Fateful Planet (2024) Season 1 Episode 4 Rise and Fall of the Dinosaurs
Fateful Planet (2024) Season 1 Episode 4 Rise and Fall of the Dinosaurs
In the Triassic a new group of reptiles rises to rule the world. The dinosaurs dominate our planet for over 150 million years. But when the last mass extinction strikes 66 million years ago, the dinosaurs vanish together with 75% of all species. A gigantic asteroid hits our planet resulting in an apocalypse. But is this rock from space really the killer of the dinosaurs? Scientists are using the latest scientific methods to unravel the mystery of the rise and fall of the dinosaurs.
#documentary
In the Triassic a new group of reptiles rises to rule the world. The dinosaurs dominate our planet for over 150 million years. But when the last mass extinction strikes 66 million years ago, the dinosaurs vanish together with 75% of all species. A gigantic asteroid hits our planet resulting in an apocalypse. But is this rock from space really the killer of the dinosaurs? Scientists are using the latest scientific methods to unravel the mystery of the rise and fall of the dinosaurs.
#documentary
Category
📺
TVTranscript
00:00Earth is born out of chaos and catastrophe.
00:07Despite such hostile conditions, life emerges on our planet.
00:14But it must withstand deadly disasters again and again.
00:20Planet Earth is a wild world, shaken by unimaginable impacts.
00:29Volcanic eruptions that flood the landscape.
00:34And drastic climate changes that lead to ice ages that freeze the world from pole to pole.
00:43Yet each assault creates a path for something new.
00:48Life always finds a way, despite being constantly put to the test.
00:56Without these catastrophes, life as we know it would not exist on our fateful planet.
01:12During the Cretaceous period, about 66 million years ago, our closest ancestors are small mammals.
01:20For them, Earth is a terrifying place.
01:24One fraught with danger and constant peril.
01:28Because this is a world ruled by terrifying creatures.
01:35The dinosaurs.
01:41They dominated Earth, undisputed, for more than 150 million years.
01:47Until a catastrophe ended their reign.
01:51A disaster so enormous, it not only wiped out most of the dinosaurs,
01:56but 75% of all species on our planet.
02:04Scientists have been investigating the cataclysm for decades,
02:08to determine what caused this mass extinction.
02:12There are various theories.
02:14But one states that an asteroid impact is responsible.
02:19Armed with the latest technology,
02:22experts are trying to unravel the mysterious circumstances
02:26behind the fateful event that changed our planet forever.
02:33Lance Creek, Wyoming.
02:37Paleontologist Philip Haflich has come here to investigate
02:41how the world of the dinosaurs came to a sudden end.
02:48He is visiting an excavation site filled with fossils of dinosaurs
02:53that lived at the end of the Cretaceous period,
02:56just before the disaster struck.
03:01The Lance Creek area is one of the most important historic dinosaur areas in the world.
03:07It was especially at the beginning of the 20th century
03:10when there was a lot of dinosaur hunters in this area.
03:14It's a place where you find plenty of dinosaur bones in one spot.
03:18It's a bone bed, let's say a layer, which is really kind of built up by dinosaurs.
03:25The rocks here reveal the ancient landscape that was home to the last dinosaurs.
03:32Observing the geology of the land's formation,
03:34like this sandstone, like this layering and so on,
03:37we can see it was a big river system.
03:39There was a lot of water about 70 million years ago in this spot.
03:43So this means it was kind of the perfect place to live for dinosaurs.
03:47And this is what we have today.
03:49Almost at every spot you go, we will find some isolated bones at least.
03:53It's kind of magic.
03:57This was home to some of Earth's most iconic dinosaurs.
04:02One sports two massive horns on its huge head,
04:06and a third smaller horn on its nose.
04:10Its Greek name, Triceratops, means three-horned face.
04:16The beast roams the plains, feeding on vegetation
04:20and smashing down taller plants by using its horns, beak and sheer bulk.
04:27But the mighty Triceratops has an even larger neighbor,
04:31one that can easily eat the three-horned beast for lunch.
04:36The T-Rex.
04:39The king of dinosaurs is on the hunt.
04:42At nearly 42 feet long,
04:45this bipedal carnivore is one of the largest predators to ever live on land.
04:52Boasting the strongest bite of all terrestrial animals,
04:56this apex predator inspires fear.
05:01This Triceratops is lucky.
05:07The T-Rex realizes it is too dangerous to try for a meal.
05:20In the dust-layered rocks, Half-Lake is searching for clues about T-Rex.
05:26In the dust-layered rocks,
05:28Half-Lake is searching for clues about gigantic battles like these,
05:32fought eons ago.
05:34It's not long before he finds the first interesting fossil.
05:39This is a vertebra of a dinosaur,
05:41actually of a duck-billed dinosaur, of an Edmontosaurus.
05:45A pretty small one, I think it's somewhere from the tail.
05:49Edmontosaurus is a bulky, herbivorous beast,
05:53reaching 42 feet in size.
