WEBVTT

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NARRATOR:
It's the worst day in the
history of life on Earth.

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A cataclysm that ends
the age of the dinosaurs.

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♪ ♪

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LINDSAY ZANNO:
If they hadn't met
their destruction,

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our story never
would have begun.

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NARRATOR:
From the ashes,

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a band of survivors rises
to become bigger...

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nimbler...

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and smarter
than any that came before.

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Our tribe-- the mammals.

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It was only after
we lose the dinosaurs

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that mammals really explode

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into the diversity of forms
that we see today.

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♪ ♪

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NARRATOR:
What happened after the impact?

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♪ ♪

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How did life surge back?

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The clues have been elusive.

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IAN MILLER:
You could go your entire career

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and not find a skull
from this time period.

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That's how rare they are.

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NARRATOR:
But now comes
a remarkable discovery.

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SHARON MILITO:
There's just nothing like
picking up something

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and finding out
it's something amazing.

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NEIL SHUBIN:
It's like winning the lottery.

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TYLER LYSON:
Bam! We hit it big.

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NARRATOR:
An unprecedented trove
of fossils

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reveals a turning point
in the history of life.

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KIRK JOHNSON:
That moment of rapid mammal
evolution

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is effectively the trigger

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to our existence here
on planet Earth.

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♪ ♪

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NARRATOR:
"Rise of the Mammals"--
right now, on "NOVA."

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♪ ♪

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♪ ♪

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NARRATOR:
We live in the age of mammals.

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All across the globe,

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they thrive in an astonishing
array of forms...

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♪ ♪

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From the great beasts
of the forests

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to giants that sound
the ocean depths...

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♪ ♪

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to us,

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mammals dominate the planet.

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(grunting)

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But it wasn't always this way.

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(dinosaur screeches)

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For 150 million years,

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mammals lived in the shadows
of the dinosaurs.

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Then, a catastrophe
gave them an opening.

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(explosion thunders)

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For years, we've known just bits
and pieces

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about how mammals seized
the moment

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and made our story possible.

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But now that's changing.

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♪ ♪

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An extraordinary discovery
in Colorado

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is revealing an unparalleled
collection of fossils

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from the time when mammals
began their reign.

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♪ ♪

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This hoard lay hidden
in plain sight

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until a young fossil hunter made
a once-in-a-lifetime discovery.

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♪ ♪

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LYSON:
I grew up in a town
of about 80 people,

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basically the middle of nowhere
in southwestern North Dakota.

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♪ ♪

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NARRATOR:
Tyler Lyson's home might look
like other outposts

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scattered
across the American West,

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but this place is unique.

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LYSON:
Right by my hometown,
about a mile away,

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are badlands that preserve
the very last moment of time

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when dinosaurs were alive.

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As a child, I would run around
the badlands

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and find dinosaur bone
after dinosaur bone,

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just tons of dinosaur bones
just tumbling out of the hills.

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♪ ♪

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NARRATOR:
Known as the Hell Creek
formation,

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this was the first place T. rex
fossils were discovered

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a century ago.

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♪ ♪

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Ever since, bone diggers have
been searching

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for more traces
of that lost world.

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♪ ♪

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(helicopter rotors whirring)

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Even as a boy,
Tyler was in the thick of it.

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JOHNSON:
Years ago, I met a kid named
Tyler Lyson.

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And he was this gangly
12-year-old kid.

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By the time he was 13,
he was going out by himself

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and finding amazing fossils.

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He found an entire dinosaur
when he was, like, 14 years old.

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NARRATOR:
Tyler even discovered
a new species

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of feathered dinosaur.

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JOHNSON:
He became sort
of this dinosaur wunderkind.

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NARRATOR:
It was a made-for-TV story.

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MAN:
High school sophomore
Tyler Lyson has walked

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just about every inch
of this land,

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and has already headed
20 dinosaur excavations.

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NARRATOR:
His most spectacular find?

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A dinosaur fossil
with preserved skin and muscle.

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He kept finding more fossils,

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and soon became an expert
in ancient turtles.

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He became fascinated
by a well-known pattern

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in where dinosaurs were
and where they weren't.

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LYSON:
I remember as a child crossing
over this band

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and getting above that area
and not finding any dinosaurs.

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NARRATOR:
The distinct layer seemed
to mark their disappearance.

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LYSON:
So, this always fascinated me.

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Why, above that boundary,
were there no more dinosaurs?

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♪ ♪

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What happened here?

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NARRATOR:
The boundary layer,
Tyler learned,

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was the signature of an event
that changed the world forever.

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(roars)

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♪ ♪

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During the age of reptiles,

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dinosaurs tower over mammals.

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Other reptiles
rule the skies and seas.

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They take on a wide range
of shapes and lifestyles.

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Many are gigantic.

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Mammals had been around
for millions of years.

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But in all of that time,
most grew no bigger than a rat.

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Then, 66 million years ago,
the cataclysm.

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♪ ♪

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A chunk of rock
over six miles wide

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tears through the atmosphere
and slams into the planet.

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(collision thunders)

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The asteroid blasts a crater
20 miles deep

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and over 100 miles wide

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in the Yucatan Peninsula.

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(dinosaurs screeching
and rumbling)

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It showers the planet
with molten rock

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and white-hot beads of glass.

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(dinosaurs screeching
and rumbling)

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LYSON:
And this broils the surface
of the Earth.

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NARRATOR:
Creatures on the surface roast.

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(creatures roaring)

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Skies across the globe darken.

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Fire gives way to frost.

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ANJALI GOSWAMI:
You have intense global cooling.

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You're talking about
immediate global winter.

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NARRATOR:
Deprived of sunlight,
plants wither.

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Lush forests collapse.

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So the animals that rely
on those plants for food,

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the animals that rely
on those animals

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that rely on plants for food,
they would all suffer.

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♪ ♪

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You really are having the
entire food chain fall apart.

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NARRATOR:
All of the dinosaurs,
except the birds, perish.

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SHUBIN:
Three out of four species

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that were alive on the planet
before the impact

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died.

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And that's just the species.

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About 90% of the creatures

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that were alive
before the impact

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are dead afterwards.

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ZANNO:
We think about
the loss of dinosaurs,

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but dinosaurs weren't the only
animals to suffer from this.

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Many, many groups of organisms
took a very serious hit,

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including mammals.

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♪ ♪

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LYSON:
It's a really bad time
for life on Earth.

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Yet some things survive, right?

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Including some of our earliest,
earliest ancestors.

09:32.900 --> 09:36.300 align:left position:45% line:89% size:45%
♪ ♪

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NARRATOR:
We don't know much
about these creatures.

09:39.400 --> 09:40.900 align:left position:45% line:89% size:45%
♪ ♪

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None was bigger than a squirrel.

09:45.633 --> 09:48.733 align:left position:15% line:83% size:75%
And their size and scarcity
have made their fossils

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hard to come by.

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Yet somehow, this band of
survivors and their descendants

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will claim the Earth.

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(birds twittering)

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♪ ♪

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(animals grunting
and chittering)

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LYSON:
Today, there are over 6,000
species of mammals.

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♪ ♪

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And they range in size
from the tiny pygmy jerboa,

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which weighs about
as much as a coin,

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to the largest animal to have
ever lived, the blue whale,

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which is about 180 tons,
the size of 15 school buses.

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GOSWAMI:
Over the last 66 million years,

10:41.133 --> 10:44.566 align:left position:12.5% line:83% size:77.5%
they've evolved an incredible
diversity of forms.

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♪ ♪

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SHUBIN:
Mammals today live in almost
every environment on the planet,

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from the tops
of the highest mountains

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to living in the trees,
to living in the water.

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♪ ♪

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NARRATOR:
They thrive in scorching deserts

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and across the frozen tundra.

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Mammals even patrol
the depths of every ocean

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and the moonlit reaches
of the sky.

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♪ ♪

11:20.066 --> 11:23.966 align:left position:42.5% line:77% size:47.5%
LYSON:
All this diversity
can be traced back

11:23.966 --> 11:27.166 align:left position:27.5% line:83% size:62.5%
to those survivors
of the extinction.

11:27.166 --> 11:29.866 align:left position:45% line:89% size:45%
♪ ♪

11:29.866 --> 11:34.033 align:left position:37.5% line:77% size:52.5%
NARRATOR:
What happened in the wake
of that catastrophic impact?

11:34.033 --> 11:36.700 align:left position:42.5% line:83% size:47.5%
LYSON:
That's what I'm interested in.

11:36.700 --> 11:40.900 align:left position:45% line:89% size:45%
♪ ♪

11:40.900 --> 11:43.333 align:left position:25% line:5% size:65%
How long did it take
for ecosystems to recover?

11:43.333 --> 11:47.933 align:left position:20% line:89% size:70%
For habitats to reform?

11:47.933 --> 11:50.066 align:left position:17.5% line:89% size:72.5%
For life to get big again?

11:50.066 --> 11:53.333 align:left position:45% line:89% size:45%
♪ ♪

11:57.366 --> 12:01.933 align:left position:37.5% line:83% size:52.5%
NARRATOR:
The answers require fossils.

12:01.933 --> 12:04.533 align:left position:17.5% line:89% size:72.5%
But such relics are rare.

12:06.566 --> 12:11.366 align:left position:40% line:77% size:50%
JOHNSON:
I've spent much of the last
35 years looking at rocks

12:11.366 --> 12:12.800 align:left position:15% line:89% size:75%
from the first million years

12:12.800 --> 12:16.233 align:left position:25% line:83% size:65%
after the extinction
of the dinosaurs.

12:16.233 --> 12:19.200 align:left position:12.5% line:5% size:77.5%
I've studied the fossil plants
from that time period.

12:19.200 --> 12:22.200 align:left position:20% line:5% size:70%
And through that entire
35 years,

12:22.200 --> 12:24.633 align:left position:27.5% line:89% size:62.5%
I think I've found

12:24.633 --> 12:29.500 align:left position:37.5% line:83% size:52.5%
one or two
fossil mammal pieces.

