0:00:03 > 0:00:07Once upon a time, dinosaurs ruled the world.
0:00:07 > 0:00:09But 66 million years ago...
0:00:11 > 0:00:14..they vanished, virtually overnight.
0:00:15 > 0:00:21So what precisely happened in the minutes, the days, the weeks
0:00:21 > 0:00:25that wiped out three-quarters of the animal species on the planet?
0:00:25 > 0:00:30Many scientists now believe it was the impact of an asteroid
0:00:30 > 0:00:32that caused their extinction.
0:00:32 > 0:00:37But nobody has been able to prove it...until now.
0:00:39 > 0:00:43Evolutionary biologist Ben Garrod and I have been granted
0:00:43 > 0:00:46exclusive access to a multi-million-pound drilling mission
0:00:46 > 0:00:50into the exact point where the asteroid hit.
0:00:50 > 0:00:53This really is one of the most impressive science laboratories
0:00:53 > 0:00:54I've ever seen.
0:00:54 > 0:00:57Could the team's findings about the asteroid
0:00:57 > 0:01:00finally solve the ultimate dinosaur mystery?
0:01:02 > 0:01:05This is an absolutely amazing event -
0:01:05 > 0:01:09mountains the size of the Himalayas were formed in seconds.
0:01:11 > 0:01:13With Ben at the impact site,
0:01:13 > 0:01:16I will be travelling across the world
0:01:16 > 0:01:19to look for evidence of the events that followed.
0:01:19 > 0:01:23That is a bit of fossilised bone,
0:01:23 > 0:01:25and they're everywhere, scattered across this hillside.
0:01:25 > 0:01:27It's just extraordinary.
0:01:27 > 0:01:29Armed with astonishing new revelations...
0:01:29 > 0:01:33Right here, we have the smoking gun, and here, we have the bodies.
0:01:33 > 0:01:37..we may finally be able to paint a picture
0:01:37 > 0:01:40of the demise of the dinosaurs.
0:02:03 > 0:02:05I'm off the coast of Mexico right now
0:02:05 > 0:02:07and this thing you can see behind me
0:02:07 > 0:02:09is a specially adapted drilling platform.
0:02:09 > 0:02:12Now, there's an international team of scientists on board
0:02:12 > 0:02:15who are drilling far beneath the seabed where we are now
0:02:15 > 0:02:19to look for evidence to see why and how the dinosaurs died.
0:02:21 > 0:02:23This is the exact spot of a huge asteroid strike
0:02:23 > 0:02:29that happened at precisely the same time the dinosaurs were wiped out.
0:02:29 > 0:02:33This is Earth, 66 million years ago.
0:02:33 > 0:02:35Here's the asteroid.
0:02:35 > 0:02:39It's nine miles across - the size of a city.
0:02:39 > 0:02:41And here's the first surprising thing -
0:02:41 > 0:02:42the speed of it.
0:02:42 > 0:02:45It may not look that fast at this scale,
0:02:45 > 0:02:50but it was travelling an unbelievable 40,000 miles an hour.
0:02:52 > 0:02:54Seen from the ground,
0:02:54 > 0:02:58it would have gone from a mere dot in the sky to impact
0:02:58 > 0:02:59in a matter of seconds.
0:03:04 > 0:03:07The asteroid smashed into a shallow sea
0:03:07 > 0:03:08north of modern-day Mexico,
0:03:08 > 0:03:11exactly where the team is starting to drill.
0:03:13 > 0:03:18The theory goes that this impact set off a chain reaction of events
0:03:18 > 0:03:20that killed the dinosaurs.
0:03:22 > 0:03:24But here's the heart of the mystery...
0:03:27 > 0:03:31When you compare the size of the asteroid and the Earth,
0:03:31 > 0:03:33well, the asteroid is comparatively small.
0:03:33 > 0:03:37It's like a grain of sand hitting a bowling ball.
0:03:37 > 0:03:41So how did this asteroid cause a mass extinction
0:03:41 > 0:03:43all around the globe?
0:03:44 > 0:03:48By extracting rock from the impact crater,
0:03:48 > 0:03:50the team hopes to find out.
0:03:54 > 0:03:57So, I'm not even strapped in, and I don't especially like heights!
0:03:57 > 0:03:59But this is great, this is great.
0:04:02 > 0:04:06This multi-million-pound operation has been decades in the planning
0:04:06 > 0:04:09and we're the only film crew to have access.
0:04:12 > 0:04:16Professor Joanna Morgan first proposed the operation.
0:04:16 > 0:04:17It's been a long wait.
0:04:17 > 0:04:19I've been excited for, you know,
0:04:19 > 0:04:2216 years, so to actually... For it to be happening
0:04:22 > 0:04:24is quite scary.
0:04:24 > 0:04:29We've had so much effort between us to get us to this point
0:04:29 > 0:04:32that...that you really want some lovely results.
0:04:32 > 0:04:35Joining her on board to co-direct operations
0:04:35 > 0:04:37is Professor Sean Gulick.
0:04:37 > 0:04:41So, this is the ultimate test of some ideas, right?
0:04:41 > 0:04:43We have all these models about how the extinction happened,
0:04:43 > 0:04:46but without some samples from ground zero,
0:04:46 > 0:04:48we can't really test them.
0:04:51 > 0:04:54This really is one of the most impressive science laboratories
0:04:54 > 0:04:57I've ever seen, and it's an amazing place -
0:04:57 > 0:04:59we're going to have a quick look around.
0:05:02 > 0:05:05This central area here is incredibly important.
0:05:05 > 0:05:09This is known as Main Street by the crew and scientists.
0:05:09 > 0:05:12Now, these shipping containers are actually science labs
0:05:12 > 0:05:14and, in each one...
0:05:15 > 0:05:17..is a whole, entire laboratory.
0:05:20 > 0:05:23You can see in here huge amounts of equipment.
0:05:23 > 0:05:25This is one of the scanning labs.
0:05:28 > 0:05:30But there are still lots of personal touches.
0:05:30 > 0:05:32You can see where all the different scientists
0:05:32 > 0:05:33and the rest of the crew are from.
0:05:33 > 0:05:35But my hometown's not on here!
0:05:39 > 0:05:41But this is the star of the show.
0:05:42 > 0:05:48This huge drill will bore through 1.5km of solid rock,
0:05:48 > 0:05:50taking us back to the time of the dinosaurs.
0:05:51 > 0:05:52This is the drill bit.
0:05:52 > 0:05:56Each one of these little nodules is an industrial diamond.
0:05:56 > 0:05:58We've had this one modified with a higher-speed head
0:05:58 > 0:06:00that allows us to core.
0:06:02 > 0:06:06Literally collecting a column of rock three metres at a time
0:06:06 > 0:06:09and, as we go further down the borehole,
0:06:09 > 0:06:11we go further back in time,
0:06:11 > 0:06:13until we actually get to the moment of the impact,
0:06:13 > 0:06:15about 66 million years ago.
0:06:17 > 0:06:19As Ben joins the team drilling down into the rock
0:06:19 > 0:06:22for evidence of the asteroid's effects,
0:06:22 > 0:06:26I'm travelling the world to look for clues from fossils.
0:06:28 > 0:06:33My first stop, 1,700 miles from the crater,
0:06:33 > 0:06:34is New Jersey.
0:06:34 > 0:06:37I'm here to see a mass prehistoric graveyard
0:06:37 > 0:06:41unlike anything that's been unearthed before.
0:06:43 > 0:06:44This disused quarry
0:06:44 > 0:06:49may be one of the most important palaeontological sites in the world.
0:06:49 > 0:06:52I'm here to view an intriguing discovery
0:06:52 > 0:06:55that may directly link the mass extinction
0:06:55 > 0:06:58to the asteroid impact.
0:06:58 > 0:07:02There's something very strange about this mass extinction.
0:07:02 > 0:07:07So many animals died on that day, and yet, it's virtually impossible
0:07:07 > 0:07:11to find casualties of this devastating event.
0:07:11 > 0:07:14But palaeontologists here in New Jersey
0:07:14 > 0:07:17think they might have found just that -
0:07:17 > 0:07:21evidence of the day the dinosaurs died.
0:07:21 > 0:07:23It's such an extraordinary claim,
0:07:23 > 0:07:27I want to see exactly what they've discovered.
