Le désert du Sahara pourrait ressembler à une mer de sable sans fin, mais il cache certains des secrets les plus stupéfiants sous sa surface ! 🌵 Des scientifiques ont découvert les ossements de baleines anciennes—oui, des baleines—prouvant que ce désert était autrefois un océan, il y a des millions d'années. Il y a aussi des gravures sur pierre mystérieuses et des outils d’humains préhistoriques qui prospéraient ici lorsqu’il s’agissait d’un paradis verdoyant et luxuriant. Oh, et n’oublions pas l’époustouflant "Œil du Sahara", une structure circulaire massive visible depuis l’espace. Certains croient même qu’il pourrait s’agir des vestiges de la cité perdue de l’Atlantide ! Le Sahara est comme le coffre au trésor de la nature, rempli de découvertes qui défient la réalité et réécrivent l’histoire. 🏜️✨ Animation créée par Sympa.
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FunTranscript
00:00You have finally arrived. The sun gives off its burning rays and thirst holds you.
00:06Your mind cannot help but think of the water and the bones that lie under your feet.
00:11You wander through the Sahara, the largest hot desert on the planet.
00:15At this moment, you are crossing an extension of sand called the Whale Valley.
00:20On its 200 square kilometers, the ground is so densely sprinkled with fossils that it is impossible not to walk on it.
00:27Palaeontologist Hesham Salam describes this scene as typical of the region.
00:31The bones emerge from the cliffs, almost inviting you to examine them.
00:36Spread out ridges cover the ground, and its gigantic vertebrae attract your gaze.
00:41Imagine the creature to which they belonged. They could reach up to 20 meters long.
00:47The fossils reveal a profiled body reminiscent of that of modern whales,
00:51while retaining ancestral features such as hind legs and feet.
00:56For scientists, this could indicate the discovery of a complete skeleton of a prehistoric whale,
01:01a creature that inhabited this region when Egypt was submerged by the waters.
01:06Today, the Whale Valley is the largest world cemetery of ancient whales.
01:11You could wonder about the presence of marine creatures in the middle of the desert,
01:15more than 100 kilometers from the nearest coast.
01:18Well, millions of years ago, this desert formed the bottom of a huge ocean,
01:22the Tethys, which extended from Europe to India.
01:25When the water level dropped, the ocean left behind it an ancient seabed, now littered with fossils.
01:32The fossils of some of the oldest known whale species rest here,
01:36offering researchers a unique perspective on the evolution of the gigantic Cetaceans.
01:42These remains are of remarkable precision, some even retaining intact stomach contents.
01:48Scientists have also discovered fossils of ancient sharks, crocodiles and turtles,
01:52allowing to reconstruct the appearance of this marine world that has disappeared for millions of years.
01:58The first whale bones were discovered in 1902,
02:02but it was only from the 1980s that the region was actually explored, when its access was improved.
02:08Unfortunately, before the site benefited from official protection,
02:12several remains were taken by collectors.
02:15Most of the fossils, barely buried under the surface, are gradually brought to life by erosion.
02:21The Whale Valley offers a fascinating window on millions of years of ancient coastal life.
02:27But let's go further.
02:29The fossils of ancient whales are not the only discovery that awaits you today.
02:33For more than 150 years, scientists have been intrigued by a strange creature that lived millions of years ago.
02:41Thanks to exceptional fossils discovered in Morocco, the mystery is finally solved.
02:46Look, these creatures are called Stilophores.
02:50They looked like a flattened armor where a long arm emerged.
02:54Researchers discovered these specimens in 2014 and were amazed.
02:59The fossils date back to about 478 million years.
03:03Nearly 450 specimens have been found and, very rarely, some still had soft preserved tissues.
03:11Until then, Stilophores were only known through their hard parts
03:15and, initially, scientists considered them as simple echinoderms, like urchins and starfish.
03:23But recent discoveries reveal that they had a central body and a nourishing arm,
03:28similar to that of starfish, equipped with an aquifer vascular system that facilitated their movement and feeding.
03:35This discovery ends a long-standing debate about the place of Stilophores in the phylogenetic tree.
03:41We now know that they are similar to echinoderms, but that they are distinguished by the absence of a 5-ray symmetry.
03:47Come and admire this gigantic fossil.
03:50Discovered in the Sahara, it allowed scientists to deepen their knowledge of the Spinosaurus, the largest known carnivorous dinosaur.
03:59Its remains, dating back to 95 million years, confirm that it was also the first identified swimmer dinosaur.
04:06The Spinosaurus had flat feet in the shape of pegs and nostrils located at the top of its skull,
04:12similar to that of a crocodile, characteristics ideal for aquatic life.