12:29.500 --> 12:30.933 align:left position:30% line:89% size:60%
And I'm looking.

12:30.933 --> 12:34.366 align:left position:15% line:83% size:75%
I'm out there looking, and I
know how rare those things are.

12:37.600 --> 12:39.966 align:left position:37.5% line:83% size:52.5%
NARRATOR:
For years, Tyler and others

12:39.966 --> 12:42.266 align:left position:20% line:83% size:70%
search for these scarce
specimens

12:42.266 --> 12:44.933 align:left position:30% line:89% size:60%
in North Dakota.

12:44.933 --> 12:47.700 align:left position:25% line:83% size:65%
He targets the rock
above the boundary layer--

12:47.700 --> 12:51.466 align:left position:25% line:83% size:65%
sediments laid down
just after the impact.

12:51.466 --> 12:56.766 align:left position:45% line:89% size:45%
♪ ♪

12:56.766 --> 13:02.366 align:left position:10% line:83% size:80%
Fossil hunters had occasionally
found mammal traces here,

13:02.366 --> 13:04.800 align:left position:15% line:89% size:75%
but Tyler has no such luck.

13:04.800 --> 13:09.033 align:left position:40% line:77% size:50%
JOHNSON:
Small animals get broken up
into fragments.

13:09.033 --> 13:11.033 align:left position:20% line:83% size:70%
So, when you're looking
for an early mammal,

13:11.033 --> 13:13.200 align:left position:32.5% line:83% size:57.5%
you're looking
for effectively the tooth

13:13.200 --> 13:15.000 align:left position:20% line:89% size:70%
of a mouse-sized animal.

13:15.000 --> 13:16.766 align:left position:15% line:83% size:75%
You're looking for something
that's about the size

13:16.766 --> 13:17.866 align:left position:22.5% line:89% size:67.5%
of the head of a pin.

13:17.866 --> 13:20.600 align:left position:10% line:83% size:80%
And they're excruciatingly hard
to find.

13:20.600 --> 13:22.366 align:left position:45% line:89% size:45%
♪ ♪

13:22.366 --> 13:23.700 align:left position:42.5% line:77% size:47.5%
LYSON:
Every year, I go back
to my hometown,

13:23.700 --> 13:25.700 align:left position:15% line:83% size:75%
and every year, I spend time
above the boundary

13:25.700 --> 13:28.333 align:left position:25% line:89% size:65%
looking for fossils.

13:28.333 --> 13:33.800 align:left position:12.5% line:83% size:77.5%
And I've found so few fossils,
it's, it's pathetic.

13:33.800 --> 13:35.666 align:left position:45% line:89% size:45%
♪ ♪

13:35.666 --> 13:37.666 align:left position:27.5% line:83% size:62.5%
And I was starting
to think about, like,

13:37.666 --> 13:39.400 align:left position:12.5% line:89% size:77.5%
"Well, where's the next area?"

13:39.400 --> 13:42.200 align:left position:10% line:89% size:80%
I was getting ready to give up.

13:42.200 --> 13:47.900 align:left position:37.5% line:77% size:52.5%
NARRATOR:
But then, Tyler gets a job--
and another shot--

13:47.900 --> 13:50.400 align:left position:35% line:89% size:55%
in Colorado.

13:52.100 --> 13:57.333 align:left position:15% line:83% size:75%
He joins up with Ian Miller,
an expert in plant fossils

13:57.333 --> 14:00.733 align:left position:25% line:83% size:65%
at the Denver Museum
of Nature and Science.

14:00.733 --> 14:06.900 align:left position:12.5% line:83% size:77.5%
Ian shares an interest in the
extinction and its aftermath,

14:06.900 --> 14:10.500 align:left position:27.5% line:83% size:62.5%
and knows Colorado
is a great place to search.

14:10.500 --> 14:12.166 align:left position:45% line:89% size:45%
♪ ♪

14:12.166 --> 14:16.000 align:left position:10% line:5% size:80%
We have this really unparalleled
record of this period of time

14:16.000 --> 14:17.366 align:left position:12.5% line:5% size:77.5%
here in Western North America.

14:17.366 --> 14:20.966 align:left position:27.5% line:83% size:62.5%
But the best place
is right here.

14:20.966 --> 14:25.700 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Together, they start exploring
locations around the state.

14:25.700 --> 14:27.833 align:left position:45% line:89% size:45%
♪ ♪

14:27.833 --> 14:30.733 align:left position:17.5% line:89% size:72.5%
One, called Corral Bluffs,

14:30.733 --> 14:35.833 align:left position:10% line:83% size:80%
offers 400 feet of exposed rock
rising above the boundary.

14:42.033 --> 14:45.366 align:left position:20% line:83% size:70%
Tyler begins by scanning
the ground for bits of bone.

14:47.600 --> 14:49.700 align:left position:42.5% line:77% size:47.5%
LYSON:
That's how we're trained
to find fossils--

14:49.700 --> 14:54.300 align:left position:17.5% line:83% size:72.5%
looking for actual scraps
of bone on the surface,

14:54.300 --> 14:55.866 align:left position:30% line:83% size:60%
or to see bones
sticking out of the ground.

15:02.733 --> 15:06.500 align:left position:37.5% line:77% size:52.5%
NARRATOR:
But at Corral Bluffs,
this approach yields

15:06.500 --> 15:08.533 align:left position:10% line:89% size:80%
just a few scattered fragments.

15:08.533 --> 15:12.933 align:left position:42.5% line:77% size:47.5%
LYSON:
I really didn't find
a whole lot.

15:12.933 --> 15:16.300 align:left position:12.5% line:83% size:77.5%
You can only look for fossils
for so long

15:16.300 --> 15:20.800 align:left position:10% line:83% size:80%
before you get really frustrated
and decide to go home.

15:23.800 --> 15:25.966 align:left position:37.5% line:83% size:52.5%
NARRATOR:
What Tyler doesn't know

15:25.966 --> 15:27.300 align:left position:17.5% line:89% size:72.5%
is that a museum volunteer

15:27.300 --> 15:30.533 align:left position:17.5% line:83% size:72.5%
had already found the key
to his quest

15:30.533 --> 15:32.233 align:left position:27.5% line:89% size:62.5%
in this same spot.

15:32.233 --> 15:37.300 align:left position:45% line:89% size:45%
♪ ♪

15:37.300 --> 15:40.900 align:left position:17.5% line:83% size:72.5%
Long before Tyler arrived
in Colorado,

15:40.900 --> 15:43.966 align:left position:12.5% line:83% size:77.5%
Sharon Milito set off to look
for fossils

15:43.966 --> 15:47.600 align:left position:30% line:83% size:60%
from the plateau
atop the bluffs.

15:47.600 --> 15:49.033 align:left position:40% line:83% size:50%
MILITO:
When we first came out,

15:49.033 --> 15:51.933 align:left position:25% line:83% size:65%
we were just looking
for whatever we could find.

15:53.800 --> 15:55.900 align:left position:12.5% line:83% size:77.5%
The important thing we wanted
to find

15:55.900 --> 15:57.600 align:left position:30% line:83% size:60%
were mammal jaws
and mammal teeth,

15:57.600 --> 15:59.133 align:left position:22.5% line:89% size:67.5%
but they were elusive.

15:59.133 --> 16:02.366 align:left position:35% line:83% size:55%
So, one day,
I was walking along in an area

16:02.366 --> 16:04.333 align:left position:15% line:89% size:75%
I'd been many times before,

16:04.333 --> 16:05.500 align:left position:10% line:89% size:80%
and I saw this white, round rock

16:05.500 --> 16:08.933 align:left position:20% line:83% size:70%
sitting there on kind of
its own little pedestal.

16:10.666 --> 16:14.833 align:left position:45% line:5% size:45%
♪ ♪

16:14.833 --> 16:16.466 align:left position:27.5% line:5% size:62.5%
And I picked it up
and looked at it,

16:16.466 --> 16:20.700 align:left position:12.5% line:5% size:77.5%
and as soon as I looked at it,
I saw these teeth

16:20.700 --> 16:24.000 align:left position:17.5% line:5% size:72.5%
that were just smiling out
at me.

16:24.000 --> 16:28.266 align:left position:27.5% line:5% size:62.5%
And I just almost
had a heart attack.

16:28.266 --> 16:31.933 align:left position:37.5% line:77% size:52.5%
NARRATOR:
She'd found part
of a mammal skull--

16:31.933 --> 16:34.600 align:left position:12.5% line:83% size:77.5%
one that could fit in the palm
of her hand.

16:34.600 --> 16:36.066 align:left position:40% line:83% size:50%
MILITO:
I was so excited,

16:36.066 --> 16:39.633 align:left position:12.5% line:83% size:77.5%
because it was really, really
well preserved.

16:39.633 --> 16:41.666 align:left position:45% line:89% size:45%
♪ ♪

16:41.666 --> 16:45.933 align:left position:37.5% line:77% size:52.5%
NARRATOR:
She brought the fossil
to the museum,

16:45.933 --> 16:48.866 align:left position:20% line:83% size:70%
where it was catalogued
and filed away.

16:52.633 --> 16:56.033 align:left position:45% line:89% size:45%
♪ ♪

16:56.033 --> 16:59.533 align:left position:35% line:83% size:55%
It was years
before Tyler happened across it.

17:03.833 --> 17:07.500 align:left position:42.5% line:5% size:47.5%
LYSON:
I was downstairs, just looking
through the collection,

17:07.500 --> 17:11.466 align:left position:10% line:5% size:80%
pulling open drawers, and there,
sitting right in the front,

17:11.466 --> 17:16.300 align:left position:15% line:5% size:75%
was the palate of a mammal.

