Documental Dinosaurios del continente helado
En las profundidades del manto de hielo de la Antártida se encuentran rastros de un mundo perdido de dinosaurios y criaturas prehistóricas. Grandes bosques cubrían una vez el continente antártico, ahora helado; gigantescos titanosaurios vagaban por sus valles y protomamíferos se movían rápidamente por la maleza. También fue el hogar del carnívoro más grande de su época, el Cryolophosaurus, el T-Rex de la Antártida.
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00:00:00ANTARCTICA
00:00:05Antarctica.
00:00:08A continent frozen in the confines of the earth,
00:00:13practically devoid of animal and plant life.
00:00:19But millions of years ago,
00:00:23this was a land of enormous dinosaurs
00:00:26that inhabited an exuberant and forest ecosystem.
00:00:34Here, agile predators hunted fast prey.
00:00:43This huge continent also served as a refuge
00:00:47for resistant creatures that survived a massive extinction
00:00:52and for giant reptiles that were more than a ton of weight.
00:01:03A team of scientists entered this lost world,
00:01:09hoping to unravel the secrets of the mysterious past of Antarctica.
00:01:14They ventured into the most inhospitable place on earth,
00:01:19where to look for fossils.
00:01:28The ancestral land.
00:01:31Dinosaurs of the frozen continent.
00:01:39More than a century ago,
00:01:41the extraction of the last fossils of a dinosaur
00:01:45contributed to changing the idea
00:01:48that Antarctica was nothing more than an inaccessible frozen territory.
00:01:53This has been one of the most extraordinary experiences of my life
00:01:58and the most difficult.
00:02:01Antarctica.
00:02:09Incredibly, this was the largest carnivore
00:02:13of the lower Jurassic on our planet.
00:02:19And it was discovered on the southernmost continent,
00:02:23of which it was thought until just 100 years ago
00:02:26that it had never housed any kind of prehistoric life.
00:02:31After the discovery of the Cryolophosaurus,
00:02:35others arrived, such as the Glacialisaurus.
00:02:39There were even signs that the largest dinosaurs on earth
00:02:43had used Antarctica as a terrestrial bridge.
00:02:52But how did the forests, plants and animals
00:02:56survive in a polar continent
00:02:59that bears four months of total darkness a year?
00:03:05And how did some Antarctic creatures manage
00:03:09to survive a massive extinction
00:03:12that ravaged life on the other continents?
00:03:19In short, how did the dinosaurs
00:03:22dominate the lost world of Antarctica?
00:03:26ANTARCTICA
00:03:32To reach the borders of the earth,
00:03:35scientists are preparing in Christchurch, New Zealand,
00:03:39the trampoline to reach the frozen continent.
00:03:45Dr. Nate Smith, along with Drs. Patty River and Libby Ives,
00:03:51will join a dozen scientists
00:03:53to carry out a summer expedition
00:03:56to the Transantarctic Mountains.
00:03:59The last time Nate was here was in 2011.
00:04:03Now he wants to repeat the success of that mission.
00:04:07It's always exciting when you get to Christchurch.
00:04:11It's when you really realize
00:04:14that you're about to travel to Antarctica to work on the ground.
00:04:18But before you go to your destination,
00:04:20you have to finish all the details.
00:04:23Safety is important.
00:04:26This is the third time that Dr. Patty River,
00:04:29a prehistoric plant expert, is going to Antarctica.
00:04:33We always have to carry walkie-talkies with us.
00:04:37So don't forget to book a pocket for a walkie-talkie.
00:04:41Right.
00:04:43For me, right now, Antarctica is that great unknown.
00:04:46It's this great red anorak.
00:04:49Right now, all the possibilities are absolutely crazy.
00:04:53Shackleton on three.
00:04:55One, two, three.
00:04:57Shackleton!
00:05:01The rocks at the top of the Transantarctic Mountains
00:05:05that surround the glaciers
00:05:07are an ideal place to look for fossils.
00:05:10This time I'm really excited to go to the Shackleton Glacier,
00:05:13a place I've never been to before.
00:05:16Because it has been a very well-known location
00:05:19in the history of Antarctic exploration,
00:05:22as well as for paleontology in the last 50 years.
00:05:27Surprisingly, this huge continent
00:05:30hasn't completely frozen up until just 15 million years ago.
00:05:38The layer of ice would completely cover the United States of America.
00:05:44The speed of the winds and low temperatures
00:05:48can't be found anywhere else on Earth.
00:05:52If you think about it,
00:05:54the amount of ice in Antarctica is enough to drive you crazy.
00:05:58The continent covers just over 14 million square kilometres,
00:06:02and about 98% of this area is covered in ice.
00:06:07But the history of how the world of ice was created
00:06:11began a long time ago, 300 million years ago.
00:06:18At that time, the world was mainly formed
00:06:21by a supercontinent called Pangea.
00:06:24It extended from the northern hemispheres
00:06:28to the frozen southern hemispheres.
00:06:31At this point in the history of the world,
00:06:33the layer of ice in Antarctica is melting
00:06:37due to an early global warming of the Earth.
00:06:47250 million years ago,
00:06:50this polar world went from being a fridge
00:06:53to becoming a greenhouse.
00:06:56And little by little, it split into two great continents.
00:06:59Eurasia, in the north,
00:07:02and Gondwana, in the south.
00:07:08But they are still not inhabited by dinosaurs.
00:07:12There is still time to get there.
00:07:15Strange and wonderful predecessors
00:07:18are already wandering through their forests and swamps.
00:07:30Among them, the most common creature of that era,
00:07:34a resistant herbivore the size of a dog called Listrosaurus.
00:07:40They occupied all of Gondwana's territory
00:07:43and were discovered in Antarctica in the late 1960s.
00:07:46They had a kind of fangs on their snouts
00:07:49and something like a beak, a short and plump tail,
00:07:52and very robust limbs.
00:08:00Here, some giant amphibians also prospered.
00:08:06Before the era of the crocodiles,
00:08:09they occupied a similar niche with a similar bite.
00:08:29They hunted smaller animals, like the Listrosaurus.
00:08:40The Listrosaurus belonged to a group of reptiles
00:08:44similar to the mammals that evolved
00:08:47to become real mammals.
00:08:53These little creatures played a key role
00:08:56in the theory of plate tectonics.
00:09:03Five decades ago,
00:09:06science did not quite accept the idea
00:09:09that the great continents were separating more and more.
00:09:13The Listrosaurus of Antarctica served as irrefutable proof
00:09:17when fossils were found thousands of kilometers away,
00:09:21in southern Africa.
00:09:24It was a great discovery to find the first Listrosaurus in the 70s
00:09:28because the theory of plate tectonics was beginning to settle
00:09:32and suddenly the same animal appears in Africa and Antarctica,
00:09:36which had a huge impact.
00:09:39We have found this animal in South Africa,
00:09:42in Antarctica, in India, in China, in Russia, in Australia.
00:09:46It is clear that this animal could not cross the oceans,
00:09:49so it had to come ashore to all those places.
00:09:53The fact of finding the same species of plants and animals
00:09:57in Antarctica that we found in other southern continents
00:10:01was the tip for the skeptics of the theory of plate tectonics
00:10:05about the position of the continents in the past
00:10:09and that still today they continue to move.
00:10:14Antarctica is the most inhospitable place on Earth
00:10:17to explore in search of fossils.
00:10:21Most of the continent is inaccessible
00:10:24since the surface is covered by huge layers of ice.
00:10:28But at some points the rock emerges from the ice.
00:10:32This is the reason why numerous expeditions
00:10:36have the Transantarctic mountains as their destination.
00:10:40Even so, their secrets are kept buried under the frozen rocks
00:10:44in the most inaccessible places.
00:10:48Millhammer, currently retired,
00:10:51spent 50 years exploring this lost world,
00:10:54full of dangers and difficulties.
00:10:58The first two trips were hard.
00:11:01You are isolated there with just a handful of people.
00:11:04But you have to choose the right people
00:11:07with whom you are going to travel to Antarctica.
00:11:10That is something I learned,
00:11:12that you have been great companions.
00:11:15We love you.
00:11:17Nate Smith was a weak student.
00:11:20But this time he leads a joint expedition.
00:11:23And one of his goals is to solve this mystery
00:11:26that intrigues the experts since they began to find fossils there.
00:11:32How could plants and animals like the Listeria survive
00:11:36in the total polar darkness of winter?
00:11:42Despite the constant displacement of the continents,
00:11:45Antarctica has never separated too much from the polar circle
00:11:49in which darkness reigns for four months a year.
00:11:54One of the eternal mysteries of Antarctic paleontology
00:11:58is to know how these ecosystems lived in high latitudes
00:12:02in a system of polar light.
00:12:13The expeditions are always carried out during the summer months
00:12:17in which they can enjoy the solar light 24 hours a day,
00:12:22so they can work with light as many hours as they want.
00:12:28After a few days of preparation in Grace Church,
00:12:31the time has come to leave.
00:12:34Antarctica is one of the hardest places in the world
00:12:38to look for fossils, and this is largely due to logistics
00:12:42to be able to get there and work on the continent.
00:12:47Smile, guys!
00:13:04It is a six-hour flight on board an American Air Force plane
00:13:09from Grace Church, New Zealand, to the frozen continent.
