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  • When I was in grade school, my teacher taught me that about 66 million years ago a huge

  • asteroid hit the earth right around Mexico and BAAAM.

  • Just like that - wiped out the dinosaurs.

  • Yeahnot true.

  • Hello survivors, Lissette here for DNews.

  • The mass extinction that doomed the dinosaurs is still a bit of a mystery.

  • As with anything that happened millions of years ago, we must rely on indirect evidence

  • to test theories about things that we can no longer directly observe or record.

  • So there are lots of theories about how the dinosaurs died off.

  • But one thing scientists are increasingly agreeing on is that the dinosaurs did NOT

  • die all of a sudden.

  • Nope, instead they died a slow, miserable, gradual death.

  • It wasn't just the asteroid that killed them.

  • Though it definitely played a part, there were many other factors involved.

  • Scientists in the UK at the University of Reading and the University of Bristol think

  • they actually started slowly dying out about 40 million years before the asteroid hit;

  • And then, after the blast, continued to die off for millions of years after.

  • Sure, they agree with most of our teachers that the asteroid at Chikshuhloob Mexico did

  • indeed kill many dinosaurs through direct impact and through the tsunami it triggered.

  • But, they argue that this was more like the straw that broke the camel's back.

  • During the Cretaceous period, before the asteroid hit, the earth was experiencing global environmental

  • changes that did not favor land roaming dinosaurs.

  • It was experiencing sea level fluctuations, a period of extreme cooling, and lots of volcanic

  • activity.

  • This meant that dinosaurs had to move around to find food and resources where the climate

  • was more favorable.

  • But, it was difficult for dinos that roamed on foot because during the course of the Cretaceous

  • period, the land itself was slowly breaking up from one large continent to many different

  • land masses.

  • Things were a little better for birds who could fly to places with resources, but even

  • then, many birds species also died out.

  • On top of that, mammals were on the rise before the asteroid - it turned out pretty good for

  • us, given that they're our ancestors.

  • But, scientists theorize that our small rodent looking relatives likely helped to knock dinosaurs

  • out.

  • They may have competed with the dinosaurs for food and other resources, eaten their

  • eggs, or infected them with disease.

  • Pretty big impact from such little guys.

  • Altogether this meant that when the asteroid did hit 66 million years ago, the dinosaurs

  • were already vulnerable to extinction.

  • The dwindling populations could not reproduce quickly enough to survive the losses from

  • the asteroid's impact, the tsunami and other environmental changes that ensued.

  • Between that, the volcanoes, the fluctuating oceans, and the global cooling (not great

  • for cold-blooded reptiles) - the dinos didn't stand a chance.

  • The asteroid certainly had an impact, but the dinosaurs had been dying millions of years

  • before it, and continued to die off millions of years afterward.

  • We can't give the rock all the credit.

  • But for more on which dinos actually survived the mass extinction.

  • Check out Tara's video here

  • What do you remember being taught about the dinosaurs?

  • Did your teachers tell you the same thing I was told about their extinction?

When I was in grade school, my teacher taught me that about 66 million years ago a huge

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如果小行星没有杀死所有的恐龙,那是什么?(If An Asteroid Didn’t Kill All The Dinosaurs, What Did?)

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    joey joey 發佈於 2021 年 04 月 27 日
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