>>AKI WATANABE (paleontologist, NYIT & AMNH):Did an asteroid kill the dinosaurs?
[MUSIC] [BOOM] >>WATANABE:
Paleontologists agree that an
asteroid did strike Earth at the end of the Cretaceous period,
at around 66 million years ago.
And we know this
because there is an impact crater in the Yucatan Peninsula of
what’s now Mexico.
And the rock layers
from that age include an element called iridium which is rare on
Earth but relatively abundant on asteroids.
And you can learn more about the asteroid itself by clicking the link here.
It obviously had a drastic impact
on life forms on Earth, including dinosaurs like
T-rex and Triceratops.
So because the asteroid was really big,
the impact would have had global consequences,
both immediate and then also long-term.
There would have been initial effects like forest fires and giant tsunamis,
but the projectiles
that came off of the impact would have led to impact winters
which would have cooled
down the Earth and also blocked sunlight fromhitting the ground.
And the vegetation would have suffered,
which would have led to the collapse of a lot of ecosystems.
So its very clear
that the asteroid impact had a major effect on life on Earth.
But what we’re trying to figure out is
whether the asteroid was the only factor, or the major
factor that led to the extinction of dinosaurs.
Some palentologists have proposed
that the dinosaurs were already on a decline before
the impact of the asteroid.
But this hypothesis is difficult to prove just
because we don’t have a clean complete
record of dinosaurs right before, during,and after the extinction event.
So it’s hard to tell
whether all the dinosaurs were already on a path to extinction, even
without help from the asteroid impact.
There’s also evidence of an increase in volcanic activity at that time.
There was a lot of lava and volcanic particles spewing out from under ground.
This would have led to similar effects asthe impact winters.
So the increase
in volcanism might have contributed additional forces that led to
the extinction of dinosaurs.
It’s not all doom and gloom though.
One dinosaur group we know as birds did survive through the extinction event.
And also us mammals did as well.
What the fossil record tells us is that certain animals,
usually smaller-bodied and also those
that lived in the oceans tended to fare better at this extinction event.
So all the animals that are alive today represent descendants
from a group that actually did
survive this asteroid impact.
So to answer the original question,
the asteroid impact did have a devastating
effect on the dinosaurs.
But paleontologists are still working outthe finer details.
And learning more about this extinction event,
could help us to learn about other extinction events,
including the one we’refacing right now.
Thanks for watching the video.
To learn more about the asteroid,
make sure to click the link above for
this weeks’ space video.
And if you have any questions about dinosaurs,
leave them in the comments section below.
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