0:07:30 > 0:07:34'I've arranged to meet palaeontologist Kenneth Lacovara,
0:07:34 > 0:07:36'one of the most experienced -
0:07:36 > 0:07:39'and luckiest - fossil hunters in the world.
0:07:39 > 0:07:42'He's going to show me where the discovery was made,
0:07:42 > 0:07:44'in what used to be the seabed.'
0:07:44 > 0:07:45We're going back through time.
0:07:45 > 0:07:49We are. Now, if you take one more step, Alice,
0:07:49 > 0:07:50you will be in the Cretaceous.
0:07:50 > 0:07:51Excellent.
0:07:51 > 0:07:55'As we descend into the quarry, we arrive at layers of sediment
0:07:55 > 0:07:58'that were deposited during the Cretaceous period,
0:07:58 > 0:08:01'when dinosaurs ruled the Earth.'
0:08:01 > 0:08:03So, down here, we're in the Cretaceous period.
0:08:03 > 0:08:08Here, we're in the Palaeogene period, after the Cretaceous.
0:08:08 > 0:08:11'The boundary between the two periods marks the moment
0:08:11 > 0:08:15'that the dinosaurs went extinct, 66 million years ago.'
0:08:15 > 0:08:18So, this is the boundary right here.
0:08:18 > 0:08:22No-one in the world has found an in-place dinosaur fossil
0:08:22 > 0:08:24one centimetre above that line.
0:08:28 > 0:08:33The team uncovered a dense layer of fossils right at this boundary line.
0:08:33 > 0:08:36It's potentially a unique discovery.
0:08:36 > 0:08:38Dinosaurs.
0:08:38 > 0:08:39No dinosaurs.
0:08:39 > 0:08:42Gosh, that's extraordinary.
0:08:42 > 0:08:48'The animals found here are typical of the late Cretaceous.'
0:08:48 > 0:08:52- That's a formidable-looking tooth. - It is, isn't it?- Yeah.
0:08:52 > 0:08:53What's that from?
0:08:53 > 0:08:56This is from a mosasaur.
0:08:58 > 0:09:02Mosasaur's a giant marine reptile, an apex predator.
0:09:02 > 0:09:04Think of a Komodo dragon that's as long as a bus,
0:09:04 > 0:09:06with paddles for limbs,
0:09:06 > 0:09:09a two-metre jaw packed full of these teeth.
0:09:09 > 0:09:14We find mosasaurs here below our bone bed and in the bone bed.
0:09:14 > 0:09:17We never find mosasaurs above the bone bed
0:09:17 > 0:09:19because they go extinct along with the dinosaurs.
0:09:21 > 0:09:24Ken believes that the mosasaurs he's found here
0:09:24 > 0:09:27may be some of the last that ever lived...
0:09:28 > 0:09:32..and that they died as part of the great extinction event.
0:09:34 > 0:09:36To understand why,
0:09:36 > 0:09:40we have to look at the other fossils that Ken has found in the quarry.
0:09:45 > 0:09:48- This is incredible, Ken! - HE LAUGHS
0:09:50 > 0:09:51Look at all those fossils.
0:09:51 > 0:09:53- 25,000 of them. - SHE GASPS
0:09:53 > 0:09:57The way you've laid them out in this grid, is this as you found them?
0:09:57 > 0:09:59These are the places in which we've found them, yep.
0:09:59 > 0:10:01- 170 square metres of them. - SHE GASPS
0:10:01 > 0:10:05It's an astonishing amount of work.
0:10:05 > 0:10:07All these fossils occur in a layer
0:10:07 > 0:10:10that's no more than ten centimetres thick.
0:10:10 > 0:10:13'For Ken, the first clue that these animals all died
0:10:13 > 0:10:15'in a single catastrophic event
0:10:15 > 0:10:20'is that the skeletons are largely intact with no teeth marks on them.'
0:10:20 > 0:10:22They weren't transported, they weren't scavenged,
0:10:22 > 0:10:25they died suddenly and they were buried quickly.
0:10:25 > 0:10:29That tells us that this is a moment in geological time
0:10:29 > 0:10:33that's days, weeks, maybe months, but this is not thousands of years,
0:10:33 > 0:10:36this is not hundreds of thousands of years.
0:10:36 > 0:10:38This is, essentially, an instantaneous event.
0:10:39 > 0:10:44'A second clue comes from the surprising mix of species
0:10:44 > 0:10:47'that had lived in many different environments.'
0:10:47 > 0:10:51I mean, I can pick out large vertebrates.
0:10:51 > 0:10:53Sure. We see the occasional bird here.
0:10:53 > 0:10:55There's a tibia from a crocodile.
0:10:55 > 0:10:58And that's laying next to a piece of the outer shell
0:10:58 > 0:11:00of a huge sea turtle,
0:11:00 > 0:11:03something that would be maybe a metre-and-a-half across.
0:11:04 > 0:11:06'And just a few feet away,
0:11:06 > 0:11:10'Ken found another turtle from a different part of the ocean.'
0:11:10 > 0:11:13This is a coastal-living turtle.
0:11:13 > 0:11:16You can see how tightly articulated it is.
0:11:16 > 0:11:19The shell doesn't flex, so we know that this turtle
0:11:19 > 0:11:21didn't dive deeply in the ocean.
0:11:21 > 0:11:24This animal was living around the coast, in the shallow water.
0:11:24 > 0:11:26So, what do you think you've got here?
0:11:26 > 0:11:28All this stuff died suddenly,
0:11:28 > 0:11:30and was buried all at about the same time,
0:11:30 > 0:11:32so that means all the stuff that comes in from the coast
0:11:32 > 0:11:34has to come in suddenly.
0:11:34 > 0:11:39And that tells us that there is an environmental disturbance going on
0:11:39 > 0:11:41on the coastline, upshore from here.
0:11:42 > 0:11:44Whatever was the cause,
0:11:44 > 0:11:46this calamity that wiped out these animals,
0:11:46 > 0:11:48it was happening in the deep water,
0:11:48 > 0:11:50it was happening along the coastline,
0:11:50 > 0:11:51and it's happening on land.
0:11:56 > 0:12:00Ken's theory is controversial, but if he's right,
0:12:00 > 0:12:03this could be the first fossil evidence
0:12:03 > 0:12:08of a sudden mass death event at the end of the Cretaceous...
0:12:11 > 0:12:18..right at that point in time when 75% of life on Earth is wiped out.
0:12:20 > 0:12:24But what caused this mass death event?
0:12:24 > 0:12:27Could all these animals have been killed by the impact of an asteroid
0:12:27 > 0:12:321,700 miles away in the Gulf of Mexico?
0:12:32 > 0:12:36Ben is with the scientists who have been drilling into the seabed
0:12:36 > 0:12:38above the asteroid crater.
0:12:38 > 0:12:41I'm here, right in the middle of the drilling platform,
0:12:41 > 0:12:44and there's a fresh core about to come out.
0:12:46 > 0:12:50We've already drilled through 500 metres of limestone sediment.
0:12:51 > 0:12:54Now, we're going to start to bring up rock core
0:12:54 > 0:12:59for the scientists to examine as we get closer to the impact crater.
0:12:59 > 0:13:01This is the first full core of the expedition,
0:13:01 > 0:13:03we're excited to say.
0:13:03 > 0:13:06The first full, three-metre-long core,
0:13:06 > 0:13:07some light layers.
0:13:07 > 0:13:09We're wondering if they're ashes or something.
0:13:09 > 0:13:11We're pretty excited.
0:13:11 > 0:13:13This, along with other core samples like it,
0:13:13 > 0:13:15can tell the team so much information
0:13:15 > 0:13:18about what was going on at the time of the impact.
0:13:20 > 0:13:23The first thing the team does with each new core
0:13:23 > 0:13:25is find out how old the rock is.
0:13:27 > 0:13:31Exactly what's living, exactly what fossils we find
0:13:31 > 0:13:32tell us what age we are.
0:13:32 > 0:13:35As soon as the core comes up on deck,
0:13:35 > 0:13:37we are given a small crumb of material,
0:13:37 > 0:13:41we take it back to the lab and give an age call
0:13:41 > 0:13:44within five minutes of the core appearing on the deck.
0:13:47 > 0:13:49I just got some sweet pictures. Look at this crystal -
0:13:49 > 0:13:52this is the same stuff from the core catcher under the microscope.
0:13:52 > 0:13:53Look at these crystals.
0:13:55 > 0:13:58Though it contains valuable information,
0:13:58 > 0:14:01this core isn't from the impact crater itself.
