Mystery of Dinosaurs | How Did They Become Extinct? | Dhruv Rathee

Hello, friends! About 100 million years ago, Earth looked completely different. With no humans, some scary animals were ruling over this planet.

Dinosaurs. Dinosaurs so big, that they were taller than buildings. With jaws so strong, that they could have crushed your bones within a second.

They were so fast, that they ran at around the speed of 90km/hr. They were truly fear-arousing creatures. They ruled over Earth for more than 170 million years.

But then one day, something happened, That completely wiped them off the planet. What happened exactly? And how?

Come, let’s understand this in today’s video. “As it gets closer to the planet, Earth’s gravitational pull gets stronger. ” “They now can’t see what’s headed their way.

” Friends, the word ‘Dinosaur’ originated from Greek. From the words Denios and Sauros. Denios means Terrible.

And Sauros means Lizard. A terrible lizard. This is the literal meaning of the word Dinosaur.

The word was used for the first time in 1841. When dinosaur fossil was discovered for the first time. Richard Owen, a British scientist used the word dinosaur.

Back then, people did not know much about dinosaurs or their appearance. So the initial drawings of how dinosaurs might have looked Are vastly different from what we know now. Megalosaurus was one of the first fossils to be discovered.

Look at the initial drawings of it. Decades later, as the researchers discovered more information about them, The drawings were modified. Trying to make them more realistic.

So the depictions look like this now. Today, more than 10,000 dinosaur fossils have been unearthed by palaeontologists worldwide, And more than 900 distinct have been identified. You might be excited by the prospect of discovering more fossils.

But interestingly, from 2003 to 2022, On average, each year, about 45 new species of dinosaurs have been identified. The work of palaeontologists is far from over. Look at the photos of the new species of dinosaurs discovered last year.

Of them, this is a bizarre dinosaur discovered in Chile, with a weapon that looks like a blade on its tail, And a beak for a mouth, It was named Stegouros Elengassen. Overall, we know a lot about dinosaurs today. But come, let’s start this story at the beginning.

Let’s dive into the past. Millions of years ago. Scientists estimate that the first dinosaur emerged about 230-240 million years.

Because the oldest dinosaur fossils that we have found till now Is from 231. 4 million years ago in Africa. Back then, Earth was much different than it is today.

The continents that you see now, Asia, Africa, Australia, Europe, All continents were joined together. There was only one supercontinent. That we call Pangaea.

Scientists believe that Pangaea looked somewhat like this. You can even see the placement of the continents that we know. Then the climate of Earth was dry and arid with only a little rain.

This time period has been named the Triassic Period. The era when the dinosaurs had started emerging. Dinosaurs were slowly populating the Earth due to evolution.

The dinosaurs of this era, aren’t anything like the ones you imagine. They were quite small in size. The common dinosaurs of the time, Were generally around 2 meters long only.

For example, Eoraptor, was a dinosaur that existed in that period. In fact, this dinosaur is known as the ancestor of other dinosaurs. The dominant animals of the era Were giant reptiles.

Some of these reptiles looked cute Like this one, that’s believed to be the ancestor of all turtles. With time, Earth started changing. 201 million years ago, the Triassic period ended.

When Earth’s climate changed suddenly. The Pangaea started breaking apart. Although I am using the word ‘suddenly’ It didn’t happen in a day or two, It was relatively sudden.

In the time scale of millions of years, It happened gradually over thousands of years. Cracks appeared in the supercontinent. Large-scale volcanic explosions took place on and around the cracks.

Due to the numerous volcanic eruptions, a large amount of carbon dioxide and sulphur dioxide was released into the atmosphere. This caused intense global warming. When the sulphur dioxides and aerosols entered the atmosphere, It blocked the sunlight and caused some cooling.

Acidification of the oceans started When the carbon dioxide and sulphur dioxide mixed with the water. The acidity of the ocean water increased. The climate was changing rapidly.

And survival became difficult for the animals that existed. Most reptiles and other species back then were cold-blooded animals. They couldn’t withstand the temperature changes.

But the dinosaurs were warm-blooded like humans. It was easier for the dinosaurs to tolerate the temperature changes. The volcanic eruptions and climate change continued for about 600,000 years.