17:16.300 --> 17:19.366 align:left position:10% line:83% size:80%
And I was absolutely astonished;
I couldn't believe it.

17:19.366 --> 17:22.866 align:left position:12.5% line:83% size:77.5%
And so I was sort of thinking
to myself, like,

17:22.866 --> 17:25.033 align:left position:17.5% line:83% size:72.5%
"If there's this complete
of a skull here,

17:25.033 --> 17:28.333 align:left position:20% line:89% size:70%
there's got to be more."

17:28.333 --> 17:32.733 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Sharon's fossil had been found
in a particular kind of rock

17:32.733 --> 17:36.666 align:left position:25% line:89% size:65%
called a concretion.

17:36.666 --> 17:40.766 align:left position:10% line:83% size:80%
Sometimes, concretions can form
around organic material,

17:40.766 --> 17:43.266 align:left position:37.5% line:89% size:52.5%
like bone.

17:43.266 --> 17:45.400 align:left position:15% line:89% size:75%
And if conditions are right,

17:45.400 --> 17:50.566 align:left position:12.5% line:83% size:77.5%
they protect the fossil inside
for eons.

17:50.566 --> 17:52.333 align:left position:42.5% line:77% size:47.5%
LYSON:
Sharon's skull
was incredibly lucky

17:52.333 --> 17:57.433 align:left position:20% line:83% size:70%
because it showed that,
yes, there are fossils inside,

17:57.433 --> 18:00.166 align:left position:15% line:83% size:75%
and this is the type of rock
to look for.

18:00.166 --> 18:01.966 align:left position:45% line:89% size:45%
♪ ♪

18:01.966 --> 18:04.466 align:left position:37.5% line:83% size:52.5%
NARRATOR:
Tyler decides to change his game

18:04.466 --> 18:08.066 align:left position:20% line:83% size:70%
and look for concretions
to crack open.

18:08.066 --> 18:11.066 align:left position:35% line:83% size:55%
(Tom Petty's
"Runnin' Down a Dream" playing)

18:11.066 --> 18:14.700 align:left position:42.5% line:77% size:47.5%
LYSON:
It was absolutely
a light bulb moment.

18:14.700 --> 18:16.766 align:left position:17.5% line:89% size:72.5%
That was the game changer.

18:16.766 --> 18:19.633 align:left position:30% line:89% size:60%
(song continues)

18:19.633 --> 18:22.800 align:left position:42.5% line:83% size:47.5%
PETTY:
♪ It was a beautiful day ♪

18:22.800 --> 18:25.600 align:left position:22.5% line:89% size:67.5%
♪ The sun beat down ♪

18:25.600 --> 18:28.566 align:left position:22.5% line:89% size:67.5%
♪ I had the radio on ♪

18:28.566 --> 18:32.200 align:left position:27.5% line:89% size:62.5%
♪ I was drivin' ♪

18:32.200 --> 18:34.366 align:left position:22.5% line:89% size:67.5%
♪ The trees went by ♪

18:34.366 --> 18:39.400 align:left position:17.5% line:83% size:72.5%
♪ Me and Del were singin'
"Little Runaway" ♪

18:39.400 --> 18:42.666 align:left position:30% line:89% size:60%
♪ I was flyin' ♪

18:42.666 --> 18:46.033 align:left position:12.5% line:89% size:77.5%
♪ Yeah, runnin' down a dream ♪

18:46.033 --> 18:47.533 align:left position:10% line:89% size:80%
♪ That never would come to me ♪

18:47.533 --> 18:49.600 align:left position:40% line:77% size:50%
MILLER:
Tyler started
to put these pieces together,

18:49.600 --> 18:52.933 align:left position:15% line:83% size:75%
thinking about this new lens
to look for these concretions.

18:52.933 --> 18:54.900 align:left position:30% line:89% size:60%
(song continues)

18:54.900 --> 18:57.433 align:left position:42.5% line:83% size:47.5%
PETTY:
♪ Runnin' down a dream ♪

18:57.433 --> 18:58.633 align:left position:27.5% line:83% size:62.5%
Just saying, like,
"We're going to go down there,

18:58.633 --> 18:59.733 align:left position:27.5% line:83% size:62.5%
blow the doors off
this thing."

18:59.733 --> 19:00.833 align:left position:15% line:89% size:75%
Nobody believes him, right?

19:00.833 --> 19:02.233 align:left position:10% line:89% size:80%
And even me, who, his colleague,

19:02.233 --> 19:05.700 align:left position:15% line:83% size:75%
I'm just, like, "That sounds
good, that sounds good, man."

19:05.700 --> 19:07.966 align:left position:30% line:89% size:60%
(song continues)

19:07.966 --> 19:10.600 align:left position:35% line:89% size:55%
(song ends)

19:13.566 --> 19:16.133 align:left position:37.5% line:83% size:52.5%
NARRATOR:
They hit the bluffs,

19:16.133 --> 19:18.733 align:left position:27.5% line:83% size:62.5%
their eyes peeled
for promising rocks.

19:18.733 --> 19:20.466 align:left position:45% line:89% size:45%
♪ ♪

19:20.466 --> 19:24.800 align:left position:20% line:83% size:70%
There's a whole hillside
of choices.

19:24.800 --> 19:26.900 align:left position:20% line:83% size:70%
One catches Tyler's eye.

19:26.900 --> 19:30.500 align:left position:42.5% line:77% size:47.5%
LYSON:
I see this rock,
this concretion on the ground,

19:30.500 --> 19:32.766 align:left position:12.5% line:5% size:77.5%
the very first one that I pick
up, and I crack it,

19:32.766 --> 19:35.066 align:left position:25% line:5% size:65%
and it was amazing.

19:35.066 --> 19:38.633 align:left position:15% line:83% size:75%
I just found a mammal skull!
(laughs)

19:38.633 --> 19:41.366 align:left position:37.5% line:83% size:52.5%
NARRATOR:
And that was just the beginning.

19:41.366 --> 19:43.133 align:left position:40% line:77% size:50%
MILLER:
It was, it was crazy
the way it happened.

19:43.133 --> 19:45.200 align:left position:25% line:83% size:65%
I mean, you could go
your entire career

19:45.200 --> 19:47.733 align:left position:17.5% line:89% size:72.5%
as a mammal paleontologist

19:47.733 --> 19:49.000 align:left position:25% line:83% size:65%
and not find a skull
from this time period--

19:49.000 --> 19:49.933 align:left position:17.5% line:89% size:72.5%
that's how rare they are.

19:49.933 --> 19:52.000 align:left position:42.5% line:83% size:47.5%
LYSON:
We found, I think,

19:52.000 --> 19:53.300 align:left position:17.5% line:89% size:72.5%
five or six mammal skulls

19:53.300 --> 19:57.100 align:left position:17.5% line:83% size:72.5%
within about a ten-minute
time span.

19:57.100 --> 19:58.800 align:left position:40% line:77% size:50%
MILLER:
We were just laughing
on the outcrop.

19:58.800 --> 20:00.466 align:left position:20% line:83% size:70%
Nothing like that's ever
happened to me before.

20:00.466 --> 20:02.633 align:left position:30% line:89% size:60%
I mean, amazing.

20:02.633 --> 20:05.466 align:left position:37.5% line:83% size:52.5%
NARRATOR:
They'd cracked the case...

20:05.466 --> 20:08.033 align:left position:45% line:89% size:45%
♪ ♪

20:08.033 --> 20:11.433 align:left position:10% line:83% size:80%
...and unearthed a trove of time
capsules filled with clues.

20:11.433 --> 20:13.600 align:left position:45% line:89% size:45%
♪ ♪

20:13.600 --> 20:17.366 align:left position:40% line:77% size:50%
JOHNSON:
It was like opening a door
into a new world.

20:21.800 --> 20:26.133 align:left position:37.5% line:77% size:52.5%
NARRATOR:
In the months that follow,
Tyler and Ian scour the bluff

20:26.133 --> 20:28.200 align:left position:35% line:83% size:55%
and discover
thousands of fossils,

20:28.200 --> 20:31.266 align:left position:27.5% line:89% size:62.5%
including plants,

20:31.266 --> 20:35.433 align:left position:10% line:89% size:80%
reptiles, and dozens of mammals.

20:35.433 --> 20:37.133 align:left position:37.5% line:89% size:52.5%
(laughing)

20:37.133 --> 20:42.433 align:left position:37.5% line:77% size:52.5%
NARRATOR:
All of them lived here
just after the mass extinction.

20:42.433 --> 20:43.766 align:left position:40% line:83% size:50%
GOSWAMI:
Most of the time, you know,

20:43.766 --> 20:47.166 align:left position:27.5% line:5% size:62.5%
we're pretty happy
if we find some nice teeth

20:47.166 --> 20:50.133 align:left position:12.5% line:5% size:77.5%
from an area that's that close
to the boundary.

20:50.133 --> 20:53.500 align:left position:17.5% line:83% size:72.5%
Having this kind of record
is really rare.

20:53.500 --> 20:55.633 align:left position:35% line:83% size:55%
You got the other side
a little bit, too?

20:55.633 --> 20:59.100 align:left position:37.5% line:77% size:52.5%
NARRATOR:
They had found their quarry
at last.

20:59.100 --> 21:03.600 align:left position:20% line:83% size:70%
But the really hard work
now lay ahead--

21:03.600 --> 21:09.433 align:left position:15% line:83% size:75%
figuring out how mammals and
their world rose from the ashes.

21:09.433 --> 21:15.666 align:left position:45% line:89% size:45%
♪ ♪

21:15.666 --> 21:20.333 align:left position:32.5% line:83% size:57.5%
What creatures
had they unearthed?

21:20.333 --> 21:22.266 align:left position:15% line:83% size:75%
What was their strange world
like?