05:56It has a long, flattened tail,
05:59and became known as a duck-billed dinosaur
06:02because of its unique, horny beak,
06:05perfect for smashing tough plants.
06:08Huge herds of Edmontosaurus graze on this landscape
06:12and are much safer prey for a hungry T-Rex.
06:24The entire area is rich with fossils
06:27that can reveal the fate of the dinosaurs
06:30at the end of the Cretaceous.
06:33But to uncover the secret behind their demise
06:37and that of 75% of all species on Earth,
06:41Half-Lake's team comes up with an unusual idea.
06:47So we wanted to get this absolutely unique bone bed,
06:51which is like that much of bones,
06:54over a surface of several square miles.
06:57You should imagine how much this will be in bones, yeah?
07:01We want to take off a piece of about 5 to 5 meters
07:05to uncover it totally, to clean the surface,
07:09to fix anything we could find.
07:13We wanted to dig it out
07:15on the highest precision ever possible
07:18and then to take it into pieces with a chainsaw
07:21and transporting it about 8,000 kilometers
07:25from Wyoming to Frankfurt, Germany.
07:29Two containers weighing a total of 30 tons
07:32were shipped by boat.
07:35The scientists hope the bone bed will reveal new details
07:39about what life was like
07:42just before the dinosaurs went extinct.
07:46Frankfurt, Germany.
07:48The dinosaur bone bed from the Lance Formation
07:52has arrived in the Sankenberg Museum for Natural History.
07:57Professor Andreas Molch
08:00is the director of the Sankenberg Research Institute.
08:05He's hoping this bone bed will help him figure out
08:08what the world was like just before the catastrophe struck.
08:14In any good detective novel,
08:16the detective looks for the killer
08:18by investigating the crime scene.
08:20We're actually doing the same thing here.
08:22We want to understand what conditions the Edmontosaurs lived in,
08:26what was the climate like, what was the vegetation like,
08:29so to understand how life and therefore the disappearance
08:32of the dinosaurs took place at the end of the Cretaceous period.
08:37Professor Molch and his colleagues
08:39recover many fossils from the bone bed,
08:42including teeth from the Edmontosaurus.
08:46Take a look at this tooth battery.
08:49They belong together?
08:50Yes, they belong together.
08:52Then the teeth just kept moving forward little by little.
08:55And this is the occlusal surface.
08:57These teeth were all hidden in the jaw.
08:59And then it grows out of the jaw.
09:01Yes, there were just lots of rows next to each other.
09:05Clues hidden within the tooth enamel
09:08will reveal more about the world in which the dinosaurs lived.
09:17When we analyze the tooth enamel of this Edmontosaurus,
09:21we get a snapshot of the environmental conditions
09:24during the Cretaceous period,
09:26just before the dinosaurs went extinct.
09:28While the isotope analyses do not allow us
09:31to directly measure temperature and climatic conditions,
09:34they do give us an insight into the conditions
09:36that prevailed at that time.
09:38We get a fingerprint of the climate and vegetation conditions,
09:41and this allows us to reconstruct quite amazing things.
09:47By analyzing isotopes preserved within the dinosaurs' tooth enamel,
09:52Molch discovers what the Edmontosaurus ate 66 million years ago.
09:58Here we can see from the carbon isotopes
10:01that Edmontosaurus fed on plants that grew in dried-up lakes or salt marshes,
10:06so they give us a special insight into the entire ecosystem.
10:12This allows the scientists to reimagine the environment
10:16where the Edmontosaurus lived at the end of the Cretaceous.
10:20Along with carbon isotopes,
10:22oxygen isotopes give further insight into the paleoenvironment.
10:30Oxygen isotopes give us information about the development
10:33of precipitation and temperature at the Earth's surface.
10:37From the variation of oxygen isotopes within the teeth,
10:40we can see how the temperature has changed over the course of the year,
10:44and we can see here that winter temperatures
10:46must have been significantly warmer than they are today.
10:49Everything indicates that we have annual temperatures
10:52that were up to 14 degrees Fahrenheit warmer,
10:55and upwards a whole lot warmer.
10:59This happened because of a significant rise in carbon dioxide.
11:04What we know today from all the data is that the Cretaceous
11:07was basically a time of high atmospheric CO2 concentration.
11:12The last time CO2 levels soared was at the end of the Permian period,
11:17where unprecedented volcanic eruptions
11:20triggered the largest mass extinction on Earth.
11:24Were the changes seen in the Cretaceous atmosphere
11:27also extreme enough to end the reign of the dinosaurs?
11:33Unlike the rise in temperature at the Permian-Triassic boundary
11:37or the climate change we are experiencing today,
11:40climate change during the Cretaceous took place over many millions of years,
11:44so ecosystems and also species had time to adapt.
11:48Long-lasting climate changes are thus much easier for ecosystems to withstand
11:53and can give rise to entirely new species and species communities.
11:59The bone bed reveals that many species benefited from the gradual increase in CO2.
12:07That's a really nice little section of the bone bed
12:10with an impressive variety of species on it,
12:13from predatory dinosaurs to Edmontosaurus teeth and pieces of a turtle.