00:13:19Located at the northern end of the island of Ross,
00:13:23McMurdo, managed by the United States, is the largest scientific base.
00:13:28This base, which houses 200 people,
00:13:32will be their home for a week,
00:13:35in which they will prepare their trip to the Sackleton Glacier.
00:13:45It is a mixture of a remote mining settlement
00:13:49and a small liberal arts faculty.
00:13:53And it is designed to resist terrible storms.
00:13:58On the ground, scientists face real risks.
00:14:06Antarctica is such an isolated place,
00:14:09and the weather conditions are so extreme,
00:14:12that it is a very dangerous place to work,
00:14:15and you have to adopt many security measures
00:14:18and undergo a demanding training.
00:14:21One of the biggest risks is the cracks,
00:14:23huge holes that can be opened without prior notice.
00:14:33All field scientists must learn to get out of them
00:14:37by climbing in case of falling into one.
00:14:41Even in the warmest months,
00:14:44storms, very strong winds and very extreme temperatures can occur.
00:14:48That is why we follow a special training
00:14:50before we enter the terrain.
00:14:53We receive training on the cracks,
00:14:56methods to sort glaciers,
00:14:59and to be prepared for those conditions.
00:15:03Soon, living under a sack will be their world for six weeks.
00:15:11As if warning them of what awaits them,
00:15:14a strong storm falls over Antarctica.
00:15:21We have had a very bad weather,
00:15:24and we have to delay the transfer to our camp,
00:15:27and obviously we cannot fly in this weather.
00:15:31They will take everything they need
00:15:34to spend six weeks in the traditional mountains of Antarctica.
00:15:38Once the storm has passed,
00:15:41they are transported to the depths of Antarctica.
00:15:57Now they are completely alone.
00:16:00They have no one to rely on.
00:16:03They have no one to rely on.
00:16:05They are completely alone,
00:16:08hundreds of kilometers from the nearest aid,
00:16:11and thousands of miles from civilization.
00:16:17Somehow you get the feeling that you are arriving to another planet.
00:16:20Their mission is to understand
00:16:23the most transcendental mass extinction
00:16:26in the history of the planet,
00:16:29which took place 250 million years ago.
00:16:38They intend to reach a well-known crest of sacred rocks,
00:16:42which has been preserved for thousands of years.
00:16:46They intend to reach a well-known crest of Sakelton,
00:16:50called Collinson Ridge.
00:16:53With decades of experience behind him,
00:16:56Bill Hammer gave advice to Nate and his team
00:16:59before embarking on the trip.
00:17:02The hardest place to reach,
00:17:05although it will be one of your best locations,
00:17:08is Collinson Ridge.
00:17:11There we find very interesting things,
00:17:13you have to get to the glacier,
00:17:16get down here, 45 minutes on a snowmobile,
00:17:19and a one-hour hike uphill to the top.
00:17:23But today, the helicopter transfer
00:17:26makes it one of the most accessible places
00:17:29for the search for fossils.
00:17:36Many of the places we go to,
00:17:39we are the first people who have stepped on them.
00:17:41It's an indescribable feeling.
00:17:44Another amazing thing about this place
00:17:47is that if there is no wind and you move away from your companions,
00:17:50the silence is total.
00:17:59You can't find anywhere else in the world
00:18:02where it's possible to experience total silence like here,
00:18:05and it's nice, it's kind of irritating, but it's nice.
00:18:08They are divided into smaller teams.
00:18:11The sedimentologists are located
00:18:14in a mountainous cliff on the outskirts
00:18:17where a key geological event occurred.
00:18:20All of this corresponds to the lower Triassic,
00:18:23so we are facing something that is about 252 million years old
00:18:27and that is trapped in time as a sample of that flood event.
00:18:31It's incredible.
00:18:34Somewhere between where I am now
00:18:36and about three feet above me,
00:18:39between 70 and 90 percent of the plants
00:18:42and animals around the world disappeared.
00:18:48The transition between the Permian and the Triassic
00:18:51is marked by what paleontologists call
00:18:54the Great Mortality.
00:18:5770 percent of terrestrial animals died,
00:19:00as well as 95 percent of marine life.
00:19:06All because of a widespread destruction
00:19:09of forests, plants and nutrient ecosystems.
00:19:15It was a catastrophe for planet Earth.
00:19:25The mass extinction at the end of the Permian was colossal.
00:19:29Life was at the edge of the knife
00:19:32and it meant a fundamental remodeling and reorganization
00:19:34of the ecosystems.
00:19:37The expedition to Antarctica
00:19:40is looking for samples of the roots of this period,
00:19:43both earlier and later.
00:19:49At 2,100 meters,
00:19:52Pete Makovicky and Akiko Shinja
00:19:55have found a fossil of the Istrosaurus
00:19:58embedded in the frozen rock.
00:20:01We are in the process of extracting
00:20:04what we found this morning.
00:20:07We think it is an Istrosaurus,
00:20:10although it is an assumption based
00:20:13mainly on the size of the specimen.
00:20:16This discovery is just another indication
00:20:19that there were still Istrosaurus around here
00:20:22after the Great Mortality.
00:20:25It is a lineage of survivors.
00:20:30One of the few lineages of terrestrial animals
00:20:32that managed to survive
00:20:35the great extinction of the Permian.
00:20:38But how did it survive?
00:20:41And what was Antarctica like afterwards?
00:20:49Forests are disappearing all over the world
00:20:52as a hot and toxic land
00:20:55ends up with life everywhere.
00:20:57All over Siberia,
00:21:00the mantle of the earth
00:21:03spat out huge volcanic lava beds
00:21:06that covered an area
00:21:09equivalent to half the size of the United States,
00:21:12with a thickness of several kilometers.
00:21:15This activity released
00:21:18huge amounts of carbon dioxide
00:21:21that heated the temperature
00:21:24to levels exceeding 10.5 degrees Celsius.
00:21:27This created too much heat
00:21:30for the survival of most animals.
00:21:33And ultimately led to a total reorganization
00:21:36of the ecosystems.
00:21:39And we also see a general alteration
00:21:42in the communities of plants,
00:21:45so that there are no forests
00:21:48after the transition between eras.
00:21:54Only the most resistant
00:21:57and adaptable species remain.
00:22:09Ancestors of the cockroach, of course.
00:22:14And the prolacerta,
00:22:17a creature similar to a lizard
00:22:20that preceded dinosaurs and crocodiles.
00:22:23The prolacerta existed about 250 million years ago.
00:22:25It is one of the first animals found
00:22:28after the great extinction of the Permian-Triassic.
00:22:31Its name means before the lizards,
00:22:34although they are actually relatives
00:22:37of dinosaurs and crocodiles.
00:22:40It belongs to the reptile lineage,
00:22:43so in a way it is the most similar
00:22:46to a dinosaur that we find
00:22:49from the lower Triassic.
00:22:52Extracting animals from the frozen rock
00:22:55is very difficult.
00:23:00Scientists have spent a long time
00:23:03focusing on places in the world
00:23:06where access and extraction are easier.
00:23:10But on many occasions
00:23:13they stumble upon the bones by chance.
00:23:16The lost world of Antarctica
00:23:19has remained hidden
00:23:22in an inaccessible continent
00:23:25for just over a century.
00:23:28No one even suspected that Antarctica
00:23:31was covered with forests
00:23:34and that there were prehistoric animals wandering around.
00:23:38So, what changed?
00:23:42The first explorers arrived in the region.
00:23:47Robert Scott discovered the first clues in 1912.
00:23:50Scott and his team tried to get to the South Pole
00:23:53when they stumbled upon rocks
00:23:56with fossils of leaves printed on them.
00:24:00Despite the extreme conditions,
00:24:03the explorers took them with them.
00:24:07But as we know,
00:24:10Scott and his team died there,
00:24:13so the fossils of Glossopteris
00:24:15were later found on a sled
00:24:18near their corpses.
00:24:21This changed our perspective
00:24:24on Antarctica and its geological history.
00:24:27As a paleontologist,
00:24:30I think it's amazing
00:24:33that these people found these remains
00:24:36and were able to recognize their importance
00:24:39to understand that Antarctica
00:24:42had been a very different place
00:24:45in the past.
00:24:48The discovery of this plant proof
00:24:51implied that the forests had previously covered
00:24:54this great continent in warmer times.
00:25:01But how did the forests survive
00:25:04in the extremes of the polar latitudes
00:25:07where the darkness was total for months?
00:25:16Scott only found leaves in Antarctica,
00:25:19but the fossilized trees of a nearby neighbor
00:25:22can give us some clues
00:25:25that help us solve this mystery.
00:25:29There was a time when New Zealand
00:25:32was much closer to the frozen polar continent
00:25:35than it is today.
00:25:38It was part of the ancient Gondwana
00:25:41in the South, joined to Antarctica and Australia.
00:25:44About 83 million years ago,
00:25:47New Zealand tore itself apart
00:25:50anchored to its own tectonic plate
00:25:53and drifted along the South-West Pacific
00:25:56carrying a biological load
00:25:59of primitive animals and plant life.
00:26:05What are we looking for?
00:26:08We're looking for fossilized wood.
00:26:10Dr. Patti Reiber, paleobotanist,
00:26:13and Dr. Libby Ives, sedimentologist,
00:26:16visited a very rare example of
00:26:19170 million year old fossilized trees
00:26:22in the South Island, New Zealand.