21:22.266 --> 21:24.200 align:left position:45% line:89% size:45%
♪ ♪

21:24.200 --> 21:26.466 align:left position:17.5% line:83% size:72.5%
And how did they establish
a foothold

21:26.466 --> 21:27.866 align:left position:17.5% line:89% size:72.5%
in a planetary wasteland?

21:27.866 --> 21:29.666 align:left position:45% line:89% size:45%
♪ ♪

21:29.666 --> 21:31.866 align:left position:17.5% line:89% size:72.5%
To answer these questions,

21:31.866 --> 21:36.233 align:left position:10% line:83% size:80%
Tyler and Ian needed to assemble
a crack team of experts.

21:36.233 --> 21:40.666 align:left position:42.5% line:77% size:47.5%
ZANNO:
The fossils are not just the
biological remains of animals.

21:40.666 --> 21:42.833 align:left position:25% line:83% size:65%
They are also buried
in a geological system,

21:42.833 --> 21:47.866 align:left position:10% line:83% size:80%
and so no one person can really
understand all the data

21:47.866 --> 21:49.266 align:left position:12.5% line:89% size:77.5%
that we can get from a fossil.

21:49.266 --> 21:50.300 align:left position:30% line:89% size:60%
We need experts

21:50.300 --> 21:51.800 align:left position:27.5% line:5% size:62.5%
to really be able
to piece together

21:51.800 --> 21:53.700 align:left position:17.5% line:5% size:72.5%
what the entire ecosystem
would have looked like.

21:55.033 --> 21:58.666 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Each fossil contains
a wealth of information,

21:58.666 --> 22:02.500 align:left position:15% line:89% size:75%
but it's hidden in the rock.

22:02.500 --> 22:06.333 align:left position:12.5% line:89% size:77.5%
The first step is to free it.

22:08.966 --> 22:12.366 align:left position:27.5% line:83% size:62.5%
So, they reach out
to a virtuoso.

22:13.533 --> 22:16.033 align:left position:32.5% line:83% size:57.5%
ROBERT MASEK:
I love working on fossils.

22:16.033 --> 22:18.433 align:left position:27.5% line:83% size:62.5%
It's so rewarding
when you start a fossil and,

22:18.433 --> 22:20.800 align:left position:17.5% line:89% size:72.5%
that you really can't see.

22:20.800 --> 22:23.933 align:left position:27.5% line:5% size:62.5%
It's, it's almost
like a piece of art, sometimes,

22:23.933 --> 22:27.800 align:left position:15% line:5% size:75%
and it also is contributing
to scientific knowledge.

22:27.800 --> 22:31.800 align:left position:32.5% line:89% size:57.5%
(tool buzzing)

22:31.800 --> 22:35.333 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Bob Masek spent his early career
working in factories,

22:35.333 --> 22:37.200 align:left position:15% line:89% size:75%
but he found he had a knack

22:37.200 --> 22:40.566 align:left position:22.5% line:83% size:67.5%
for releasing captives
from rocks.

22:40.566 --> 22:44.266 align:left position:42.5% line:77% size:47.5%
MASEK:
When I was little,
I used to work on models.

22:44.266 --> 22:47.800 align:left position:22.5% line:83% size:67.5%
So, I did learn to do
detailed work.

22:47.800 --> 22:49.600 align:left position:22.5% line:89% size:67.5%
It was sort of in me.

22:52.933 --> 22:54.866 align:left position:10% line:89% size:80%
My contribution as a preparator

22:54.866 --> 23:01.566 align:left position:12.5% line:83% size:77.5%
is to make the fossil readable
so it can be used for science.

23:01.566 --> 23:03.433 align:left position:40% line:77% size:50%
GOSWAMI:
And you can imagine, you have
to be incredibly careful

23:03.433 --> 23:05.666 align:left position:17.5% line:83% size:72.5%
that you don't break your
fossils while you're doing that,

23:05.666 --> 23:07.966 align:left position:27.5% line:83% size:62.5%
or even shape them
with your own ideas

23:07.966 --> 23:09.133 align:left position:12.5% line:89% size:77.5%
of what they should look like.

23:10.666 --> 23:15.066 align:left position:37.5% line:77% size:52.5%
NARRATOR:
The painstaking process can take
months for a single fossil.

23:15.066 --> 23:21.700 align:left position:15% line:83% size:75%
But it reveals secrets held
tight for millions of years.

23:21.700 --> 23:24.633 align:left position:42.5% line:77% size:47.5%
MASEK:
As you're working,
you do start to realize

23:24.633 --> 23:28.333 align:left position:12.5% line:83% size:77.5%
that this was a living animal,
a living thing.

23:28.333 --> 23:31.966 align:left position:20% line:83% size:70%
I'm bringing it sort of
back to life.

23:31.966 --> 23:36.166 align:left position:45% line:89% size:45%
♪ ♪

23:36.166 --> 23:39.966 align:left position:37.5% line:83% size:52.5%
NARRATOR:
One by one, the fossils emerge.

23:39.966 --> 23:43.500 align:left position:12.5% line:89% size:77.5%
Each is exquisitely preserved.

23:43.500 --> 23:46.800 align:left position:27.5% line:83% size:62.5%
But what are they,
and what do they reveal

23:46.800 --> 23:49.900 align:left position:20% line:89% size:70%
about the mammals' rise?

23:49.900 --> 23:55.666 align:left position:45% line:89% size:45%
♪ ♪

23:57.000 --> 23:59.233 align:left position:42.5% line:77% size:47.5%
LYSON:
Stephen Chester is a vertebrate
paleontologist

23:59.233 --> 24:02.566 align:left position:15% line:89% size:75%
who specializes in mammals.

24:02.566 --> 24:06.466 align:left position:12.5% line:83% size:77.5%
So when I made this discovery,
I needed to bring him on board

24:06.466 --> 24:10.500 align:left position:12.5% line:83% size:77.5%
to help me identify all these
mammals that I was finding.

24:12.566 --> 24:16.933 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Stephen examines each fossil
to find details that reveal

24:16.933 --> 24:19.533 align:left position:22.5% line:89% size:67.5%
what it's related to.

24:19.533 --> 24:24.200 align:left position:15% line:83% size:75%
Not an easy job so far back
on the mammalian family tree.

24:25.433 --> 24:28.666 align:left position:40% line:77% size:50%
CHESTER:
We're talking about species
that can be

24:28.666 --> 24:31.433 align:left position:15% line:5% size:75%
very difficult to identify,

24:31.433 --> 24:34.366 align:left position:10% line:5% size:80%
because they don't look exactly
like what you might expect

24:34.366 --> 24:36.700 align:left position:20% line:89% size:70%
for, for living mammals.

24:36.700 --> 24:39.033 align:left position:45% line:89% size:45%
♪ ♪

24:39.033 --> 24:43.666 align:left position:37.5% line:77% size:52.5%
NARRATOR:
It's a common problem
in tracing ancestry.

24:43.666 --> 24:48.833 align:left position:22.5% line:83% size:67.5%
Consider how different
an elephant is from a hyrax,

24:48.833 --> 24:51.833 align:left position:32.5% line:89% size:57.5%
or a manatee.

24:51.833 --> 24:53.766 align:left position:40% line:77% size:50%
GOSWAMI:
You might not think
that they are closely related.

24:53.766 --> 24:56.133 align:left position:12.5% line:83% size:77.5%
They are incredibly different
animals.

24:56.133 --> 24:58.000 align:left position:22.5% line:89% size:67.5%
But their DNA shows us

24:58.000 --> 24:59.866 align:left position:22.5% line:83% size:67.5%
that they are actually
really closely related.

24:59.866 --> 25:02.033 align:left position:45% line:89% size:45%
♪ ♪

25:02.033 --> 25:03.800 align:left position:37.5% line:5% size:52.5%
NARRATOR:
Descendants of a common ancestor

25:03.800 --> 25:08.166 align:left position:15% line:5% size:75%
don't always look like each
other, or the ancestor,

25:08.166 --> 25:10.466 align:left position:20% line:5% size:70%
because they've evolved
in their own directions

25:10.466 --> 25:13.500 align:left position:22.5% line:5% size:67.5%
for millions of years.

25:13.500 --> 25:18.100 align:left position:17.5% line:5% size:72.5%
But they're bound to share
some common traits.

25:18.100 --> 25:23.733 align:left position:15% line:83% size:75%
That's why Stephen examines
each skull feature by feature.

25:25.700 --> 25:27.766 align:left position:10% line:89% size:80%
His first task is to figure out

25:27.766 --> 25:31.366 align:left position:25% line:83% size:65%
what kind of mammal
they've unearthed.

25:31.366 --> 25:35.966 align:left position:30% line:89% size:60%
(birds chirping)

25:35.966 --> 25:39.400 align:left position:27.5% line:83% size:62.5%
All mammals share
a few key features.

25:39.400 --> 25:40.933 align:left position:22.5% line:89% size:67.5%
They're warm-blooded,

25:40.933 --> 25:44.700 align:left position:37.5% line:89% size:52.5%
grow hair,

25:44.700 --> 25:49.600 align:left position:22.5% line:83% size:67.5%
and have bigger brains
than other animals their size.

25:50.700 --> 25:53.700 align:left position:17.5% line:83% size:72.5%
They also give their young
a jump start in life

25:53.700 --> 25:57.566 align:left position:30% line:89% size:60%
by nursing them.

25:57.566 --> 26:01.966 align:left position:12.5% line:83% size:77.5%
But how they have these babies
sets them apart.

26:03.766 --> 26:07.566 align:left position:20% line:5% size:70%
Some, like kangaroos and
opossums, use a pouch

26:07.566 --> 26:10.333 align:left position:10% line:5% size:80%
to bring their embryos to term.

26:11.933 --> 26:15.900 align:left position:22.5% line:83% size:67.5%
A handful-- platypuses
and echidnas-- lay eggs.