12:20We find plant remains, mammals, fish, everything that lived in and around the river.
12:26It is therefore clear that this great diversity also brought with it a diverse ecosystem.
12:34The high level of CO2 stimulates evolution for the majority of species.
12:40Dinosaurs in particular thrive in this new environment
12:44since their metabolism functions much better in warmer climates.
12:49We can definitely say that the high temperatures and the high CO2 concentration
12:53at the end of the Cretaceous were not the killer of the dinosaurs.
12:5966 million years ago, the concentration of CO2 is high.
13:05And so is the biodiversity.
13:08Life is thriving in a warming tropical world.
13:12But things are about to change.
13:16The reign of the dinosaurs is about to end,
13:20along with three quarters of all life on the planet.
13:24Only this time, a changing atmosphere won't be to blame.
13:30Something even more deadly and immediate is just around the corner.
13:40South Dakota.
13:42In the Hell Creek Formation, one of the world's leading dino hunters
13:46is looking for the remains of the ancient catastrophe.
13:52Peter Larson has discovered many fossils in the area
13:56that date to the extinction of the dinosaurs.
13:59So about 66 million years ago, this looked a whole lot different than it does today.
14:06Our fateful planet is constantly changing,
14:10as its tectonic plates reshape the surface.
14:15During the Cretaceous, North America is slowly shifting into the geography we know today.
14:22The area around the Hell Creek Formation was a low-lying floodplain
14:27consisting of rivers, streams, and wetlands.
14:31It's the land of the dinosaurs, where countless species roam freely.
14:38So, if we were here 66 million years ago,
14:41you'd probably see off in the distance a giant herd of duck-billed dinosaurs,
14:47maybe as many as 10 to 20,000 of them in one group,
14:50out just basically foraging and getting as much food as they can.
14:53Maybe you'd see an isolated Triceratops or maybe a family group over in here.
14:58And then somewhere in the taller trees,
15:00maybe there's a T-Rex kind of waiting for its opportunity to strike.
15:05Larson's picture of the Cretaceous world is based on decades of work by many paleontologists.
15:13Every new discovery provides another clue about the creatures that lived here.
15:19This is cool.
15:21It isn't long before the veteran dino hunter uncovers a new piece of the puzzle.
15:27We've got a couple of ribs, or maybe the same rib, just broken.
15:31And this cervical vertebra of a Triceratops.
15:36A bone broken in this way means a larger and stronger dinosaur was involved,
15:42likely a T-Rex hoping for dinner.
15:46This Triceratops was probably killed by a T-Rex.
15:49It's almost positive it was eaten by a T-Rex.
15:52And it was actually one of the last dinosaurs to live.
15:56These fossils paint a vivid picture of life here 66 million years ago.
16:03But then the story ends.
16:05Just somewhere above us, there's a line in the sand that the dinosaurs never crossed.
16:11To an untrained eye, this change in the rocks is nearly invisible.
16:20But its significance is huge.
16:25So this is the line in the sand that the dinosaurs never crossed.
16:31And it was, for a long time people looked at this, because there's no dinosaur bones above it,
16:37but there's dinosaur bones below it. All the time we find dinosaur bones below it.
16:41This line is known as the K-P-G boundary.
16:45It represents the end of the Cretaceous period and the end of the dinosaurs.
16:51This clay layer was deposited literally worldwide from some event.
16:59And there's fellows by the name of Walter and Louis Alvarez who were tracing this clay layer.
17:06And they found it in Italy and they found it in Denmark.
17:09And basically wherever we had marine sediment that preserves that moment in time, they find this clay.
17:16This boundary marks exactly when one of the greatest mass extinctions took place on Earth.
17:23Radiometric dating reveals that the layer is 66 million years old.
17:29But scientists are still trying to solve the mystery of how and why it happened.
17:35This discovery of this boundary clay and what it means is super important to our understanding of how the dinosaurs died.
17:42It's about two centimeters thick. It's a layer of clay and it's high in the element iridium.
17:49Iridium is a rare earth element, which means it's very rarely found on Earth.
17:53But it is common in asteroids and meteorites.
17:56Just after our planet formed, meteorite strikes were common.
18:01But as billions of years passed, most dangerous space debris was cleared from the solar system.
18:08Still, the threat of a major impact remained.
18:12And so they came up with a hypothesis that this clay layer was formed by the collision of an asteroid with the Earth.
18:21And with the amount of iridium, they theorized that this asteroid would have had to have been somewhere around 10 kilometers in diameter
18:30in order to deposit this much iridium in that small amount of time.
18:35But there was no crater. Nobody knew of a crater that was that time or that size.
18:41Because that would mean it was a 300 kilometer crater that this 10 kilometer wide asteroid would have created.
18:48This killer asteroid theory is popular in the scientific community.
18:54But the crime scene remains elusive.
18:57Where did it strike?
19:00The Berenger Crater in Arizona is one of the most famous craters on Earth.
