Unraveling the Mystery of Dinosaur Extinction: What Has the Latest Research Revealed?
About 66 million years ago, one of the most dramatic events in Earth’s history, the extinction of the dinosaurs, took place.
For many years, various theories have been proposed to explain the cause of this mass extinction, but the Giant Asteroid Impact Theory is currently the most widely accepted.
In the spring of 2010, news was reported that a team of experts from around the world concluded that a giant asteroid impact was the cause of this great extinction, after examining a large amount of data.
The Reasons Why the Asteroid Impact Theory Is the Undisputed Leading Candidate
Why the Asteroid Impact Theory is the undisputed leading candidate
So why is the Asteroid Impact Theory the most plausible?
The answer is hidden in the geological layer that marks the boundary between the Mesozoic Cretaceous period and the subsequent Cenozoic Paleogene period, commonly known as the K-Pg boundary.
This K-Pg boundary layer contains numerous unique traces that are not found in normal geological strata.
Specifically, the following three pieces of evidence support the asteroid impact:
High Concentration of Iridium
Iridium, a precious metal that exists in very small quantities on Earth’s surface, was detected in high concentrations in this layer.
In rock samples from Wyoming, USA, the K-Pg boundary was found to contain 1,000 times more iridium than the layers above and below it.
Since elements like iridium and platinum are rare in the Earth’s crust but abundant in asteroids, this suggests that material from space settled on Earth.
Traces of Impact
Shocked quartz and microscopic diamonds, which are generated by the immense pressure of a meteor impact, were found in this layer.
These minerals do not form through normal terrestrial processes.
Non-Biological Amino Acids
Amino acids believed to be of cosmic origin, which are not found on Earth, have also been discovered. This is another strong indication of a celestial body’s arrival.
This conclusive evidence points to the fact that a roughly 10-kilometer asteroid collided with Earth.
The impact site is believed to be the Yucatán Peninsula in present-day Mexico, where a giant crater measuring 170 km in diameter remains.
This crater is called the Chicxulub Crater. The energy of the impact was equivalent to 1 billion times that of the Hiroshima atomic bomb, and its destructive power was beyond imagination.
The Chain-Reaction Extinction Triggered by the Giant Asteroid Impact
The chain-reaction extinction triggered by the giant asteroid impact
Dinosaurs didn’t die from the direct impact of the asteroid alone.
It is believed that the extinction of dinosaurs worldwide, not just those in a small part of the Yucatán Peninsula, was caused by a chain of disasters triggered by the collision.
Specifically, the following four processes are thought to have occurred in succession:
Hit by a Heatwave of Several Thousand Degrees
Centered on the impact site, the surface of the Earth’s crust vaporized and became a gigantic heatwave that engulfed life, including dinosaurs.
This heatwave is believed to have reached as far as present-day Canada.
Widespread Forest Fires Occurred
The heatwave reached into space, and high-temperature dust rained down over a wide area, causing the atmosphere to exceed 1,000 degrees Celsius.
As a result, massive forest fires broke out on the ground, becoming a secondary cause of death for creatures, including dinosaurs, that weren’t directly hit by the initial heatwave.
A Tsunami Several Hundred Meters High Occurred
The asteroid impact created a massive crater measuring 200 km in diameter.
Hours after the collision, seawater flowed into the crater. The backwash from this event created a gigantic tsunami that overwhelmed the dinosaurs.
It’s believed this impact extended beyond the immediate Yucatán Peninsula region, affecting the entire world.
A Prolonged “Nuclear Winter” Arrived
The vast amount of dust thrown into the atmosphere blocked out sunlight for several months, or even years, creating a state similar to a “nuclear winter.”
This caused a rapid drop in temperature and prevented plants from growing. As a result, many dinosaurs lost their food sources and went extinct.
Large creatures like dinosaurs, which required a lot of food, are thought to have gone extinct faster than smaller ones.
It Wasn’t Just the Asteroid Impact? The Compound Factor Theory That Delivered the Final Blow
The compound factor theory that delivered the final blow to extinction
While the giant asteroid impact is undoubtedly the most plausible theory, a growing number of experts believe that it was not the sole cause of extinction.
It is known that large-scale volcanic eruptions in the Deccan Plateau, located in present-day India, continued for thousands of years around the same time as the extinction event.
It is thought that these massive volcanic eruptions also released huge amounts of dust and volcanic gases, which significantly impacted the Earth’s climate.
However, there are arguments that volcanic eruptions alone could not have caused such a global extinction, as it would have required massive, continuous eruptions for thousands of years.
Therefore, it is highly likely that this volcanic activity acted as a “final blow” in addition to the drastic environmental changes caused by the asteroid impact, driving many creatures to extinction.
Other Extinction Theories and the Life That Survived
Other extinction theories and the life that survived
In addition to the asteroid impact and volcanic eruption theories, various other extinction theories have been proposed over the years.
For example, there was the Great Flood Theory, which suggested that a massive comet approached Earth and caused a great flood; the Epidemic Theory, which proposed that a highly fatal virus spread; and theories that blamed excessive global warming or the arrival of an ice age.
However, these theories are not considered plausible today due to a lack of definitive evidence or their inability to explain the extinction of dinosaurs in specific regions.
For example, the Ice Age theory is contradicted by evidence that the climate at the end of the Cretaceous period was actually quite warm.
Conversely, the Global Warming theory cannot explain why dinosaurs in colder regions like the Arctic and Antarctic would have died out.
The Epidemic Theory also faces the counterargument that a single virus would have difficulty spreading across oceans to distant islands.
Some creatures survived this unprecedented mass extinction.
For example, frogs, which were relatively vulnerable in the ecosystem, are believed to have survived these extreme conditions.
Birds, a group of dinosaurs, also survived and continue to thrive today.
On the other hand, many creatures, such as ammonites, went extinct at the end of the Cretaceous period. Research is still ongoing to determine what made the difference between the species that survived and those that perished.
Similarly, in the oceans, the sunlight was blocked, preventing phytoplankton from performing photosynthesis. The creatures that fed on them died out, and gigantic marine reptiles like Elasmosaurus and Mosasaurus, as well as ammonites, disappeared.
New Facts Revealed by the Latest Dinosaur Research
New facts revealed by the latest dinosaur research
Research on the Chicxulub impactor, the primary cause of dinosaur extinction, has advanced remarkably.
Using the latest scientific technology, analyses are revealing the origin and details of the impact.
In 2024, a research team analyzed the chemical composition of ruthenium, a rare element from the meteorite’s remnants. They confirmed that the Chicxulub impactor was a carbonaceous chondrite meteorite formed in the “outer solar system” beyond Jupiter.
This discovery confirmed that the object was not a comet or any other celestial body, strongly supporting the theory that an asteroid collision ended the Cretaceous Period.
It is believed that this asteroid originated from the Baptisina asteroid family, located between Mars and Jupiter, and began its journey toward Earth over 160 million years ago, more than 100 million years before the dinosaurs went extinct.
Additionally, in 2021, a research team led by the University of Tokyo discovered a layer within the Chicxulub Crater containing a high concentration of asteroid-derived elements.
This layer, which includes iridium-rich impact dust, serves as evidence that the dust rained down globally.
Summary
The exact cause of the dinosaur extinction is not yet fully understood.
However, with evidence left in the K-Pg boundary layer and the latest research suggesting multiple compounding factors, the mystery is gradually being unraveled.