00:26:26Is it possible that these fossilized trees
00:26:29are a time capsule
00:26:32and offer us a window
00:26:35to look into the ancient Antarctica?
00:26:40Look, Patti.
00:26:42What?
00:26:44Look at this.
00:26:46It's incredible.
00:26:48Between the pools that leave the tides
00:26:51there are petrified trees.
00:26:54How tall do you think they are?
00:26:57Is this the total length?
00:27:00No, this is just the central trunk.
00:27:03It's one of the few places on Earth
00:27:06where we have a fossil forest
00:27:08that hasn't been moved from where they were
00:27:11when they were living trees.
00:27:14These forests probably grew in the polar circle
00:27:17or near it when New Zealand was thousands of miles
00:27:20further south.
00:27:23What's certain is that the trees in Antarctica
00:27:26had to survive months of polar darkness.
00:27:29These are plants that grew in a dark environment
00:27:32for four months,
00:27:35and the sun didn't set for another four months.
00:27:38It's not like that today.
00:27:41How did plants manage to do that?
00:27:44To keep on living and survive?
00:27:47So, we've got this really long tree,
00:27:50and if you crouch,
00:27:53you can even see the rings.
00:27:56These rings show that the tree grew
00:27:59until it was about 90 years old
00:28:02and remained inactive for certain periods,
00:28:05like an extreme version of the current winter
00:28:08that causes the leaves to fall
00:28:11and interrupt the growth.
00:28:14Could it be a strategy of the polar winter,
00:28:17or simply a variation of a normal winter?
00:28:20To find out,
00:28:23we have to keep on investigating.
00:28:30In the Sackleton Glacier,
00:28:33Patty has found the oldest trees
00:28:35buried in the frozen rocks.
00:28:38I did study the rings of these trees,
00:28:41and what they do is they work at full speed,
00:28:44and suddenly they stop very quickly.
00:28:47It's almost instantaneous.
00:28:50The variation in the rings of the trees
00:28:53indicates these periods of extreme inactivity
00:28:56in which growth was interrupted very quickly
00:28:59compared to today.
00:29:02But this doesn't completely solve the mystery.
00:29:06Current plants and trees
00:29:09wouldn't survive this tension
00:29:12and would die during the months of complete darkness.
00:29:15How did they manage to come back to life
00:29:18with such long periods without doing photosynthesis?
00:29:23There is an old lineage plant
00:29:26that could help us.
00:29:29The Ginkgo tree.
00:29:32The only survivor
00:29:35of the Triassic period
00:29:38and direct descendant of its prehistoric cousin
00:29:41solves the mystery.
00:29:45Scientists introduced ginkgo plants
00:29:48along with others in experimental greenhouses
00:29:51to emulate the polar seasons.
00:29:57To imitate the polar atmosphere of the Cretaceous,
00:29:59they experimented with another ingredient,
00:30:02carbon dioxide.
00:30:06The phase of the Great Morte
00:30:09at the end of the Permian period
00:30:12greatly increased CO2 levels.
00:30:15During the upper Cretaceous period,
00:30:18the current levels were still doubling.
00:30:21Surprisingly,
00:30:24ginkgo plants survived the experiment.
00:30:27They did it by absorbing more energy
00:30:30during the simulated summer
00:30:33to compensate for the simulated polar winter
00:30:36in which they were submerged in a vegetative period.
00:30:39The higher levels of CO2
00:30:42turned out to be key to their survival.
00:30:45The evidence that the Glosopteris trees
00:30:48that Scott found
00:30:51were destroyed by the Great Morte
00:30:53remains evident even today in Antarctica.
00:31:01We go from having wood everywhere,
00:31:04in these deposits of the aluvial plain,
00:31:07to having nothing at all.
00:31:10However, in the Middle Triassic,
00:31:13other plants such as the ancestors of ginkgo
00:31:16had already returned.
00:31:19The environment of toxicity
00:31:22that had ended with so many creatures
00:31:25has already dissipated
00:31:28and has been replaced by subtropical forests,
00:31:31rivers and watercourses,
00:31:34which allowed new species of aquatic creatures,
00:31:37fearsome amphibians,
00:31:40to occupy the niches of predators and prey.
00:31:43The fossils extracted from the frozen rock
00:31:45in the 1980s by Wilhammer and others
00:31:48drew a new panorama of an Antarctica
00:31:51that was recovering during this period.
00:31:55This included a giant amphibian
00:31:58the size of a crocodile
00:32:01that has not been found anywhere else on Earth,
00:32:04called Antartosuchus.
00:32:07It took more than 20 years
00:32:10to join the remains and identify them.
00:32:12I was lucky to be able to study,
00:32:15along with Bill, an animal called Antartosuchus,
00:32:18which had a skull between 75 cm and 1 m,
00:32:21so the entire animal was about 3 m long.
00:32:24If we could see it today,
00:32:27we would probably think it looks like a giant salamander,
00:32:30but these were the most common animals
00:32:33in the Middle Triassic in Antarctica.
00:32:36It is a fact that the most diverse group of animals
00:32:39that we have found to have survived
00:32:42since today we usually consider amphibians
00:32:45a barometer of environmental degradation.
00:32:48However, they have survived all the great extinctions
00:32:51since the Devonian and they did very well in the Triassic.
00:32:54But in Gondwana,
00:32:57this great amphibian was surpassed
00:33:00by a giant predator reptile.
00:33:06The Erythrosuchus.
00:33:09Although to date
00:33:12it has not been discovered in South Africa,
00:33:15it is assumed that it lived in the then-nearby Antarctica
00:33:18during the Middle Triassic.
00:33:21It is possible that this animal
00:33:24will also reach Antarctica.
00:33:27The Erythrosuchus would have been one of the largest predators
00:33:30of its time in the Triassic period.
00:33:33It was a monster of 3 m,
00:33:36with a head of almost 1 m in length,
00:33:39with longer legs
00:33:42than a crocodile,
00:33:45and teeth almost the same size as those of a Tyrannosaurus rex.
00:33:48This early reptile
00:33:51was one of the predecessors of dinosaurs
00:33:54and the super predator of its time.
00:34:08Even so,
00:34:10the Erythrosuchus is not a force
00:34:13that can be taken lightly.
00:34:30This great predator occupies a niche
00:34:33whose time is running out.
00:34:36Slowly but constantly,
00:34:39dinosaurs begin to evolve,
00:34:42small at first.
00:34:47The days of the Erythrosuchus
00:34:50are counted as the next great extinction approaches.
00:34:56Although it is not the end for some amphibians.
00:35:00The Themnospondyls are the main group
00:35:02to which the Antarctosuchus belongs.
00:35:05There are people who believe that modern amphibians,
00:35:08such as frogs and salamanders,
00:35:11actually come from the Themnospondyls.
00:35:14So somehow they are still among us,
00:35:17although these huge amphibians disappeared
00:35:20and had their apogee in the Triassic.
00:35:26Around this time,
00:35:29fossil records show a new extinction.
00:35:32This event gave rise to the transition
00:35:35between the Triassic and the Jurassic.
00:35:38At the end of the Triassic period,
00:35:41about 200 million years ago,
00:35:44perhaps up to 70% of all life forms were lost.
00:35:47The cause is still a mystery.
00:35:51It is one of the great less known extinctions
00:35:54because the dinosaurs survived it.
00:35:57So some of the first dinosaurs
00:35:59that already existed at that time
00:36:02managed to survive extinction
00:36:05because the end of the Triassic
00:36:08eliminated a large number of its competitors.
00:36:11So the success of the dinosaurs
00:36:14may be due only to the coincidence of that great extinction
00:36:17at the end of the upper Triassic.
00:36:20This event, the fourth great extinction
00:36:23that occurred on Earth from the dawn of life,
00:36:26allowed the rise of the dinosaurs,
00:36:29who were the dominant terrestrial animals on the planet.
00:36:33As the Earth recovered,
00:36:36life on the southernmost continents of Gondwana
00:36:39was different from other territories.
00:36:42But Nate and his team
00:36:45are still looking for an answer
00:36:48to how the creatures of Antarctica
00:36:51managed to survive the long polar nights.
00:36:54Unlike plants,
00:36:56animals must conserve energy
00:36:59in a totally different way.
00:37:02By making such a small number of expeditions
00:37:05to this part of the globe,
00:37:08time goes against it to find the answers.
00:37:13Back to the Shackleton Glacier.
00:37:18Luckily, this time the weather conditions
00:37:21have been favorable
00:37:23and they have been able to spend more time on the ground
00:37:26looking for clues about the mysteries of the polar vertebrates.
00:37:31But this frozen desert
00:37:34is the most inhospitable place on Earth
00:37:37to dig in search of fossils.
00:37:40Given the scarce erosion of Antarctica,
00:37:43they must look for minute traces
00:37:46on the surface of the rocks.
00:37:49When the paleontologists locate them,
00:37:51they go to electric saws to extract them.
00:37:56The first thing I saw when I walked along this slope
00:37:59is a leg.
00:38:02This here is a hind leg
00:38:05and it is quite articulated, as it would have been in life.
