00:00If dinosaurs once dominated the earth, we could expect to find their bones everywhere.
00:07But this is not the case.
00:09So why?
00:11No conspiracy is at work.
00:14In fact, the search for remains of dinosaurs is much more complex than it seems.
00:20Yes, the bones of dinosaurs are indeed real.
00:24We have discovered a multitude of them, and we have to find them on every continent, although some doubt it.
00:30The unequal distribution of these prehistoric treasures is in fact only a bizarreness of nature.
00:37It turns out that fossilization is an incredibly rare phenomenon, which occurs only in very specific conditions.
00:45When a dinosaur dies, the fossilization process begins.
00:49The carcass must be quickly covered with sediment, then buried under many layers, creating a kind of geological autoclave.
00:57The minerals then impregnate the bones, transforming them into stone.
01:01This unique recipe takes place mainly underwater, where sediments such as sand and mud can gently envelop the deceased giants.
01:09This is why the dinosaurs who were breathing their last on earth were rarely fossilized.
01:15Thus, it is very rare to find fossils of species that have lived in the jungles or in the mountains.
01:23Researchers tell us that many fossils come from areas near lakes or rivers.
01:28That these dinosaurs were drowned in a sudden flood or carried away by the rains, they still had the chance to be fossilized.
01:35These are the reasons why we do not discover new dinosaurs in every corner of the street.
01:40The reality is that we could never discover many species of dinosaurs due to the limits of fossilization.
01:46Nearly 71% of dinosaurs will never be found.
01:50We do not even know how many species have been lost due to inadequate conditions.
01:55With great luck, we could find fossils of dinosaurs from the mountains in the rivers downstream, but this remains very rare.
02:03Despite the fact that dinosaurs inhabited the globe, all the fossils discovered so far have been thanks to exceptional luck.
02:11This makes us think about the general lifespan of dinosaurs.
02:15We tend to picture them as living in slow motion, wandering through the centuries until reaching colossal sizes.
02:22Ironically, the reality is quite different.
02:25In fact, dinosaurs burned, the candle spoke standing, and lived quite briefly, a bit like rock stars.
02:32Once their sexual maturity reached, they were often already on the express way to fossilization, before having reached their maximum size.
02:41What is interesting is that the life cycle of dinosaurs aligns with the rhythm of trees.
02:46You may know that it is possible to determine the age of a tree by counting its horns.
02:51In fact, each pair of light and dark horns corresponds to a year of growth.
02:56Similarly, the horns of trees tell us about their age.
02:59The bones of dinosaurs tell us about them.
03:01Researchers examine bone slices with a microscope and analyze the different tissues to evaluate growth rates.
03:07Thick rings indicate rapid growth, while narrow rings indicate slower growth.
03:15In the animal kingdom, a large size generally means a longer life.
03:19Some therefore wonder if the great dinosaurs really lived longer.
03:23Apparently, yes.
03:24The huge sauropods, similar to ancient colossi, probably took about 30 to 35 years to reach their maximum size.
03:32After that, they could take advantage of a few additional decades to rampage in the Jurassic.
03:38For the smallest dinosaurs, such as ornithopods, life was shorter.
03:42They reached their adult size after about 4 to 5 years.
03:46However, after only 3 to 4 years of life, these small dinosaurs, unless extremely lucky, would no longer be from this world.
03:53Thus, it turns out that many dinosaurs did not live for hundreds of years.
03:57Even the largest rarely reached the fifties.
04:00This may seem surprising when compared to today's giants such as blue whales and elephants.
04:05These animals have a lifespan similar to ours.
04:09Blue whales live about 80 to 90 years, and many elephants reach 60 to 70 years.
04:16And yet, they are not as big as some dinosaurs.
04:20It is regrettable that these creatures left our planet so early, depriving us of the opportunity to study them more.
04:26What is even sadder is that the dinosaurs were condemned from the start.