Due to this, almost all the other species became extinct. The only animals remaining on Earth were the dinosaurs, crocodiles, turtles, and early mammals. This event is known as the Triassic-Jurassic Extinction Event.

As I said, after this, the Triassic period ended. And the Jurassic period began. If this sounds like a familiar name, This is the inspiration for the name of the Jurassic Park films.

The word Jurassic refers to this Jurassic Period. The Jurassic period lasted from 201 million ago to 145 million years ago. During this time, dinosaurs emerged as the most dominant species on the planet.

Due to evolution, some of them became quite large in size. Like some of the earliest Titanosaurus. They lived around 160 million years ago.

Each of them weighed up to 15,000 kg. And could be up to 15 metres long. Some other iconic dinosaurs of the time were During the Jurassic period, some dinosaurs evolved to fly.

One of the first feathered dinosaurs was Archaeopteryx. It looked somewhat like this. At this time, the Pangaea supercontinent, Was divided into two.

Two smaller supercontinents. We named them Laurasia and Gondwanaland. Friends, due to the Jurassic Park films, The Jurassic period is the most widely known.

But it was the next period when dinosaurs truly flourished. The Cretaceous period. Because at this time, we saw an explosion in the diversity of dinosaurs.

Several new species of dinosaurs evolved. T-Rex, perhaps, the most famous dinosaur to be shown in films. Existed in the Cretaceous period.

It reached peak dominance only at the end of the Cretaceous period. Around 65-68 million years ago. Though this is debated among researchers, Most scientists believe that T-Rex didn’t exist in the Jurassic period.

It’s quite ironic that in the film ‘Jurassic’ Park, T-Rex is used for their logo. The Cretaceous period was the longest time in the era of dinosaurs. Starting around 145 million years ago It lasted til 65 million years ago.

The 2 supercontinents, Laurasia and Gondwanaland, Started breaking up, And the structure of the continents, Looked similar to what we see today. Several flowering plants evolved at this time. Several flowering plants evolved around this time.

And the average temperature of the Earth was warmer than it was in the past. Sea levels were quite high, And almost all kinds of dinosaurs that you can imagine, Existed during this period. Raptors, Armored Dinosaurs, Giant herbivorous dinosaurs, Dangerous carnivorous dinosaurs.

Titanosaurus, one of the largest land animals. Argentinosaurus, which could weigh up to 77 tonnes. And T-Rex that could be up to 40 feet long Believed to be the apex predator of its time.

It had the strongest and most powerful jaws compared to any other animal. A fun fact, the evolution of grass began only 70 million years ago. In the story that I have been telling you, Don’t imagine a grass-filled Earth.

There were other kinds of plants. T-Rex and Triceratops evolved 68 million years ago, Do you know what this means? We are closer to the dinosaur T-Rex Than it was to the Jurassic Period.

Since there's 80 million years between the Jurassic period and the T-Rex evolution. But only 68 million years between us and T-Rex. Another interesting dinosaur that existed then Were the Ornithomimids.

They looked like ostriches, They were among the fastest dinosaurs. They could run at the speed of 80 km/hr. And in terms of flying, instead of running, The largest flying dinosaur was Quetzalcoatlus, Had a wingspan of 10-11 meters.

As you can see, this was the most prosperous period for dinosaurs. The climate was favouring them, new species were evolving, And there were no other animal species to compete with them. They were simply ruling over Earth.

Everything was going well, Until one day, something happened that completely wiped off dinosaurs from Earth forever. A large asteroid, with a diameter of roughly 10-15 km, Came hurling towards Earth and crashed into it. This happened 66 million years ago.

And this asteroid strike ended the Cretaceous period. The speed of the asteroid was 30 km per second. 150 times faster than a jet airliner.

Specifically speaking, it hit the Yucatan Peninsula in Mexico. The same place where millions of years later, the Mayan tribe emerged. And built historical wonders like Chichen Itza.

I explored the Yucatan Peninsula in my vlogs as well. You can watch the vlogs of this place if you want to. The link will be in the description.

When the asteroid hit Earth, It created a large crater. With a diameter of 180 km, Due to its impact, energy was released at such a speed, That could be released with 100 teratonnes of TNT. [100 trillion tonne or 100,000 trillion kg] If you compare this with the atomic bombs dropped on Hiroshima and Nagasaki, The asteroid produced 1 billion times their energy.

