What If the Meteor that Helped Wipe out the Dinosaurs Had Missed Earth?

After the Chicxulub meteor hit what's now the Yucatan Peninsula about 65 million years ago, over half of the species living on Earth went extinct. Learn how prehistory may have unfolded without the Chicxulub impact in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,
Lauren Vogel bomb Here on the northern coast of the
Yucatan Peninsula, near the town of Chichi Lob, Mexico, is
a crater about a hundred and twenty miles in diameter.
That's about a hundreds The asteroid that created this crater
was about six miles that's ten kilometers wide and hit

(00:22):
the Earth sixty five million years ago. In spite of
these immense measurements, the crater is hard to see, even
if you're standing right on its rim. To get a
good map, NASA researchers examined it from space. Ten years
before the discovery of the Chichi Lob crater, physicist Louise
Alvarez and geologist Walter Alvarez, a father son team, proposed

(00:42):
a theory about the impact that we know today created it.
They noted increased concentrations of the element a ridium in
sixty five million year old clay. A Ridium is rare
on Earth, but it's more common in some objects from space,
like meteors and asteroids. According to the Alvarez theory, a
massive asteroid it had hit the Earth, blanketing the world
in a ridium. But a shower of particles wasn't the

(01:05):
only effect of the collision. The impact caused fires, climate change,
and widespread extinctions. At the same time, dinosaurs, which until
then had managed to survive for a hundred and eighty
million years, died out. Geo Physicist Doug Robertson of the
University of Colorado at Boulder theorizes the impact heated Earth's
atmosphere dramatically, causing most big dinosaurs to die within hours.

(01:27):
This mass extinction definitely happened. Fossil evidence shows that about
seventy of species living on Earth at that time became extinct.
The massive die off marks the border between the Cretaceous
and Tertiary periods of Earth's history, which are also known
as the Age of Reptiles and the Age of Mammals, respectively. Today,
scientists call the extinction the KT event, after the German

(01:48):
spellings of Cretaceous and Tertiary. The KT event had an
enormous effect on life on Earth. But what would have
happened if the asteroid had missed. Would it have led
to a world where people and dine sours would coexist
or one in which neither could live? In a world
where an asteroid whizzed past Earth instead of crashing down

(02:08):
with the force of a hundred million tons of TNT,
life could have progressed much differently sixty five million years ago.
Some of the animals and plants that are common today
we're just getting started. These include placental mammals, which are
mammals that develop inside a placenta in the womb, and angiosperms,
which are flowering plants. Insects that rely on flowers, such
as bees, were also relatively new. Many of these life

(02:32):
forms thrived after the KT event, and without that mass
reptilian extinction to clear the way, they may not have
found ecological niches to fill. In this scenario, today's world
might be full of reptiles and short on mammals, including people.
But even if the asteroid hadn't hit, dinosaurs and other
Cretaceous life forms might have become extinct anyway. Some dinosaur

(02:53):
species had started to dwindle long before the asteroids impact.
This has led many researchers to conclude that the asteroid
was just one spect of a complex story. Other global
catastrophes like massive volcanic eruptions in what is now India
most likely played a role. Also, the Earth's changing landscape
as the supercontinent Pangaea broke up into today's continence probably

(03:14):
had something to do with it too. Then, there's another
argument that the Chicktullub asteroid hit the Earth too early
to have caused the extinction. Researchers GERTA. Keller and Marcus
Harding both conclude that the impact took place three thousand
years before the end of the Cretaceous period. Keller theorizes
the Chicktullub impact was one of at least three massive collisions.

(03:36):
Harding argues that the iridium layer didn't come from the
Chichillub asteroid, but from another event, such as a series
of meteors burning up in the atmosphere. He bases this
theory on spheroid particles ejected during the impact. Most of
these are in an older layer of the Earth than
the Katie irridium layer. According to both of these points
of view, the absence of the chick Tallub asteroid strike

(03:58):
may not have had a big effect on the Hayti extinction.
Earth was a warm planet for most of the time
that dinosaurs lived. After the end of the Cretaceous period,
the world got a lot colder and experienced several ice ages.
Whether dinosaurs could have survived such a change in climate
is debatable. It's hard to come to a definitive conclusion
about what the world would look like today without the

(04:19):
Chick to Love impact, but the question of whether people
and dinosaurs could have coexisted is a captivating one. The
idea is present in everything from the congo legend of
mokol Ambenbe to King Kong to the pervading kitch of
the Flintstones. Then, of course, there's the prevailing scientific theory
about the origin of birds that they are, in essence,
dinosaurs that we are coexisting with today. Today's episode was

(04:46):
written by Tracy V. Wilson and produced by Tyler Klang.
Brain Stuff is a production of I Heart Radio as
How Stuff Works. To hear more from Tracy, check out
the podcast Stuff You Missed in History Class, and for
more on this and lots of other historic topics, visit
our home planet how Stuff Works dot com. And for
more podcasts from my heart Radio, visit the I heart
Radio app, Apple Podcasts, or wherever you listen to your
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