04:31Even if an asteroid had not hit our planet by chance, they would probably have disappeared anyway.
04:37The Chicxulub meteorite crashed on Earth 66 million years ago.
04:41It did not completely destroy the population of dinosaurs, only the nonavians.
04:46The others became our modern birds.
04:48And yes, some of these colossal creatures evolved to give the little hens and pigeons we know today.
04:54It's not just the wolves that got lost yesterday.
04:57But even before this impact, the Earth was slowly preparing a disaster, just for them.
05:02Recent research shows that the previous era of the impact of the asteroid had nothing of a paradise.
05:08It was rather a period full of environmental challenges.
05:14Scientists have studied the Deccan Traps, one of the largest volcanic regions in present-day Western India.
05:20They have developed an innovative technique to explore the past through volcanoes,
05:25by measuring the concentration of sulfur in the rocks.
05:28Thanks to this, they have discovered that the Deccan Traps, by ejecting millions of cubic kilometers of lava,
05:34have contributed to global climate change.
05:37More than 100,000 years before the impact of the famous Chicxulub meteorite,
05:41global temperatures would have dropped several degrees,
05:45probably because of the sulfur emissions from the Deccan Traps.
05:49This sudden fall has created extremely difficult climatic conditions.
05:55The Earth has experienced volcanic winters, making life extremely hard for fauna and flora,
06:00and preparing the ground for the final extinction of dinosaurs.
06:04Thus, even without the impact of the asteroid, the latter would probably not have survived for long.
06:13For a long time, scientists have been debating whether it was the asteroid or the volcanic activity that caused the extinction of dinosaurs.
06:20Today, thanks to many technological advances, we can better answer this question.
06:25An artificial intelligence system, developed by researchers, offers a new perspective.
06:30Thanks to more than 100 processors powered by geological and climatic data,
06:35the IA has explored fossil records and simulated more than 300,000 possible scenarios to establish the truth.
06:42According to this IA, volcanic theory is by far the most plausible.
06:46It has shown that the climatic changes necessary for a mass extinction
06:50had probably been caused by the Deccan Traps on their own, without even the impact of the asteroid.
06:56These volcanic eruptions coincided with the Paleogenic Cretaceous Limit,
07:00beginning 300,000 years before the asteroid and continuing over a prolonged period.
07:05This raised questions about the human judgment opposed to that of the IA.
07:10Scientists have expressed their skepticism and underlined the possible biases of artificial intelligence.
07:16The researchers who led the project, as for them, are excited by the novelty of their method
07:21and its potential to explore other periods of terrestrial history.
07:25But it will probably have to wait before all the researchers fully trust this IA.
07:31We have already mentioned that some non-ship dinosaurs have survived this apocalyptic event.
07:38Neither the volcanoes nor the asteroid have annihilated everything on our planet.
07:42Many animals have survived and evolved into mammals, while many plants have continued to thrive.
07:49In reality, plants have gone through this disaster better than animals.
07:53A massive extinction eliminated about 75% of terrestrial species.
07:58But these botanical wonders have survived.
08:01About 78% of our current plant species owe their existence to the resilience of their ancestors.
08:07Alas, plants do not transform into fossils as easily as animals.
08:12And we already know that this process is neither fast nor very widespread.
08:17Thus, the researchers had to turn to the tree of evolution for their analysis.
08:22They studied up to 73,000 surviving plant species,
08:26and the results revealed a remarkable history of dominance and adaptation.
08:31It turns out that after the great extinction, these rusty plants were able to seize their chance,
08:35just like mammals took on importance after the era of dinosaurs.
08:39Major families, such as manta, magnolia and orchids,
08:43not only coexisted with dinosaurs, but also prospered after their extinction.
08:48The secret to their success lies in their ability to adapt to pollination.
08:52They adapted to being pollinated by the wind, insects or any other available means.
08:58Thanks to this incredible adaptability, which scientists call the power of flowers,
09:03their heritage persists and still thrives today.
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