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.
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