is joined at the Diamond Light Source by Professor of Natural History,
00:42:38Phil Manning, of the University of Manchester.
00:42:41They've already run initial tests on the spherules in America.
00:42:46What have you found out so far?
00:42:48These little glass spherules, these globs of molten material from the impact site,
00:42:53have a chemical signal that ties it with where they came from.
00:42:56Because when an asteroid hits, it melts the ground that it hits,
00:43:00but also that glass has a little bit of contamination from the asteroid itself.
00:43:05And that gives you a unique geochemical fingerprint.
00:43:08We can see once we've scanned it and looking at spherules from other sites in North Dakota,
00:43:13we can get a baseline for what the ejector should look like when it's related to the Chicxulub crater.
00:43:20You can see each element here and the ratios of those elements.
00:43:24And when we look at Tannis, it's a match.
00:43:27I mean, it perfectly overlays.
00:43:30So I think this is powerful evidence supporting that Tannis and Chicxulub are linked.
00:43:37And what do these findings mean for the rest of the fossils that you're finding in Tannis?
00:43:42This data is key for the entire site.
00:43:45Because once you have that link and you know what impact affected Tannis,
00:43:50then you essentially know that every object in that site,
00:43:53all the animals and the plants and everything buried in those sediments,
00:43:58are linked to the last day of the Cretaceous.
00:44:02And the synchrotron here in the UK reveals something even more remarkable.
00:44:08So this is showing a beautiful synchrotron scan of the half of one spherule.
00:44:17The glass is a good geochemical fingerprint.
00:44:20And we've got calcium, some iron, we've got strontium.
00:44:25But when we look at the entire thing, we see something quite unexpected.
00:44:30That's your entire spherule.
00:44:32What's this?
00:44:35In this, we've got a little bit of a nugget.
00:44:37There is a little particle right there.
00:44:39So we scan it.
00:44:40And that's a lot of iron in there.
00:44:43Over here, we've got chromium, a big peak in chromium.
00:44:47Over here, we've got a big peak in nickel.
00:44:48And the abundances of iron, nickel and chromium all together,
00:44:53that matches what you expect to see in a meteoric body.
00:44:56That does not match what you would normally have down here.
00:44:59So this is extraterrestrial material.
00:45:03If you were to sort of grind up and stuff into a spherule a piece of meteorite,
00:45:10that's what it's going to look like.
00:45:11This could be a piece of the Chicxulub asteroid.
00:45:15The piece of the bullet that killed the dinosaurs.
00:45:17No.
00:45:25Robert could have found a fragment of the asteroid itself in Tanis.
00:45:31Physical evidence linking this site to the Chicxulub impact.
00:45:36But Tanis is almost 2,000 miles away from where the asteroid hit.
00:45:41So exactly how did it cause the creature's deaths?
00:45:49To answer that question, Robert is searching in the mass death layer.
00:45:57Right here, we've got this intertangled mass of fish.
00:46:01There's one fish here.
00:46:02Another sturgeon goes this way underneath the body of a paddlefish.
00:46:05There's another sturgeon that goes this way underneath this log
00:46:09and continues out the other side.
00:46:11And his head hit that log and is deflected downward at a 90 degree angle.
00:46:18Robert uncovered a tangled mass of fossilized creatures and logs surrounded by spherules
00:46:26and crushed together in what's known as a log jam.
00:46:30He has a theory that the creatures were swept to their death in some kind of turbulent surge of water
00:46:36and quickly entombed in sediment, which is why they're so well preserved.
00:46:42But what could have caused the wave?
00:46:48One theory is a tsunami.
00:46:50The asteroid hit at sea.
00:46:58Recent studies show it may have caused the wave almost a mile high.
00:47:03The height of the wave would have gradually reduced as it spread across the oceans.
00:47:21In the late Cretaceous, North America was divided by a narrow sea that's been called the Western Interior Seaway.
00:47:30The tsunami could have traveled up this towards Tannis.