00:38:08So what I'm working on here is
00:38:11with an early relative of reptiles called Procolophon,
00:38:14which was a small-sized animal that dug burrows.
00:38:17So this is a kind of animal
00:38:19that fled from lower latitudes in South Africa
00:38:22to higher latitudes here in Antarctica.
00:38:31The Procolophon is a type of primitive reptile
00:38:34of a size similar to the Gila monster,
00:38:37a reptile of our time that stalks the deserts today.
00:38:43This whole block that we have cut
00:38:46contains a range of different bones.
00:38:49What we'll do is sort of clean it,
00:38:52take it and lug it back to the helicopter
00:38:55and catalog it back to Shackleton Camp.
00:38:58We'll skip one of the big blocks
00:39:01and slip it over.
00:39:08Studying a small reptile like the Procolophon
00:39:11can lead to great discoveries.
00:39:15Perhaps primitive reptiles had some property
00:39:17that helps us understand
00:39:20how some Antarctic animals survived
00:39:23the long polar nights?
00:39:27How did they orient themselves in the dark
00:39:30to hunt enough food to survive?
00:39:36If an ancient reptile could be resurrected,
00:39:39what secrets could it tell us?
00:39:43In New Zealand, there is a creature like this.
00:39:48The separation of Gondwana 80 million years ago
00:39:51left us with an animal that is still alive
00:39:54and that boasts of a very ancient lineage.
00:39:59The Tuatara.
00:40:02An extraordinarily rare reptile
00:40:05that lives without drawing attention
00:40:08in the temperate forests of this country
00:40:11of the South Pacific.
00:40:14It is the only member that remains alive
00:40:17for 70 million years.
00:40:20Today, New Zealand is located
00:40:235,000 km further north
00:40:26than when it was in a polar latitude.
00:40:29Is it possible that it still maintains some quality
00:40:32that reveals to us how its ancestors managed to survive?
00:40:38In St. Bathans, on the southern island of New Zealand,
00:40:41paleontologists have discovered
00:40:44the oldest examples of Tuatara fossils.
00:40:47We have found three fragments
00:40:50of a jaw similar to that of the Tuatara.
00:40:53They are nothing more than small pieces of just a few millimeters
00:40:56in which you can see the teeth,
00:40:59which in fact are identical to those of the current Tuatara.
00:41:02That is why we start from the hypothesis
00:41:05that they are ancestors of the Tuatara of our days,
00:41:08which seems to indicate that the history of the Tuatara
00:41:11in this country comes from far away.
00:41:14These ancient teeth of Tuatara
00:41:17show that they cut their food
00:41:20like a meat knife,
00:41:23instead of completely swallowing their prey,
00:41:26as reptiles usually do.
00:41:29It is possible that their ancestors of the Triassic
00:41:32had a much more varied diet
00:41:35and possessed the ability to chew their food.
00:41:38Perhaps that was a useful adaptation
00:41:40to survive in the dark forests of polar winter.
00:41:45However, the secret characteristic
00:41:48that modern Tuatara have in their heads
00:41:51could give us the most important clue.
00:41:54Oddly enough,
00:41:57the Tuatara has a third eye hidden by the skin
00:42:00called the parietal eye.
00:42:03It has its own cornea,
00:42:06a retina and a lens.
00:42:09As well as a nervous connection with the brain.
00:42:17In other animals,
00:42:20this third eye serves as a calendar.
00:42:23It is able to warn that the days get longer
00:42:26and the nights get shorter
00:42:29and it can be used to schedule the reproduction.
00:42:32It could also intervene in the thermal regulation
00:42:35that the hot-blooded mammals have,
00:42:38such as reptiles,
00:42:41to help them overcome the polar winter without sunlight.
00:42:45But did these adaptations exist
00:42:48among the Antarctic creatures
00:42:51to be able to survive the long polar winter?
00:42:54Resorting to a living creature
00:42:57in search of clues is due to the enormous difficulty
00:43:00of finding sufficient evidence
00:43:03in the Antarctic fossil records.
00:43:05In the 60s and 70s,
00:43:08scientists made discoveries
00:43:11that brought to light a fascinating hidden prehistoric world.
00:43:14But no trace of the dinosaurs.
00:43:19Perhaps the dinosaurs
00:43:22could not adapt in the polar regions.
00:43:25However, the absence of evidence
00:43:28is not proof of their absence.
00:43:31It took many expeditions
00:43:33to collect and prepare all those bones.
00:43:36In that area, there is very bad weather,
00:43:39the surface of the rocks freezes and defrosts,
00:43:42which makes it difficult to collect.
00:43:45It can take a long time
00:43:48until a discovery is made
00:43:51until one of those dinosaurs is identified.
00:43:54This is particularly true in Antarctica.
00:43:57In 1986,
00:44:00fossils were discovered on an Antarctic island.
00:44:03Scientists did not know what they were
00:44:06and they were stored in Argentina
00:44:09to study them in the future.
00:44:12Working meticulously,
00:44:15over time they have been fitting the pieces of the puzzle.
00:44:18In 2006,
00:44:21the name was officially given
00:44:24and it was accepted as a dinosaur,
00:44:27so it became the first to be discovered.
00:44:34It was an armored herbivore
00:44:37close relative of the ankylosaur.
00:44:45These dinosaurs wandered
00:44:48through North America,
00:44:51in the upper Cretaceous,
00:44:5470 million years ago,
00:44:57and are famous for their claw-shaped tails.
00:45:00This Antarctic relative of 6 meters
00:45:03was named Antartopelta
00:45:06and presumably jumped from South America
00:45:09to Antarctica when they were still united.
00:45:14Thus,
00:45:17the dinosaurs emigrated or evolved in Antarctica
00:45:21with or without polar adaptations.
00:45:26We know that the dinosaurs emerged
00:45:29after the fourth great extinction
00:45:31at the end of the Triassic,
00:45:34to become the dominant species
00:45:37during the Jurassic period,
00:45:40even in Antarctica. But why?
00:45:43At the dawn of the Jurassic,
00:45:46there was an important climate change
00:45:49that created a perfect environment
00:45:52for herbivorous dinosaurs,
00:45:55whose number would grow exponentially.
00:45:58This rich ecosystem was created
00:46:01180 million years ago.
00:46:10The Eurasia, the northern part,
00:46:13is separated from the southern part,
00:46:16Gondwana, with Antarctica,
00:46:19located further south.
00:46:22Between these two masses of land
00:46:25an entire sea erupts.
00:46:28The sea of Tethys
00:46:31carries humidity to the earth
00:46:34and alters the climate all over the world,
00:46:37which becomes a hot, humid and jungle place.
00:46:40The Jurassic.
00:46:51However, despite the abundant fossils
00:46:54of dinosaurs of the Jurassic period
00:46:57all over the world,
00:47:00it is still a huge effort to find them
00:47:03on the frozen rock of Antarctica.
00:47:06Many times the fossils are so poorly preserved
00:47:09that the only way to identify a prehistoric animal
00:47:12is by the teeth.
00:47:15Teeth are better preserved
00:47:18than many other parts of animals,
00:47:21as happened with this discovery
00:47:24of amphibian teeth
00:47:27I was taking a piece of bone out of here
00:47:30and I thought this was fossil wood
00:47:33because the material is very dark.
00:47:36So I was cleaning this
00:47:39and suddenly this little block fell
00:47:42to reveal this beautiful tooth of an amphibian.
00:47:45Here we clearly see a magnificent specimen
00:47:48with its teeth and without a doubt
00:47:51it is a sample that we can collect.
00:47:54This creature of the lower Jurassic
00:47:57was also discovered thanks to a single upper canine.
00:48:00It was named Tritilodon.
00:48:04Of hot blood,
00:48:07they probably had some kind of fur,
00:48:10a proto-mammal that pointed to what was to come.
00:48:15Unfortunately for the Tritilodons,
00:48:18they lived in the same time
00:48:21as the super carnivorous predator Antarctic.
00:48:28The Cryolophosaurus.
00:48:33The Terrex of Antarctica.
00:48:42In the next episode,
00:48:45the discovery of the first giant carnivore of Antarctica
00:48:48and very fast herbivores.
00:49:03The appearance of the largest dinosaurs of all time.
00:49:11While the continent of ice
00:49:14gives us the keys to some of the greatest mysteries of the Earth.
00:49:17How did the dinosaurs survive
00:49:20in the polar darkness?
00:49:23And perhaps the greatest mystery of all.
00:49:26Are the birds the living descendants of the dinosaurs?
00:49:37The lower Jurassic.
00:49:40Exuberant forests full of life
00:49:43of all shapes and sizes.
00:49:46We are not in the Amazon.
00:49:49It is the Antarctica of 190 million years ago.
00:49:53The current Antarctica is a very different place
00:49:56from what it was in the past.
00:49:59A scientific team has traveled
00:50:02to the Sackleton Glacier,
00:50:05160 kilometers long,
00:50:08to unravel the mysteries of this prehistoric world.
00:50:11If we want to understand what has happened on the planet
00:50:13throughout history, we must go everywhere.
00:50:16We have to go to places like Antarctica.
00:50:22The fossils buried in the rock
00:50:25tell us about creatures
00:50:28who lived a hell on Earth to survive.
00:50:35Including the greatest extinction
00:50:38in the history of our planet.
00:50:40It is a lineage of survivors.
