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  • You probably already have a vague notion of stegosaurus and other dinosaurs running amuck

  • and being trampled by roaring, panicked T-Rexs while fiery asteroids rain down from the heavens

  • and burn them all to death.

  • Well, yes, some dinosaurs were killed by asteroids, but the mass extinction of the dinosaurs is

  • a little more complicated than that.

  • First, it's thought that dinosaurs roamed the earth for about 200 million years.

  • It's likely that many types of dinosaurs lived and died out long before extinction

  • ended them for good.

  • There are three consecutive geologic time periods within the Mesozoic Era during which

  • the dinosaurs lived; the Triassic, Jurassic, and Cretaceous Periods.

  • Different dinosaur species lived during each of these three periods.

  • The Jurassic period dinosaur the Stegosaurus already had been extinct for approximately

  • 80 million years before the Cretaceous period dinosaur Tyrannosaurus came to be.

  • So no, Tyrannosaurus never trampled a Stegosaurus while running from asteroids.

  • At the end of the Cretaceous period there was a mass extinction where around 75% of

  • life on earth was suddenly wiped out.

  • This included everything from fish, to trees to T-rexs.

  • This event is called the CretaceousTertiary or K–T extinction which occurred 66 million

  • years ago.

  • The extinction is apparent in the geological record; no dinosaur remains have been found

  • in rocks younger than 66 million years.

  • Try to wrap your mind around this crazy fact--the time period separating the existence of Stegosaurus

  • and Tyrannosaurus (80 million years) is greater than the time period separating Tyrannosaurus

  • and modern humanity or you (66 million years).

  • For many years, paleontologists thought the mass die-off was most likely caused by climate

  • change which disrupted the dinosaurs's food supply.

  • In 1980, nuclear physicist Luis Alverez and his son geologist Walter Alvarez were conducting

  • research in Italy.

  • They discovered a layer of iridium-rich clay in the K–Pg boundary which marks the end

  • of the Cretaceous Period.

  • This layer has about 200 more times the amount of iridium in it compared to the strata formed

  • before and after.

  • This was significant because iridium is rare on earth, but much more common in space.

  • The Alvarezes hypothesised that the iridium was deposited because of an astronomical event

  • where a large meteor, comet or asteroid collided with the earth.

  • Furthermore, this enormous impact could have caused the extinction of the dinosaurs.

  • In 1991, a massive meteor crater was discovered on the edge of the Yucatán Peninsula, extending

  • into the Gulf of Mexico.

  • The Chicxulub Crater, which was named for a nearby village, is 112 miles in diameter

  • (180 km).

  • For many in the scientific community, this crater confirms the Alvarez hypothesis--it

  • has become the widely accepted theory for the extinction of non avian dinosaurs.

  • Researchers believe that around 66 million years ago, an enormous asteroid somewhere

  • between 6-9 miles in diameter (9.6-14.5 km) struck the earth at 40,000 miles per hour

  • (64,373 kph).

  • The impact released 2 million times more energy than the biggest nuclear bomb.

  • But even with such a massive impact, how could that kill the majority of life on earth, including

  • dinosaurs thousands of miles from the impact zone?

  • As the massive asteroid streaked across the sky, chucks may have broken off, igniting

  • wildfires wherever they landed.

  • When the asteroid slammed into the Yucatan peninsula, it bore several miles down into

  • the seafloor creating a bubbling cauldron of melting rock and super hot gases.

  • This created an effect similar to a volcanic plume-heated seawater and lava were ejected

  • mountain-high into the atmosphere.

  • The plume quickly collapsed back into the sea where it cooled, altering temperature,

  • currents and the land formation.

  • The asteroid also vaporized sulfur rich rocks, releasing an estimated 357 billion tons (325

  • billion metric tons) of sulfur gas into the air.

  • Some of the gas quickly fell as acid rain, acidifying the ocean and killing off most

  • marine life.

  • At the same time virtually all life within around 1,000 miles (1,609 km) of the impact

  • was incinerated due to the heat.

  • The impact also created a shock wave and displaced ocean water, forming a towering tsunami that

  • might have traveled as far inland as present-day Illinois before receding.

  • The particles of dust and gases tossed into the atmosphere blocked the sun, plunging the

  • earth into darkness and cold temperatures.

  • The lack of sunlight reaching plants caused a massive collapse of the ecosystem throughout

  • the whole food chain.

  • The majority of plants and trees rapidly died off.

  • Shortly thereafter, herbivores starved to death because they had nothing to eat.

  • The carnivorous dinosaurs lasted a little longer, since they could feast on the dead

  • and dying herbivores.

  • But within a month or so of the asteroid impact, most of the life on earth had died.

  • Only small, scavenging animals that were quickly able to adapt survived.

  • These animals, which most likely subsisted on insects and seeds, burrowed into the ground

  • to escape the cold.

  • Over time these creatures evolved into modern reptiles and birds.

  • So technically dinosaurs never fully went extinct, they just became canaries and chickens.

  • Could an astronomical event destroy life as we know it on earth?

  • Check out our answer here:

  • If a crocodile fought a great white shark, who would win?

  • Or are they evenly matched?

  • See the victor here:

You probably already have a vague notion of stegosaurus and other dinosaurs running amuck

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B2 extinction cretaceous asteroid earth tyrannosaurus iridium

How Did the Dinosaurs Die?

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    林宜悉 posted on 2021/03/10
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