The Jurassic era fascinates modern people, and how the dinosaurs, the overlord of the earth, became extinct, have also been studied by the new masters of the modern earth.
Various opinions and hypotheses have emerged over the years, and just in 2020, one of the extinction hypotheses was further confirmed.
The asteroid impact became a further definite statement
The latest study, published in June 2020, is consistent with the catastrophic events caused by asteroid impacts over the years.
First, an asteroid fell and hit the coast of present-day Mexico, and the gas and dust from the explosion covered the sky for at least a few decades.
Then the earth ushered in a long winter, and a large number of dinosaurs died directly in the explosion. The dinosaurs that survived were also unable to adapt to the harsh climate and eventually became extinct.
The catastrophic consequences of the impact have been converging over the years. The difference lies in the specific area where the disaster occurred and the course of the disaster.
Now, the original theory has been further confirmed because scientists have made more new discoveries in new research. For example, in the new study, scientists used computers to build a model of the Earth after the impact, and further calculated the damage to the dinosaur habitat caused by the impact.
Previous studies have focused on the anomalies of certain elements in the Earth's strata. The impact hypothesis was proposed by an American scientist named Alwatts in the 80s of the last century, because he found that one of the elements called iridium in the strata at the end of the Cretaceous period was abnormal.
This element does not exist on Earth, so it can only come to Earth by meteorite impacts and other circumstances. With this, the impact hypothesis thus has a theoretical basis.
By 2022, relevant researchers have conducted a new summary analysis of various previous studies. Eventually, a scientific team of scientists from 12 countries reaffirmed the possibility of the impact view.
Scientists have analyzed evidence found over the past 20 years and further deduced that the impact that occurred 65 million years ago was 1 billion times larger than the nuclear explosion in contemporary Hiroshima.
Because the asteroid that hit the Earth at that time was more than 15 kilometers in diameter, the crater created after the impact was deeper than the height of the modern Himalayas. As a result, the earth's environment has been reversed.
It is worth mentioning that in the past, in addition to the impact view, there was also the view that volcanic eruptions caused catastrophic consequences. The latest research suggests that the impact and the eruption of the Earth's supervolcano should have occurred around the same time.
Some scientists believe that asteroid impacts and volcanic eruptions have created a superimposed effect, which in turn jointly launched an "encirclement" of the dinosaurs.
Others argue that volcanic eruptions, despite their size, are relatively short-lived and do not lead to a rapid and massive extinction of life on Earth in a short period of time.
Therefore, the latest scientists believe that only asteroid impact can form a rapid and sustained destructive force.
Scientists believe that the new research will lead to a consensus in the scientific community about the real cause of the extinction of the dinosaurs, and that the topic will no longer be controversial in the future.
In addition to the reaffirmation of the impact theory, new research in recent years has also shown that the dinosaurs and contemporaries may not have gone extinct on a large scale, assuming that the asteroid had hit other regions back then.
The location and angle of impact are critical
The driving force behind this research was Collins of Imperial University London. In a previous study, he found that the area and angle were so critical that even the slightest deviation could change the fate of the dinosaurs.
In Collins's view, the coincidental impact site and the impact angle of the asteroid formed a catastrophic storm that the dinosaurs could never change. Now we all know that the site of the impact is right on the east coast of Mexico.
In the Chicxulub region where the asteroid struck, the melting of the rock formations caused sulfides to eject directly into the air thousands of meters, a devastating consequence that caused the Earth to barely see the sun for decades afterward, Collins said.
However, if the asteroid falls into the ocean, such as the Atlantic Ocean or somewhere in the Pacific Ocean, the action of the sea water will reduce the degree of melting of the underground rock formations, and the scale of sulfide production will not be as large, and the final gas will not obscure the sun.
In this way, even if a large number of dinosaurs died during the impact, it is still possible for other dinosaurs and creatures to survive after the impact because the earth's devastated ecology is still maintained.
In addition to the area of impact, the angle of the asteroid's subduction impact is also a top priority. Collins found that the angle of the asteroid impact was between 45° and 60°.
The inclination at this angle is conducive to the vaporization of debris in the rock layer after hitting the ground, and the melted magma and sulfides will also be ejected more violently.
If the impact angle is less than 45° or less, the asteroid will slide forward under the strong inertial force after contact with the ground, instead of smashing deeper into the surface. As a result, magma and sulphides are produced much less.
Similarly, if the angle of impact is greater than 60° or right angle, the asteroid will be embedded deeper into the Earth's interior, and the magma and sulfides below the surface will be less easily ejected.