00:50:43One of the few lineages of terrestrial animals
00:50:47who managed to survive the great extinction of the Permian.
00:50:51The Listerosaurus managed to survive
00:50:54all the bad things that the Earth offered him.
00:50:59From the ashes of the great extinction
00:51:02emerges a 2.0 Earth
00:51:05in which little by little
00:51:07occupies the foreground
00:51:10a new dominant force.
00:51:13The dinosaurs.
00:51:16However, as the continents separated,
00:51:19how did they survive the polar conditions?
00:51:22And how did Antarctica transform
00:51:25into the frozen continent of today?
00:51:28The Ancestral Land.
00:51:31Dinosaurs of the Frozen Continent.
00:51:34The first dinosaurs
00:51:37appeared about 231 million years ago.
00:51:40During the Upper Triassic.
00:51:43However, their dominance
00:51:46was extended during the Jurassic period
00:51:4950 million years later.
00:51:54In the first expeditions to Antarctica,
00:51:57scientists were only able to find
00:52:00proto-mammals.
00:52:03Giant amphibians.
00:52:07And primitive reptiles.
00:52:14In 1986,
00:52:17scientists discovered, without knowing it,
00:52:20the first dinosaur on an Antarctic island.
00:52:23Later, it will be identified
00:52:26as a relative of the Ankylosaurus,
00:52:29with a claw-shaped tail.
00:52:31But the first discovery
00:52:34about the land took place four years later.
00:52:39Bill Hammer, an authority in Antarctica,
00:52:42knew immediately that it was something special.
00:52:45We go around a big rock
00:52:48and suddenly we find a femur of one meter long.
00:52:51A huge femur.
00:52:54I looked at it and David told me,
00:52:57what is this? And I told him, it has to be a dinosaur.
00:52:59And he told me, it is a dinosaur.
00:53:03A pteropod.
00:53:06A two-legged carnivore.
00:53:10One of the largest land carnivores of its time.
00:53:17They called it Cryolophosaurus.
00:53:21Which means,
00:53:24frozen crest lizard.
00:53:29If you find a dinosaur,
00:53:32you have to change your phone number.
00:53:35You call the New York Times,
00:53:38the National Public Radio, everyone will call you.
00:53:41Dinosaurs excite everyone.
00:53:44And the most surprising thing
00:53:47is that this dinosaur had some similarities
00:53:50with the Tyrannosaurus rex,
00:53:53although it had nothing to do with this great carnivore,
00:53:55which would not wander the earth
00:53:58until 124 million years later.
00:54:03It has a strange feature on its head,
00:54:06a bone plate in the shape of a crest
00:54:09from which it takes its name.
00:54:12Some dinosaurs had bone plates
00:54:15that served to defend themselves,
00:54:18but this one in particular does not seem to have any function.
00:54:21The Cryolophosaurus was first discovered
00:54:23near the Viedmoor Glacier,
00:54:26170 kilometers from the Sackleton expedition camp.
00:54:30It took many attempts
00:54:33to extract it from the frozen rocks.
00:54:36Finally, after three expeditions
00:54:39over 20 years, in 2011,
00:54:42Hammer and his team managed to recover
00:54:45the last pieces of the fossil's puzzle.
00:54:48The two leaders of the current joint expedition,
00:54:50Dr. Nate Smith and Dr. Pete McCovey,
00:54:53participated in that historical excavation.
00:54:56I'm Nate Smith, from the Field Museum.
00:54:59We have come to the Cryolophosaurus camp,
00:55:02and as you can see,
00:55:05the rock begins to have a more defined shape.
00:55:08The expedition to the Cryolophosaurus camp
00:55:11was very emotional for me,
00:55:14something very exciting,
00:55:17one of the most difficult moments of my career.
00:55:20There were about 30 bones in sight,
00:55:23and many of them seemed to be articulated,
00:55:26that is, they were still naturally joined.
00:55:29So in the rock we may have between a third
00:55:32and half of the animal.
00:55:35Instead of extracting the fossilized bones,
00:55:38the team cuts the entire block of rock
00:55:41in which the remains are embedded.
00:55:44Block by block they carry the precious rock
00:55:47to the helicopter that awaits them.
00:55:51We finally end up in this camp,
00:55:54a camp with which we began in 1990,
00:55:57and 20 years later,
00:56:00we have finally removed the last bones.
00:56:12This has been one of the most
00:56:15extraordinary experiences of my life.
00:56:17Coming to Antarctica has been amazing.
00:56:20This time it has been perhaps the best,
00:56:23although it has also been the most difficult.
00:56:26The discovery of a super-predator
00:56:29like the Cryolophosaurus leads us to the next question.
00:56:32What prey did this two-legged carnivore hunt?
00:56:35They would need a considerable meat diet
00:56:38to get ahead in the polar forests.
00:56:41In the same area of fossils
00:56:44that the Cryolophosaurus,
00:56:48now we know it as Glacialisaurus.
00:56:53The Glacialisaurus is a dinosaur
00:56:56that I baptized together with Diego Paul in 2007.
00:56:59We know that it was a very large animal.
00:57:02It is likely that it was the largest herbivore
00:57:05that lived in Antarctica during the lower Jurassic.
00:57:08This herbivorous dinosaur
00:57:117 meters long and 5 tons was very fast.
00:57:18When these lower Jurassic dinosaurs
00:57:21erupted on stage,
00:57:24the land they stepped on
00:57:27was also in motion.
00:57:30The supercontinent of the earth, Pangea,
00:57:33separated to form smaller earth masses,
00:57:36Eurasia and Gondwana.
00:57:39And the ocean that separated them
00:57:42was the trigger for the eruption.
00:57:44The Mesozoic Era.
00:57:47If we go back in time to the Mesozoic,
00:57:50to the time of the dinosaurs,
00:57:53Antarctica was still connected
00:57:56to the other southern continents and Gondwana
00:57:59and had no ice at all.
00:58:02It had a warmer climate
00:58:05where animals and plants could thrive.
00:58:08The Mesozoic was a time
00:58:11when there was no ice,
00:58:14and there was no water.
00:58:21Glacialisaurus had to be fast,
00:58:24since it was one of the main prey
00:58:27of the cryolophosaurus.
00:58:30Hidden among the Jurassic forests of Antarctica,
00:58:33this solitary hunter
00:58:36would stalk the herds of Glacialisaurus,
00:58:39as the great cats do today
00:58:41and watch the herbivores in the savannah.
00:58:52For these great carnivores,
00:58:55a long-necked herbivore
00:58:58could feed them for days.
00:59:12But first they had to be caught.
00:59:32This 7-meter-long theropod
00:59:35ran at almost 40 kilometers per hour.
00:59:41But sometimes evolution gives the prey
00:59:44an advantage in a race like this one.
00:59:48The cryolophosaurus cannot maintain
00:59:51its maximum speed for a long time.
00:59:54It will need a stroke of luck.
01:00:04A herd of Glacialisaurus
01:00:07facing it makes it think twice.
01:00:12It is not easy to catch it.
01:00:25Because of its mysterious crest,
01:00:28it is sometimes nicknamed Elvisaurus.
01:00:32But what was it for?
01:00:35Maybe to attract a couple.
01:00:41To relieve the group,
01:00:44the male has smelled the trace of a close female.
01:01:03It is even possible that the cryolophosaurus
01:01:06had striking colors on its head
01:01:08to attract its mates.
01:01:11As casuaries do today.
01:01:15My colleague Pete Makovicki
01:01:18has done extensive research
01:01:21on the crests and colors of modern birds.
01:01:24One of his findings is that
01:01:27it is often not the crest itself
01:01:30that gives that elaborated color,
01:01:33but the skin around the eye,
01:01:35Until now, no remains of cryolophosaurus
01:01:38have been found anywhere on Earth.
01:01:43It probably dominated the period
01:01:46of the lower Jurassic in Antarctica.
01:01:49And as the period advanced,
01:01:52the dinosaurs were increasing in size
01:01:55all over the world,
01:01:58due to an explosion of plant life
01:02:01that brought the new global warming.
01:02:05The colossi of the Jurassic world.
01:02:08The sauropods.
01:02:11There were numerous species
01:02:14of these giant herbivores.
01:02:17But even among this group of huge creatures
01:02:20there was a species that stood out
01:02:23above all the others.
01:02:26The culmination of this group of sauropodomorphic dinosaurs
01:02:29are the titanosaurs.
01:02:32They are the largest terrestrial animals
01:02:35in the world.
01:02:38The titanosaurs were colossal.
01:02:4336 meters long
01:02:46and a weight of approximately 60 tons.
01:02:52The equivalent of a dozen elephants.
01:02:57Adults did not have natural predators.
01:03:00Only a natural disaster could stop them.
01:03:08The titanosaurs are a mystery of biology.
01:03:11They are nothing like any other animal
01:03:14that has ever lived on Earth.
01:03:18These colossal vegetarian beasts
01:03:21dominated the Jurassic period
01:03:24and later the Cretaceous period
01:03:26except for Antarctica.
01:03:29Or so the scientists thought.
01:03:36In 2011, a fossil was unearthed
01:03:39on the island of James Ross in Antarctica.
01:03:42Which showed that these giants
01:03:45of the world of dinosaurs
01:03:48did visit the southernmost earth mass.