19:07It was formed by a meteorite that struck the Earth's surface approximately 50,000 years ago.
19:15The meteorite is estimated to have been around 160 feet in diameter.
19:22The impactor that may have caused the dinosaurs to vanish is believed to be far larger.
19:29So the same must be true for the crater it created.
19:34But such a massive crater dating from the late Cretaceous had not been found anywhere on land.
19:41So scientists turned their search to the sea.
19:44Perhaps the crater was hidden beneath the waves.
19:49During the 1970s, Mexican oil company Pemex was scouting the seafloor in the Gulf of Mexico.
19:57They didn't find oil.
19:59But near the Yucatan town of Chicxulub, they did discover strange rocks that hinted at something else.
20:08Professor Ulrich Riller at the University of Hamburg analyzes maps of the area.
20:16The map shows a gigantic ring structure that is located at a depth of more than half a mile below the Earth's current surface.
20:24It extends to a depth of 12 miles with a diameter of about 120 miles.
20:32It is a huge pattern.
20:35It is a huge pattern that has all the characteristics of an impact crater.
20:41Could this be the site?
20:43Half of the crater is submerged, so the scientists begin searching for the other half on land.
20:52Mexico.
20:53A series of mysterious sinkholes dot the landscape.
20:58These holes, known as cenotes, appear randomly across the vast Yucatan peninsula.
21:06No rivers or lakes exist in this part of the Yucatan,
21:10so villages sprang up around many of the cenotes that filled with fresh water.
21:17Professor Riller believes the fascinating cenotes may hold clues to what happened here eons ago.
21:28Since the 1990s, there has been a suggestion that the cenotes could be related to an asteroid impact.
21:36NASA had mapped the water holes at that time and found that many of them are circular in shape.
21:43However, a plausible explanation for this observation was not offered at the time.
21:56Thousands of small dots show where the cenotes are located.
22:01A large part of them lies on a perfect semicircle.
22:05NASA experts suspected that this formation could represent the southern part of the crater ring.
22:12The underwater formation matches the ring of cenotes perfectly, except for one hitch.
22:20But the hypothesis had a problem.
22:23The rock in which the cenotes are located is much younger.
22:29Ulrich Riller.
22:31Ulrich Riller thinks the cenotes may have formed because of the impact crater, but more recently.
22:37To test his theory, he prepares an experiment with his Ph.D. student Jan-Oliver Eisenmann.
22:43They want to simulate how an impact crater might affect the surrounding sediment over a long period of time.
22:50The scientists pour a mixture of sand and flour over a layer of silicon, which simulates the Earth's crust.
22:57A rotating blade produces a crater.
23:00Then they check how this affects the surface over time.
23:04Time-lapse records any movement.
23:08The crater depression is partially leveled by the silicon substrate over time.
23:16The experiment clearly shows that the crater floor has risen as an entire platform
23:23and that the area surrounding the crater has sunk.
23:28This explains how the cenotes were formed.
23:31Because rock along the crater's rim moves in opposite directions after the impact, cracks form in the much younger rock.
23:40This ultimately creates cenotes.
23:43Everything fits.
23:45And the crime scene of the killer asteroid still exists.
23:49And the crime scene of the killer asteroid seems to have been found.
23:53But for definitive proof, the scientists must obtain samples of the rock from inside the submerged crater.
24:04In 2016, Professor Sean Gulick from the University of Texas led an international group of scientists on a mission to drill into the Chicxulub crater.
24:16Right now, beneath the drilling rig and beneath where we're sitting on this transport vessel is the peak ring of Chicxulub.
24:23It's buried by 66 million years of limestones.
24:28We picked this site because it's the place where the peak ring is closest to the modern sea floor.
24:37Woohoo! Here we go!
24:41Alright!
24:43It has taken years to prepare for the drilling, but the scientists may finally prove the crater's significance.
24:53It was an opportunity to sort of put to bed all the questions about,
24:58is it for sure that that impact crater is the one that is observed as the global boundary layer?
25:05Is it for sure that that is the impact that actually caused the mass extinction 66 million years ago?
25:14The water is very shallow at the drilling spot, so the team must use unconventional equipment to sample the ancient sediments.
25:25We used a land mining rig, actually, and hung it off the bow of the vessel and drilled for two months into the crater.
25:34And then we continued drilling literally until we ran out of money at 1,335 meters down.
25:42And so when we were finally on the drilling platform, drilling into the impact crater, and the first cores came up, it was just a heady experience.
25:52Look at the color of the matrix. It goes from green to red.
25:58That looks like melt. That looks like a giant cloud of melt.
26:02We are now fully into impact rocks directly. It's really easy to see because it's granite, and so you can see the spotted leopard-looking big chunks.
26:13We reached rocks that were clearly not normally laid down as you see in the ocean sediments, but something else.
26:21And we realized, of course, that that was the impact.
26:23The evidence suggests that a six-mile-wide asteroid impacted Earth at this site, completely altering the rock.
26:31One of the amazing things was just the, if you will, the resolution of the record.
