00:00Our planet has experienced five massive extinctions.
00:03One of them was so devastating
00:05that it destroyed more than 95% of life forms on Earth,
00:09and scientists think they have found the culprit, the volcanoes.
00:14By analyzing ancient rocks from a dozen sites around the world,
00:18they have discovered high levels of mercury,
00:21released by volcanoes millions of years ago.
00:24This suggests that volcanic eruptions
00:26are probably the cause of the extinction of Permian Trias.
00:30Mercury was not only found in rocks, but also in the atmosphere.
00:34This means that when volcanoes erupted,
00:37they released this toxic gas into the air.
00:40They spat out about 3 million cubic kilometers of ash,
00:43much more than the famous eruption of Mount St. Helens.
00:47The gas left a mark on one of the most significant disasters in history,
00:51and prepared the ground for the era of dinosaurs.
00:54These eruptions also probably released mercury
00:57by inflating large deposits of coal.
01:00The shallower waters revealed mercury spikes
01:03just at the main horizon of the extinction.
01:06While the deeper sections recorded spikes
01:09several tens of thousands of years earlier.
01:12This could mean that the effects of volcanic activity
01:15and the extinction it caused
01:17varied according to the different oceanic depths.
01:20It also means that this extinction was prolonged and complex.
01:24It not only resulted from a major global warming at the time,
01:27but also caused other harmful effects,
01:29such as acid rains,
01:31aggravating the situation for plants and animals.
01:34Although few traces of Permian have survived to this day,
01:37we can get an idea of what the world looked like at that time
01:41thanks to the fossils discovered in eastern Kansas.
01:44252 million years ago,
01:46the earth was in full abundance.
01:48The terrestrial continents gathered to form the supercontinent Pangaea.
01:52The earth was mainly arid,
01:54resembling an austere desert
01:56with vast rocky expanses
01:58and few water sources.
02:00The climate alternated between hot summers
02:02and icy winters.
02:04Some plants, mainly conifers,
02:06giant ferns and primitive mosses
02:09grew in areas with a little water.
02:12The earth was dominated by creatures similar to dinosaurs,
02:15such as pelicosaurs and therapsids,
02:18often called mammalian reptiles.
02:20The formidable Dimetrodon,
02:22with its remarkable veiled dorsal fin,
02:25was also one of the main predators of the time.
02:29Small reptiles and amphibians also populated the landscape,
02:32alongside emerging insects such as beetles and dragonflies,
02:35which thrived in this dry environment.
02:38But the most interesting events
02:40took place mainly in shallow tropical seas.
02:44The marine environments were full of life,
02:47rich in coral reefs,
02:49a quantity of molluscs called brachiopods,
02:52bryozoares and large unicellular fusilinidae,
02:56resembling small forms covered in moss.
02:59Ammonites, small and fascinating,
03:02were also widespread,
03:04evolving alongside brachiopods,
03:06bonefish and sharks.
03:08Trilobites,
03:10ancient marine organisms
03:12that lived for the first time 500 million years ago
03:14during the Cambrian period,
03:16persisted until the Permian period.
03:18They were highly diversified,
03:20ranging from active predators to carnivores,
03:22as well as plankton eaters.
03:24However, almost all these magnificent creatures
03:27would be brought to extinction
03:29during the extinction of the Permian-Trias.
03:31It proved to be truly pitiful.
03:34More than two-thirds of amphibian and reptile species
03:36disappeared,
03:38and nearly one-third of all insect species
03:40were destroyed.
03:42Usually, insects are among the most resilient
03:44among the survivors,
03:46which illustrates the extent of this event.
03:48Among these missing animals
03:50was the terrifying Meganeuropsis,
03:52a giant libellule
03:54with a width of nearly 80 cm,
03:56which lived in the center of Kansas
03:58near Elmo.
04:00The place is famous for its rich collection
04:02of insect fossils of the Permian,
04:04including crickets and ancient slugs.
04:06For some time,
04:08the exact cause of this event
04:10has remained mysterious.
04:12Theories allude to the impact
04:14of a huge asteroid
04:16on natural pollutants
04:18depriving the oceans of oxygen,
04:20as well as dust clouds
04:22resulting from colossal volcanic eruptions
04:24that would have masked the sun
04:26and cooled the planet.
04:28There is evidence supporting each of these scenarios.
04:30However, a recent discovery
04:32seems to favor volcanoes.
04:34It is also possible
04:36that the cause of this extinction
04:38is not limited to volcanoes.
04:40Researchers funded by NASA
04:42have recently discovered what could be
04:44the digital footprints of this former
04:46responsible, or at least one of his accomplices.