00:47:35But there's a big question about the tsunami idea.
00:47:41Oh, which fish is that?
00:47:46Which fish is that?
00:47:47It's a new, it's a new contact.
00:47:49Yeah.
00:47:49If a tsunami killed the fish, it would have to have hit while ejecta spherules were falling.
00:47:59Because spherules were found in the fish's gills.
00:48:04So how long after impact did the spherules arrive at Tannis?
00:48:10Pretend this ball of foil is a piece of ejecta coming out of the crater.
00:48:14It would then go on an arc path, ballistic trajectory, out of the crater and to wherever it lands.
00:48:19In this case, Tannis.
00:48:22If we know the distance between myself and the landing site,
00:48:26and if we know the size of that ball, we can accurately calculate how long it would take to get there.
00:48:35The result is surprising.
00:48:37Robert and his team calculated that these ejecta spherules
00:48:42landed at Tannis between 13 minutes and 2 hours after the impact.
00:48:50If a wave killed the fish, it must also have reached Tannis within 2 hours.
00:48:59Data from recent tsunamis show even a powerful one would take much longer than that
00:49:05to travel almost 2000 miles from the impact site to Tannis.
00:49:12So if it wasn't a tsunami, what could have caused the surge of water at Tannis?
00:49:16Professor Stein Bondovic is an expert in tsunamis.
00:49:35The fires in Norway are very special.
00:49:37We have tall mountains surrounding bodies of water, so the water is usually very pumped.
00:49:47In 2011, something very strange happened.
00:49:52The water in the fjord began to move violently.
00:49:56The height of the water increased by one and a half meter.
00:50:01Like a maelstrom with turbulent water, someone said that the fjord was boiling.
00:50:07News started to roll in. There'd been an earthquake 5,000 miles away in Japan.
00:50:18A journalist from the local newspaper called me,
00:50:20and he said that people were observing waves here in the fjords.
00:50:27I got a video clip of the waves.
00:50:30I saw immediately that they looked like a tsunami wave.
00:50:33So later in the afternoon, you can see that the fjord is perfectly calm.
00:50:40But at the beach here, you can see that the water is sloshing back and forth.
00:50:44And no one had ever seen anything like it.
00:50:49Some people got very upset and afraid.
00:50:55A magnitude 9 earthquake had devastated the northeast of Japan around Fukushima.
00:51:03But how did that affect a fjord so far away?
00:51:11So no one in Norway could feel the earthquake.
00:51:16But I could see that the times matched the arrival of the waves here in the fjord.
00:51:25Eventually, Stein and his team realized that this might have something to do with
00:51:31seismic waves, shock waves, that pass quickly through the earth during an earthquake.
00:51:39So it took only 12 minutes before the first signal of the earthquake in Japan reached
00:51:44all the way here to western Norway.
00:51:46So it was the seismic waves that caused the normally calm water in the fjord
00:51:54to slosh turbulently back and forth.
00:51:58Just thinking of that, scientifically, it's fantastic.
00:52:02Could something similar have happened in Tannis?
00:52:18Trying to find out is geophysicist Professor Mark Richards, who's been studying the site at Tannis for several years.
00:52:26He's working with Robert to discover what could have caused a surge of water here.
00:52:40A tsunami can't get here in less than minimum 12 hours.
00:52:45But seismic waves traveling from the Yucatan impact site to North Dakota can arrive here fairly quickly.
00:52:51In the late Cretaceous, the western interior seaway that divided North America
00:53:00could have been connected to Tannis through a system of rivers.
00:53:09If you have a very large body of water, like the western interior seaway,
00:53:13and you can shake it back and forth, you can generate a large water wave coming up this river at Tannis.
00:53:27So seismic waves from the impact could have caused surges of water in the Tannis river system.
00:53:35Seismic waves get here quickly enough, coming up the Tannis river,
00:53:40inundating this area arriving at the same time these spherules are still falling out of the air.
00:53:48The mystery of the wave and the thick layer of crumbly rock has been solved.
