The age of dinosaurs is called Mesozoic. For more than a hundred and fifty million years, dinosaurs ruled the earth. Around 65 million years ago, their reign was ended forever. There are countless theories about the agent of such destruction, from caterpillars eating all the plants leaving nothing for the herbivores. To a sudden decrease in sexual activity, meaning no dinosaur babies were born. And even the detonation of a nearby supernova emitting deadly radiation across the globe. There are many theories about how did dinosaurs die.
Although some of the rocks point to long-term environmental changes like vast global volcanic eruptions that contributed to their decline, some of the evidence in the rocks point to long-term environmental changes. Most of us will have heard that it was a sudden asteroid impact that finished them off.
Scientists say that the rate of animal extinction over the past 200 years is rapidly approaching the rate at which dinosaurs, marine reptiles, and pterosaurs disappeared 66 million years ago. Now, starting with a common ancestor of all tetrapods, amphibians branched off first, then mammals, followed by turtles, lizards, and snakes. And then the group we call archosaurs. It contains crocodilians, pterosaurs, and finally, dinosaurs. Scientists know that 22 types of dinosaurs lived in Hell Creek, including triceratops, tyrannosaurs, and this duck-bill, some 9 meters or 30 feet long. The more complete the skeleton, the easier it is to reconstruct the past.
What killed the dinosaurs?
According to the most common theory, the mass extinction of dinosaurs was triggered by the fall of a huge asteroid or comet. A recent explanation suggests that dinosaurs went extinct after a huge meteorite crashed to earth near the Gulf of Mexico. A big meteorite could have landed with lots of debris and dust and blocked sunlight for an extended period. Due to this, many deadly events started. Without the sun rays, all the plants died, and without the plants, all the plant-eaters died. Traveling 20 times faster than a bullet, a chunk of rock more than twice the size of Mount Everest.
It left behind a crater 150 kilometers wide and more than 30 kilometers deep, spreading a layer of asteroid-rich debris worldwide. The collision itself would have released a billion times more energy than World War II atomic bombs. Because traveling through the vacuum of space, it would have slammed into the Earth’s atmosphere at 80,000 kilometers per hour. As it gets closer to the planet, the earth’s gravitational pull gets stronger, causing the asteroid to accelerate at high speed.
How did dinosaurs die?
As the asteroid encounters the atmosphere, friction turns it into a fireball. It takes just four minutes to cross the Atlantic Ocean on its way towards Mexico. It crushes and superheats the air surrounding it as it travels, turning gas and debris into white-hot plasma at around 20000 degrees Celsius. The asteroid’s trajectory is shallow. It flies in at about a 30-degree angle to the surface. It means that the full brunt of its destructive power will be thrown forward of the impact point. Even before the fireball touches down, its brightness in the sky is unimaginable. The asteroid hits with an explosive force of 100 trillion metric tons.
If the asteroid had crashed into the deep ocean, some of the force would have been absorbed. Instead, it hits the shallow waters of the Gulf of Mexico, which instantly vaporize. In a fraction of a second, the entire asteroid disintegrates into the planet. Earth and rock are hurled skyward at one hundred and sixty thousand kilometers an hour. Behind them, more than 300000 cubic kilometers of the earth’s crust explodes from the ground.
- Eight hundred kilometers from the crash site, the air temperature reaches 300 degrees Celsius. It is so hot that the water and the dinosaur skin boils, escaping in bursts of steam. The fiery blast sucks every drop of moisture from the surrounding vegetation. Anything directly exposed to the blistering heat is burned alive like giant dinosaurs.
The shock wave would have obliterated everything in its path. Fires would have been started across the Americas as molten rock drained from the sky, and vast tsunamis swamped coastal areas worldwide. These immediate effects would have been catastrophic on a scale the earth has never seen since.
- The ash dust and gases like sulfur dioxide thrown into the atmosphere blocked out the Sun, causing freezing temperatures for years afterward. With drastically reduced sunlight, plants couldn’t vote a synthesized, so they died in their masses. With no food, the herbivores soon followed, and the carnivores that relied on the plant-eaters also went hungry and died.
Meanwhile, the sulfur dioxide dissolved into rainwater which turned the oceans inhospitably acidic. At the peak of their dominance, at least 2,000 species of dinosaurs roamed the earth with a wide range of shapes, sizes, and lifestyles. Within 10,000 years, they had all. But they disappeared in a catastrophic mass extinction along with three-quarters of all life on Earth.