This was such a big impact, That everything around it disintegrated in the blink of an eye. The impact threw a lot of soil into the air, The land heated up, And the hot dust rained over the other areas. The global temperatures rose by several degrees for hours.

All animals within thousands of kilometres of range from here, Were cooked alive by the sheer heat. It’s believed that only small animals could survive the impact of this initial blast. Because they found underground shelter.

Or they hid underwater, in caves, or in large tree trunks. But this was only the initial impact. This was followed by shock waves, heat pulses, Wildfires in the forests for thousands of kilometres.

And big tsunamis. It’s speculated that there would have been an immediate tsunami with a 2 km tall wave. Can you even imagine a 2 km tall tsunami wave?

Volcanic eruptions started once again. Acid rain fell and earthquakes occurred. The short-term effects were quite deadly.

But you would think that, on the other side of the Earth, that wasn’t hit, Animals could have perhaps survived there. But the long-term consequences were even deadlier. The dust particles in the air Blocked sunlight for the next year all around the planet.

The planet went into a nuclear winter. The temperature dropped drastically. It’s estimated that for the next 3 years, The earth was at freezing temperatures.

It killed many plants and animals. Since the sunlight was blocked for 1 year, It was impossible for plants to use photosynthesis. The plants died.

With dying plants, the herbivorous animals had nothing to eat and they died out. Even the carnivorous animals were left with nothing to eat, and they too died out. A chain reaction was caused.

The only animals safe of these consequences, Were small omnivorous animals. Such as mammals, lizards, turtles, and some birds. These animals could survive because They could survive as scavengers as well.

The dead dinosaurs, fungus, decaying plant matter, These were the food that kept them alive. These small creatures could survive for a significant amount of time. The impact of the asteroid had destroyed carbonate rocks too.

This caused carbon and sulphur to be released into the atmosphere once again, And for the next several thousand years, The sunlight was significantly reduced. That was not at the normal levels. Apart from this, acid rain continued for thousands of years.

When the nuclear winter ended, The dust in the atmosphere settled down, Sunlight reached the planet once again. But the problem was that a large quantity of carbon dioxide was already released into the atmosphere. This caused intense global warming.

Think about this friends, One asteroid changed earth’s history for the next thousands of years. If we ignore a few exceptions, No 4-legged creature weighing more than 25 kg, Could survive this event. All terrestrial dinosaurs went extinct.

And with them, the plant and animal species once thriving on Earth, More than 75% of it went extinct. Friends, at this point, the Cretaceous period ended. And the next era began.

The Paleogene period. Friends, it wasn’t as if everything had ended. This event was like an opportunity for the rest of the animal species.

The rulers of the planet, Dinosaurs, were no more. So it was an opportunity for the other animals to come up and rule. Humans should be thankful for this asteroid Because this awarded a good opportunity for the evolution of mammals, After the extinction of dinosaurs.

The gap in the food chain left by the dinosaurs, Was filled in by several mammals. It was in this period that we saw the evolution of horses, whales, bats, and primates. Several snakes and smaller lizards started emerging in this period.

The only group of dinosaurs that could survive, were the flying dinosaurs. Gradually they evolved and became the birds that we now know. Yup, you read that right.

The birds that you see flying around today, The flying dinosaurs are their ancestors. Most studies have confirmed that, Birds belong to the same family as dinosaurs. Specifically speaking, ancestry is shared most closely by Chickens and ostriches.

This is why people might say that The closest living relative of T-Rex, a dangerous dinosaur, Is a chicken. You might have a question about the asteroid. How did we find out, The spot where the asteroid crashed?

And that it crashed 66 million years ago? How did we figure out the date? This is evidenced by a rare mineral.

Iridium. Scientists found that at a few places on Earth, We have a high concentration of iridium on the ground. But when the geologists analysed Earth, they found that it is a very rare mineral on Earth.

Despite that, it is so abundant on our ground. How could this be? This could happen because comets and asteroids, Have a high concentration of iridium.

And when scientists put the iridium into carbon dating, They found that the iridium layer that we find, Is 66 million years old. This could happen only when the asteroid hit the planet And in the pursuing blast, this mineral spread all around. You might also wonder that since the asteroid had an impact this big, We should be able to see the crater it left on Earth.