00:53:54Seismic waves traveling through the earth could have caused powerful surges of water at Tannis.
00:54:00Seismic waves, possibly carrying mud and marine creatures like ammonites from the western interior seaway.
00:54:13Dumping them on the Tannis sandbank and burying everything at the same time as spherules fell.
00:54:20Over millions of years, the mud would turn into the layer of crumbly rock.
00:54:36And that's the beauty of Tannis. What you're seeing is a deposit that is literally recording the last,
00:54:44say, 45 minutes to an hour and a half of the Cretaceous.
00:54:59If the extinction of the dinosaurs was a crime, the detectives solving it would have plenty of evidence.
00:55:07They would see that the asteroid was in the right place at the right time.
00:55:11They would see that no dinosaurs survived after the hit.
00:55:16They would have a piece of the murder weapon, a fragment of the asteroid.
00:55:21But they would be missing one very important thing.
00:55:25A body.
00:55:31No one has ever found the fossil of a dinosaur that was killed by the effects of the asteroid impact.
00:55:38But Robert did find part of a triceratops in the crumbly lair at Tannis.
00:55:45So could that be the remains of a dinosaur that died on that day?
00:55:51I'm still dubious about the horn. I kind of want to keep the horn in the jacket.
00:55:53I think if you took it off, at least take this section off to see what's going on under here.
00:55:58Yeah.
00:56:00To find out, the team needs to establish cause of death,
00:56:04which can be difficult when you only have a piece of skin and a horn to go on.
00:56:12This is the horn after they'd cleaned it up.
00:56:15The team is particularly interested in these lines here.
00:56:20And they found that the fractures go right through the horn.
00:56:25So rather than dying as a result of the impact,
00:56:29they wondered whether it had been killed in a fight.
00:56:31But when they looked at the fractures in more detail, they found signs of new bone growth here.
00:56:44An indication that the bone had started to heal.
00:56:48So it looked as though the triceratops survived the event that broke its horn.
00:56:52Could this triceratops have survived until the day of the impact?
00:57:03The team found evidence, including sagging in the skin,
00:57:06which suggested that there was decay underneath.
00:57:10That means its body had started to rot before it was entombed and preserved by the surge.
00:57:17So it seems that this dinosaur didn't die as a result of the asteroid impact.
00:57:25Perhaps in the months before the impact,
00:57:28the broken horn put the triceratops at a disadvantage over its rivals.
00:57:46And that might have led to starvation.
00:58:02Robert has still not found direct evidence of a dinosaur that was killed by the asteroid.
00:58:21We've got all these bones in the ground right now, but the one thing that we would
00:58:25just dream of finding is that one dinosaur that died on the day of the impact.
00:58:30And the weather isn't helping his search.
00:58:45How?
00:58:45That theropod print is toasted.
00:58:57Yeah, it was in a low corner.
00:58:59It's full of mud and water.
00:59:03The problem is it's wet.
00:59:04Look, see, if we're not careful, we're going to lose the print.
00:59:09And that's the biggest theropod print we've got.
00:59:10I see some areas that could use glue right now, too.
00:59:17The team is racing to excavate the footprints along with dozens of fish fossils tangled together in
00:59:23a logjam before storms wash them away.
00:59:27We're up against the clock here.
00:59:30The stuff that could be exposed right now is going to get ruined by the rain.
00:59:37But then Robert comes across something that looks very unusual.
00:59:41That's my guy.
00:59:44What is going on right there?
00:59:46Are we sure this isn't crocodilian?
00:59:48That's not crocodilian.
00:59:50No.
00:59:50All right, I'm going to try this piece right here.
00:59:53I'm going from the top and then twist up and it separates on right on that line.
00:59:57Oh, that's skin right there.
01:00:00That's actually scaly skin.
01:00:02No, no, no, no, no.
01:00:03Look, look, look.
01:00:04Look at that pattern right there.
01:00:06Have you ever seen elongated scales like that before, Dave?
