Pourquoi ne Retrouve-t-on pas des os de Dinosaures Partout ?

Sympa

Les os de dinosaures ne se trouvent pas partout car la fossilisation est un processus rare qui nécessite des conditions spécifiques. La plupart des os se décomposent avant qu'ils puissent se fossiliser, et seulement une petite fraction est préservée dans la roche sédimentaire. L'érosion, les catastrophes naturelles et l'activité humaine peuvent également détruire les fossiles avant qu'ils ne soient découverts. De plus, de nombreux fossiles sont enterrés profondément sous terre, ce qui les rend difficiles à trouver. Découvrez notre dernière vidéo pour en savoir plus sur le processus fascinant de formation des fossiles et pourquoi ces trésors anciens sont si rares !  Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com   Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna​ ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/  Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ----------------------------------------------------------------------------------------  Si tu en veux encore plus, fais un tour ici:  http://sympa-sympa.com

Transcript

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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