26:17.933 --> 26:20.666 align:left position:37.5% line:89% size:52.5%
(chitters)

26:20.666 --> 26:25.000 align:left position:10% line:83% size:80%
But what about the biggest group
of mammals alive today--

26:25.000 --> 26:29.633 align:left position:10% line:83% size:80%
those that carry their offspring
in the mother's womb?

26:29.633 --> 26:32.533 align:left position:40% line:89% size:50%
Like us,

26:32.533 --> 26:36.200 align:left position:17.5% line:89% size:72.5%
they're called placentals.

26:36.200 --> 26:39.600 align:left position:15% line:83% size:75%
And they include the mammal
Stephen examines

26:39.600 --> 26:41.600 align:left position:25% line:89% size:65%
from Corral Bluffs.

26:44.300 --> 26:48.100 align:left position:10% line:83% size:80%
It's one of the oldest placental
fossils ever discovered.

26:49.666 --> 26:53.800 align:left position:12.5% line:89% size:77.5%
A creature called loxolophus.

26:53.800 --> 26:59.233 align:left position:15% line:83% size:75%
It's not yet clear if it has
any living descendants.

26:59.233 --> 27:05.133 align:left position:25% line:83% size:65%
But the fossil hints
at a highly adaptable creature.

27:05.133 --> 27:08.500 align:left position:40% line:77% size:50%
CHESTER:
This mammal is probably
about the size of a skunk.

27:08.500 --> 27:10.833 align:left position:17.5% line:83% size:72.5%
It has teeth in the front
of its mouth

27:10.833 --> 27:13.033 align:left position:22.5% line:83% size:67.5%
that are probably good
for tearing meat,

27:13.033 --> 27:15.766 align:left position:17.5% line:83% size:72.5%
but the back of its mouth
has other teeth

27:15.766 --> 27:18.166 align:left position:25% line:83% size:65%
that would be better
at processing plants.

27:18.166 --> 27:21.033 align:left position:25% line:83% size:65%
It's probably eating
a mixed diet.

27:23.233 --> 27:25.500 align:left position:37.5% line:77% size:52.5%
NARRATOR:
This versatility would have been
a great advantage

27:25.500 --> 27:27.333 align:left position:22.5% line:89% size:67.5%
in a recovering world,

27:27.333 --> 27:31.500 align:left position:20% line:83% size:70%
where the types of food
were probably limited.

27:33.533 --> 27:35.766 align:left position:20% line:83% size:70%
Team member Karen Cuevas

27:35.766 --> 27:37.766 align:left position:25% line:83% size:65%
finds other insights
about how it lived

27:37.766 --> 27:40.300 align:left position:12.5% line:89% size:77.5%
by peering inside the fossil.

27:40.300 --> 27:42.266 align:left position:40% line:83% size:50%
CUEVAS:
When I first heard

27:42.266 --> 27:45.800 align:left position:20% line:5% size:70%
about how mammals became
what they are today,

27:45.800 --> 27:47.433 align:left position:15% line:89% size:75%
I was really excited to see

27:47.433 --> 27:50.633 align:left position:20% line:83% size:70%
how much we could deduce
from these fossils

27:50.633 --> 27:54.800 align:left position:22.5% line:83% size:67.5%
and paint this picture
from so many million years ago.

27:54.800 --> 27:58.166 align:left position:10% line:83% size:80%
One of the things that we can do
with the CT scan

27:58.166 --> 28:01.333 align:left position:17.5% line:89% size:72.5%
is view the inner anatomy.

28:02.733 --> 28:04.766 align:left position:42.5% line:77% size:47.5%
ZANNO:
CT reconstructions
give us insight

28:04.766 --> 28:06.233 align:left position:35% line:83% size:55%
into tissues
that aren't preserved,

28:06.233 --> 28:08.900 align:left position:27.5% line:89% size:62.5%
and teach us a lot

28:08.900 --> 28:10.600 align:left position:20% line:83% size:70%
about what those animals
were really like

28:10.600 --> 28:12.166 align:left position:10% line:89% size:80%
as living, breathing creatures.

28:14.433 --> 28:19.000 align:left position:37.5% line:77% size:52.5%
NARRATOR:
The data help the team imagine
what the living animal was like.

28:19.000 --> 28:24.533 align:left position:40% line:77% size:50%
CHESTER:
Based on CT scans, this animal
had a hole underneath its eye.

28:25.800 --> 28:30.233 align:left position:37.5% line:77% size:52.5%
NARRATOR:
A passage for nerves
from sensitive whiskers.

28:30.233 --> 28:33.000 align:left position:40% line:77% size:50%
CHESTER:
It also has a large portion
of its brain

28:33.000 --> 28:35.766 align:left position:10% line:89% size:80%
dedicated to the sense of smell.

28:35.766 --> 28:38.266 align:left position:45% line:89% size:45%
♪ ♪

28:38.266 --> 28:40.933 align:left position:37.5% line:5% size:52.5%
NARRATOR:
These senses would have been key
to its lifestyle

28:40.933 --> 28:44.433 align:left position:27.5% line:5% size:62.5%
in this new world.

28:44.433 --> 28:49.866 align:left position:15% line:5% size:75%
Details from related species
suggest how it walked.

28:49.866 --> 28:52.833 align:left position:40% line:5% size:50%
CHESTER:
We would assume that this animal
was moving around on the ground

28:52.833 --> 28:56.066 align:left position:10% line:5% size:80%
on all fours, probably something
like a raccoon.

28:56.066 --> 28:59.066 align:left position:35% line:89% size:55%
(chittering)

29:00.633 --> 29:02.233 align:left position:37.5% line:83% size:52.5%
NARRATOR:
It's a lot to have learned

29:02.233 --> 29:05.300 align:left position:17.5% line:83% size:72.5%
about one of the creatures
that roamed the new world.

29:09.266 --> 29:12.766 align:left position:17.5% line:83% size:72.5%
But Corral Bluffs is about
to reveal something even bigger.

29:15.166 --> 29:17.666 align:left position:42.5% line:83% size:47.5%
LYSON:
The discovery here extends

29:17.666 --> 29:20.733 align:left position:35% line:83% size:55%
well beyond
any one particular fossil.

29:20.733 --> 29:24.866 align:left position:15% line:83% size:75%
Here, we're dealing with the
recovery of an entire ecosystem.

29:24.866 --> 29:27.266 align:left position:45% line:89% size:45%
♪ ♪

29:27.266 --> 29:31.833 align:left position:37.5% line:77% size:52.5%
NARRATOR:
If the team can determine
the age of each fossil,

29:31.833 --> 29:37.033 align:left position:17.5% line:83% size:72.5%
they can start to see how
the mammals evolved over time,

29:37.033 --> 29:41.866 align:left position:15% line:83% size:75%
and how their world changed
alongside them.

29:41.866 --> 29:43.366 align:left position:40% line:77% size:50%
GOSWAMI:
When we find some interesting
fossils,

29:43.366 --> 29:45.433 align:left position:12.5% line:83% size:77.5%
then the next thing that we do
is spend a huge amount of effort

29:45.433 --> 29:48.766 align:left position:25% line:83% size:65%
trying to figure out
exactly how old they are.

29:48.766 --> 29:54.033 align:left position:12.5% line:83% size:77.5%
But getting accurate dates on
fossil sites is incredibly hard.

29:54.033 --> 29:57.000 align:left position:37.5% line:77% size:52.5%
NARRATOR:
To estimate the age
of their fossils,

29:57.000 --> 30:00.100 align:left position:20% line:83% size:70%
Tyler and Ian reach out
to specialists.

30:00.100 --> 30:02.366 align:left position:12.5% line:89% size:77.5%
(people talking in background)

30:02.366 --> 30:07.066 align:left position:22.5% line:83% size:67.5%
Geologists Will Clyde
and Anthony Fuentes.

30:07.066 --> 30:11.633 align:left position:12.5% line:83% size:77.5%
Their goal: determine the age
of each layer in the rock

30:11.633 --> 30:15.766 align:left position:22.5% line:83% size:67.5%
by building a timeline
up the cliff.

30:15.766 --> 30:21.066 align:left position:10% line:83% size:80%
To do it, they'll rely on clues
forged by planetary forces.

30:21.066 --> 30:24.600 align:left position:45% line:89% size:45%
♪ ♪

30:24.600 --> 30:27.933 align:left position:25% line:83% size:65%
Earth is surrounded
by a magnetic field,

30:27.933 --> 30:33.633 align:left position:12.5% line:83% size:77.5%
which creates north and south
magnetic poles.

30:33.633 --> 30:37.433 align:left position:17.5% line:83% size:72.5%
These may seem permanent,
but they're not.

30:37.433 --> 30:42.100 align:left position:27.5% line:83% size:62.5%
From time to time,
the field reverses.

30:42.100 --> 30:43.533 align:left position:25% line:5% size:65%
And so what is today

30:43.533 --> 30:44.966 align:left position:10% line:5% size:80%
the magnetic north for the Earth

30:44.966 --> 30:46.900 align:left position:15% line:5% size:75%
sometimes flips and becomes
the magnetic south.

30:46.900 --> 30:49.033 align:left position:45% line:89% size:45%
♪ ♪

30:49.033 --> 30:52.533 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Some rocks can record the
direction of the magnetic field

30:52.533 --> 30:57.233 align:left position:22.5% line:89% size:67.5%
at the time they form.

30:57.233 --> 30:59.800 align:left position:27.5% line:83% size:62.5%
As these build up
on top of each other,

30:59.800 --> 31:04.700 align:left position:17.5% line:83% size:72.5%
they can capture a record
of magnetic reversals over time.

31:04.700 --> 31:08.200 align:left position:22.5% line:83% size:67.5%
The date of each flip
has been firmly established

31:08.200 --> 31:10.233 align:left position:17.5% line:89% size:72.5%
in rocks across the world.

31:10.233 --> 31:11.966 align:left position:75% line:83% size:15%
CLYDE:
Four, five...