0:14:01 > 0:14:05Instead, it's from the layers of sediment above it.
0:14:05 > 0:14:09The team needs to drill a further 130 metres down into the sediment
0:14:09 > 0:14:11to get to the crater itself.
0:14:13 > 0:14:17The further down they go, the harder the rock is,
0:14:17 > 0:14:20so that means weeks of 24-hours-a-day drilling.
0:14:23 > 0:14:26They want to pull core from an area of the inner crater
0:14:26 > 0:14:29called the peak ring,
0:14:29 > 0:14:32found only in the largest of super craters.
0:14:35 > 0:14:38They're formed when the massive impact of an asteroid
0:14:38 > 0:14:42forces rock to erupt in a central uprising,
0:14:42 > 0:14:46which then collapses outwards to form the distinctive peak ring.
0:14:47 > 0:14:51It's these rocks that contain the clues to what happened
0:14:51 > 0:14:53in the moments after impact.
0:14:59 > 0:15:04It's been three weeks since the team started drilling into the seabed
0:15:04 > 0:15:06and time and money are running short.
0:15:06 > 0:15:09We didn't sample that because it's in the middle of a core.
0:15:09 > 0:15:13The drill is nearly through the hundreds of metres of limestone
0:15:13 > 0:15:15that has built up since the asteroid struck,
0:15:15 > 0:15:18approaching rock layers from the day of impact.
0:15:20 > 0:15:21I mean, look at this on the microscope.
0:15:21 > 0:15:27I would say somewhere between about 64.5 million years ago
0:15:27 > 0:15:31and 63.5.
0:15:31 > 0:15:32Wow.
0:15:32 > 0:15:36- Wow, so this was E4...- Yup. - ..which is 53 million.
0:15:36 > 0:15:39Now we are 63, so we have 10 million.
0:15:39 > 0:15:41Yeah, that sounds like a good estimate,
0:15:41 > 0:15:44- so 10 million years in three metres. - In three metres.
0:15:44 > 0:15:46We've been stuck in the same zone for a while,
0:15:46 > 0:15:48going forward very slowly, and then all of a sudden...
0:15:48 > 0:15:51- HE CLICKS HIS FINGERS - ..boom, big jump in time.
0:15:51 > 0:15:55The team are noticing clues in the latest cores -
0:15:55 > 0:15:56something extraordinary.
0:15:59 > 0:16:02But as you go down, it's just more and more and more of it.
0:16:02 > 0:16:04It's got this greenish tint.
0:16:04 > 0:16:06Yeah, there's one right there.
0:16:06 > 0:16:12We've now had four cores of ever-coarsening sands.
0:16:12 > 0:16:15I think the only process on Earth that can do that is a tsunami.
0:16:18 > 0:16:23Tsunamis are huge, turbulent waves that rip material from the seabed.
0:16:23 > 0:16:24When the wave passes,
0:16:24 > 0:16:30the material is deposited back on the ocean floor in size order.
0:16:30 > 0:16:33The heaviest, most coarse sand settles first,
0:16:33 > 0:16:36the finer sand on top.
0:16:36 > 0:16:39The thicker the deposit, the bigger the tsunami.
0:16:43 > 0:16:46And the fact it's already, like, 12 metres thick
0:16:46 > 0:16:48probably already makes it one of the largest,
0:16:48 > 0:16:50maybe the largest tsunami deposit ever discovered.
0:16:50 > 0:16:53And if it keeps getting thicker as we go, it will absolutely,
0:16:53 > 0:16:57unquestionably, be the largest tsunami deposit ever discovered.
0:16:57 > 0:17:00And, of course, it's right here in ground zero of the impact.
0:17:00 > 0:17:05It's the first major clue of how the impact of this asteroid
0:17:05 > 0:17:07could have caused a deadly chain of events,
0:17:07 > 0:17:11starting with the biggest tsunami in history.
0:17:13 > 0:17:161,700 miles away in New Jersey,
0:17:16 > 0:17:18Ken Lacovara has also picked up evidence
0:17:18 > 0:17:21of what could have been a tsunami.
0:17:23 > 0:17:27After that asteroid hit, it's just chaos on the continent.
0:17:27 > 0:17:30There are tsunami waves lapping up against the continent.
0:17:30 > 0:17:33You're going to have trees floating down the estuaries.
0:17:33 > 0:17:35You're going to have sediment choking the rivers.
0:17:35 > 0:17:38And that's exactly what we see there.
0:17:38 > 0:17:41Here in our fossil bed, we get a mixture of marine organisms
0:17:41 > 0:17:43and organisms that came in from the land.
0:17:43 > 0:17:46One of our more common fossils is wood.
0:17:50 > 0:17:52In the Gulf of Mexico, the crew are on the verge
0:17:52 > 0:17:55of breaking into the asteroid impact crater,
0:17:55 > 0:17:59but, at the worst possible moment, they've hit a roadblock.
0:18:01 > 0:18:02So they just woke me up because there's
0:18:02 > 0:18:04a problem with the drilling.
0:18:04 > 0:18:07We don't know if it's snapped or if it just got stuck a little bit.
0:18:07 > 0:18:09We don't know, but they have to bring it back
0:18:09 > 0:18:11to the surface to take a look.
0:18:11 > 0:18:13As they get nearer the crater,
0:18:13 > 0:18:15the rock is getting tougher to penetrate,
0:18:15 > 0:18:18and that's causing problems with the drill.
0:18:18 > 0:18:19TOOL BUZZES
0:18:19 > 0:18:21Getting to the point where you start pushing the drill
0:18:21 > 0:18:24beyond its capacity, and right now, there's no...
0:18:24 > 0:18:28There's no drilling rods, no bit, no anything in the hole.
0:18:31 > 0:18:33While the engineers fix the rig,
0:18:33 > 0:18:36the scientists lose valuable drilling time.
0:18:36 > 0:18:39Behind me, you'll notice the rig is not moving.
0:18:39 > 0:18:41SPARKS CRACKLE
0:18:41 > 0:18:44The pump that allows it to turn is actually broken.
0:18:46 > 0:18:49RUMBLING
0:18:49 > 0:18:51We're in a bit of a race against time now.
0:18:54 > 0:18:56We're going to struggle to get to 1,500 metres.
0:18:58 > 0:19:00So we're all hopeful -
0:19:00 > 0:19:02fingers, toes and so on are crossed -
0:19:02 > 0:19:04and we'll see how this goes.
0:19:08 > 0:19:11Finally, after a month of drilling,
0:19:11 > 0:19:14the team are pulling rock from the asteroid crater itself.
0:19:16 > 0:19:19Already, they're seeing evidence of the incredible heat
0:19:19 > 0:19:21generated by the impact -
0:19:21 > 0:19:23rock that has melted.
0:19:23 > 0:19:24And look at...
0:19:24 > 0:19:28In this part, it is very clear that we have different kinds of colours,
0:19:28 > 0:19:29like this red colour.
0:19:29 > 0:19:32It goes from green to red...
0:19:32 > 0:19:34- I think it's melting the material. - Melted...- Yeah.
0:19:34 > 0:19:36- What about this? - I think that is a big cluster melt.
0:19:36 > 0:19:39That does, too. Look at that. That looks like the suevite.
0:19:39 > 0:19:41And we are now fully into impact rocks directly,
0:19:41 > 0:19:45and it's really easy to see, because it's granite,
0:19:45 > 0:19:51and so you can see these spotted, leopard-looking big chunks.
0:19:51 > 0:19:52So, in effect, you know,
0:19:52 > 0:19:55these were formed, you know, on the days that the dinos died.
0:19:58 > 0:20:00Quite heavy, these, aren't they?
0:20:00 > 0:20:03Yeah, you really appreciate just...just how solid this rock is.
0:20:03 > 0:20:05How deep have you gone with this so far?
0:20:05 > 0:20:09We've got to just 1,330 metres, about that.
0:20:09 > 0:20:11So, we were hoping to get 1,500 metres,
0:20:11 > 0:20:14but we've got 700 metres of peak ring materials,
0:20:14 > 0:20:16so we're pretty happy.
0:20:16 > 0:20:18Why couldn't you get 1,500?
0:20:18 > 0:20:19SHE LAUGHS
0:20:19 > 0:20:21Cos...cos the budget ran out.
0:20:21 > 0:20:22Oh, no!