01:00:09Scutalates and birds.
01:00:11Just careful.
01:00:13Oh, it's changing again.
01:00:15It's changing again.
01:00:18We're seeing it for the first time in 66 million years.
01:00:22I think we've got ourselves a dinosaur.
01:00:28A dinosaur fossil.
01:00:30And unlike the triceratops, this is located in the logjam, the mass death layer,
01:00:36surrounded by the fish with spherules in their gills.
01:00:45This is the most incredible thing that we could possibly imagine here.
01:00:47The best case scenario.
01:00:49We're excavating this mass death layer of fish from the surge sent up by the impact.
01:00:54And we've got dinosaur remains.
01:00:57The one thing that we would always want to find at this site.
01:01:01And here we've got it.
01:01:02This is unreal.
01:01:04I cannot process this in my brain.
01:01:06No, I am absolutely blown away by this.
01:01:09Just my heart is literally pumping out of my chest, wondering what is behind there.
01:01:12Just a couple of centimeters back in the outcrop.
01:01:15What is waiting for us back there?
01:01:21The team keeps digging.
01:01:25So this could be a rib cage.
01:01:26It could be laying against ribs that are curved.
01:01:28There's something here.
01:01:31That's hard.
01:01:32That's bone right next to the skin.
01:01:34That's an articular surface right there.
01:01:36So this is either a hip or a shoulder element.
01:01:42After hours of painstaking work.
01:01:48And we can go from the thigh of the animal.
01:01:51There's the knee.
01:01:52And then you've got the little calf muscles of the dinosaur.
01:01:56They're bulging out.
01:01:57And you go down to the ankle bones.
01:02:00And these are the toes of the feet.
01:02:03We've got nails at the tips of the toes.
01:02:05It's a beautifully preserved leg.
01:02:06All articulated, covered with skin.
01:02:10The complete leg of a dinosaur.
01:02:14In my wildest dreams, I never expected to find a dinosaur leg in this deposit.
01:02:18Yeah.
01:02:18I mean, and it's got skin and tissue.
01:02:22It does look just like a drumstick.
01:02:24It looks like a Thanksgiving turkey just laid out in the ground.
01:02:28And this weird scale pattern on the thigh of the animal,
01:02:31which we've never seen in a dinosaur before.
01:02:33Well, Thessalosaurs don't have any form of defense.
01:02:36So they have to have camouflage or something.
01:02:39That's a good point.
01:02:40So this could have been some sort of camouflage marking.
01:02:42Yeah.
01:02:42Robert thinks he has found the body in question.
01:02:48A dinosaur that might itself have witnessed the cataclysmic impact.
01:02:57Dinosaur fossils are not known from the last years of the Cretaceous.
01:03:02And it was unclear whether they were already extinct or in decline or what was going on.
01:03:07So they were just sort of absent.
01:03:12And this answers that question.
01:03:13Were dinosaurs still there then?
01:03:15Well, yes, this one likely died in that search.
01:03:19For such big claims, Robert needs verification.
01:03:31He's brought the dinosaur leg to London to get a second opinion.
01:03:36And then here are the pads of the toes.
01:03:38We see all those beautiful scales lined up.
01:03:41From Professor Paul Barrett, an expert in ornithischian dinosaurs from the Natural History Museum.
01:03:50So what do you think this might be?
01:03:52When we look at the leg, it has claws.
01:03:55Like the claws we see in small, agile, bipedal running dinosaurs that are plant eaters.
01:04:02We can rule out things like triceratops,
01:04:04partly just because it's not big and stocky.
01:04:07And the proportions of those legs are also different from some of the other plantees,
01:04:10as we see, in that they have this rather long ankle and shin compared with its thigh bone.
01:04:17So as we narrow those possibilities down,
01:04:19what we're left with probably is an animal called a Thessalosaur.
01:04:22Thessalosaurs lived next to rivers where there was plenty of rich vegetation to feed on.