01:03:51But how could a bigger animal
01:03:53exist on Earth than a blue whale?
01:03:56You'd think it's impossible
01:03:59for those gigantic bodies to exist on Earth.
01:04:02They are not like the whales
01:04:05that float in the water in the absence of gravity.
01:04:08They walked on solid ground.
01:04:11Therefore, the sauropods made
01:04:14certain anatomical adaptations
01:04:17that helped them survive
01:04:20in those terrestrial environments.
01:04:23Their spine was so long
01:04:26that they have been called
01:04:29a walking spine.
01:04:33Their incredibly long necks
01:04:36were full of airbags
01:04:39like modern birds,
01:04:42which helped them breathe
01:04:45and lighten the load of their huge skeletons.
01:04:48At the end of their long necks
01:04:50they had a tiny brain
01:04:53and teeth adapted to eat plants.
01:04:58Their heart, which weighed several hundred kilos,
01:05:01was the size of a man.
01:05:04Each of their beats
01:05:07pumped 90 liters of blood through the arteries.
01:05:12So trying to understand
01:05:15how these organisms lived for hundreds of millions of years
01:05:17with this size
01:05:20is one of the greatest mysteries of paleontology.
01:05:23Perhaps the titanosaurs competed with each other
01:05:26as the giraffes do today.
01:05:33The competition to be the dominant male or alpha
01:05:36must have been brutal.
01:05:47Many questions in the research
01:05:50carried out by paleontologists
01:05:53when joining the puzzle of fossil remains
01:05:56with millions of years of antiquity.
01:06:09It is known that these giants
01:06:12prospered all over the world
01:06:14in the exuberant tropical forests of the Cretaceous.
01:06:25There have been indications
01:06:28that at least the titanosaurs
01:06:31could consider Antarctica a kind of route of passage.
01:06:36Although the earliest titanosaur fossils
01:06:39were found in South America,
01:06:41in recent years
01:06:44some species have been extracted on rocks
01:06:47on the other side of the world,
01:06:50in Australia.
01:06:53Fossils similar to their
01:06:56older South American equivalents.
01:06:59If we look at some of these dinosaurs,
01:07:02such as the Argentine titanosaurs,
01:07:05Antarctica and Australia,
01:07:08we can see that they were somehow related to each other.
01:07:11Although it goes back to when all continents
01:07:14were part of Gondwana.
01:07:18The fact that they were discovered in Australia
01:07:21implies that these gigantic dinosaurs
01:07:24had to cross the polar forests.
01:07:27Ancient Antarctica served as a land bridge,
01:07:30which allowed the titanosaurs
01:07:33to reach Australia from South America,
01:07:36where they were abundant in number.
01:07:38It makes sense, since the southern continents
01:07:41were connected at that time.
01:07:44Those titanosaurs had to be able to cross Antarctica
01:07:47to reach other regions.
01:07:56In Antarctica,
01:07:59the giant titanosaurs would find
01:08:02a somewhat colder climate,
01:08:05but without ice and covered with forests.
01:08:08It was an epic journey to Australia.
01:08:15No predator could stop
01:08:18these colossal forces of nature.
01:08:21Being giant is a good strategy
01:08:24if you want nothing to eat you.
01:08:27In modern ecosystems, such as sub-Saharan Africa,
01:08:30we see that elephants don't have natural predators
01:08:33when they are adults.
01:08:35If you can be big, why not be it?
01:08:38It's the best strategy not to be someone else's food.
01:08:46Today's titans, such as elephants,
01:08:49could never reach that size
01:08:52because they breed their young in the uterus.
01:08:55The titanosaurs did not have this limitation.
01:09:01They were oviparous.
01:09:05Herds of females laid thousands of eggs in a group,
01:09:08up to 40 at a time,
01:09:11in their shallow nests.
01:09:21But their young were not so invincible.
01:09:25They were extraordinarily vulnerable
01:09:28to predators.
01:09:31Probably the highest mortality levels
01:09:33in the titanosaurs
01:09:36were among the newborns,
01:09:39which is when they would be most vulnerable to predators.
01:09:42Abandoned to their fate by adults,
01:09:45these young needed their own evolutionary lifeguard.
01:09:50It was difficult to live being small
01:09:53in the Jurassic or the Cretaceous,
01:09:56with all those huge dinosaurs roaming around.
01:09:59So one of their strategies was a very fast growth rate.
01:10:01The faster you grow,
01:10:04the more likely you are to survive.
01:10:07However, trying to calculate
01:10:10how fast these dinosaurs grew
01:10:13from adult specimens is difficult,
01:10:16if not impossible.
01:10:19Until Dr. Rogers found a series of non-catalogued
01:10:22fossils in 2012.
01:10:26I was searching for crocodile bones
01:10:28and turtle bones in a collection
01:10:31and when I did, I found small sauropod bones.
01:10:36And at the end of the day I realized
01:10:39that I had a large part of the skeleton,
01:10:42bones belonging to a single small sauropod,
01:10:45which turned out to be the smallest we have
01:10:48after hatching from the egg.
01:10:51I knew immediately that it was very important
01:10:54that we hadn't found tiny fossils of young animals.
01:10:58To locate those small bones,
01:11:01I had an idea of what those tiny animals would look like.
01:11:06If you search in a museum's collection,
01:11:09just by opening the drawers,
01:11:12there is always something new to discover.
01:11:15Some important discoveries in paleontology
01:11:18are made because someone adopts a different approach
01:11:21to something that someone else picked up
01:11:2420 or 100 years ago.
01:11:26These bones made it clear
01:11:29that the titanosaurids had very early offspring.
01:11:32Their little ones were almost independent
01:11:35as soon as they came out of the egg.
01:11:38Now we believe that by breaking the shell,
01:11:41these young ones were quite able to fix them on their own.
01:11:44The question is, how long did it take
01:11:47for them to become giants?
01:11:50By increasing the microscope to very fine
01:11:53transversal sections of the fossils,
01:11:56and the bloodstream,
01:11:59and determining the rate of growth.
01:12:02When you take a look at a section of a dinosaur bone like this,
01:12:05we see a lot of little circles all over the bone,
01:12:08which are the points where the blood vessels
01:12:11would come in and out of the bone.
01:12:14The more blood vessels it had,
01:12:17the more directions it went, the faster the animal grew.
01:12:20These cells tell us that it grew very fast.
01:12:23All the blood vessels distributed by the bone
01:12:26were in the bloodstream as well.
01:12:32The mortality rate was high among young titanosaurids,
01:12:36but their rapid growth gave them a chance.
01:12:41As a comparison,
01:12:44a human baby doubles in size every five months,
01:12:47while the titanosaurids doubled in size every five days.
01:12:50At the time of their first year,
01:12:53they weighed from 20 kilos to 1,600.
01:13:00This is the femur of a three-month-old titanosaur,
01:13:03next to the femur of a 20-year-old titanosaur.
01:13:06Observing the difference in size,
01:13:09we realize how fast this little animal had to grow
01:13:12to reach that size in just 20 years.
01:13:15The fact that the Antarctic continent
01:13:17was connected to other terrestrial masses at that time
01:13:20made it a gateway for the migration of animals
01:13:23as large as the titanosaurids.
01:13:26But the Antarctic was different.
01:13:29Despite its temperate climate
01:13:32and its endless polar summers,
01:13:35they suddenly transformed into very long winters
01:13:38where darkness reigned.
01:13:41One of the eternal mysteries of Antarctic paleontology
01:13:44is to know what these animals were like.
01:13:47These animals experienced several months
01:13:50of perpetual light in summer
01:13:53and several months of perpetual darkness in winter.
01:13:56During this period,
01:13:59plant life entered a state of inactivity
01:14:02and the highest levels of carbon dioxide
01:14:05helped plants survive
01:14:08during the long months without sun.
01:14:11Despite the absence of photosynthesis during the winters,
01:14:14somehow the vegetation managed to survive
01:14:17in that environment.
01:14:20But how did the dinosaurs survive
01:14:23in the middle of polar darkness?
01:14:32It is not only because the sun does not cross
01:14:35the Antarctic darkness for four months,
01:14:38but also because the temperature drops to temperatures below zero.
01:14:43It is difficult to imagine
01:14:45what the ecosystem was like for the dinosaurs.
01:14:48Here the dinosaurs lived in the middle of total darkness
01:14:51for several months in winter
01:14:54and at temperatures below zero.
01:14:57Some days it was less cold, yes,
01:15:00but in general it must have been a very complicated environment
01:15:03for any animal that lived in it.
01:15:08In the Transantarctic mountains,
01:15:11the team is still looking for some clue
01:15:13to shed light on this enigma.
01:15:16Paleobotanists are lucky
01:15:19in the search for fossils in this expedition.
01:15:22Ok, I think there is something.
01:15:25Yes, there is something here.
01:15:28Wonderful, wonderful, yes.
01:15:31However, it is never easy for paleontologists
01:15:34to extract fossils from the frozen rock.
01:15:37One of the possible keys to solving
01:15:40the mystery of survival in polar conditions
01:15:43lies in the depths of the ancient rocks
01:15:46of the former neighboring Antarctica, Australia.
01:15:49During the Cretaceous period,
01:15:52100 million years ago,
01:15:55the southeast of Australia was within the polar region.