0:20:22 > 0:20:25I'm dying to ask the question that I wanted to know as a kid -
0:20:25 > 0:20:26where's the asteroid?
0:20:26 > 0:20:30- Yes, a lot of people think I'm going to find the asteroid...- Yeah.
0:20:30 > 0:20:31..and ask me that question a lot.
0:20:31 > 0:20:35Something like 95 or more percent of the asteroid is vaporised.
0:20:35 > 0:20:39- Mm-hm.- So, in fact, there's hardly any asteroid here
0:20:39 > 0:20:41beneath the surface.
0:20:41 > 0:20:43The asteroid material has been, sort of,
0:20:43 > 0:20:44spread all around the globe,
0:20:44 > 0:20:48so it's been ejected way above the Earth's atmosphere,
0:20:48 > 0:20:51travelled round the globe, and landed around the Earth.
0:20:54 > 0:20:56After eight weeks, the work here is done.
0:20:58 > 0:21:00I don't think it could have gone much better.
0:21:00 > 0:21:03I'll not forget this place.
0:21:03 > 0:21:06It's been an amazing expedition, and I expect we'll have lots more
0:21:06 > 0:21:08discoveries to come.
0:21:08 > 0:21:10More than 300 rock cores have been extracted,
0:21:10 > 0:21:15which the team hopes will tell the story of how the dinosaurs died.
0:21:34 > 0:21:37Four months and over 5,000 miles later,
0:21:37 > 0:21:39the rock cores are now here
0:21:39 > 0:21:42at the University of Bremen in Germany,
0:21:42 > 0:21:43for the second phase
0:21:43 > 0:21:47of this colossal and unparalleled scientific journey.
0:21:47 > 0:21:51I'm inside a huge fridge that's now home to all the samples that
0:21:51 > 0:21:54were taken up from the Gulf of Mexico,
0:21:54 > 0:21:57and it's really cold in here, as you might expect.
0:21:57 > 0:22:00Now, this is to stop any organisms from growing
0:22:00 > 0:22:02and contaminating these samples.
0:22:05 > 0:22:09This is a test recording. Say something.
0:22:09 > 0:22:11Oh. Hello, hello.
0:22:11 > 0:22:15Here in Bremen, the research team is working to find out what happened,
0:22:15 > 0:22:18minute by minute, after the asteroid struck,
0:22:18 > 0:22:20and what that meant for the dinosaurs.
0:22:23 > 0:22:26OK, this is day two that we've had the samples,
0:22:26 > 0:22:30and I'm going to take you through the...around the labs
0:22:30 > 0:22:32where everybody's started their analyses.
0:22:32 > 0:22:35Over here we can see people looking through microscopes,
0:22:35 > 0:22:38looking at thin slides that have been collected from offshore.
0:22:38 > 0:22:41Hi, Philippe. I'm going to film you while you take a look at this core.
0:22:41 > 0:22:43Hey!
0:22:47 > 0:22:50Unravelling these cores is a mammoth task.
0:22:50 > 0:22:55Over 800 metres of rock has to be carefully split,
0:22:55 > 0:22:56tested and photographed.
0:23:00 > 0:23:03But what they're starting to reveal about the force of the impact
0:23:03 > 0:23:05is literally earth-shattering.
0:23:09 > 0:23:13This core, from above the crater, is what typical geology looks like -
0:23:13 > 0:23:17layer upon layer of similar-looking rock,
0:23:17 > 0:23:20laid down on the seabed very slowly.
0:23:21 > 0:23:26This three metres of limestone took millions of years to accumulate.
0:23:28 > 0:23:30But when the asteroid struck...
0:23:32 > 0:23:34..it was geology at hyperspeed.
0:23:37 > 0:23:43The next 600 metres of rock were deposited in a single day,
0:23:43 > 0:23:46leaving a unique and chaotic jumble.
0:23:53 > 0:23:56Sean, I mean, how do you make sense of this incredible place
0:23:56 > 0:23:57- that you've got here?- It is amazing.
0:23:57 > 0:24:00This is 150km worth of core,
0:24:00 > 0:24:02collected by the International Ocean Discovery Programme
0:24:02 > 0:24:04- and all its predecessors back to the late '60s.- Mm-hm.
0:24:04 > 0:24:06But from all these cores,
0:24:06 > 0:24:08- the most amazing is the one we just collected...- Yeah.
0:24:08 > 0:24:10- ..in the Chicxulub impact crater. - Of course, yeah.
0:24:10 > 0:24:14You can see this black, flowing texture of the rock.
0:24:14 > 0:24:15This is actually...
0:24:15 > 0:24:18- It looks like it flowed, right?- Mm. - You can see the textures in it.
0:24:18 > 0:24:20This is actually melted basement rock,
0:24:20 > 0:24:24melted granite, and it actually takes amazing pressures to do that,
0:24:24 > 0:24:26and amazing pressures to melt the rock.
0:24:26 > 0:24:27This is...
0:24:27 > 0:24:29So I've got a piece of what would be considered, sort of,
0:24:29 > 0:24:31normal granite, if you will -
0:24:31 > 0:24:34the kind that you might put on your countertop,
0:24:34 > 0:24:36and that's why we use it, cos it's nice and hard.
0:24:36 > 0:24:38- I mean, it... Right?- Pretty solid.
0:24:38 > 0:24:39But this... Yeah, exactly.
0:24:39 > 0:24:44This stuff has actually seen shock of an incredible level,
0:24:44 > 0:24:47so think of it as pressure waves moving down through the granite,
0:24:47 > 0:24:50like lots and lots of little earthquakes.
0:24:50 > 0:24:51And what it's done to it is,
0:24:51 > 0:24:53all the way down at the scale of a crystal,
0:24:53 > 0:24:55- is it's actually deformed it... - Mm-hmm.
0:24:55 > 0:24:56..so that the final granite...
0:24:59 > 0:25:00..can be broken.
0:25:00 > 0:25:02- It just crumbled up. That's...that's amazing.- Yeah.
0:25:02 > 0:25:07Oh, wow. Just such incredible, amazing forces at work here.
0:25:07 > 0:25:10This whole event, it's... I'm still finding it difficult.
0:25:10 > 0:25:13Well, even as a geophysicist, where we study this for a living,
0:25:13 > 0:25:16it's really hard to wrap our brains around the enormity of
0:25:16 > 0:25:18the pressures involved, and the enormity of the destruction
0:25:18 > 0:25:21- that happens in the middle of an impact, and so quickly.- Mm-hm.
0:25:21 > 0:25:24This all happened in less than ten minutes.
0:25:25 > 0:25:29It's becoming clear just how mind-bogglingly huge
0:25:29 > 0:25:31the Yucatan impact really was.
0:25:33 > 0:25:35And to help grasp its scale,
0:25:35 > 0:25:40Sean is taking a trip to a more recent impact site in Arizona.
0:25:48 > 0:25:53This simple crater here was created by about a 50-metre, or 150-foot,
0:25:53 > 0:25:56asteroid impacting the Earth, about 50,000 years ago.
0:25:57 > 0:26:00It's about a mile across. It's actually quite small.
0:26:00 > 0:26:03It's basically, simply, a bowl-shaped crater.
0:26:03 > 0:26:05Everything above the red line that you see there is actually
0:26:05 > 0:26:09material that used to be buried that has been flipped up on end,
0:26:09 > 0:26:11and is now...or flipped upside-down,
0:26:11 > 0:26:14and is now laying as a pile of broken-up material.
0:26:16 > 0:26:19By studying the shape of the crater and the upheaval of the rock layers,
0:26:19 > 0:26:22Sean, Jo and the team can compare this site to
0:26:22 > 0:26:25the Yucatan impact zone,
0:26:25 > 0:26:28Even a small asteroid strike like this
0:26:28 > 0:26:31would have had dramatic consequences.
0:26:31 > 0:26:35So it comes in at something like 26,000mph.
0:26:35 > 0:26:3910km away from here, we would have a fireball reaching,
0:26:39 > 0:26:42maybe 20km away from here, a shock wave,
0:26:42 > 0:26:45and, say, 40km away from here are hurricane-force winds,
0:26:45 > 0:26:47but that would just have been a bad day
0:26:47 > 0:26:49in, today, northern Arizona.
0:26:52 > 0:26:55So this is what a 50m-wide asteroid can do -
0:26:55 > 0:26:58it's devastating, but localised.