01:04:39They had leaf-shaped teeth common amongst herbivores and claws on their short front limbs,
01:04:46of their own animals.
01:04:47Excellent for digging.
01:04:56And how did Robert's Thessalosaur die?
01:05:06How did Robert's Thesalosaur die?
01:05:11Could it have been killed by another dinosaur?
01:05:14It's a possibility.
01:05:15This is a relatively agile animal.
01:05:18And that turn of speed would have been its primary defence against the large predators
01:05:22living alongside it.
01:05:25So, to escape a hungry T-Rex, a Thesalosaur's first line of defence...
01:05:35...would have been to run.
01:05:41But it may have had another defensive trick.
01:05:53Living next to rivers, it's possible Thesalosaur were able to swim.
01:05:58It doesn't seem to me like there is any evidence that this animal was predated.
01:06:16None of the obvious tooth marks or leftover bits of carnivore teeth to suggest it's been eaten.
01:06:22So, how do you think it died?
01:06:25It didn't have any particularly nasty diseases when it died.
01:06:29As we can see, the bones look okay.
01:06:31So, this is an animal that was probably living and healthy at the time that this happened to it.
01:06:36Could this be a victim of the meteor strike?
01:06:41I think it's entirely possible.
01:06:43This is actually a shoulder bone.
01:06:46And this bone in the living animal would actually be way over here.
01:06:49And similarly, this little bone here would have been from about maybe a third of the way
01:06:54along the tail, maybe halfway down.
01:06:56So somehow, these two bones have been telescoped together.
01:06:59So maybe this animal has been tumbled around.
01:07:03We've ruled out a lot of other possible causes of death for this animal.
01:07:08So it could well be that this is an animal that was there being tumbled around in its death
01:07:12throes in that river as a result of the asteroid impact.
01:07:15Well, it is exactly analogous to those human bodies found in Pompeii.
01:07:22It's very similar in terms of that quick entombment.
01:07:25Yes.
01:07:26And it's almost as evocative.
01:07:29That's absolutely true.
01:07:30You've got literally the blink of an eye at the end of the Cretaceous, snapped up into
01:07:35history and there it is ready to be dug up.
01:07:41Wow.
01:07:51After years of investigation, Robert has found out a great deal about the creatures which
01:07:57lived at Tannis.
01:07:58And he knows that many of them were alive on that fateful day when the asteroid devastated
01:08:05our planet.
01:08:07But how exactly did they die?
01:08:09Robert's finds now allow us to tell the story of that day and finally answer that question.
01:08:20One of the most important days in Earth's history probably started much like any other late
01:08:26spring morning.
01:08:32We know the season because Robert found fossils of young fish that died at the size they reach
01:08:38at that time of year.
01:08:40And this agrees with evidence already found by other scientists.
01:08:47Perhaps this day that would end with so much death began with something different.
01:08:55A new life.
01:09:20No one can be certain of the exact timings of the day when the asteroid collided with
01:09:25our planet.
01:09:27But it's estimated that within just 40 minutes of the impact, the consequences for the creatures
01:09:33of Tannis would have been profound.
01:09:39Based on Robert's finds and the latest evidence from other scientists, this is how the catastrophe
01:09:45might have unfolded.
01:09:47The asteroid is around seven miles across, bigger than Mount Everest, and traveling at close
01:09:58to 45,000 miles an hour.
01:10:09The impact causes an explosion bigger than a billion Hiroshima atomic bombs.
01:10:19At Tannis, almost 2,000 miles away, it's completely silent.
01:10:29But at the impact site, the asteroid vaporizes.
01:10:37More than three trillion tons of rock are ejected into space in a blast of superheated violence.
01:10:49The winds higher than 600 miles an hour, a colossal earthquake, followed by a ring of massive tsunamis.
01:11:00All the while, the creatures at Tannis go about their business.
01:11:17The evidence suggests that baby pterosaurs emerged from the egg, ready to fend for themselves.
01:11:46And that includes...
01:11:47Flying?
01:11:48Well, almost.