A vast mass of pulverized debris would have been blasted into space, some of it orbiting the earth before raining back down. The debris may have blocked out the sun for months. If the asteroid landed in the ocean, the crater might never be found. Even so, there would still be a trail of debris, ejecta, blasted from the crater.
- If an asteroid 10 kilometers across landed in the sea or at the edge of a continent, it would displace incredible amounts of rock and water, causing tsunamis over 100 meters high. These giant waves would have crossed the sea with the speed of a jet, ripping up the seafloor, moving tons of sediment.
Within 1,000 kilometers of the impact, death came quickly. For dinosaurs further away, death may have been delayed, but not for long. Soon, vaporized ejecta and smoke from fires filled the air. Photosynthesis would have stopped. Plants, plant-eaters, and then meat-eaters would have died. This was the asteroid impact hypothesis for how the Mesozoic era ended. When the Alvarez hypothesis was first proposed, it was difficult for many scientists to accept. Now, they hear a proposal that something could come from outer space and rewritten the history of life.
How long did it take for the dinosaurs to die after the asteroid? There is much discussion over the actual kill mechanism and how long that period lasted. It would take one day, one month, or one year depending on the situation and place. Many dinosaurs would have died within weeks. The carnivores who feasted on the herbivores would have died a month or two later.
As that debris came to rest in what, today, is the Brazos River basin. It would have mixed with ejecta falling from the sky. Geologist Jan Smit discovered glass-like beads in K/T boundaries called spherules formed when vaporized rock cools and rains back down. Another key clue was the rock that had been so shocked by the impact. It had crisscrossing bands of dislocated minerals. This was shocked quartz.
Dinosaurs were in good company as ammonites, giant marine reptiles, and 90% of mammals of the time met their end together. Smaller mammals and cold-blooded reptiles needed less food. And a chance adaptation to eating seeds before. The impact was a stroke of luck for a few dinosaurs with plants and mates suddenly gone seeds would have been a more lasting food source. A small group of dinosaurs with beaks were among the few that could eat them. That group made it through the toughest of times and diversified. Once, they had the chance to become the modern dinosaurs that walk among us today. We know them as birds.
Scientists found a layer in rocks called the K-PG boundary. It is rich in Iridium. Iridium isn’t found on the earth’s surface but is abundant in asteroids. Proving that an asteroid crashed the earth. It caused large rocks to blast into the air and fall back as molten rocks.
More reasons about dinosaur’s extinction
Super volcanic eruptions spewed out lava, dust, soot, and various gases into the atmosphere. This triggered a drastic climate change, slowly reducing the dinosaur count. In ancient times natural disasters happen much more often than today. And at some points, they put an end to the whole race of giant reptiles. Significant asteroid impacts on earth could send seismic waves causing supervolcanic eruptions. It helped wipe out the dinosaurs and other creatures.
Some research suggests heavy lava flow from the Deccan Traps in western India may have spewed poisonous levels of carbon dioxide and sulfur into the atmosphere and cost the extinction. Several paleontologists say they did suffer from diseases like parasites, fever-specific allergic reactions, and bone infections. Dinosaurs and mammals evolved during a similar period. Maybe mammals destroyed or ate the eggs of dinosaurs, driving them to extinction.
Several paleontologists suggest an ice age could have frozen water, and dinosaurs were unable to survive. They slowly died out. But scientists have no evidence of an ice age occurring during the life of the dinosaurs. A team from Holland and Italy discovered fossilized cold water plankton that dates back 65 million years in an area previously warm in Tunisia. The fossils indicate that something suddenly made the water cold enough to support the tiny creatures.
A meteor strike may have produced vast quantities of sulfate particles, such as those blown into the atmosphere during a volcanic eruption. And these particles would have shielded the Earth’s surface from sunlight. The decrease in solar energy ultimately would have caused a prolonged cold spell, called impact winter. So the ice age may have been the method of extinction.
The supervolcano theory argues that the asteroid impact was merely a prelude to many volcanic eruptions in India’s area named the Deccan Traps. Researchers have discovered four separate waves of explosions that released vast clouds of sulfur dioxide into the air, bringing acid rain showers in turn. These waves are estimated to have occurred around 65 million years ago. Geophysicists argue that the asteroid impact could not have kicked up enough dust to cause global climate change. The supervolcanoes may have dispersed 150 billion tonnes of sulfur dioxide with each pulse.