26:36Because normally, at most, a centimeter might be a thousand years in an ocean core, in a scientific drill core.
26:43And in this case, we actually had 130 meters that, because it had a tsunami layer on the top and had impact melt on the bottom,
26:50we could say was effectively all deposited within the first day of the Cenozoic.
26:56So you can normally think about drilling into the ocean sediments that you might get, you know, a sentence about a time.
27:04And because we have 130 meters, it's like we have an entire novel about a single day preserved in the rock record.
27:12All of the Chicxulub drill cores are safely stored in the expedition's repository at College Station, Texas.
27:21This is where Sean Gulick examines them, hoping to prove that Chicxulub was, in fact, ground zero of the impact.
27:30So it turns out that the peak ring itself was made of granites, but these granites are fundamentally altered by having been in an impact crater.
27:39It is much more porous than it should be. It's actually weaker. In fact, you could crush it with your hands.
27:46And in fact, that's proof positive that this is in an impact crater, that you see these planetary deformation features.
27:53And all of these other observations of shock also say it has to be in an impact crater.
27:59The analysis shows that Chicxulub is definitely an impact crater.
28:05But can the scientists conclude that this impact led to the demise of the dinosaurs?
28:12What is viewed as the global boundary layer, what is viewed as the evidence everywhere outside of the crater as that there was an impact, is the presence of iridium.
28:24And so one of the interesting questions here is, do we find it in the crater itself?
28:29Can we directly tie the impact crater back to this global layer?
28:32And so to check that, we sent samples to four different laboratories around the world.
28:38And what we discovered is all the laboratories agreed that right at that location, right in that singular spot in the core, is where the iridium is found.
28:48All of the evidence suggests that Chicxulub is ground zero.
28:53By finding the iridium layer in the crater, directly on top of all of the deposits generated by the impact in the first day to weeks to months to a few years,
29:06we were able to conclusively say that Chicxulub absolutely is the location of the impact.
29:13The drill cores provide indisputable proof that the Chicxulub crater was formed by a six-mile-wide asteroid.
29:22And the impact occurred at the exact time that dinosaurs and many other life forms vanished from our planet.
29:32To understand if this single event was strong enough to cause the mass extinction,
29:38the scientists must calculate the effects an impactor of this size would have on the Earth.
29:45Freiburg, Germany.
29:48At the Fraunhofer Ernst-Mach-Institut, Frank Schaefer and Professor Thomas Kenkmann want to see what happens
29:55when a six-mile-diameter asteroid crashes into a planet at several thousand miles per hour.
30:01For this experiment, they engage one of the fastest guns ever created.
30:08So, this is our projectile, the downscaled asteroid.
30:13The aim is to achieve as much speed as possible to simulate the impact on the Chicxulub crater in the laboratory.
30:23The two-stage light gas gun uses a combination of highly pressurized gases and rapid expansion
30:31that will accelerate projectiles at super high speeds.
30:34The first stage initiates the acceleration, while the second stage provides additional propulsion for even greater velocity.
30:43Unlike natural craters, here we are witnessing the process as it happens.
30:49Chicxulub is a gigantic crater, but we only see the end result of a very, very complex process.
30:56Here we can experience all stages of the formation.
31:00The high-speed cameras allow us to follow what is happening at microsecond intervals.
31:07The gas gun cannon can launch projectiles at more than 17,000 miles per hour,
31:13so the team must take extra precautions.
31:20Three, two, one, fire!
31:30Nominal, trigger points, all right. I think that was a successful shot.
31:37Yeah, let's take a look at it.
31:40In addition to analyzing the high-speed footage, the team wants to investigate the crater that was created.
31:49The crater is quite deep, flat at the bottom and full of dust.
31:54There's a lot of dust in the chamber.
31:57You can see steep edges in the limestone and in the center.
32:02This seems to be the deep rock.
32:07What really surprises me is the amount of dust and small splinters that have been produced.
32:14It's very finely fragmented material.
32:17You can see it, you can feel it, you can hold it in your hand.
32:20It's fine dust. And this dust was also ejected by Chicxulub.
32:25But this topic is still subject of debate.
32:31The impact didn't just make a crater.
32:38The incredible force changed the molecular structure of the once solid rock.
32:43What we see here is the mineral quartz.
32:46There are strange, straight lines.
32:49These lines are exactly what we were looking for.
32:52They are shock indicators that show us that a shock wave has traveled through the rock.
32:58That's what the experiment shows us.
33:01It's just like the subsurface of the Chicxulub crater.
33:06Professor Kai Wünemann must now apply a new method of analysis.
33:10Professor Kai Wünemann must now apply data from the experiment to the proper scale.
33:17He plans to calculate the effects from the asteroid impact 66 million years ago.
33:26Now we can actually simulate the right dimensions and quantities, such as the right gravity.
33:33And that should tell us something about how much energy was released.
33:40The colossal asteroid was on an inescapable collision course with Earth.
33:47Traveling at an astronomical speed, when the behemoth pierced the atmosphere, it ignited in the sky.