0:26:58 > 0:27:01but what about an asteroid that is nine miles across
0:27:01 > 0:27:04and leaves a crater 120 miles wide?
0:27:09 > 0:27:11To understand the effects of that impact,
0:27:11 > 0:27:15the team needs to know exactly how much energy it released.
0:27:17 > 0:27:20To do that, they're comparing rock samples from Yucatan
0:27:20 > 0:27:27to data gathered from some of the largest ever man-made explosions.
0:27:33 > 0:27:37This is the Nevada Test Site,
0:27:37 > 0:27:40the most bombed place in the world.
0:27:42 > 0:27:48The US military have detonated 904 atomic bombs here.
0:27:48 > 0:27:52To help us understand how atomic bombs connect to asteroids,
0:27:52 > 0:27:53we've enlisted the help
0:27:53 > 0:27:56of physicists Mark Boslough and David Dearborn.
0:27:58 > 0:28:00The blast must have come all the way through,
0:28:00 > 0:28:02and I bet these windows blew out.
0:28:02 > 0:28:05Those shards of glass would be accelerated by 90mph wind.
0:28:05 > 0:28:09- Wind, the windows were gone. Yes. - And they're totally...boom.
0:28:09 > 0:28:12This house was part of a test village called Survival Town,
0:28:12 > 0:28:15built to study the effects of a nuclear blast.
0:28:17 > 0:28:22It actually survived a blast called Apple-2 in May 1965.
0:28:22 > 0:28:24EXPLOSION
0:28:24 > 0:28:27WIND HOWLS
0:28:28 > 0:28:31Most of the damage is done by the fireball...
0:28:34 > 0:28:38..and the heat that is generated, or the blast wave as it goes by...
0:28:41 > 0:28:43..and the houses that were in closer didn't survive.
0:28:52 > 0:28:54Those of us who work on asteroid impacts,
0:28:54 > 0:28:57we naturally started comparing them to nuclear explosions.
0:28:57 > 0:28:59It's a similar phenomenon.
0:29:00 > 0:29:02The experimenters had high-speed cameras,
0:29:02 > 0:29:05they had gauges that measured the intensity of the shock wave,
0:29:05 > 0:29:08the blast wave in the air.
0:29:09 > 0:29:12The tests found that nuclear explosions are devastating
0:29:12 > 0:29:15even at a microscopic level,
0:29:15 > 0:29:19causing catastrophic shock to minerals such as quartz.
0:29:22 > 0:29:25The pressure is so high in a shock wave from a nuclear explosion
0:29:25 > 0:29:29that it actually exceeds the strength of a crystal.
0:29:29 > 0:29:32Crystal is made up of a uniform array of atoms
0:29:32 > 0:29:36and that uniformity is completely disrupted by a strong shock wave,
0:29:36 > 0:29:38and that's what shocked quartz is.
0:29:41 > 0:29:44In Bremen, Professor Joanna Morgan is looking at quartz
0:29:44 > 0:29:48found in rock cores from the asteroid impact site.
0:29:48 > 0:29:52From nuclear test data, she knows exactly how much force
0:29:52 > 0:29:55it takes to shock quartz.
0:29:55 > 0:29:58From this, she can tell how much force the Yucatan rock
0:29:58 > 0:30:02has been subjected to and begin to calculate the exact amount of
0:30:02 > 0:30:04energy released when the asteroid struck.
0:30:04 > 0:30:09So this is a piece of shocked quartz that we recently drilled
0:30:09 > 0:30:10from the Chicxulub impact crater.
0:30:10 > 0:30:12There's lots of lines here.
0:30:12 > 0:30:15Essentially, the more lines we have on the screen,
0:30:15 > 0:30:18different directions, the more shocked this rock has been.
0:30:18 > 0:30:20These are caused by the impact,
0:30:20 > 0:30:22by the shock wave that travels through this piece of quartz.
0:30:22 > 0:30:25So we used exactly the same hydrocodes, they're called,
0:30:25 > 0:30:30to model nuclear explosions as we do to model the impact craters.
0:30:30 > 0:30:34We've actually stolen these codes and applied them to our simulations
0:30:34 > 0:30:35of impact crater formation.
0:30:35 > 0:30:37What sort of force were we actually talking about
0:30:37 > 0:30:39from the asteroid hitting it?
0:30:39 > 0:30:42This event was equivalent to about 10 billion Hiroshimas,
0:30:42 > 0:30:45so, absolutely enormous.
0:30:45 > 0:30:48The most dramatic event in the last 100 million years.
0:30:48 > 0:30:5010 billion Hiroshimas combined?
0:30:50 > 0:30:52- That's the amount of force going into this?- Absolutely.
0:30:52 > 0:30:53It's incredible, it really is.
0:30:59 > 0:31:01Finally, we have hard evidence
0:31:01 > 0:31:06of just how powerful the asteroid strike really was.
0:31:06 > 0:31:0810 billion Hiroshimas.
0:31:08 > 0:31:10It's a major revelation.
0:31:12 > 0:31:15But the truly incredible thing about this asteroid strike
0:31:15 > 0:31:18was that it changed the face of our planet within seconds.
0:31:18 > 0:31:21And now we know that,
0:31:21 > 0:31:24we can do something that has never been done before.
0:31:25 > 0:31:29'Create a simulation of exactly how the impact affected Earth
0:31:29 > 0:31:31'and the dinosaurs.'
0:31:32 > 0:31:36Here's what the new results tell us about those crucial initial minutes
0:31:36 > 0:31:38after the asteroid struck.
0:31:41 > 0:31:44The asteroid, nine miles wide,
0:31:44 > 0:31:48smashes into the Yucatan at 40,000mph...
0:31:57 > 0:31:59..vaporising instantly.
0:32:01 > 0:32:08The impact makes a hole in the earth 20 miles deep and 120 miles across,
0:32:08 > 0:32:13turning the surrounding sea to steam and shattering the earth below.
0:32:14 > 0:32:19Rock from deep in the Earth's crust then rises miles into the air,
0:32:19 > 0:32:23forming a tower higher than the Himalayas
0:32:23 > 0:32:28that collapses to form a strange ring of peaks that exists today.
0:32:30 > 0:32:33All this in the first ten minutes.
0:32:35 > 0:32:37What did this mean for the dinosaurs?
0:32:37 > 0:32:42Well, it started an unstoppable and devastating chain of events.
0:32:44 > 0:32:47First, like an enormous nuclear explosion,
0:32:47 > 0:32:51a radiation fireball 10,000 degrees centigrade
0:32:51 > 0:32:54spreads out from the impact zone.
0:32:56 > 0:33:00This searing hot sphere fries everything within
0:33:00 > 0:33:03a 600-mile radius in an instant.
0:33:05 > 0:33:10The truly global devastation had its roots not in the blast,
0:33:10 > 0:33:12but in the huge vapour plume
0:33:12 > 0:33:15that rose out of the crater and through the atmosphere.
0:33:19 > 0:33:24A red-hot cloud of vaporised asteroid and rock,
0:33:24 > 0:33:27expanding upwards 600 miles,
0:33:27 > 0:33:31spreading rapidly outwards to fill the planet's atmosphere.
0:33:37 > 0:33:41Back then, faraway New Jersey was covered in ocean.
0:33:45 > 0:33:50And it too would soon feel the effects of the impact.
0:33:51 > 0:33:551,700 miles from the site of the impact,
0:33:55 > 0:33:58the fireball wouldn't have been visible.
0:33:58 > 0:34:01That blazing, towering, swirling cloud
0:34:01 > 0:34:03would've been just over the horizon,
0:34:03 > 0:34:06but we might have seen a faint glow.
0:34:06 > 0:34:10The animals here were safe from the direct radiation.
0:34:13 > 0:34:15Two-and-a-half hours later,
0:34:15 > 0:34:17like the sound of heavy traffic in the distance,
0:34:17 > 0:34:21the shock wave, now a sound wave, arrived.
0:34:25 > 0:34:29Wind starts to whip up, growing stronger and stronger until
0:34:29 > 0:34:32we're facing into hurricane-force winds.
0:34:38 > 0:34:40The blast wave from the impact
0:34:40 > 0:34:42surged across the Earth at enormous speed.
0:34:44 > 0:34:47Its effects would have been short-lived,
0:34:47 > 0:34:50but those few traumatic hours
0:34:50 > 0:34:54left an indelible impression in the earth's geological record.