04:17This amazing dinosaur, with its long neck, trunk, tail and a crest of 2 meters on its back,
04:24probably spent a lot of time in the water.
04:27With a length exceeding 15 meters, it could even have been more imposing than the Tyrannosaurus.
04:33The first remains of Spinosaurus were discovered in Egypt about a century ago,
04:38but it was only with this Moroccan fossil that scientists were able to reconstruct the anatomy of this incredible dinosaur.
04:45Researchers paid particular attention to its shortened posterior limbs and its large claws,
04:51adaptations typical of aquatic life.
04:54Its elongated muzzle and the density of its bones also confirmed its swimming skills,
05:00while its crest probably played a role in the attraction of partners.
05:04Hey, hi handsome.
05:07Here is another impressive discovery made in Tunisia.
05:11Remains of Machimosaurus rex.
05:14Considered so far as the largest crocodile ever identified,
05:18this ancient reptile measured nearly 10 meters long for a weight of about 3 tons.
05:24It reigned as a dominant predator about 130 million years ago, with a skull measuring more than 1.5 meters.
05:31This discovery is significant because it proves that these crocodiles have survived much longer than we thought.
05:38Before that, scientists estimated that they had disappeared during a minor episode of extinction between the Jurassic and Cretaceous periods.
05:47Let's go back to the fact that the Sahara, formerly covered with water,
05:50housed some of the most gigantic marine creatures ever known.
05:54A study published in the American Museum of Natural History's bulletin
05:58mentions an ancient water plan called the Trans-Saharan Maritime Route.
06:03It would have existed between 100 and 50 million years ago, and extended over part of West Africa.
06:09Scientists spent nearly two decades reconstructing this prehistoric ecosystem.
06:15They discovered that it was hot and shallow,
06:18hosting terrifying creatures such as 1.5-meter-tall cichlids and 12-meter-tall sea snakes.
06:24Frightening, isn't it?
06:27This maritime network, isolated from the great oceans for long periods,
06:31would have favored the increase in the size of these predators,
06:34thanks to a constant availability of resources.
06:38This is a classic case of evolution,
06:41leading to the phenomenon that scientists call gigantism in isolated environments.
06:47In addition, all this water did not disappear without leaving a trace.
06:51Under the dunes of the Sahara, researchers have discovered a gigantic ancient lake,
06:56nicknamed Megalak, a well-deserved name.
06:59This lake was formed about 250,000 years ago, when the Nile flooded the east of the Sahara.
07:04At its peak, it covered more than 100,000 square kilometers,
07:08which is about half the area of Kansas.
07:11Scientists have also discovered traces of a smaller lake,
07:15located 150 kilometers west of the Nile,
07:18at a slightly lower level and covering nearly 50,000 square kilometers.
07:23All this adds to the growing evidence that there used to be many lakes in North Africa,
07:28which could have formed migration routes,
07:31thus facilitating the movement of the first humans across the continent.
07:35The Sahara is not only home to fossils of strange animals.
07:38In May 2020, unusual rocks, decorated with verdant crystals,
07:43were discovered in a sandy region in southern Algeria.
07:46After analysis, scientists concluded that these rocks did not come from the Earth,
07:51but were actually fragments of a meteorite called Erg Chech 0023.
07:57This meteorite is extremely old,
08:00being considered the oldest volcanic rock ever found.
08:03It formed billions of years ago,
08:05in the incandescent heart of a protoplanet that has now disappeared.
08:09A recent study, published in Nature Communications,
08:13revealed that the analysis of lead and uranium isotopes present in Erg Chech 002
08:19allowed it to date back more than 4.5 billion years.
08:23Another intriguing discovery made in the Sahara turned out to be totally unexpected.
08:29Scientists have discovered what they consider to be the oldest colors in the world,
08:35of a sparkling pink.
08:37These pigments, extracts of old rocks of about 1.1 billion years,
08:41come from microorganisms, at a time when animals did not yet exist.
08:46This discovery was made by a PhD student,
08:50who crushed the ancient rocks and studied their pigments.
08:53The latter turned out to be an ancient chlorophyll
08:56derived from photosynthetic organisms that had been living in an ocean for a long time.
09:01Researchers are now convinced that this discovery could enlighten us
09:04on the reason why larger and more complex organisms
09:07appeared much later in our history.
09:10Before these pink pigments were discovered,
09:13scientists ignored what slowed the evolution of large animals in the food chain.
09:18They now understand that microscopic cyanobacteria were at the base of this chain.
09:24This discovery is not limited to the identification of ancient pigments,
09:28but is a major step forward in understanding the history of life on our planet.