33:55It hurtled towards Earth at nearly 45,000 miles per hour.
34:00Its path of compressed air caused a shock wave to reverberate across the planet's surface with a cosmic boom.
34:09Blazing a trail of fire, the asteroid plummeted towards the ground.
34:15Then it crashed into the shallow ocean with apocalyptic force.
34:19The impact released 4.5 billion times the energy of the Hiroshima atomic bomb.
34:27This energy that is released melts the rock.
34:31And it doesn't just melt it.
34:33It actually reaches temperatures in the region of 36,000 degrees Fahrenheit.
34:39That leads to the rock being vaporized.
34:45The energy it released was devastating.
34:49After a flash illuminates the sky, an eerie bright white sphere grows over the impact site.
34:57Bedrock melts into a scalding plasma that releases a shock wave even greater than the first.
35:04Even deep rocks are so heavily fractured, they fly like water.
35:10It's actually very similar to what you see when you throw a stone into water, which also creates a crater.
35:16It usually doesn't last very long.
35:18We hardly see it, but it also collapses, and then it splashes up in the middle, and it forms what we call a central mountain.
35:24So it resembles the splashing up in the middle.
35:29The surrounding ocean water is displaced or instantly evaporates when the asteroid strikes.
35:37Molten crust forms a temporary mountain, taller than any on Earth today.
35:45This tower of fiery liquid plasma collapses quickly.
35:50And at the same time, the water that was previously displaced flows back into the crater.
35:57And through the collapse of this temporary mountain in interaction with the returning water,
36:03waves are generated that are nearly a mile high and then spread out, comparable to tsunami waves.
36:10And this, of course, also devastates coastlines thousands of miles away from the impact center.
36:16The impact destroys everything living in the immediate vicinity.
36:21First, it is burned, then blasted by the shock wave.
36:27Anything left drowns in a miles-high tsunami.
36:31But such an apocalyptic wave should have left evidence in the rock record.
36:37800 miles from the impact crater, Sean Gulick searches for clues in the Brazos River in Texas.
36:48This is one of the locations where the exact time of the impact comes to the surface,
36:54so right where the end of the Cretaceous and the start of the Paleogene is preserved.
36:58It's preserved in the Brazos River, and it's preserved within little waterfalls within the creeks nearby.
37:04So it's a great place to search for evidence of the impact.
37:07Gulick wants to build a complete picture of one of the most terrifying days in the history of our planet.
37:14Three-quarters of life on Earth died out in the same geologic moment.
37:19It's one of the most terrifying days in the history of our planet.
37:23Three-quarters of life on Earth died out in the same geologic moment.
37:28It's an incredible exposure of the K-Pg boundary.
37:32Basically, the shaly stuff at the bottom predates the impact.
37:36This is the time of the dinosaurs and the large marine reptiles, and then this is the boundary.
37:42And the contact is actually, you know, it's kind of erosional.
37:46It's got a lot of energy in it that carves into what was there before.
37:50And then a series of events are basically recorded in this more than a meter of material that is the K-Pg boundary.
37:59You see it here, right? These cross-stratified, these dipping layers that are present right here within the rocks,
38:06and this high-energy-looking material above it of the finer particles,
38:11all of this probably represents the arrival of the tsunami here in central Texas.
38:16The tsunami is global, with an estimated force 30,000 times greater than any in recorded history.
38:25Each piece of evidence gives the scientists a clear snapshot of how the disaster unfolded at the end of the Cretaceous.
38:34If you were living 66 million years ago, the effects of the impact would depend where you were compared to ground zero in the Yucatan Peninsula.
38:43So we're at about 1,300 kilometers away from the site.
38:47Anything within probably 1,500 kilometers would have experienced the direct heat from the impact itself.
38:54In other words, the impact explosion was so large, you could see it over the horizon.
39:00You would have been killed at the speed of light by just the thermal radiation coming out from the impact.
39:05If you were a little bit further away, you would have felt the hurricane-force winds, you would have felt the earthquakes.
39:09The extent of the impact is impossible to imagine.
39:14Thousands of miles away on both Pacific and Atlantic shores, enormous tsunamis wreak havoc, inundating everything in their paths.
39:24The presence of a tsunami layer, especially one as thick as this, you know, 1,300 kilometers away from the crater, is just testament to the incredible energy.
39:34In fact, the energy released by the impact is billions of times the energy of a World War II-era nuclear bomb.
39:42But despite the epic scale of the event, Gulick needs more evidence to support that the impact had global consequences for life.
39:50The thermal radiation, the tsunamis, and the hurricanes were not sufficient to cause the extinction of 75% of species 66 million years ago.
40:00He must search for additional clues to uncover what happened to dinosaurs worldwide.
40:08By carefully analyzing the prehistory recorded in the KPG rocks, he finds a clue that might explain their demise.
40:16Yeah, you can see the spherules. There's little glassy looks, but you can still see little hints of the layers of spherules that are all present inside this rock.