0:34:57 > 0:35:02These are beads of molten rock that rained down from the skies
0:35:02 > 0:35:04and as they cool, they become glass.
0:35:04 > 0:35:06And if you melt rock and you cool it fast,
0:35:06 > 0:35:10it doesn't have a chance to turn back into rock, it forms glass.
0:35:10 > 0:35:11Glass called spherules.
0:35:11 > 0:35:14And we find these little spherules right here
0:35:14 > 0:35:16in this mass death assemblage.
0:35:19 > 0:35:23What produces the kind of energy and heat needed
0:35:23 > 0:35:26to form these spherules, then?
0:35:26 > 0:35:28Well, when you have an asteroid impact,
0:35:28 > 0:35:31it melts the rock and it flies up through the atmosphere
0:35:31 > 0:35:34and these bits of molten rock rain down on the planet.
0:35:34 > 0:35:39'These 66-million-year-old droplets of molten rock show that
0:35:39 > 0:35:40'debris was falling on landscapes
0:35:40 > 0:35:43'far away from the impact zone itself.'
0:35:43 > 0:35:48Protected by the water, marine creatures like the mosasaurs
0:35:48 > 0:35:51may have been able to survive these immediate events.
0:35:51 > 0:35:54But for the dinosaurs on land, with nowhere to hide,
0:35:54 > 0:35:57this was the beginning of the end.
0:35:59 > 0:36:02To show how the effects might have played out
0:36:02 > 0:36:03for dinosaurs on the ground,
0:36:03 > 0:36:08we've enlisted palaeontologists Steve Brusatte and Tom Williamson
0:36:08 > 0:36:09to our international team.
0:36:09 > 0:36:12They've come to New Mexico,
0:36:12 > 0:36:151,200 miles from the impact zone,
0:36:15 > 0:36:19hunting for remains in one of the richest dinosaur fossil sites
0:36:19 > 0:36:20in the world.
0:36:20 > 0:36:23- Yeah. OK.- Whoa.
0:36:23 > 0:36:25- Got a bone layer. - Look at this. Check this out.
0:36:25 > 0:36:29A lot of times, we'll just be walking around in the Badlands,
0:36:29 > 0:36:32looking for stuff that's sticking out of the rock.
0:36:32 > 0:36:34That's always the first clue.
0:36:34 > 0:36:37This one's really sticking out. We can tell from the shape of it
0:36:37 > 0:36:39that it's part of the backbone of a dinosaur.
0:36:41 > 0:36:45It's a bone from the backbone of a horned dinosaur.
0:36:45 > 0:36:48This is probably Pentaceratops,
0:36:48 > 0:36:50which means five-horned face,
0:36:50 > 0:36:54two brow horns, a nasal horn and then a cheek horn on each side.
0:36:54 > 0:36:57Triceratops has three horns on its face.
0:36:57 > 0:37:00This guy had two more horns, so five horns total,
0:37:00 > 0:37:03so an even gaudier dinosaur.
0:37:04 > 0:37:08The ceratopsians, like Pentaceratops and Triceratops,
0:37:08 > 0:37:11were a large group of plant-eating dinosaurs
0:37:11 > 0:37:14that roamed the American landscape
0:37:14 > 0:37:17for the 20 million years leading up to the asteroid impact.
0:37:21 > 0:37:24- There it is.- Pretty good. Look at that.- Not bad.
0:37:25 > 0:37:26This whole area here,
0:37:26 > 0:37:29honestly, it's littered with these kind of bones.
0:37:29 > 0:37:31These were the cows of the Cretaceous,
0:37:31 > 0:37:33they would've been everywhere on this landscape.
0:37:33 > 0:37:3866 million years ago, this area would've looked very different.
0:37:38 > 0:37:42Today, it's known as the San Juan Badlands.
0:37:42 > 0:37:45Back then, it wasn't so bad at all.
0:37:46 > 0:37:49This whole area was a lush jungle.
0:37:51 > 0:37:53Dense vegetation.
0:37:55 > 0:37:58Thick forests cut through by flowing rivers.
0:38:04 > 0:38:09When that day started, this whole area here would've been teeming
0:38:09 > 0:38:15with dinosaurs, and then, about 2,000km or so,
0:38:15 > 0:38:191,200 miles in this direction to the south-east, the asteroid hit.
0:38:29 > 0:38:32And very quickly, the dinosaurs would've realised
0:38:32 > 0:38:34that something was wrong,
0:38:34 > 0:38:38because there would've been an enormous red glowing cloud
0:38:38 > 0:38:41that would've filled up much of the sky here.
0:38:42 > 0:38:45The glowing cloud would've looked dramatic,
0:38:45 > 0:38:47but this far from the impact zone,
0:38:47 > 0:38:51the dinosaurs here would've been safe...for now.
0:38:52 > 0:38:54Now, their cousins down in Texas,
0:38:54 > 0:38:58about 1,000 kilometres closer to the impact site,
0:38:58 > 0:38:59they were toast.
0:38:59 > 0:39:01They were incinerated, they were vaporised.
0:39:01 > 0:39:04By studying the Yucatan rock core,
0:39:04 > 0:39:06we know the exact timing of what happened next.
0:39:08 > 0:39:1011 minutes after the impact,
0:39:10 > 0:39:14the vapour cloud arrived in New Mexico.
0:39:14 > 0:39:19The skies darkened and the temperature started to rise.
0:39:23 > 0:39:26It wasn't really a case of fire and brimstone
0:39:26 > 0:39:27raining down from the heavens.
0:39:27 > 0:39:31It was more a case of all of that stuff heating up the atmosphere
0:39:31 > 0:39:35and turning the atmosphere into a giant radiator.
0:39:40 > 0:39:42The heat was so intense that,
0:39:42 > 0:39:45over 1,000 miles away from the impact,
0:39:45 > 0:39:48many animals would have been roasted alive.
0:39:50 > 0:39:52Climate specialist Dr Brian Toon
0:39:52 > 0:39:56is the first scientist ever to theorise what happened next.
0:39:56 > 0:40:03A devastating global firestorm he's studied for more than 20 years.
0:40:03 > 0:40:08It wasn't falling on you, it was 60km above the ground or so,
0:40:08 > 0:40:13and the glowing hot lava was emitting an amount of energy
0:40:13 > 0:40:16that's a few times larger than the sun.
0:40:18 > 0:40:20This is not a normal fire.
0:40:20 > 0:40:23The fire was started everywhere, which causes what's called
0:40:23 > 0:40:25a mass fire.
0:40:27 > 0:40:31Mass fires can be much hotter than a normal fire.
0:40:31 > 0:40:34Well, the leaves on the ground caught fire,
0:40:34 > 0:40:36leaves in the trees caught fire...
0:40:38 > 0:40:39The underbrush caught fire.
0:40:42 > 0:40:45There's winds at hurricane speeds rushing into the fire,
0:40:45 > 0:40:49drawing upward into the rising flames
0:40:49 > 0:40:51and they consume everything.
0:40:55 > 0:40:58And this vapour quickly spread across the planet.
0:40:58 > 0:41:00Probably only took a few hours
0:41:00 > 0:41:03for it to reach the furthest reaches of the Earth.
0:41:10 > 0:41:14Thanks to our new model of what happened after the impact,
0:41:14 > 0:41:19we now know that fires spread right around the globe.
0:41:19 > 0:41:23But were these fires devastating enough to cause the extinction
0:41:23 > 0:41:27of all of the world's dinosaurs in a single day?
0:41:30 > 0:41:33'To find out, I'm travelling far from the impact site
0:41:33 > 0:41:36'to the very tip of South America
0:41:36 > 0:41:40'and the remote wilderness of Patagonia.'
0:41:41 > 0:41:45Over 4,000 miles away from where the asteroid hit.
0:41:54 > 0:41:59I am all the way down here in Chile.
0:41:59 > 0:42:01Now, we tend to think of this asteroid
0:42:01 > 0:42:05as being absolutely enormous, and it was - 14km in diameter -
0:42:05 > 0:42:08but in the context of the size of the Earth,
0:42:08 > 0:42:11that's like a grain of sand impacting on a bowling ball.
0:42:11 > 0:42:15And I want to understand what kind of impact
0:42:15 > 0:42:20the asteroid landing here had on the dinosaurs
0:42:20 > 0:42:23right down here at the toe of South America.
0:42:28 > 0:42:33Leading the hunt for clues is palaeontologist Marcelo Leppe.