04:48Studying rocks from all over the world,
04:50they found clues suggesting
04:52that a massive impact of asteroids
04:54could also be involved.
04:56They discovered unusual molecules
04:58in the form of rugby balls
05:00and called fullerenes.
05:02These molecules contain rare gases
05:04of extraterrestrial origin
05:06suggesting that a huge asteroid,
05:08perhaps as large as Mount Everest,
05:10would have crashed on Earth,
05:12contributing to the extinction.
05:14It seems that a series of catastrophic events
05:16have occurred.
05:18Volcanoes have spat out
05:20huge amounts of lava and gas,
05:22thus altering the climate.
05:24The formation of the Pangea
05:26disturbed the meteorological and oceanic
05:28patterns, and an asteroid
05:30also hit the Earth.
05:32We still find a way to be reborn,
05:34proving the adaptability of our planet.
05:38It is interesting to note that
05:40this was not an isolated event.
05:42The extinction of the late Devonian
05:44about 360 million years ago
05:46is also linked to volcanic activity.
05:48The eruptions and proliferation
05:50of terrestrial plants
05:52could have changed the flow of nutrients
05:54towards the oceans.
05:56The extinction of the Jurassic Trias
05:58occurred about 200 million years ago,
06:00shortly before the appearance of dinosaurs,
06:02could also be due to the combination
06:04of volcanic eruptions
06:06and an impact of asteroids.
06:08Finally, about 66 million years ago,
06:10a last drastic change
06:12took place on Earth.
06:14Our planet went from the era
06:16of dinosaurs to that of mammals.
06:18This size change
06:20is known as the Cretaceous-Paleogene
06:22extinction.
06:24Like the Permian extinction,
06:26it is a sudden event that
06:28produces new forms of life.
06:30And, once again, two great theories
06:32explain what happened.
06:34The most widespread theory
06:36states that dinosaurs would have
06:38disappeared because of a huge asteroid.
06:40The Chicxulub meteorite
06:42crashed into what is now
06:44the south of Mexico,
06:46forming the crater that bears its name.
06:48This meteorite was about 10 km in diameter
06:50and headed towards Earth
06:52at a prodigious speed.
06:54The impact instantly vaporized
06:56everything that was nearby
06:58and released an unequal amount of energy
07:00in a billion years.
07:02The consequences were catastrophic.
07:04Earthquakes shook the continents
07:06and the ground wavered like a
07:08flooded sea. The dust raised
07:10by the asteroid fell back on Earth
07:12in a scorching rain, heating
07:14the atmosphere to the point of burning
07:16the forests of the entire world.
07:18Shortly after, a gigantic tsunami
07:20caused by the upheaval of the seabed
07:22submerged the coasts
07:24near the Gulf of Mexico.
07:26All the dinosaurs did not
07:28instantly disappear. In regions
07:30like New Zealand, some populations
07:32first survived. However,
07:34a sky obscured by ashes
07:36ended up enveloping the planet,
07:38hiding the sun and plunging the world
07:40into cold and darkness.
07:42This long-term effect
07:44truly sealed the fate of the dinosaurs.
07:46Without sunlight, the food chain
07:48quickly collapsed.
07:50Herbivores slowly disappeared,
07:52followed by carnivores that depended on them,
07:54while ash falls
07:56accentuated environmental
07:58upheavals and temperature fluctuations,
08:00making survival difficult.
08:02However,
08:04there is another theory according to which
08:06the asteroid would have been
08:08only a stroke of grace. The extinction
08:10of the dinosaurs was already
08:12inevitable because of the volcanoes.
08:14About a million years before their
08:16disappearance, an intense volcanic activity
08:18began in the subsoil of
08:20the present day. This event created
08:22the famous Deccan Trap,
08:24a vast lava plateau covering
08:26a surface as large as France.
08:28For hundreds of thousands
08:30of years, these volcanoes ejected
08:32sulfur dioxide and carbon dioxide
08:34into the atmosphere, darkening the
08:36skies and causing acid rain,
08:38poisoning food sources
08:40and turning the oceans into toxic baths.
08:42These gradual but relentless changes
08:44put the ecosystems to the test,
08:46breaking down food chains
08:48and causing a slow but continuous decline
08:50of many species, including dinosaurs.
08:52Although we do not know
08:54with certainty which theory is
08:56the most precise, scientists now
08:58think that the two phenomena
09:00played a role. Maybe one day
09:02we will have a clear picture of how
09:04the reign of dinosaurs
09:06ended so abruptly.
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