01:15:58Here, a small dinosaur could adapt
01:16:01to the sunless winters in a singular way.
01:16:04The Lialinasaura was a small dinosaur
01:16:07from which fragments were found
01:16:10in a place called the Dinosaur Gorge.
01:16:13It is named after the daughter of Patricia Vickerson Rich
01:16:16and Tom Rich, Lialin.
01:16:21The Lialinasaura was a herbivorous dinosaur
01:16:24the size of a turkey,
01:16:27and it is likely that it permanently resided
01:16:30in the polar forests.
01:16:33Unlike other larger dinosaurs,
01:16:36the Lialinasaura was not big enough
01:16:39to travel thousands of kilometers
01:16:41as many animals and birds do today
01:16:44to avoid the current winters.
01:16:47It was too small to migrate,
01:16:50so it takes a lot of energy, a lot of food
01:16:53to travel thousands of kilometers,
01:16:56and if you also have short legs,
01:16:59it takes a lot more effort to do that.
01:17:02In the fossil of the small Lialinasaura,
01:17:05scientists found a possible indication
01:17:08of how dinosaurs evolved
01:17:11in large cavities,
01:17:14that is, the cavities in which the eyes used to be.
01:17:17But towards the back of the skull,
01:17:20the sand filled the area where the optical lobe
01:17:23would have been found,
01:17:26and it seems that it was also relatively large in the skull too.
01:17:29So, these two clues point to the possibility
01:17:32that the Lialinasaura could see well in the dark.
01:17:35In the case of nocturnal animals,
01:17:38their large eyes take full advantage
01:17:41of the little light available.
01:17:44In turn, the larger optical lobes
01:17:47are able to process the visual information
01:17:50they perceive more effectively.
01:17:53However, science is not clear
01:17:56about this specimen of Lialinasaura.
01:17:59We know that there are great variations
01:18:01in the proportions of the organs of animals,
01:18:04such as the eyes,
01:18:07and we know that,
01:18:10both among modern birds and among dinosaurs,
01:18:13smaller animals usually have
01:18:16proportionally larger eyes.
01:18:19Having a good night vision
01:18:22must have been important when hunting,
01:18:25but even so, they would need other strategies
01:18:28to face life during four months of cold darkness.
01:18:31This is the case with polar bears.
01:18:34The fossil expert Anthony Martin
01:18:37found a possible answer just a few kilometers away
01:18:40from the place where the Lialinasaura was discovered.
01:18:43I am in Victoria, Australia,
01:18:46in Ollies Creek,
01:18:49observing some of the cretaceous rocks
01:18:52that are in this area.
01:18:55In that cliff I saw a tubular structure
01:18:58that descended, expanded,
01:19:01and I remember having a feeling inside
01:19:04that said to me,
01:19:07wait, that looks familiar.
01:19:10It has a similar structure above,
01:19:13full of sand, and it presents a shape
01:19:16somewhat in a spiral.
01:19:19As we move to the right,
01:19:22we see that there is a third structure
01:19:25that is similar, but that is a little more collapsed.
01:19:28And that moment is when I thought
01:19:31that polar bears can use burrows
01:19:34to take refuge from the heat
01:19:37or from the extreme cold,
01:19:40and the three cave structures in Australia
01:19:43had the right size
01:19:46for a small dinosaur
01:19:49that trusted to be able to protect itself
01:19:52from a polar winter.
01:19:55That made me wonder
01:19:58what kind of animals could have lived there,
01:20:01the small-sized dinosaurs
01:20:04that lived in the area at that time.
01:20:07It is possible that the creatures
01:20:10used this adaptation in the different eras
01:20:13to survive in Antarctica,
01:20:16even during the most massive extinction
01:20:19in the history of the Earth,
01:20:22recorded 250 million years ago.
01:20:25But is there any other clue in Antarctica?
01:20:28The answer may come
01:20:31from an existing lystrosaur.
01:20:34A reptile similar to a mammal
01:20:37that survived the great mortality
01:20:40that killed 90% of the animals
01:20:43at the end of the Permian period.
01:20:46Back to the Sackleton Glacier,
01:20:49Chris Sider and Megan Whitney
01:20:52are making great progress
01:20:55in the preparation of a fossil
01:20:57of a lystrosaur
01:21:00that was in a totally vertical face of a cliff.
01:21:03This is something new for me.
01:21:06I have never done anything on such a steep wall.
01:21:09It is not usual to find fossils in such a place.
01:21:12It was a coincidence that this one stood out a bit,
01:21:15but we had to extract it from the vertical wall,
01:21:18and for that we had to surround it.
01:21:21We ended up using the drilling hammer,
01:21:24making many holes
01:21:27and doing all kinds of things.
01:21:30Yes, I see the crack.
01:21:33Yes.
01:21:36There it is.
01:21:39Just where we wanted.
01:21:42Well, we have extracted...
01:21:45The first fragment.
01:21:48The first fragment.
01:21:51This goes here, but it was the easy fragment.
01:21:54What comes now will be much more complicated, I think.
01:21:57Fossils of lystrosaur
01:22:00from polar regions such as Antarctica,
01:22:03with others from regions such as South Africa,
01:22:06a surprising possibility arises.
01:22:09A transversal section of its small fangs
01:22:12shows a variation in the speed of growth,
01:22:15the first clue about how they could have survived
01:22:18the polar winter.
01:22:21Chris Sider and Megan Whitney
01:22:24have studied in detail the growth lines
01:22:27of Antarctic animals,
01:22:30as in some of the fossils of South Africa,
01:22:33and what they discovered is that in the first ones
01:22:36certain periods are observed in which very close lines are seen,
01:22:39which correspond to difficult periods in the environment,
01:22:42when perhaps the animal would slow down part of its growth,
01:22:45and that it is compatible with the seasonal lethargy,
01:22:48moments in which these animals experience
01:22:51a lower metabolic activity,
01:22:54possibly during the Antarctic winters.
01:22:57It was the lystrosaur after this great extinction
01:23:00that ended with 95% of all living beings on Earth.
01:23:03We have found that they survived,
01:23:06and I do not think it was by chance.
01:23:09Animals still resort to lethargy today.
01:23:12In its most extreme phase is hibernation,
01:23:15which consists of the reduction of metabolism,
01:23:18body temperature and activity for weeks.
01:23:20If there are signs of some form of lethargy
01:23:23in the fangs of the ancestor mammal, the lystrosaur,
01:23:26animals could resort to this adaptation
01:23:29to survive the Antarctic conditions
01:23:32and even to massive extinctions hundreds of millions of years.
01:23:35Despite the polar nights,
01:23:38life has taken the hand of creativity,
01:23:41and it is not surprising that the animals
01:23:44have been able to survive
01:23:46despite the polar nights.
01:23:49Life has taken the hand of creativity to survive,
01:23:52waiting for the good times to return
01:23:55in the long summer months.
01:24:00More than 180 million years after the Great Mortality,
01:24:03dinosaurs continued to dominate our planet.
01:24:09But suddenly, 66 million years ago,
01:24:12a rock from the solar system
01:24:14swung towards the atmosphere of the Earth,
01:24:17something that even the dinosaurs could not adapt.
01:24:21An asteroid of 15 kilometers in diameter
01:24:24fell on the Yucatan Peninsula in Mexico.
01:24:33The effects it caused
01:24:36greatly contributed to the extinction of dinosaurs.
01:24:45The evidence is abundant
01:24:48in the geological record of our planet
01:24:51known as the Cretaceous-Tertiary Limit.
01:24:55The enriched layer of iridium
01:24:58is one of the key evidence
01:25:01that supports the hypothesis of the impact of an asteroid,
01:25:04since it is found at the same time
01:25:07in many regions of the world.
01:25:10The dust that raised the impact of the asteroid
01:25:12eclipsed the sun,
01:25:15so the ecosystem collapsed almost completely.
01:25:1875% of life forms disappeared,
01:25:21including all animals
01:25:24weighing more than 25 kilograms,
01:25:27even in the polar region of Antarctica.
01:25:32But who took their place?
01:25:38The animals that survived the extinction
01:25:40are the ancestors of reptiles,
01:25:43amphibians, mammals,
01:25:46and fish of today.
01:25:49In addition, a strange species of bird
01:25:52would arrive in Antarctica,
01:25:55the penguin.
01:25:58A halo of mystery envelops its extravagant evolution
01:26:01since they were discovered.
01:26:06Numerous species of penguin
01:26:08live in the coastal margins and islands of Antarctica.
01:26:12But only the emperor penguin
01:26:15and the deadelia live here permanently.
01:26:18They feed in the ocean and nest on land
01:26:21or in sea ice.
01:26:24But where and how did they evolve
01:26:27and what links do they have with the end of the dinosaur era?
01:26:30Can the predecessors of the modern penguin
01:26:33give us some clue about what happened
01:26:35after the disappearance of the dinosaurs?
01:26:38The fossil record of birds
01:26:41is considerably irregular and scarce,
01:26:44since most birds have very light skeletons
01:26:47and delicate bones.
01:26:50The case of penguins is very different
01:26:53since having thicker bones,
01:26:56we have a much better fossil record
01:26:59of them than of other bird groups.
01:27:02The first fossil was discovered in 1980.
01:27:05At the time, it was unknown.