40:27Spherules look like little glass balls. The largest you might ever find would be maybe a centimeter, but most of the time they're millimeters or even sub-millimeters in scale.
40:37So they're either referred to as melt that ejected out of the crater and cooled into a sphere and traveled and then rained down,
40:45or they're actually vapor in the plume that condensed into a glass sphere that then rained down.
40:52These innocuous glass balls are key to the events set in motion after the impact.
40:58The spherules are found on the KPG boundary around the world and clearly coincide with the impact at the end of the Cretaceous 66 million years ago.
41:10They are a solid connection to that moment in time.
41:14When the asteroid slams into the bedrock, molten and vaporized rock is thrown into the sky. Some even reaches space.
41:25Small droplets of rock in the plume condense and solidify, falling back to Earth as tiny glass beads.
41:33So in any location around the world that has a well-preserved boundary layer, you see material that arrived as ejecta, and you see material that was basically a dust that rained out later.
41:46The ejecta was moving at high velocities, and so that is the spherules that we see here. It's a big wedge.
41:53Could the ejecta have contributed to the extinction of the dinosaurs?
42:00Back in Hell Creek, Peter Larson, a geologist at the National Geographic Observatory,
42:06found the remains of a dinosaur.
42:09This is a dinosaur.
42:11This is a dinosaur.
42:13This is a dinosaur.
42:15This is a dinosaur.
42:17This is a dinosaur.
42:19This is a dinosaur.
42:20Back in Hell Creek, Peter Larson is analyzing how the Chicxulub effects unfolded across the planet.
42:32So here we have a piece of the boundary clay and the coal that's just above it.
42:37So if we kind of scrape away the boundary clay a little bit, and I'm not sure that that's soot,
42:45but sometimes we can find a layer of soot that's actually right above the very top of the boundary clay here.
42:53So that is indicative of forest fires.
42:56Remnants of ancient burned forests are expected at an impact site.
43:01But Larson is in South Dakota, 2,000 miles from where the meteorite struck.
43:08There was, all of this molten material was flung up out of the atmosphere and rained down.
43:15But as they came through the atmosphere, they heated the atmosphere up to the point where basically all the forests and all the plants had to burn.
43:23The atmosphere was so hot.
43:25Some have estimated as more than 2,000 degrees at the surface of the earth in some places.
43:31Earth is on fire.
43:34Wildfires are raging globally, with trees and life within the forests turning to ash.
43:43Earth is scorched in the aftermath, and many creatures die.
43:48But was this the definitive mechanism that led to the mass extinction?
43:54Sean Gulick returns to the lab to re-examine the Chicxulub crater drill cores.
44:00They might hold a hidden piece that will solve the puzzle.
44:05Sean discovers a strange anomaly he missed before.
44:09It isn't because of what he finds, but about what he doesn't see.
44:16There is a glaring absence of light.
44:19It's about what he doesn't see.
44:22There is a glaring absence of sulfur-bearing minerals, and they should be here.
44:28One of the key clues to understanding, you know, what ultimately caused the extinction event
44:36turned out to be that even though we knew the original rocks of the Yucatan Peninsula were 30 to 50 percent sulfur-rich rocks,
44:45we don't find any evidence of the anhydrite or the gypsum left in the crater.
44:51And so the conclusion that comes from that is that preferentially all of these sulfur-rich rocks got put up into the atmosphere.
45:0066 million years ago, life was doomed when the Chicxulub asteroid impacted a spot that caused marine rocks to vaporize.
45:10Copious amounts of sulfur were released into the sky.
45:16We would have had an incredible amount of sulfur.
45:19In fact, the estimates are something like 335 gigatons of sulfur would have been put into the atmosphere.
45:27A chemical reaction between sulfur from the vaporized rocks and water expels more than 300 gigatons of sulfur aerosols into the atmosphere.
45:38The aerosols scatter incoming solar radiation, which reduces the sun's ability to warm the surface of the Earth.
45:47This leads to rapid planetary cooling.
45:51Even if you use just 100 gigatons of sulfur and you run a climate model,
45:56you can drop the global temperatures by 25 degrees Celsius, just with, you know, a third of what we think we put into the atmosphere.
46:05Plunging temperatures on the planet are just one terrible effect produced by the sulfur.
46:12The ensuing darkness is even deadlier.
46:18It was the dust and the sulfur in the atmospheres that caused darkness and maybe twilight for years
46:24that meant that all of the things that eat the sun for their energy,
46:29so phytoplankton in the oceans and plants on land,
46:32that these would have started dying out,
46:36and therefore those that ate the phytoplankton or ate the plants on land started dying out,
46:42and then the carnivores that ate them started dying out,
46:45and it caused this collapse all the way up the food chain.
46:49The impact winter lasts many years.
46:53It freezes and starves most life on our planet.
46:57Darkness in the wake of the Chichalup impact, 66 million years ago, spells death for plants.
47:05Consequently, most herbivores die, which leads to the death of carnivores too.
47:12As the food chain collapses, 75% of all life forms on Earth become extinct.
47:19Sulfur turns out to be the real killer.