0:42:33 > 0:42:36He's taking me to look for dinosaur remains
0:42:36 > 0:42:40in a mountain valley that's best accessed on four legs.
0:42:50 > 0:42:54Marcelo, can you explain to me how the geology of this valley works?
0:42:54 > 0:42:58Actually, we are passing through time
0:42:58 > 0:43:01and we are moving to the end of the Cretaceous,
0:43:01 > 0:43:04to the end of the age of the dinosaurs.
0:43:04 > 0:43:07We are, at the moment, in 80 million years ago,
0:43:07 > 0:43:08this is Campanian.
0:43:08 > 0:43:09So this is fantastic.
0:43:09 > 0:43:12As we ride along the valley, as we ride north,
0:43:12 > 0:43:15we're riding from 80 million to 66 million years.
0:43:15 > 0:43:16Through time.
0:43:17 > 0:43:20Getting closer to that extinction event.
0:43:23 > 0:43:26We've reached the Valley of the Dinosaurs.
0:43:26 > 0:43:30Now I want to see what sort of dinosaurs lived here and find out
0:43:30 > 0:43:33what happened to them in the hours after the impact.
0:43:36 > 0:43:38So, shall we get off and have a look?
0:43:38 > 0:43:42- Yeah, let's leave the horses and look.- Seems like a good idea.
0:43:45 > 0:43:48The place is literally full of bones.
0:43:48 > 0:43:50As you can see, this sunlight is the best
0:43:50 > 0:43:54because the angular light is reflecting the bones.
0:43:54 > 0:43:57- Let's see if we can find a dinosaur, then.- Yeah, let's...let's see.
0:43:58 > 0:44:00Oh, for example, there.
0:44:01 > 0:44:03Or here.
0:44:03 > 0:44:05Look, just beside you.
0:44:05 > 0:44:08- This, here? - Yes, this is a dinosaur bone.
0:44:08 > 0:44:10Oh. That's fantastic.
0:44:10 > 0:44:12They're different colour. Greyish, or white.
0:44:12 > 0:44:14Yeah, so what's that, then?
0:44:14 > 0:44:17Oh, it looks like a vertebrae.
0:44:17 > 0:44:18Probably the first one.
0:44:18 > 0:44:20OK, so...yeah.
0:44:20 > 0:44:22That looks like a facet, it looks like the surface of a joint
0:44:22 > 0:44:24and that would be where the skull sits.
0:44:24 > 0:44:26Any ideas what species?
0:44:26 > 0:44:30- Yeah, probably a hadrosaur. 99%. - Really?- Yeah.
0:44:30 > 0:44:33- That's your first hadrosaur, yeah? - Yeah, it is.
0:44:34 > 0:44:38'This valley is now a bone bed, four miles long.'
0:44:39 > 0:44:44Yes, that is a bit of fossilised bone and they're everywhere.
0:44:44 > 0:44:45Scattered across this hillside.
0:44:45 > 0:44:47It's just extraordinary.
0:44:50 > 0:44:52Once, it was home to herds of hadrosaurs.
0:44:57 > 0:45:02Plant-eaters up to 30-feet long with a distinctive duck-billed face.
0:45:04 > 0:45:07But did the dinosaurs down in Patagonia
0:45:07 > 0:45:10die on the day the asteroid hit?
0:45:16 > 0:45:19Thanks to the team in Bremen,
0:45:19 > 0:45:22we now know that once the asteroid struck the Yucatan Peninsula
0:45:22 > 0:45:25over 4,000 miles away,
0:45:25 > 0:45:29it took 42 minutes for the superheated cloud of debris
0:45:29 > 0:45:31to reach Patagonia.
0:45:33 > 0:45:34For much of the planet,
0:45:34 > 0:45:37the fires triggered by the burning sky
0:45:37 > 0:45:39led to total destruction.
0:45:46 > 0:45:49But Marcelo has found evidence
0:45:49 > 0:45:51that that may not have been the story here.
0:45:53 > 0:45:56Plants that the hadrosaurs used to eat.
0:45:56 > 0:45:59This is Nothofagus, the southern beech.
0:45:59 > 0:46:02They're all around here, aren't they?
0:46:02 > 0:46:07And if you want to see it, look at that architecture.
0:46:07 > 0:46:10And I want to show you also this one.
0:46:10 > 0:46:11This is from Las Chinas,
0:46:11 > 0:46:14the same valley we were looking for the hadrosaurs.
0:46:14 > 0:46:15Oh, this is fantastic.
0:46:15 > 0:46:18- This is what the hadrosaurs were walking on.- Yeah.
0:46:18 > 0:46:21- And if you want to compare it... - Well, that looks incredibly similar.
0:46:21 > 0:46:23Is there actually a relationship
0:46:23 > 0:46:25between this fossil leaf and this living one?
0:46:25 > 0:46:28Oh, there is a direct line
0:46:28 > 0:46:32from this fossil and this one that is living today in Patagonia.
0:46:32 > 0:46:35So this is fantastic evidence that, down here in Patagonia,
0:46:35 > 0:46:37some spaces did actually make it through.
0:46:40 > 0:46:4366 million years ago, this region was warm, wet
0:46:43 > 0:46:46and dense with vegetation like the southern beech.
0:46:48 > 0:46:52A species of plant that survived the fires on impact day.
0:46:55 > 0:46:56And if plants survived,
0:46:56 > 0:46:59maybe the dinosaurs here could have done, too.
0:47:04 > 0:47:08Life down here should have been badly hit,
0:47:08 > 0:47:12but the fossil evidence, particularly of plant life,
0:47:12 > 0:47:14is telling us a different story -
0:47:14 > 0:47:17that the immediate fallout from Chicxulub
0:47:17 > 0:47:21in Patagonia was not as bad as predicted.
0:47:21 > 0:47:25So perhaps our hadrosaurs had a stay of execution,
0:47:25 > 0:47:28maybe they made it through that first day.
0:47:28 > 0:47:30But something...
0:47:30 > 0:47:32Something got them in the end.
0:47:36 > 0:47:40To determine exactly what did happen in the days, weeks and months
0:47:40 > 0:47:44after the asteroid struck, the Bremen team are still
0:47:44 > 0:47:47hard at work studying rock samples from the impact crater.
0:47:52 > 0:47:57Dr Philippe Claeys thinks he's found perhaps the most important clue yet.
0:48:02 > 0:48:05So, Philippe, when this asteroid struck Earth,
0:48:05 > 0:48:07it had a massive and devastating impact.
0:48:07 > 0:48:09But that didn't quite seal the fate of the dinosaurs, did it?
0:48:09 > 0:48:13Probably not. Remember, the dinosaurs were ideally adapted
0:48:13 > 0:48:15to the late Cretaceous environment.
0:48:15 > 0:48:18They were the ultimate animal for the Cretaceous.
0:48:18 > 0:48:20What happened here is that
0:48:20 > 0:48:23we have an incredible change in the Earth's system,
0:48:23 > 0:48:27basically kills the dinosaur everywhere on Earth -
0:48:27 > 0:48:30in Africa, Antarctica, in the forests, or in the savanna.
0:48:30 > 0:48:32But what made them extinct?
0:48:32 > 0:48:33You talk about a global scale, suddenly.
0:48:33 > 0:48:36- What went global? What happened? - What went global is really
0:48:36 > 0:48:39the ejection of material from the crater.
0:48:39 > 0:48:42- Look at what I have in my pocket - this is gypsum.- Right, OK.
0:48:42 > 0:48:46- This was part of Yucatan at the time of impact.- Yeah.- OK?
0:48:46 > 0:48:49And this material here contains sulphate.
0:48:49 > 0:48:54And this gypsum affects the chemistry of the atmosphere.
0:48:54 > 0:48:56It changes it drastically.
0:48:56 > 0:48:58This area's meant to be rich in this sort of stuff.
0:48:58 > 0:49:02It's supposed to be full of it. But it's not.
0:49:02 > 0:49:05We can look for the remnants of it here.
0:49:05 > 0:49:07In the core, it's totally absent,
0:49:07 > 0:49:10which means that almost the entire sequence of gypsum
0:49:10 > 0:49:13that was present in the sedimentary target
0:49:13 > 0:49:15at the time of impact went into the atmosphere.
0:49:20 > 0:49:23This is a huge discovery.
0:49:23 > 0:49:26The presence of gypsum means the plume of vaporised rock
0:49:26 > 0:49:31that spread across the world was dense with sulphates
0:49:31 > 0:49:32that blocked sunlight.