Well, you are not wrong. But an event that occurred so long ago, 66 million years ago, Might not look like you’d imagine it to be. Because since then, the continents have been relentlessly shifting.

The crater of this asteroid is hidden in the Yucatan Peninsula. But several digging expeditions were conducted, That proved that it had actually happened, And the exact location it happened. If you look at the map, this is the exact location.

Half of it is submerged under the sea, And the other half is on land. A real-world impact that we can still see Are the cenotes in this Mexican area. These beautiful sinkholes show a pattern.

The crater formed by the asteroid, The cenotes can be found in a ring formation around the crater. Nowadays they are famous tourist attractions. You can go swimming in these cenotes.

And overall, these cenotes, form the world’s largest underground cave system. After hearing this astounding story of this asteroid strike, You might be thinking about what would happen If such an asteroid comes and hits the planet now? Will humans go extinct?

This is definitely a threat. The asteroids that might hit Earth in the foreseeable future, Are known as Near Earth Asteroids, NASA and other space agencies are continuously tracking all near-earth asteroids To compute their path and if and when they will collide with Earth. As of April 2022, more than 28,000 near earth asteroids have been identified.

Of which more than 800 have a diameter of 1 km or more. This is a scary number. So many asteroids that may potentially collide with Earth.

But today, you don’t need to be scared about this. Because scientific calculations are so advanced that We can clearly predict their path, And can calculate the exact location of the impact. We can even estimate the chances of it actually colliding with Earth.

And if they are indeed on a path of collision, What can we do to stop it? This was the idea behind NASA’s DART space mission launched in 2021. Double Asteroid Redirection Test.

They planned to have a spacecraft collide with an asteroid, So that the path of the asteroid can be altered. And if, in future, there’s an asteroid about to collide with Earth, We can alter its path. This might sound like science fiction.

But this idea was already successful. In September 2022, a test was launched On an asteroid that was not on the path towards Earth, NASA sent a spacecraft to it, The spacecraft collided with the asteroid, and its path was altered. If they could successfully do it to that asteroid, It can be done to any asteroid on the way to Earth in future.

But that doesn’t mean that there’s no danger at all. Humans are the danger here. The asteroid strike that killed the dinosaurs, Is known as the 5th extinction event in Earth’s history.

After this, scientists believe that the 6th extinction event, Has already begun. This isn’t due to any volcano or asteroid, It is caused by humans. This is named the Holocene Extinction Event.

Over the last 100-200 years, We have seen the loss of biodiversity at an unprecedented scale. Animals and plant species are rapidly going extinct due to humans, Biologists agree that it is a mass extinction. Deforestation by humans Pollution in oceans and atmosphere, Due to this, the normal rate is more than 100-1,000 times more than the current rate of extinction.

Habitats of the animals that exist now, Are being destroyed. Thousands of mammals, birds, reptiles, and amphibians, Are now in the endangered category Or have already gone extinct due to humans. To stop this destruction, a United Nations Convention on Biological Diversity Meeting was held in Japan in 2010.

20 biodiversity targets were set To be achieved by 2020. Unfortunately, only 6 of those have been partially achieved. In January 2020, a new Paris-style plan was set to prevent biodiversity and ecosystem collapse.

The deadline was set as 2030. Its purpose is to ensure that 30% of the land and oceans are given the status of being protected. To reduce pollution by at least 50%.

Scientists have proposed that the extinctions taking place, Need to be limited to 20 per year or fewer. We’ll have to see how many targets can be met. But one thing is certain that it is important to do these, Because if plants and animals species go extinct now In the same way, it happened in the previous extinction events, Perhaps it wouldn’t be possible for humans to survive.

It’s interesting to note that As per calculations, humans originated merely 300,000 years ago in Africa. As per the data. Compared to the dinosaurs, Who were the dominant species on Earth for 174 million years.

We’ve been here for only 300,000 years, While they lived for 174 million years, 600 times longer than humans. What do you think? Can humans beat the record set by dinosaurs?

Or will humans go extinct before they’re 1 million years old? Comment below with your opinion. Obviously, the right answer will depend on, Our collective efforts to save this planet.

If you liked this video, click here, to watch more such videos on historical topics and science-related topics. And I’ll see you in the next video. Thank you very much!