01:27:08It was going to become the oldest penguin fossil
01:27:11that has been discovered.
01:27:14It lived between 60 and 62 million years ago,
01:27:17not long after the extinction of the dinosaurs.
01:27:23This specimen, known as guaymanu,
01:27:26which means aquatic bird in Maori,
01:27:29was a kind of hybrid
01:27:32between a sea bird and a modern penguin
01:27:35that looked like a modern bird
01:27:38from New Zealand.
01:27:44The guaymanu is a penguin,
01:27:47but it has many characteristics
01:27:50very similar to other groups of modern marine birds,
01:27:53such as the cormorants,
01:27:56that are distributed all over the world.
01:27:59The guaymanu was a primitive penguin
01:28:02and it is unlikely that it had the ability to fly.
01:28:05It was known as a non-flying bird,
01:28:08but it used the smallest wings
01:28:11to propel itself through the water.
01:28:14The first time you see a penguin,
01:28:17it is not easy to forget that they are birds,
01:28:20but they are.
01:28:23They have a beak, they lay eggs,
01:28:26they have feathers.
01:28:29If we look at all aspects of their physiology
01:28:32and their behavior,
01:28:35they are very similar to the guaymanu
01:28:38that we know today.
01:28:41They are closely related to the procelariiformes,
01:28:44which are the birds of tubular beaks
01:28:47such as the petreles, albatros, pardelas, etc.
01:28:50In the end, one of those ancestors
01:28:53adapts by staying longer in the water,
01:28:56trying to capture its food by immersing more
01:28:59and swimming for longer.
01:29:02Nowadays, penguins have adapted
01:29:05to the predators of the ocean,
01:29:08living and building their nests on land.
01:29:11They only go into the sea to fish.
01:29:14But the evidence has revealed
01:29:17something even more surprising.
01:29:20The fossil record shows
01:29:23that after the guaymanu,
01:29:26even larger versions of penguins were discovered
01:29:29in Antarctica and several species also in New Zealand.
01:29:35Some of these giant species
01:29:38were up to 30 cm higher
01:29:41and they doubled the weight of the largest penguin
01:29:44we have today, the emperor.
01:29:49But why did such a large penguin live then
01:29:52and not now?
01:29:56The asteroid that fell on Earth
01:29:5966 million years ago
01:30:02not only killed terrestrial animals,
01:30:05but also killed the vast majority
01:30:08of the great marine predators,
01:30:11which opened a niche in the ecosystem for the penguin.
01:30:14Let's imagine an ocean probably devoid
01:30:17of a large number of primary predators
01:30:20and, on the other hand, a few marine birds
01:30:23that were beginning to spread around the world
01:30:26and that realize that there are all these open niches,
01:30:29empty spaces that were waiting
01:30:32for a species to evolve to exploit its resources.
01:30:35After the death of the terrestrial dinosaurs
01:30:38new and strange creatures emerged in Antarctica
01:30:41and the seas began to fill again
01:30:44with marine life.
01:30:47However, the giant penguins
01:30:50and flying creatures of Antarctica and New Zealand
01:30:53have contributed to shake the greatest mystery
01:30:56of the current paleontology.
01:30:59Are they the true descendants of the dinosaurs?
01:31:06Did their lineage disappear
01:31:09to which it had also gone for 165 million years
01:31:12with that catastrophe?
01:31:15Or a part of the dinosaurs
01:31:18managed to survive to us
01:31:21in the form of birds?
01:31:26The first penguins point out
01:31:29that their flying relatives already existed
01:31:32before the fall of the asteroid.
01:31:35Now we know that some dinosaurs
01:31:38had feathers
01:31:41and laid eggs like birds.
01:31:44A mysterious hybrid fossil named Archaeopteryx
01:31:47discovered on the other side of the world
01:31:50gave us another clue.
01:31:53Archaeopteryx played a crucial role
01:31:56in establishing the link between
01:31:59modern dinosaurs and birds.
01:32:02It is clear that it was a dinosaur with feathers
01:32:05and it showed many characteristics
01:32:08that still retained much of the anatomy of dinosaurs,
01:32:11but at the same time it already had many of the features
01:32:14that we find in modern birds.
01:32:17However, the Archaeopteryx
01:32:20of 150 million years of antiquity
01:32:23is nothing more than a test.
01:32:26The discovery of another fossil
01:32:29would bring us a lost link later.
01:32:32A paleontologist who worked
01:32:35with the Archaeopteryx started with this fossil.
01:32:39As it happens with many discoveries,
01:32:42it was cornered and unidentified
01:32:45for two decades.
01:32:48But a casual review
01:32:51left scientists amazed.
01:32:54The fossilized skeleton
01:32:57dated approximately from the time
01:33:00of the impact of the asteroid.
01:33:02It had many different features
01:33:05in common with modern ducks and geese.
01:33:08It was baptized as Begabis.
01:33:11It could be like a primitive flying duck.
01:33:18It is potentially the ancestor
01:33:21of ducks and geese.
01:33:26And the most impressive thing,
01:33:29it had the oldest known example
01:33:32of a caviar, a resonance box
01:33:35like modern aquatic birds have.
01:33:38It is an early ancestor
01:33:41that presents much of the features
01:33:44that were developing in its group,
01:33:47like the syringe.
01:33:50Having such an ancient bird fossil
01:33:53of the Cretaceous, well settled
01:33:56in the genealogical tree of birds,
01:33:59indicates that the deep diversification
01:34:02took place in the Late Cretaceous,
01:34:05not older.
01:34:08Thus, some avian dinosaurs
01:34:11survived the Great Extinction
01:34:14to become birds,
01:34:17while all non-avian dinosaurs
01:34:20disappeared.
01:34:23When creatures like the giant penguin
01:34:26took its place,
01:34:29and modern mammals gave roots,
01:34:32it created a forest system
01:34:35during the next 31 million years.
01:34:38However,
01:34:41approximately 35 million years ago,
01:34:44when the southern continents separated more,
01:34:47Antarctica was totally isolated
01:34:50in the confines of the Earth,
01:34:53which brought devastating consequences.
01:34:56During the Great Extinction of the Cretaceous,
01:34:59Antarctica was a very different place.
01:35:02One of the main factors
01:35:05is the separation of the southern continents.
01:35:08We are not talking about something instantaneous,
01:35:11but a gradual process,
01:35:14and we witness the creation of a circumpolar current.
01:35:17This is the kind of events that are key
01:35:20to the change of climate in Antarctica,
01:35:23and that allows ice to be formed again.
01:35:26Antarctica is surrounded
01:35:29by a sea of low temperatures
01:35:33On land,
01:35:36temperatures plummet.
01:35:39Snow in winter melts in spring,
01:35:42and then in summer.
01:35:45When the layers of ice return,
01:35:48the terrestrial mammals disappear from Antarctica.
01:35:53Over millions of years,
01:35:56layers and layers of ice accumulate,
01:35:59and 15 million years ago,
01:36:02they would have returned.
01:36:08Today,
01:36:11these layers reach a thickness of up to 5 kilometers.
01:36:14Any trace of prehistoric animals
01:36:17remained hidden under an ice mantle,
01:36:20until at the beginning of the 20th century,
01:36:23some explorers found fossilized leaves.
01:36:25A century later,
01:36:28the most recent expedition comes to an end.
01:36:37In the base camp of Shackleton,
01:36:40scientists catalog their findings.
01:36:43Boxes and boxes of fossils
01:36:46embedded in rocks,
01:36:49waiting to be extracted in the laboratory.
01:36:52A great reason to celebrate
01:36:55after six weeks living
01:36:58in one of the most isolated places on Earth.
01:37:05First, a brief transfer to McMurdo,
01:37:08and then a long flight back
01:37:11to New Zealand and beyond.
01:37:21But when they return to the laboratory,
01:37:23that's when the real work begins.
01:37:26The cryolophosaurus.
01:37:29These dorsals came out perfectly.
01:37:32To reveal the mysteries of the lost world
01:37:35of the dinosaurs of Antarctica.
01:37:38It's kind of like getting back to Christmas,
01:37:41when you have everything in the laboratory
01:37:44and you start opening the boxes and preparing everything.
01:37:47It's like rediscovering everything again.
01:37:50Wow, look at this, how well preserved.
01:37:53It's a thousand kilometers from here,
01:37:56except where the ice was, the state of conservation is extraordinary.
01:37:59The bone is phenomenal.
01:38:02We found better fossils and more complete ones,
01:38:05remains that may belong to new species.
01:38:08For us, Antarctica is nothing more than another piece
01:38:11of the puzzle to understand the evolution of the climate
01:38:14and how it influenced plants and animals at that time.
01:38:17There are still many things to discover.
01:38:20Every place we go has its own story.
01:38:23Little by little, the secrets of Antarctica are revealed.
01:38:29The paleontology that comes from Antarctica
01:38:32has an incalculable value because it serves us
01:38:35to unravel a piece of the puzzle of the history of life.
01:38:38How was life in those polar environments
01:38:41for a very long period of time?
01:38:46But it is clear that while the human being continues to explore,
01:38:50this is not the end of the history of life.
01:38:53It is the beginning of an ancestral life in Antarctica.
01:38:57With each new discovery,
01:39:00the dinosaurs of the frozen continent reappear.