A wealth of fossil bones, teeth, trackways, and other concrete evidence has proven that the dinosaurs ruled the Earth for at least 230 million years. However, no sign of dinosaur remains has been discovered in rocks younger than 66 million years. But the question remains, why did dinosaurs go extinct?
At that point, as the Cretaceous epoch gave way to the Paleogene, it appears that all non-avian dinosaurs vanished.
They were followed by deadly marine reptiles such as mosasaurs, ichthyosaurs, and plesiosaurs, as well as all pterosaurs, which were flying reptiles. Much of the planet’s ancient woods appear to have burned off.
While some mammals, birds, small reptiles, fish, and amphibians survived, the variety of the remaining life-forms plummeted.
Why Did Dinosaurs Go Extinct
Around 75% of all species on Earth, including dinosaurs, died off at the same period. So, how did a rock crashing into the coast of Central America produce a global mass extinction?
‘The asteroid hit at great velocity and effectively vaporized,’ Paul explains. It created a massive crater, causing catastrophic devastation in the surrounding area. A massive blast wave and heatwave erupted, blasting massive amounts of material into the skies.
‘It dispersed soot all over the world. It did not entirely obscure the Sun, but it did reduce the amount of light reaching the Earth’s surface. As a result, it had an effect on plant growth.’
This cascaded up the food chain, leading the ecology to collapse. The decline in plant life had a significant influence on herbivores’ ability to survive, which meant that carnivores would have suffered as well due to a lack of food.
Breeding seasons would have been shorter, and conditions would have been harsher. All living things, both on land and in the sea, would have been affected in some way.
‘There has been a lot of debate over the actual kill mechanism and how long that period lasted. There are still many unknowns. But it was a tremendous catastrophe that affected all life on Earth, from bacteria to dinosaurs,’ Paul explains.
The list of casualties is lengthy. Ammonites, minuscule plankton, and other organisms, and large marine reptiles are among them
Did an Asteroid Kill the Dinosaurs?
Nobel Prize-winning physicist Luis Walter Alvarez and his geologist son Walter proposed a theory in 1980 that a massive asteroid crashing with Earth generated a historic layer of iridium-rich clay.
The immediate devastation in the near neighborhood, as well as the global subsequent consequences of an asteroid hit, were thought to be the reasons for the dinosaurs’ extinction.
Asteroids are massive rocky bodies that revolve around the Sun. They range in size from a few meters to hundreds of meters. A meteorite is any asteroid fragment that survives its impact with Earth.
The Alvarez hypothesis was initially controversial, but it is now the most widely recognized idea for the Mesozoic extinction.
How Big Was the Asteroid That Killed the Dinosaurs?
‘An asteroid collision is supported by pretty excellent evidence since we’ve located the crater,’ Paul explains. It’s currently mostly submerged on the ocean floor off the coast of Mexico.
It is the same age as the extinction of non-bird dinosaurs, which can be found in rock records all throughout the world.’
The impact site, known as the Chicxulub crater, is located on Mexico’s Yucatán Peninsula.
The asteroid is considered to have been between 10 and 15 kilometers broad, but the collision created a significantly wider crater, 150 kilometers in diameter. It is the world’s second-largest crater.
large tidal waves washed over areas of the American continents as a result of the dinosaur-killing collision, which sent large volumes of debris into the air. There is also evidence of significant fires from that time period.
It was long considered that non-bird dinosaurs perished out 65 million years ago.
‘The dating of those layers of clay around the planet is pretty accurate – it’s estimated to be within a couple of thousands of years,’ Paul says.
‘Recent redating has refined it, and the dinosaur extinction date is 66.0 million years ago,’ says the author.
The Deccan Traps and global climate change
The asteroid cannot be held entirely responsible. Earth was undergoing climate change at the time of the crash landing. This was making life on our planet more difficult.
There was significant volcanic activity in what is now central India, which, while unconnected to the asteroid impact, was producing issues of its own. The lava outcrop that resulted is today known as the Deccan Traps.
‘For two million years, there was a massive amount of volcanic activity going on, blasting gasses into the atmosphere and having a significant impact on world temperature,’ Paul adds.
‘Longer-term alterations occurred as well. The continents were migrating about and splitting apart, creating larger oceans that affected ocean and atmospheric patterns all throughout the earth. This had a significant impact on the climate and vegetation.’
The final non-bird dinosaurs lived throughout a period of environmental change, some of which had begun millions of years before they became extinct. The asteroid delivered the killing blow.
Could the Dinosaurs have Survived?
According to studies, if the impact had occurred somewhere else on the globe, the fate of life on Earth could have been drastically different.
If the asteroid had fallen just a few minutes later, it would have crashed in deeper water, causing less rock to vaporize and rise, blocking off the Sun’s light and warmth. This would have reduced the likelihood of a cataclysmic extinction.
But, if the dinosaurs’ reign hadn’t been cut short by an asteroid, Paul believes we might still see some (other than birds) around today.
‘I believe some of them are still alive. We don’t know much about the last 10 million years of their reign, and what we do know is limited to western North America. There is a very excellent record of the final non-bird dinosaurs, such as Tyrannosaurus and Triceratops.
‘From that section of the planet, it appears that dinosaurs are thriving in terms of numbers, but the variety of dinosaurs is decreasing. We don’t know if that pattern was repeated elsewhere; it’s still a mystery.’
If it hadn’t been for the asteroid, dinosaurs would have persisted a bit longer, albeit with modern birds, mammals, and reptiles emerging, they might not have ruled as much.
Final Thoughts
While these theories provide plausible reasons for dinosaur extinction, the exact order of events and the proportional relevance of each element are still being researched and debated.
The Cretaceous extinction catastrophe was a watershed moment in Earth’s history, clearing the way for the advent of animals and, eventually, the formation of the diversified ecosystems we witness today.
READ ALSO!!!