01:11:51Elsewhere, as the devastation spreads out across North America towards Tannis, dinosaurs
01:12:11and creatures of all shapes and sizes are obliterated by the blast.
01:12:16At Tannis, for a few more precious minutes, life carries on as usual.
01:12:18But the clock is ticking.
01:12:19At Tannis, for a few more precious minutes, life carries on as usual.
01:12:33The blast from the impact never reaches Tannis, but seismic shock waves do.
01:13:00They are far more powerful than any earthquake ever recorded.
01:13:19The Thessalosaur might head for a place of safety.
01:13:26But seismic waves are now slowly shaking the whole region, causing water to slosh and churn.
01:13:38But Tannis, strange currents in the river give a hint of what is still to come.
01:13:58Next, it begins to rain.
01:14:02Ejector spherules are falling back to Earth.
01:14:06As the spherules begin their fall, friction heats them until they're red hot.
01:14:21Then the heat transfers to the air.
01:14:32Temperatures rise with every second.
01:14:34As the heat builds, the creatures of Tannis are fighting for their lives.
01:14:49And then, as seismic waves continue to slowly rock the whole region...
01:14:56A violent surge wave, ten meters high, rushes up the Tannis river.
01:15:11A violent surge wave, ten meters high.
01:15:27Surviving the turbulence of the surge is a challenge even for the best swimmers.
01:15:32Then, the powerful rocking of the river system slowly begins to draw the water back the way it came.
01:15:51Swimming may have saved the Thessalosaur in the past, but not this time.
01:16:13A large, robust animal like a T-Rex might have survived the surge.
01:16:18As might a hard-shelled reptile.
01:16:27But there is much more to come.
01:16:30As billions of tons of superheated spherules continue to fall, the atmosphere gets even hotter.
01:16:40Igniting dead leaves and sparking wildfires.
01:16:48Earthquakes.
01:16:53Fire.
01:16:55Devastation.
01:17:00Little would survive for long.
01:17:03On land.
01:17:09Or in the air.
01:17:10As the air reaches the temperature of an industrial oven.
01:17:22Those that live deep underground may have a better chance.
01:17:23The air reaches the temperature of an industrial oven.
01:17:31Those that live deep underground may have a better chance.
01:17:36Those that live deep underground may have a better chance.
01:17:41As the slow sloshing of the river system continues.
01:17:51Another powerful surge hits.
01:17:52Another powerful surge hits.
01:17:56Another powerful surge hits.
01:17:57Another powerful surge hits.
01:17:58Another powerful surge hits.
01:18:03Then Azura comes.
01:18:05Late in.
01:18:07On opportunity to fight for an area.
01:18:09After a lot of adventures.
01:18:11The F
01:18:23Fall In.
01:18:25For many of the creatures of Tannis.
01:18:28Their stories end under water.
01:18:46In less than two hours, the world has changed forever.
01:18:50The mud the surge waves leave behind will gradually turn into the thick layer of crumbly rock entombing the creatures which died here.
01:19:09Until 66 million years later, when they're finally unearthed.
01:19:20Robert's finds have helped us understand in remarkable detail what happened at Tannis in the minutes after the asteroid impact.
01:19:34But what about the rest of the world?
01:19:39The impact triggered catastrophic events such as earthquakes all over the planet.
01:19:44And as ferules continued to fall,
01:19:51wildfires may have sprung up around the globe.
01:19:55As that horrific day drew to a close,
01:20:00many of the world's dinosaurs were already dead.
01:20:04Research shows that the angle at which the asteroid hit and the sulfur rich rocks at the impact site amplified the devastation.
01:20:20Billions of tons of sulfur were ejected into the atmosphere, blocking the sunlight.
01:20:25Without light, most plants died and food became scarce.
01:20:36As the weeks and months passed, any dinosaur left alive would have died of hunger.
01:20:41In the oceans, it was the same.
01:20:47Nearly all of the world's plankton disappeared, leading to the starvation of most marine creatures.
