Why And How Did Dinosaurs Disappear?
Written by Serene Joshua, contributing writer
The main, and most accepted, theory is that a meteor from outer space crashed into the Earth, which caused a deep impact and wiped out a large amount of plant and animal life.
Written by Serene Joshua, contributing writer
We all know about dinosaurs, the giant and sometimes terrifying creatures that once walked the Earth millions of years ago, but where did they disappear to, and how exactly did that happen?
Let’s find out…
How did dinosaurs disappear?
It is believed that dinosaurs became extinct about 66 million years ago.
How did it happen?
So, there are many theories as to how these gigantic creatures were wiped out, but these are still just theories and no one knows for certain how these happened.
Scientists have used whatever evidence they could find through studying fossils, archaeology, climate patterns, etc., and have pieced together different theories to explain their disappearance.
Experts also believe that this happened at the end of, what is known as the Cretaceous period – about 66 million years ago
Where did the dinosaurs go?
Theory 1 – A meteor hit the Earth
The main, and most accepted, theory is that a meteor or asteroid from outer space crashed into the Earth, which caused a deep impact and wiped out a large amount of plant and animal life.
This is called the Alvarez theory named after the scientists who established this explanation.
In 1980 two scientists who were father and son – Luis and Walter came up with the Alvarez theory that proposed that a meteor as large as a mountain had hit the Earth about 66 million years ago.
This impact resulted in large amounts of dust, gas, tidal waves, fires, and other particles that changed the climate of the Earth at the time. This debris didn’t stay in the air for a short time, but for years!
Alvarez also pointed out that the impact caused debris and soot to travel around the world and reduced the amount of sunlight that the Earth received and negatively affected plant growth.
This hindrance of sunlight affected plant growth and did not leave much for the herbivores to eat and causing them to die out, which in turn caused a lack of animals for the carnivore species to eat. This caused the ecosystem to fall apart!
This drastically changed the Earth’s environment and many species didn’t survive.
How did they know this?
The Alvarez’s have pretty good evidence to support the meteor theory that they found in Mexico!
They found the crater – the site where an asteroid crashed, known as the Chicxulub crater on the Yucatan Peninsula in Mexico around the time that dinosaurs went extinct (66 million years ago) and this crater is about 10 to 15 kilometers wide!
This explanation is also supported by the fact that Iridium, an extra-terrestrial metal found on meteoroids, is usually present in all layers of rock covering dinosaur fossils.
Theory 2 – Volcanoes
Another theory that attempts to explain this mass extinction is one that involves volcanoes in India – volcanoes that led to the creation of what’s called the Deccan Traps.
What are the Deccan Traps and what do they have to do with Dinosaur extinction?
Deccan Traps are a massive plateau in western India, which were formed as a result of molten lava solidifying and turning into rock. This is said to have happened around 66 million years ago, when there was massive volcanic eruptions and magma from inside the Earth erupted to the surface.
These eruptions, say historians, has catastrophic impact on the environment – like large amounts of carbon dioxide being released into the atmosphere, rise in levels of other toxic gases (like sulfur and chlorine). This led to greenhouse effect and also acid rain.
Some historians believe that these Deccan Traps eruptions caused climate change, mainly due to the greenhouse effect – as this happened around the same time as the dinosaurs went extinct. They believe that the volcanic eruptions and their impact were a factor in the extinction of dinosaurs – even before a meteor hit the Earth.
One caused the other?
Some theories suggest that the Chicxulub impact and the Deccan trap’s volcanic activity happened around the same time and that the asteroid may have caused the volcanic eruptions.
Some believe the opposite explanation, that volcanic eruptions weakened the ecosystem which made it vulnerable to a meteor crash.
Theory 3 – gradual extinction
A third theory suggests that dinosaurs didn’t disappear suddenly, but that the decline was slower and more gradual in pace.
Scientists who support this theory suggest that there were long-term climate changes that were present for a long period of time which affected the number of species way before an asteroid impact or volcanoes.
This also most particularly affected Saurischian and Ornithischian dinosaurs- two species of large dinosaurs who could not adapt to these changes.
This has been evidenced through studies of fossils, which shows that dinosaurs were slowly declining over a period of a million years.
What if dinosaurs were still alive?
Well, technically dinosaurs do still exist among us!
Birds originated in the Jurassic era, which is when land dinosaurs originated as well, and having the advantage of being able to fly, they survived most disasters on land.
Although the birds we see today are small they all evolved from large flying dinosaurs.
One prediction is that we would not have been around if dinosaurs had. Due to their dominance and threat, a lot of mammals including humans simply would not have evolved like we are today as they would not have survived the reign of flesh-eating dinosaurs.
In the case of Herbivores, these dinosaurs would have consumed a large amount of the plant diversity we have today and plant life would not be able to keep up with their diet causing most plant life and grasslands to die out.
The way that dinosaurs look would have changed drastically as well. The dinosaurs we know of in books and movies would have evolved to look very different to adapt to changing landscapes and climate of the earth as well.
As mentioned before, these theories are still just theories and scientists are constantly trying to improve and find more evidence for how these creatures disappeared.
So… which theory do you think is more possible, asteroids? Volcanoes? Both?
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