31:11.966 --> 31:13.600 align:left position:62.5% line:89% size:27.5%
Four, five.

31:13.600 --> 31:15.033 align:left position:42.5% line:83% size:47.5%
CLYDE:
So if we can find

31:15.033 --> 31:18.466 align:left position:25% line:5% size:65%
certain flip-flop in
the polarity in the rocks here,

31:18.466 --> 31:22.433 align:left position:22.5% line:83% size:67.5%
then we know the date
of that change.

31:22.433 --> 31:24.833 align:left position:67.5% line:89% size:22.5%
Six-four.

31:24.833 --> 31:26.966 align:left position:60% line:89% size:30%
To the east.

31:26.966 --> 31:29.266 align:left position:37.5% line:83% size:52.5%
NARRATOR:
To look for these flips,

31:29.266 --> 31:31.833 align:left position:27.5% line:83% size:62.5%
they collect rocks
along the bottom of the bluffs,

31:31.833 --> 31:34.433 align:left position:12.5% line:89% size:77.5%
where the impact boundary is,

31:34.433 --> 31:37.200 align:left position:22.5% line:89% size:67.5%
and work their way up.

31:39.200 --> 31:41.666 align:left position:10% line:83% size:80%
They then bring each sample back
to their lab

31:41.666 --> 31:44.500 align:left position:37.5% line:83% size:52.5%
to measure
its magnetic orientation.

31:46.966 --> 31:48.733 align:left position:37.5% line:83% size:52.5%
NARRATOR:
Near the bottom of the bluffs,

31:48.733 --> 31:54.033 align:left position:30% line:83% size:60%
they find a flip
from 350,000 years after impact,

31:54.033 --> 31:56.266 align:left position:12.5% line:89% size:77.5%
and trace it across the land.

31:58.533 --> 32:02.066 align:left position:10% line:89% size:80%
But a single date isn't enough.

32:02.066 --> 32:05.333 align:left position:40% line:77% size:50%
MILLER:
If you get one date
in a pile of rocks,

32:05.333 --> 32:07.066 align:left position:10% line:89% size:80%
you know where that one date is.

32:07.066 --> 32:10.533 align:left position:10% line:83% size:80%
But above it, you don't know how
fast the rocks are accumulating.

32:10.533 --> 32:12.366 align:left position:15% line:5% size:75%
There could be a ton of rock
in a short period of time,

32:12.366 --> 32:15.333 align:left position:10% line:5% size:80%
or it could be a small amount of
rock in a long period of time.

32:15.333 --> 32:17.766 align:left position:45% line:89% size:45%
♪ ♪

32:17.766 --> 32:20.566 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Most of the bluffs,
and the team's discoveries,

32:20.566 --> 32:23.733 align:left position:27.5% line:83% size:62.5%
lie above the flip
they've found.

32:23.733 --> 32:28.433 align:left position:10% line:83% size:80%
They need a second one higher up
to bracket the dates

32:28.433 --> 32:30.666 align:left position:27.5% line:89% size:62.5%
of their fossils.

32:32.533 --> 32:36.800 align:left position:20% line:83% size:70%
They work their way up,
one layer after another.

32:37.966 --> 32:39.333 align:left position:40% line:83% size:50%
MILLER:
As we went up the hill,

32:39.333 --> 32:40.800 align:left position:17.5% line:83% size:72.5%
you know, you're sampling,
you're sampling,

32:40.800 --> 32:41.966 align:left position:25% line:83% size:65%
but there's no flip,
there's nothing,

32:41.966 --> 32:44.366 align:left position:22.5% line:83% size:67.5%
and we're just running
out of rock.

32:44.366 --> 32:48.366 align:left position:37.5% line:77% size:52.5%
NARRATOR:
They test samples
right up to the top.

32:48.366 --> 32:50.533 align:left position:40% line:89% size:50%
Still...

32:50.533 --> 32:52.566 align:left position:40% line:89% size:50%
No flip.

32:52.566 --> 32:56.766 align:left position:30% line:83% size:60%
No way to place
their discoveries in time.

32:56.766 --> 32:59.066 align:left position:45% line:89% size:45%
♪ ♪

32:59.066 --> 33:01.966 align:left position:30% line:83% size:60%
Then, they find
a small outcrop

33:01.966 --> 33:05.233 align:left position:32.5% line:83% size:57.5%
perched above
the rest of the bluffs.

33:05.233 --> 33:09.733 align:left position:25% line:83% size:65%
It's one last chance
to catch the flip.

33:09.733 --> 33:14.666 align:left position:45% line:89% size:45%
♪ ♪

33:14.666 --> 33:16.833 align:left position:30% line:89% size:60%
And it delivers.

33:16.833 --> 33:19.533 align:left position:45% line:5% size:45%
♪ ♪

33:19.533 --> 33:23.566 align:left position:32.5% line:5% size:57.5%
They've found
the second date they need.

33:23.566 --> 33:25.366 align:left position:40% line:5% size:50%
MILLER:
That allowed us to place
all these fossils

33:25.366 --> 33:27.333 align:left position:12.5% line:5% size:77.5%
in this incredible time frame.

33:28.433 --> 33:29.666 align:left position:20% line:5% size:70%
We had the whole thing,

33:29.666 --> 33:32.033 align:left position:22.5% line:5% size:67.5%
and that was a shock.

33:32.033 --> 33:33.766 align:left position:22.5% line:89% size:67.5%
We didn't expect that.

33:33.766 --> 33:35.500 align:left position:12.5% line:83% size:77.5%
We thought we might be missing
a part of the record,

33:35.500 --> 33:36.833 align:left position:25% line:89% size:65%
but it's all there.

33:36.833 --> 33:39.233 align:left position:45% line:89% size:45%
♪ ♪

33:39.233 --> 33:41.200 align:left position:37.5% line:83% size:52.5%
NARRATOR:
The towering face of the bluffs

33:41.200 --> 33:45.233 align:left position:10% line:83% size:80%
chronicles the first one million
years of the recovery.

33:45.233 --> 33:46.700 align:left position:40% line:83% size:50%
SHUBIN:
If you were to choose

33:46.700 --> 33:49.766 align:left position:15% line:5% size:75%
any one-million-year sliver
of time

33:49.766 --> 33:52.966 align:left position:20% line:5% size:70%
in the four-and-a-half-
billion-year history of Earth,

33:52.966 --> 33:55.066 align:left position:12.5% line:83% size:77.5%
it's an enormously lucky event
to have one that happens

33:55.066 --> 33:56.833 align:left position:15% line:83% size:75%
right after a giant asteroid
impact.

33:56.833 --> 33:59.266 align:left position:12.5% line:89% size:77.5%
It's like winning the lottery.

33:59.266 --> 34:00.866 align:left position:45% line:89% size:45%
♪ ♪

34:00.866 --> 34:04.166 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Now all the extraordinary
fossils of Corral Bluffs

34:04.166 --> 34:09.366 align:left position:22.5% line:89% size:67.5%
can be placed in time.

34:09.366 --> 34:12.966 align:left position:15% line:89% size:75%
But what story do they tell?

34:12.966 --> 34:16.266 align:left position:32.5% line:83% size:57.5%
Another fossil
reveals a turning point.

34:16.266 --> 34:19.900 align:left position:45% line:89% size:45%
♪ ♪

34:19.900 --> 34:22.333 align:left position:42.5% line:77% size:47.5%
LYSON:
In the middle part
of the bluffs,

34:22.333 --> 34:25.600 align:left position:15% line:89% size:75%
I found a much larger skull.

34:25.600 --> 34:29.700 align:left position:37.5% line:77% size:52.5%
NARRATOR:
This creature lived 300,000
years into the recovery.

34:31.466 --> 34:33.000 align:left position:42.5% line:83% size:47.5%
LYSON:
What's interesting about it

34:33.000 --> 34:38.133 align:left position:32.5% line:83% size:57.5%
is that it has
these really large teeth.

34:38.133 --> 34:43.900 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Mammals today use teeth like
these to grind leaves and stems.

34:43.900 --> 34:49.500 align:left position:10% line:83% size:80%
It suggests this creature dined
mostly on plants.

34:49.500 --> 34:52.266 align:left position:42.5% line:77% size:47.5%
LYSON:
And this is really the first
major specialization that we see

34:52.266 --> 34:54.900 align:left position:15% line:5% size:75%
in the mammal fossil record

34:54.900 --> 34:57.000 align:left position:17.5% line:5% size:72.5%
right after the extinction
of the dinosaurs.

34:58.766 --> 35:02.100 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Just after the impact,
the mammals that survived

35:02.100 --> 35:05.733 align:left position:22.5% line:83% size:67.5%
had been opportunistic
scavengers.

35:05.733 --> 35:10.200 align:left position:22.5% line:83% size:67.5%
But now, mammals were
specializing in eating plants

35:10.200 --> 35:13.733 align:left position:25% line:83% size:65%
and seizing a niche
long held by dinosaurs.

35:13.733 --> 35:17.033 align:left position:45% line:89% size:45%
♪ ♪

35:17.033 --> 35:20.200 align:left position:20% line:89% size:70%
It's a major milestone.

35:20.200 --> 35:22.533 align:left position:22.5% line:89% size:67.5%
But how did it happen?

35:25.233 --> 35:30.666 align:left position:15% line:83% size:75%
The answer could lie in the
story of the plants themselves.

35:30.666 --> 35:36.366 align:left position:25% line:83% size:65%
And Colorado's rocks
are packed with clues.

35:41.666 --> 35:43.433 align:left position:40% line:83% size:50%
MILLER:
A lot of leaves.

35:43.433 --> 35:46.233 align:left position:10% line:89% size:80%
But just two species right here.

35:46.233 --> 35:49.233 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Some leaves are
so beautifully preserved,

35:49.233 --> 35:51.966 align:left position:20% line:83% size:70%
they look as if they had
just fallen.