01:20:55It's thought that the nuclear winter that followed caused a global temperature drop of at least 25 degrees centigrade.
01:21:04The fossil record tells us that this huge change in climate marked the disappearance of three quarters of all species, including the dinosaurs.
01:21:17The planet was in semi-darkness for around a decade as dust and soot slowly fell to Earth.
01:21:24But then came something wonderful, a new beginning.
01:21:37Once the dust cleared from the atmosphere and the sunlight returned,
01:21:43plant life was gradually restored,
01:21:46led by ferns, the spores of which had lain dormant deep underground.
01:21:52And the world began to turn green once more.
01:21:58But what about the animals?
01:22:03Back at Tannis, Robert has unearthed something that could have helped save some of the creatures from the devastating fires.
01:22:12We saw a little thing poking out, so we kind of followed it back.
01:22:15And I'm so glad that we did, because what we have here is a fossil burrow from an animal 66 million years ago.
01:22:24The only animals that would have been around back then that would likely build a burrow like this would be the small mammals, roughly ferret sized, and also some reptiles.
01:22:33If it is from a mammal, this is sort of a window into the lifestyle of some of our oldest ancestors out here.
01:22:43This guy would have burrowed sideways right into the riverbank.
01:22:47They actually have some scratch marks on there from the interior when they were digging it.
01:22:51Going back, and he would have lived back here and sought shelter from the dinosaurs, because they just did not want to get eaten.
01:22:58Burrows are part of the reason that mammals survived the great extinction.
01:23:11During the nuclear winter, a burrow would have provided warmth, protection, and a place to store food.
01:23:18Mammals that survived were resourceful omnivores, and insects would have been a plentiful source of food.
01:23:40And they had another advantage.
01:23:43Their size.
01:23:44If conditions are right, many animal species get larger as they evolve over millions of years.
01:23:53Take T-Rex as an example.
01:23:56This is the cast of the lower jaw of a predecessor called Gorgosaurus, which lived 72 million years ago.
01:24:06Whereas this is the cast of the lower jaw of a T-Rex, which lived 5 million years later.
01:24:14Look at the difference in size.
01:24:17But the bigger the creature, the more energy they need to stay alive.
01:24:22So when catastrophe strikes and food is scarce, the largest tend to die out, whilst the smallest often survive.
01:24:30That's one of the reasons why many of the smaller mammals lived through the great darkness.
01:24:41And they weren't alone.
01:24:42Robert's fossil turtle may have been unlucky, but many others survived.
01:24:54As did crocodiles, snakes, and many fish species.
01:25:00And as for the dinosaurs, did the impact really kill them all?
01:25:07Well, this beautiful fossilised feather isn't from a bird, but from a predatory dinosaur.
01:25:14So we have to be careful when we say that dinosaurs are extinct.
01:25:19Because what we call birds originally evolved from the smallest feathered dinosaurs.
01:25:27So to be correct, we should say all non-avian dinosaurs are extinct.
01:25:32Robert's finds have given us a better idea than ever before about what happened on the day that led to the extinction of the largest beasts ever to walk the earth.
01:25:51Dinosaurs were perhaps some of nature's most extraordinary creatures, dominating the planet for over 150 million years before they became extinct.
01:26:09But extinction comes in different forms.
01:26:12And many of the amazing creatures and plants alive today are also threatened.
01:26:17It's possible that humanity is having as big an impact on the world as the asteroid that ended the age of the dinosaurs.
01:26:27As human beings, we are unique in our ability to learn from the distant past.
01:26:34Now, we must use that ability wisely and do our very best to protect the millions of species for whom, alongside us, this planet is home.
01:26:47So, let's life and do our own teams.
01:26:48We must use that ability to protect our bodies.
01:26:51So, let's go.
01:26:53For that, we may be a model of the planet.
01:26:55We may not use this.
01:26:58And the world that we may be in the world.
01:27:00And the world that we may be in the world.
01:27:12Transcription by CastingWords
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