Therefore, in the view of Collins and other researchers, the location of the impact and the angle of the impact are fatal to living beings everywhere. This is tantamount to showing that God did not intend to let the dinosaurs live, but to wipe them out of the face of the earth completely.
What is clear is that the impact worked. Modern research speculates that at the moment of impact, the scale of the eruption of underground magma and sulphides was at least several billion tons.
At the same time, the impact caused widespread earthquakes all over the world, and it is important to note that earthquakes occur not in the area of impact, but in the whole world.
In the aftermath of the earthquake, surges and backfilling of water sources occurred in all areas of the world where surface water existed. Tsunamis occurred in coastal areas and in areas with lakes.
And that's just the momentary cataclysm that happened during the impact. In just these few minutes, all kinds of creatures around the world, including dinosaurs, died in advance.
Creatures that survive the impact will soon discover that it is better to be vaporized by magma at the moment of impact than to die in torture.
What happened after the impact
In essence, asteroids, like impacts and volcanic eruptions, tear a "big hole" in the earth's surface, and too much material suddenly erupts from the earth's interior, which eventually changes the earth's ecological climate.
However, compared with volcanic eruptions, asteroid impacts create larger surface "wounds", and the more material that can change the atmosphere is released from the Earth's interior. So, what exactly is the whole process?
The dinosaurs that survived the impact may still be in a state of complete confusion, but soon they will encounter something even more bewildering - the sun in the sky is actually gone.
The sulfides released in large quantities from the interior of the earth are all vaporized and floated into the sky, acting like a visor, completely isolating the sunlight from the earth.
In addition, many of the substances gushing out of the ground are still toxic gases. Therefore, in the surrounding area of the impact, living organisms will be quickly carried away by a wave as the oxygen content in the atmosphere drops rapidly.
Next, the living dinosaurs and other creatures barely saw the sun again in their lifetimes. Sunlight disappears for a long time, plants are unable to photosynthesize, and trees and grasses around the world are withering and dying one after another. The herbivorous dinosaurs soon lost their food source and starved to death.
Carnivorous Tyrannosaurus rex, etc., can still live by eating their own kind for the time being, but days without sunlight mean that herbivores cannot survive, so such days can't last long.
A more serious problem is that the lack of sunlight also causes the temperature of the earth's surface to drop rapidly. In other words, carnivorous dinosaurs will most likely not survive when the food is completely gone.
After the cold temperature and the plants died to harvest a wave of dinosaurs, the remnants of the creatures could only continue to perish in poisonous gas and poisonous water. Because sulfide gas forms acid rain, it kills plants directly, and it also kills animals that drink acid rain.
That is to say, even if a dinosaur dodges the impact, it cannot escape poisonous gas, poisonous water, lack of food, and low temperatures. The extreme ecological environment that has appeared one after another is to completely kill life.
Moreover, the violent impact may also cause chaos in the Earth's magnetic field, which will also disturb the Earth's original ecological climate. Therefore, under the harvest of the Grim Reaper, the dinosaurs that have dominated the earth for more than 200 million years have come to an end.
Views of other dinosaurs extinction
In addition to the asteroid impact, there are other ideas surrounding the extinction of dinosaurs over the years. Volcanic eruptions are also relatively popular, but as mentioned above, the latest research suggests that even if the earth experienced a supervolcanic eruption at that time, the ecological disaster caused by it would not be enough to kill the dinosaurs in a short period of time.
In addition, there are some more niche views that the gradually changing climate of the dinosaur era caused them to be unable to adapt to the new environment and eventually became extinct.
Scientists who oppose this view argue that environmental change needs to be driven by external factors, because climate change cannot happen without warning.
Finally, there is the view that the extinction of the dinosaurs was replaced by other smaller, more evolved animals. These smaller animals were agile and often ate the eggs laid by the dinosaurs, which led to the dinosaurs having fewer offspring and eventually watching their genes die.
This view does not believe that the extinction of dinosaurs occurred in a short period of time, but gradually died out over a long process. However, according to the many dinosaur fossils unearthed in the past, many dinosaurs died at the same time.
This can show that the dinosaurs at that time suffered some kind of unexpected situation before they died intensively. And if they are replaced by competitors in the long evolution, they will not suddenly die at some point.
epilogue
The extinction of the dinosaurs represented the end of an era in which the Earth's environment was once again suitable for life for a long time, but the overall situation was completely different from the past.
In this way, the ecological void created by the disappearance of the dinosaurs was occupied by the mammals that came from behind. For Earth, this seems to be the beginning of a new cycle.
Resources:
"Asteroid Impact Is the Main Cause of Dinosaur Extinction?What Are the Mysteries of Dinosaurs?", China News Network, July 4, 2020