35:51.966 --> 35:53.800 align:left position:45% line:89% size:45%
♪ ♪

35:53.800 --> 35:58.600 align:left position:12.5% line:83% size:77.5%
But other telling fossils are
invisible to the naked eye.

35:58.600 --> 36:02.066 align:left position:35% line:89% size:55%
Like pollen.

36:02.066 --> 36:04.633 align:left position:12.5% line:89% size:77.5%
A thimble-sized chunk of rock,

36:04.633 --> 36:08.166 align:left position:22.5% line:83% size:67.5%
it might have 100,000
pollen grains in it.

36:08.166 --> 36:11.500 align:left position:15% line:83% size:75%
Each of the different kinds
of trees, the little shrubs,

36:11.500 --> 36:16.166 align:left position:17.5% line:83% size:72.5%
produce different kinds of
pollen based on who they are.

36:16.166 --> 36:20.300 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Ian and scientists around
the world have documented

36:20.300 --> 36:22.433 align:left position:22.5% line:83% size:67.5%
the microscopic record
from this time.

36:22.433 --> 36:24.366 align:left position:45% line:89% size:45%
♪ ♪

36:24.366 --> 36:25.500 align:left position:40% line:83% size:50%
MILLER:
Take a chunk of rock,

36:25.500 --> 36:26.800 align:left position:30% line:89% size:60%
you dissolve it,

36:26.800 --> 36:28.300 align:left position:12.5% line:83% size:77.5%
you take all the pollen spores
out of it,

36:28.300 --> 36:31.600 align:left position:12.5% line:83% size:77.5%
put it on a slide, and you see
many different types of plants.

36:31.600 --> 36:33.500 align:left position:12.5% line:83% size:77.5%
And then you can sort of paint
this image

36:33.500 --> 36:36.966 align:left position:10% line:89% size:80%
of what these worlds were like.

36:36.966 --> 36:38.466 align:left position:45% line:89% size:45%
♪ ♪

36:38.466 --> 36:40.833 align:left position:17.5% line:83% size:72.5%
And so right at that mark
where we see the evidence

36:40.833 --> 36:41.966 align:left position:10% line:89% size:80%
of this extraterrestrial impact,

36:41.966 --> 36:45.366 align:left position:10% line:89% size:80%
the pollen just dives right off.

36:45.366 --> 36:47.666 align:left position:20% line:89% size:70%
Everything seems to die.

36:47.666 --> 36:49.500 align:left position:37.5% line:83% size:52.5%
NARRATOR:
After the impact,

36:49.500 --> 36:52.300 align:left position:17.5% line:83% size:72.5%
one primitive form of life
resurges,

36:52.300 --> 36:56.500 align:left position:30% line:83% size:60%
and it's a sign
of a devastated world.

36:56.500 --> 36:57.966 align:left position:40% line:83% size:50%
MILLER:
Right after the boundary,

36:57.966 --> 37:03.400 align:left position:25% line:83% size:65%
there's an explosion
of fungal spores.

37:03.400 --> 37:06.900 align:left position:12.5% line:83% size:77.5%
The thing is that fungus grows
on things that are dead.

37:06.900 --> 37:09.900 align:left position:25% line:83% size:65%
So most of the world
must have been rotting.

37:11.833 --> 37:16.100 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Forests destroyed
by heat and darkness

37:16.100 --> 37:21.033 align:left position:37.5% line:83% size:52.5%
decompose
beneath this fungal carpet.

37:21.033 --> 37:24.266 align:left position:12.5% line:89% size:77.5%
But then some plants rebound.

37:24.266 --> 37:28.200 align:left position:45% line:89% size:45%
♪ ♪

37:28.200 --> 37:30.900 align:left position:40% line:77% size:50%
MILLER:
Following immediately on top
of the fungal world,

37:30.900 --> 37:32.733 align:left position:12.5% line:89% size:77.5%
we see a spike in fern spores.

37:32.733 --> 37:35.733 align:left position:45% line:89% size:45%
♪ ♪

37:35.733 --> 37:40.566 align:left position:12.5% line:83% size:77.5%
Ferns are this group of plants
that come back after disasters

37:40.566 --> 37:45.066 align:left position:12.5% line:83% size:77.5%
before the rest of the forest
is able to re-establish itself.

37:45.066 --> 37:48.500 align:left position:15% line:83% size:75%
First thing that comes back
are a blanket of ferns.

37:48.500 --> 37:52.333 align:left position:20% line:83% size:70%
And that probably lasts
for a few thousand years.

37:52.333 --> 37:54.566 align:left position:45% line:89% size:45%
♪ ♪

37:54.566 --> 37:57.133 align:left position:37.5% line:83% size:52.5%
NARRATOR:
The world is green again,

37:57.133 --> 38:01.366 align:left position:12.5% line:83% size:77.5%
but ferns are a limited source
of food.

38:04.966 --> 38:09.300 align:left position:27.5% line:83% size:62.5%
New options arise
as the landscape evolves,

38:09.300 --> 38:12.333 align:left position:22.5% line:83% size:67.5%
and long-dormant seeds
spring to life...

38:15.433 --> 38:18.866 align:left position:32.5% line:89% size:57.5%
A new forest.

38:18.866 --> 38:21.133 align:left position:40% line:77% size:50%
MILLER:
One of the big surprises
was this incredible abundance

38:21.133 --> 38:25.000 align:left position:30% line:89% size:60%
of palm pollen.

38:25.000 --> 38:30.933 align:left position:10% line:83% size:80%
And we get tons of palm fronds--
huge, beautiful palm fronds.

38:30.933 --> 38:35.966 align:left position:12.5% line:83% size:77.5%
They're so dominant, it feels
like the world is all palms.

38:35.966 --> 38:41.833 align:left position:22.5% line:83% size:67.5%
And it probably lasts
about 100,000 years.

38:41.833 --> 38:44.366 align:left position:12.5% line:83% size:77.5%
What I'm thinking right now is
that if you were a mammal,

38:44.366 --> 38:48.366 align:left position:15% line:83% size:75%
there would have been a big
canopy of palms above your head.

38:48.366 --> 38:51.833 align:left position:22.5% line:83% size:67.5%
But there still wasn't
that great source of food.

38:51.833 --> 38:54.500 align:left position:27.5% line:89% size:62.5%
(insects chirping)

38:54.500 --> 39:01.100 align:left position:37.5% line:77% size:52.5%
NARRATOR:
The habitat looks lush,
but still lacks diversity.

39:01.100 --> 39:04.800 align:left position:22.5% line:83% size:67.5%
That, in turn, limits
the variety of animals,

39:04.800 --> 39:08.233 align:left position:30% line:83% size:60%
as a close look
at the team's fossils reveals.

39:12.333 --> 39:14.166 align:left position:15% line:5% size:75%
When there's an extinction,

39:14.166 --> 39:17.000 align:left position:15% line:5% size:75%
it kind of ripples from the
bottom of the ecosystem,

39:17.000 --> 39:22.100 align:left position:17.5% line:83% size:72.5%
starting from the plants,
up into all of the other levels.

39:22.100 --> 39:25.900 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Gussie Maccracken deciphers
what happened

39:25.900 --> 39:28.066 align:left position:20% line:83% size:70%
to some of the smallest
creatures:

39:28.066 --> 39:31.366 align:left position:40% line:89% size:50%
insects.

39:31.366 --> 39:35.300 align:left position:12.5% line:89% size:77.5%
Insects don't fossilize well,

39:35.300 --> 39:38.200 align:left position:10% line:89% size:80%
but what they do to plants can.

39:38.200 --> 39:40.300 align:left position:35% line:77% size:55%
MACCRACKEN:
Insect damage on a leaf
can tell us

39:40.300 --> 39:43.600 align:left position:27.5% line:83% size:62.5%
about the ecology
of the ecosystem in the past

39:43.600 --> 39:48.833 align:left position:15% line:83% size:75%
in a way that no other types
of fossils can.

39:48.833 --> 39:51.466 align:left position:37.5% line:83% size:52.5%
NARRATOR:
Some insects are generalists,

39:51.466 --> 39:55.166 align:left position:22.5% line:83% size:67.5%
and feed on many types
of leaves.

39:55.166 --> 39:58.900 align:left position:10% line:83% size:80%
They carve signature marks that
can be preserved in fossils.

39:58.900 --> 40:00.833 align:left position:45% line:89% size:45%
♪ ♪

40:00.833 --> 40:02.600 align:left position:32.5% line:89% size:57.5%
Simple holes,

40:02.600 --> 40:06.233 align:left position:30% line:83% size:60%
or chunks bitten
from the leaf's edge.

40:06.233 --> 40:08.666 align:left position:45% line:89% size:45%
♪ ♪

40:08.666 --> 40:11.833 align:left position:17.5% line:83% size:72.5%
But other kinds of damage
are caused by insects

40:11.833 --> 40:15.066 align:left position:30% line:83% size:60%
that specialize
in certain plants.

40:15.066 --> 40:19.133 align:left position:35% line:5% size:55%
MACCRACKEN:
They leave these wild patterns

40:19.133 --> 40:22.766 align:left position:22.5% line:5% size:67.5%
and we can tell things
like if it's a moth,

40:22.766 --> 40:26.200 align:left position:27.5% line:5% size:62.5%
or if it's a fly,

40:26.200 --> 40:29.000 align:left position:22.5% line:5% size:67.5%
or sometimes a beetle.

40:29.000 --> 40:31.000 align:left position:37.5% line:83% size:52.5%
NARRATOR:
Before the asteroid struck,

40:31.000 --> 40:34.866 align:left position:15% line:83% size:75%
the insect world was filled
with specialists.

40:34.866 --> 40:39.466 align:left position:17.5% line:89% size:72.5%
But that changes abruptly.