0:49:38 > 0:49:42The same thing happened after the 1991 eruption of Mount Pinatubo
0:49:42 > 0:49:44in the Philippines.
0:49:45 > 0:49:49Sulphates reduced the amount of sunlight reaching land by 10%,
0:49:49 > 0:49:52which caused a drop in global temperatures.
0:49:55 > 0:49:5925 years ago, Pinatubo had an incredible effect on the atmosphere.
0:49:59 > 0:50:04It cooled it by very little, but it had an effect.
0:50:04 > 0:50:06- And it stayed for a couple of years. - Right.
0:50:06 > 0:50:09Here, we have an event which is orders of magnitude more important.
0:50:09 > 0:50:12Pinatubo is nothing compared to the Chicxulub impact.
0:50:12 > 0:50:15It is really going global, no place is protected,
0:50:15 > 0:50:17no dinosaur can escape
0:50:17 > 0:50:19the consequence of the Chicxulub impact.
0:50:19 > 0:50:21This is the gypsum.
0:50:21 > 0:50:24- This is what killed the dinosaurs.- Wow.
0:50:28 > 0:50:31This astonishing find is the final piece of the jigsaw...
0:50:33 > 0:50:35..allowing us, for the first time,
0:50:35 > 0:50:38to model what finally killed the dinosaurs.
0:50:40 > 0:50:43It's what happened in the days after the impact
0:50:43 > 0:50:46that made it a global extinction.
0:50:48 > 0:50:51Our blue planet turned grey.
0:50:54 > 0:50:59Long after the hot skies cooled, ash and dust in the atmosphere
0:50:59 > 0:51:01almost completely blocked out the sun.
0:51:02 > 0:51:06As the lights went out, global temperatures plunged
0:51:06 > 0:51:08more than ten degrees centigrade within days.
0:51:13 > 0:51:16This is where we get to the great irony of the story.
0:51:21 > 0:51:24Because in the end, it wasn't the size of the asteroid...
0:51:26 > 0:51:29..the scale of the blast,
0:51:29 > 0:51:33or even its global reach that made dinosaurs extinct.
0:51:34 > 0:51:36It was where the impact happened.
0:51:39 > 0:51:42Had the asteroid struck a few moments earlier,
0:51:42 > 0:51:44or maybe even a couple of seconds later,
0:51:44 > 0:51:47then rather than hitting shallow coastal waters,
0:51:47 > 0:51:50it might have hit deep ocean.
0:51:52 > 0:51:55An impact in the nearby Atlantic or Pacific oceans
0:51:55 > 0:51:57would have meant much less vaporised rock,
0:51:57 > 0:51:59including the deadly gypsum.
0:52:02 > 0:52:04The cloud would have been less dense
0:52:04 > 0:52:07and sunlight could have still reached the planet's surface...
0:52:09 > 0:52:12..meaning what happened next might have been avoided.
0:52:14 > 0:52:16In this cold, dark world,
0:52:16 > 0:52:19food ran out in the oceans within a week,
0:52:19 > 0:52:22and shortly after, on land also.
0:52:22 > 0:52:25With nothing to eat anywhere on the planet,
0:52:25 > 0:52:28the mighty dinosaurs stood little chance of survival.
0:52:36 > 0:52:41In Patagonia, 10% of plant species went extinct.
0:52:41 > 0:52:44The southern beeches would have shed their leaves,
0:52:44 > 0:52:48shutting down for the long winter that the asteroid set off.
0:52:48 > 0:52:50The hadrosaurs were left to starve.
0:52:55 > 0:52:58The demise of the dinosaurs down here in Patagonia
0:52:58 > 0:53:03was nowhere near as dramatic as being obliterated by a blast wave,
0:53:03 > 0:53:05or drowned in a tsunami,
0:53:05 > 0:53:08or even being caught up in a colossal forest fire.
0:53:08 > 0:53:11But they were doomed, nonetheless.
0:53:15 > 0:53:19The dinosaurs as a group were hugely successful and diverse,
0:53:19 > 0:53:23they'd been on the planet for more than 150 million years.
0:53:24 > 0:53:28But this Chicxulub event was more than just a local phenomenon.
0:53:29 > 0:53:32It changed the climate globally,
0:53:32 > 0:53:35plunging the world into a deep, deep winter.
0:53:35 > 0:53:38And there was no time to adapt.
0:53:38 > 0:53:40So, in some ways,
0:53:40 > 0:53:43the dinosaurs that died instantaneously were the lucky ones.
0:53:49 > 0:53:53This sudden climate change may finally solve the mystery of
0:53:53 > 0:53:54what happened in New Jersey.
0:53:57 > 0:54:01As the food supply in the oceans dwindled,
0:54:01 > 0:54:03shallow water creatures roamed ever deeper.
0:54:05 > 0:54:07But eventually, the food would run out.
0:54:10 > 0:54:16And all of those animals from different parts of the oceans died,
0:54:16 > 0:54:18coming to rest in a single layer.
0:54:29 > 0:54:34It's been an incredible adventure decades in the planning.
0:54:34 > 0:54:38A multi-million-pound scientific expedition,
0:54:38 > 0:54:43weeks of drilling rock samples from deep inside a super crater,
0:54:43 > 0:54:48and months of studying hundreds of metres of rock samples.
0:54:48 > 0:54:53- So, this was E4.- Yep. - Which is 53 million to 55.
0:54:53 > 0:54:57We were just jazzed about the science, all day long.
0:54:57 > 0:54:59Many people have been up for 20 hours
0:54:59 > 0:55:01and they were still just going with enthusiasm,
0:55:01 > 0:55:04describing the cores, looking at the microfossils.
0:55:04 > 0:55:07It was a heady experience.
0:55:07 > 0:55:11All that hard work has paid off in a big way.
0:55:11 > 0:55:16The team has been able to reveal extraordinary new details,
0:55:16 > 0:55:19evidence about how the dinosaurs died.
0:55:19 > 0:55:23But perhaps even astonishing than what killed the dinosaurs...
0:55:24 > 0:55:27..is what happened after they were gone.
0:55:30 > 0:55:34The asteroid and its aftermath ended the age of the dinosaurs.
0:55:37 > 0:55:42But as the cloud started to clear, months or years later,
0:55:42 > 0:55:45the dormant plants came back to life.
0:55:46 > 0:55:52And a tiny group of animals came out of hiding to inherit the Earth.
0:55:52 > 0:55:55Creatures that would, over millions of years,
0:55:55 > 0:55:58evolve into a huge range of different species...
0:55:58 > 0:56:00Including us.
0:56:00 > 0:56:02On the tip of my finger right here
0:56:02 > 0:56:08is a lower tooth of something called mesodma.
0:56:08 > 0:56:11This was a little guy who was probably about the size of a mouse.
0:56:14 > 0:56:17This is one tough little mammal.
0:56:17 > 0:56:19One of the very few species known to survive
0:56:19 > 0:56:22through the global devastation.
0:56:22 > 0:56:23It's a blade-like tooth.
0:56:23 > 0:56:27It was able to feed on things like insects and seeds,
0:56:27 > 0:56:30so it didn't have to rely on photosynthesis.
0:56:32 > 0:56:38Mammals had lived in the shadow of the dinosaurs for 100 million years.
0:56:38 > 0:56:41But now it was their turn.
0:56:41 > 0:56:44This chance event that was the doom of the dinosaurs
0:56:44 > 0:56:48was a stroke of luck for the surviving mammals.
0:56:50 > 0:56:52With the dinosaurs gone,
0:56:52 > 0:56:55suddenly, the landscape was empty of competitors
0:56:55 > 0:56:56and ripe with possibilities.
0:57:09 > 0:57:12Just half a million years after the extinction of the dinosaurs,
0:57:12 > 0:57:16and landscapes around the globe had filled up with mammals
0:57:16 > 0:57:17of all shapes and sizes.
0:57:22 > 0:57:25Fast forward another 60 million years or so,
0:57:25 > 0:57:28and we have the evolution of an extraordinary upright walking ape
0:57:28 > 0:57:31that contemplates its own existence
0:57:31 > 0:57:35and the demise of ancient creatures they'd never even seen.
0:57:35 > 0:57:38Chances are, if it wasn't for that asteroid,
0:57:38 > 0:57:41we wouldn't be here to tell the story today.