Geologist Gerta Keller states that after the initial pulse, most species would have disappeared. And by the fourth flow, the extinction would have been complete. The supervolcano theory is the biggest challenger to the classic impact theory.
Food chain imbalances
This led to the starvation of the dinosaurs and may cost their death. Most paleontologists believe that birds and crocodiles are the only surviving dinosaurs. So they aren’t extinct because their descendants are still living, but there is no solid evidence of this. Disease and starvation are other theories. Some scientists believed a great plague decimated the dinosaur population. And then spread to the animals that feasted on their carcasses. Starvation was another possibility: Large dinosaurs required vast amounts of food and could have stripped bare all the vegetation in their habitat.
What happened after the dinosaurs died?
In 2014 when the scientists first visited coral bluffs, a fossil site near Colorado Springs, they were not impressed. After finding absolutely nothing new there, the researchers decided to come back a few months later. That’s when they made a historic discovery. Mellor and License found that this place has a unique sequence of remains of different animals and plants which lived on earth during the first million years after the death of the dinosaurs. Scientists had to pay more attention to the so-called concretions. These are clusters of rocks that formed around organic materials, including bones.
When Licen and Miller turned their attention to these geological formations, everything started coming along. Scientists found entire skulls and, in some cases, these skeletons of mammals and, right next to them, fossilized plants. Researchers have excavated about 7,000 fossils which lined up in chronological sequence. The ash layers played a great role in this from nearby volcanoes found by the scientists.
The fact is that volcanic ash contains radioactive minerals that store information about the changes in the earth’s magnetic fields. Thus the discovery became something like a natural clock for scientists. They told geologists about the rapid changes in the ecosystem since the fall of the asteroid 66 million years ago.
The first million years
As one might expect the first million years after the asteroid, the planet recovered from the catastrophe it had to ensure. Not surprisingly, since about 75% of all fauna and 50% of all flora died, they quickly recovered. At first, they were pretty primitive plants and animals on the planet. Nevertheless, soon the flora began to become more and more diversified.
While tiny mammals started to increase in size following the development of plants, slowly is an example of how mammal populations change dramatically and rapidly at the time. It’s known that only small animals weighing no more than half a kilogram survived the fall of the asteroid.
After 1000 years
It is possible to establish that mammals the size of a raccoon began to appear on earth a hundred thousand years later. That’s about five or six kilograms of waste and ferns that were replaced by palm trees. By the end of the next 200,000 years, it is known as the palm period. Walnut trees began to appear on earth. At the same time, mammalian diversity on the planet increased threefold. They were now species with a nut-based diet. Some of the animals that emerged at that time already weighed up to 25 kilograms.
After 700 years
Seven hundred years after the great extinction, they were already leguminous plants rich in protein on earth. This influenced the development of fauna. Mammals weighed up to 50 kilograms. A predatory animal that looks like a wolf or a bear with hooves instead of claws. According to scientists, the temperature of the atmosphere increased by five degrees Celsius. The higher it rose, the more developed and diverse the plants and animals inhabiting the planet became.
But why is this research necessary? It proves that the dinosaurs’ extinction was indeed primarily caused by the fall of a specific celestial body. And reconstructs in detail the chronology of the world’s rebirth after this catastrophe. Scientists have concluded that the extinction of giant animals, especially dinosaurs, ultimately positively impacted biodiversity. If it hadn’t been for the asteroid disaster, perhaps our planet would never have been home to so many different mammals. Thousand years after the asteroid, the number of plants and animals on the earth was the same as before.
Three hundred thousand years later, the planet was more diverse than before the catastrophe. And 700 thousand years later, completely new species of animals appeared. After the fall of the asteroid, their size took mammals ten million years to finally reach the size of modern bison or antelopes. Nature indeed has amazing abilities for self-regeneration, but these processes take hundreds of thousands of years.
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Langer, Max C.; Ferigolo, Jorge. “The Late Triassic dinosauromorph Sacisaurus agudoensis (Caturrita Formation; Rio Grande do Sul, Brazil): anatomy and affinities.” Geological Society, London, Special Publications.
Cabreira, S.F.; Kellner, A.W.A.; “A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet.” Current Biology.
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