47:22Perhaps the dinosaurs would have survived if the asteroid hadn't crashed into sulfur-rich rocks.
47:29If it had actually hit 30 seconds earlier and hit the Atlantic Ocean,
47:33or 30 seconds later and hit the Pacific Ocean,
47:36instead of sulfur-rich rocks and limestone dust, we'd have just had water vapor,
47:41and probably not a massive extinction event like happened 66 million years ago.
47:46But how could any living thing have survived this catastrophe?
47:53The Chichalup impact triggered the last of the five mass extinctions in Earth's history.
47:59But if there's one lesson we can learn from the previous cataclysms,
48:03it's that life always finds a way.
48:07It takes around 20 years for the atmosphere to be cleared of dust and sulfur.
48:12Once again, the sun pierces through a clean sky.
48:16Plants reappear.
48:19But what about the animals?
48:22Paleontologist Philip Hofflich joins Pete Larson at Hell Creek.
48:29They're hunting for clues that might reveal how life re-emerged after the impact.
48:36Near the end of the Chichalup impact,
48:38they spot a familiar fossil.
48:42Holy crap!
48:44This is not a rock at all.
48:46That is not a rock, that's a dinosaur bone.
48:48Oh, wow.
48:50Oh, and look at how close we are.
48:52Oh, man.
48:54Oh, that's so cool.
48:56It's a tail vertebra from a duck-billed dinosaur.
48:59It's like, holy crap.
49:01Right here.
49:03Right here.
49:05Half a meter below the bone.
49:06Right here.
49:08Half a meter below the boundary.
49:10But it's actually washed down, so it maybe was really, really close to the boundary.
49:14So, this dinosaur might have seen that asteroid crash into the earth.
49:20I mean, it's possible.
49:22It's close enough that it could have washed down that much.
49:25So, certainly one of the last dinosaurs to live.
49:28No question about that.
49:30You poor, unlucky thing.
49:33Soon, they find signs of what they are really searching for.
49:39No.
49:41Is it?
49:43I think it's a little multi-tuberculate tooth.
49:45Come on, come on.
49:47I think so.
49:49Is that cool?
49:51Hey, I can see the rootlets.
49:53It is, it is.
49:55So, this is a multi-tuberculate tooth.
49:57Multi-tuberculates lived in the Hell Creek,
49:59they lived in the Cretaceous,
50:00they made it all the way through into the Paleocene.
50:02They're a very small mammal.
50:04With over 200 distinct species,
50:07these rodent-like mammals range in size from tiny mice-like creatures
50:12to the bulk of modern beavers.
50:14They lead diverse lifestyles.
50:17Some tunnel underground,
50:19while others navigate canopies like squirrels
50:22or hop across the landscape.
50:24These little guys were able to survive simply because they were so tiny and so small.
50:30They could hide in little cracks and crevices into a burrow,
50:34where a dinosaur couldn't go.
50:36They also didn't need all the food to eat.
50:38So, if this animal could survive on dried out
50:43and maybe even partially burnt plants,
50:45or if it was a carnivore,
50:47it could exist in the carcass of a dinosaur.
50:50There's lots of food there, you know,
50:52lots of jerky that this animal could exist on for a long, long time.
50:55And so, it was able to survive that nuclear winter
50:57that was the result of that asteroid crashing into the Earth.
51:02As the impact winter finally fades away,
51:06small mammals like these find ways to thrive in a world
51:10that had been leveled by catastrophe.
51:13They are the true survivors.
51:16They owe their success to one special characteristic,
51:20being small.
51:22The larger the animal,
51:24the more energy it requires to survive.
51:27Because food is scarce,
51:29size is a liability,
51:31and only the smallest persevere.
51:34When all these dinosaurs died,
51:37not only were there some survivors,
51:39but it left open ecological niches,
51:42which were kind of like job opportunities.
51:44And so, little guys like this,
51:46little tiny, tiny mammals,
51:48grew into things like,
51:50eventually into things like elephants.
51:52Today, mammals are extremely diverse.
51:55From the tiny to the colossal,
51:58mammals span a remarkable range of sizes.
52:02They inhabit wildly different ecosystems,
52:06from icy Arctic tundras,
52:08to lush rainforests and arid deserts.
52:12They enjoy the air,
52:14the water,
52:16and the land.
52:18Surprisingly, dinosaurs didn't become completely extinct either.
52:22Some of the small, avian-like dinosaurs survived,
52:26and evolved into birds.
52:29Their ancestors thrive today,
52:32with a vast array of colors,
52:34shapes, and behaviors.
52:37The dramatic chain of events
52:39that began with the Chicxulub asteroid impact
52:4266 million years ago,
52:44drastically altered life on Earth.
52:48All non-avian dinosaurs,
52:50including the iconic T. rex,
52:53could not survive the long-term effects of the impact.
52:57Their demise would pave the way to the rise of mammals,
53:02and ultimately, to the evolution of humankind.
53:20Transcribed by ESO, translated by —
53:50Transcription by ESO, translated by —