What if the asteroid wasn't what killed the dinosaurs?
Sixty-six million years ago, a vast meteorite the size of Mount Everest hit the earth,
eradicating 75% of living things, especially dinosaurs.
But what if I told you that it's possible that the meteorite wasn't the cause of the dinosaurs
going extinct? What if dinosaurs were already going extinct long before the meteorite fell?
Surprisingly there is a theory that indicates that it is likely that a meteorite was not the cause of
the extinction of the dinosaurs as we thought. Are you ready? Let's go! "
As we all know, the most accepted theory today about the extinction of the dinosaurs is the
fall of a giant meteorite; if you want to know how scientists came to this conclusion,
we recommend you watch the previous video about "Where was the meteorite that killed
the dinosaurs?" "
Today we have enough evidence that suggests that approximately 66 million years ago,
a meteorite at least 10 km in diameter fell on earth, some of that evidence is the colossal
crater of Chixulub in the Yucatan Peninsula in Mexico, which is the largest on the entire
planet and the date of its creation agrees with the date of the extinction of the dinosaurs.
Another proof of the collision of a meteorite of these dimensions on earth is the excess of Iridium
in the sedimentary rocks that mark the transition of the KT period, a period in which a sudden mass
extinction occurred and in which the levels of Iridium in the atmosphere suddenly increased,
Iridium is a metal found mainly in asteroids. All this suggests that the extinction of the
dinosaurs was caused by a space rock that hit the earth. Still, although this is the
most accepted theory today, it is not the only one that scientists have formulated,
as other events could also explain the sudden extinction of the dinosaurs.
DINOSAURS WERE ALREADY GOING EXTINCT BEFORE THE METEORITE FELL?
Some of these theories are based on the fact that researchers tracked the species
that appeared and those that disappeared over millions of years and estimated the
rates of speciation and extinction over time. The results show that dinosaurs were already
in decline globally 10 million years before the asteroid impact,
affecting both carnivores such as tyrannosaurs or Tarbosaurus, as well as herbivorous groups,
such as Triceratops or Diplodocus. According to researchers Fabien Condamine and
Guillaume Guinot of the Institute of Evolutionary Sciences in Montpellier, France, 56 million years
ago, dinosaur ecosystems began to change and become increasingly cold. Species that fed on
plants tended to disappear first, which made later ecosystems unstable and susceptible to collapse
if environmental conditions worsened; the lack of herbivorous animals encouraged carnivores to
begin migrating to areas with more food, causing an acceleration in the decline of herbivores.
Two main factors led to the slow decline of the dinosaurs before the meteorite fell. First,
temperatures around the planet gradually became colder, making life more difficult for dinosaurs,
which depended on warm temperatures. Remember that contrary to what is thought,
even though dinosaurs were reptiles, recent studies show that most of them were endotherms,
that is, warm-blooded, so they were accustomed to high temperatures,
such as tropical ones. The problem with this is that being so large; herbivores needed large
amounts of food to stay at that temperature. It is possible that at that time, the entire
planet was entering a climate change that caused a decrease in temperatures and plants.
This climate change could have been due to a reorganization of ocean currents that caused
the high and tropical temperatures to which the dinosaurs were accustomed to drop considerably.,
leaving an average temperature of 7 °C in the northern hemisphere and 10 °C in the south.
This new cold climate and lack of food was a difficult challenge to face for the largest
and oldest dinosaurs. They had adapted to a hot climate and abundant food for millions of years,
so they could not adapt so quickly to a cold climate. Because of this,
the large herbivores began to die from the lack of food and the low temperatures that their
bodies were not able to withstand; this broke the trophic chain and triggered a chain of extinctions
in which several species of dinosaurs, such as the Triceratops died it is possible that all the
Triceratops died long before the meteorite fell. The second factor that led to this decline of the
dinosaurs was the loss of herbivores; this made the ecosystems unstable and susceptible to a
cascading extinction that led the carnivores to fight for the few remaining herbivores.
Does this mean that what killed the dinosaurs was climate change and not the meteorite? Not
necessarily; the theory holds that dinosaurs began to go extinct long before the meteorite fell,
but when the meteorite fell, many species were still beginning to adapt to the new
cold climates, mainly birds and mammals. With the slow decline of giant herbivorous
dinosaurs and carnivores, new opportunities opened up for smaller animals that no longer
had as much competition. This is how, little by little, mammals began to take
an important place in the diversity of species. It is possible that, if the meteorite had never
fallen, a large part of the dinosaurs would have adapted to the world's new cold climate. But,
still, mammals would have taken a suitable place without other dinosaur species.
SIMULTANEOUS VOLCANIC ERUPTIONS Another of the most popular theories
that could explain the extinction of the dinosaurs is that thousands of years before
the meteorite fell on Earth, much of all the volcanoes on the planet erupted simultaneously.
The theory arises from a study conducted in northern China by researcher Laiming Zhang of the
Chinese University of Geosciences in Beijing. The team analyzed ancient sediments at the bottom of a
lake basin and found that the lake's temperature had begun to rise hundreds of thousands of years
before the impact of the Chixulub crater, which presumably made the dinosaurs extinct.
This warming coincides with the eruptions on the stairs of the Deccan in India.
The Deccan Stairs are one of the most significant volcanic formations on Earth.
They are composed of several solidified basaltic flood layers covering an area of 500 000 km² and
2000 m thick, approximately the area of France. This formation originated approximately 68 million
years ago in the area of what is now India from a large number of volcanic veins that massively
opened in the ground and expelled immense amounts of lava uninterruptedly for a million years.
Suppose these types of eruptions are replicated simultaneously throughout the planet. In that
case, this could cause an increase in greenhouse gases, such as methane, carbon dioxide,
and sulfur dioxide, which generated a climate change that raised temperatures and intoxicated
the oceans, weakening living organisms and killing those that could not adapt.
Although the data show changes in the planet's pre-impact temperature worldwide,
the team also discovered something more alarming. Zhang and his colleagues found that many fossils
in the ancient sediments disappeared during this sudden warming. Two-thirds of the region's
extinctions occurred after the onset of volcanism and hundreds of thousands of years before impact.
In summary, the studies provide strong evidence that at least 8 million years
before the meteorite fell; volcanoes destabilized the global climate in a series of simultaneous
eruptions that suddenly raised the temperature across the planet, killing a large part of
the species almost immediately. Subsequently, thousands of years after the eruptions began,
the smoke caused by soot and sulfur darkened the sky. Eventually, there was a decrease
in the temperatures of the entire planet. The climate went from being warm and tropical
to cold and dry; the plants began to die, the most enormous herbivorous dinosaurs began to
decrease by not being able to adapt as well as the aquatic animals died due to the increase
of toxins in the waters, which produced a cascading extinction of all living beings.
THE FINAL EXECUTIONER The extinction of the dinosaurs
began much earlier than we thought, and thanks to science, we now know that the changes in the world
significantly weakened the species of that time, so for better or worse, the meteorite that fell
on the earth 66 million years ago was only the cherry on the cake of a series of catastrophes
that had begun long before its arrival. In a way, the meteorite only finished
extinguishing the dinosaurs already going extinct long before.
What would have happened if the meteorite had never fallen on the ground?
Do you think it's possible that dinosaurs would have managed to adapt and survive or
would have gone extinct anyway to make way for the mammals that rule the world today?
Let us know your opinion by writing your valuable comment!