40:39.466 --> 40:44.700 align:left position:35% line:77% size:55%
MACCRACKEN:
During recovery, a lot of the
specialist insect damage types,

40:44.700 --> 40:49.066 align:left position:22.5% line:83% size:67.5%
like from leaf miners
and galling insects,

40:49.066 --> 40:50.433 align:left position:30% line:89% size:60%
just disappear.

40:50.433 --> 40:52.166 align:left position:45% line:89% size:45%
♪ ♪

40:52.166 --> 40:55.900 align:left position:37.5% line:83% size:52.5%
NARRATOR:
The specialists were doomed.

40:55.900 --> 41:00.700 align:left position:25% line:83% size:65%
In a world with only
a few kinds of plants,

41:00.700 --> 41:04.166 align:left position:20% line:83% size:70%
insects that can live on
anything have an advantage

41:04.166 --> 41:06.700 align:left position:25% line:89% size:65%
over pickier eaters.

41:06.700 --> 41:12.600 align:left position:20% line:83% size:70%
It echoes what happened
to the mammals.

41:12.600 --> 41:15.600 align:left position:12.5% line:89% size:77.5%
Only the generalists survive.

41:15.600 --> 41:18.000 align:left position:42.5% line:77% size:47.5%
ZANNO:
At the time
of an extinction event,

41:18.000 --> 41:21.066 align:left position:17.5% line:5% size:72.5%
any species that's highly
dependent on a single lifestyle

41:21.066 --> 41:24.200 align:left position:25% line:5% size:65%
or a single location
or a single food source

41:24.200 --> 41:28.033 align:left position:12.5% line:83% size:77.5%
is likely going to go extinct
when those ecosystems collapse.

41:28.033 --> 41:30.900 align:left position:45% line:89% size:45%
♪ ♪

41:30.900 --> 41:33.300 align:left position:37.5% line:83% size:52.5%
NARRATOR:
But in time, new plants arise

41:33.300 --> 41:36.633 align:left position:17.5% line:83% size:72.5%
and chances to specialize
return.

41:36.633 --> 41:40.566 align:left position:40% line:77% size:50%
MILLER:
The forests become
more and more diverse.

41:40.566 --> 41:44.566 align:left position:10% line:5% size:80%
We get different kinds of trees
growing on the landscape.

41:44.566 --> 41:48.766 align:left position:45% line:5% size:45%
♪ ♪

41:51.066 --> 41:54.266 align:left position:37.5% line:5% size:52.5%
NARRATOR:
300,000 years
after its collapse,

41:54.266 --> 41:56.433 align:left position:17.5% line:5% size:72.5%
the forest has recovered.

41:56.433 --> 42:00.333 align:left position:45% line:5% size:45%
♪ ♪

42:00.333 --> 42:02.766 align:left position:40% line:5% size:50%
MILLER:
And it's right there
when the animals can specialize

42:02.766 --> 42:05.533 align:left position:20% line:5% size:70%
in eating certain kinds
of plants.

42:05.533 --> 42:08.366 align:left position:37.5% line:5% size:52.5%
NARRATOR:
And get bigger.

42:08.366 --> 42:11.833 align:left position:22.5% line:5% size:67.5%
These new plant-eaters
were now larger

42:11.833 --> 42:13.200 align:left position:17.5% line:5% size:72.5%
than mammals had ever been

42:13.200 --> 42:17.466 align:left position:17.5% line:83% size:72.5%
in over 100 million years
on the planet.

42:17.466 --> 42:19.866 align:left position:45% line:89% size:45%
♪ ♪

42:19.866 --> 42:24.933 align:left position:12.5% line:83% size:77.5%
They've shattered their record
in just a fraction of that time.

42:24.933 --> 42:28.133 align:left position:22.5% line:83% size:67.5%
And their growth spurt
was just beginning.

42:34.066 --> 42:36.233 align:left position:42.5% line:77% size:47.5%
LYSON:
In the very upper part
of the bluffs,

42:36.233 --> 42:43.100 align:left position:10% line:83% size:80%
I started to find a whole array
of large and diverse mammals.

42:48.733 --> 42:52.533 align:left position:10% line:83% size:80%
One of the mammals that we found
is called taeniolabis.

42:52.533 --> 42:57.133 align:left position:20% line:83% size:70%
This is about 80 pounds,
so really a large animal.

42:58.933 --> 43:01.300 align:left position:37.5% line:83% size:52.5%
NARRATOR:
It was ten times the size

43:01.300 --> 43:05.566 align:left position:30% line:83% size:60%
of the omnivore
they'd found earlier.

43:05.566 --> 43:08.966 align:left position:42.5% line:77% size:47.5%
LYSON:
It had these really big
incisors,

43:08.966 --> 43:11.166 align:left position:15% line:83% size:75%
much like modern-day beavers
have.

43:14.033 --> 43:17.633 align:left position:10% line:83% size:80%
We think this animal was living
in or near the rivers,

43:17.633 --> 43:22.400 align:left position:10% line:83% size:80%
because we only find this animal
in riverine sediments.

43:22.400 --> 43:25.733 align:left position:45% line:89% size:45%
♪ ♪

43:28.200 --> 43:29.833 align:left position:37.5% line:83% size:52.5%
NARRATOR:
Near this fossil,

43:29.833 --> 43:34.433 align:left position:22.5% line:83% size:67.5%
Tyler finds the skull
of an even bigger mammal.

43:34.433 --> 43:39.566 align:left position:42.5% line:77% size:47.5%
LYSON:
This is a large animal
that was about 100 pounds,

43:39.566 --> 43:42.666 align:left position:12.5% line:89% size:77.5%
so almost the size of a wolf.

43:42.666 --> 43:47.100 align:left position:10% line:83% size:80%
And this animal had really big,
flat back teeth,

43:47.100 --> 43:51.633 align:left position:10% line:83% size:80%
and it seems to be eating seeds
and other plants.

43:51.633 --> 43:55.000 align:left position:37.5% line:77% size:52.5%
NARRATOR:
In less than a million years
since the extinction,

43:55.000 --> 43:59.933 align:left position:22.5% line:83% size:67.5%
mammals have exploded
from just a couple of pounds.

43:59.933 --> 44:02.366 align:left position:17.5% line:89% size:72.5%
Some are 50 times bigger.

44:05.566 --> 44:12.200 align:left position:10% line:83% size:80%
It would take nearly 20 million
years to make such a leap again.

44:12.200 --> 44:15.900 align:left position:17.5% line:83% size:72.5%
But what might have fueled
this dramatic change?

44:19.566 --> 44:22.133 align:left position:27.5% line:83% size:62.5%
An intriguing clue
lay just a few feet

44:22.133 --> 44:24.433 align:left position:17.5% line:89% size:72.5%
from the beasts' remains.

44:24.433 --> 44:28.600 align:left position:17.5% line:89% size:72.5%
(kids talking in distance)

44:28.600 --> 44:30.766 align:left position:10% line:89% size:80%
Ian was leading a group of teens

44:30.766 --> 44:33.566 align:left position:22.5% line:83% size:67.5%
studying at the museum
for the summer.

44:33.566 --> 44:36.533 align:left position:10% line:83% size:80%
Probably about...
I'd say about the same...

44:40.033 --> 44:41.466 align:left position:40% line:77% size:50%
MILLER:
We were doing all kinds
of different things,

44:41.466 --> 44:44.566 align:left position:20% line:83% size:70%
and it wasn't a terribly
exciting site.

44:44.566 --> 44:47.733 align:left position:10% line:83% size:80%
A lot of fossils people hand you
are just sticks.

44:47.733 --> 44:48.900 align:left position:12.5% line:83% size:77.5%
So, a lot of people are just,
like,

44:48.900 --> 44:50.000 align:left position:35% line:5% size:55%
"Oh, this is
an incredible fossil!"

44:50.000 --> 44:51.033 align:left position:37.5% line:5% size:52.5%
I'm, like,
"Yeah, it's just a stick,"

44:51.033 --> 44:52.133 align:left position:15% line:5% size:75%
you know, "throw that back."

44:52.133 --> 44:56.766 align:left position:22.5% line:83% size:67.5%
But this one student,
her name is Aeon.

44:56.766 --> 44:58.866 align:left position:10% line:83% size:80%
We're thinking about moving on,
and going somewhere else,

44:58.866 --> 45:03.133 align:left position:17.5% line:83% size:72.5%
and she hands me this rock
and she's, like, "What's this?"

45:03.133 --> 45:06.933 align:left position:35% line:77% size:55%
Did you get something?
I don't know.

45:06.933 --> 45:08.000 align:left position:25% line:83% size:65%
And so I took it up,
looked at it in the light,

45:08.000 --> 45:09.300 align:left position:27.5% line:89% size:62.5%
and lo and behold,

45:09.300 --> 45:12.066 align:left position:22.5% line:83% size:67.5%
it was the middle part
of a bean pod.

45:12.066 --> 45:14.933 align:left position:10% line:5% size:80%
Um, I found this legume
two seconds ago

45:14.933 --> 45:16.866 align:left position:10% line:5% size:80%
from this rock
that's sitting in my lap.

45:16.866 --> 45:20.933 align:left position:72.5% line:77% size:17.5%
MILLER:
Right here, 700,000 years
into the recovery.

45:20.933 --> 45:23.700 align:left position:22.5% line:83% size:67.5%
This is the earliest record
of the legume family ever

45:23.700 --> 45:25.200 align:left position:37.5% line:89% size:52.5%
in the fossil record.

45:25.200 --> 45:28.700 align:left position:22.5% line:89% size:67.5%
So that's pretty cool.

45:32.966 --> 45:35.466 align:left position:37.5% line:5% size:52.5%
NARRATOR:
Aeon's legume was alive
right at the time

45:35.466 --> 45:40.200 align:left position:27.5% line:5% size:62.5%
when mammals' size
was exploding.

45:40.200 --> 45:43.133 align:left position:15% line:89% size:75%
A new food for a new world.

45:43.133 --> 45:46.566 align:left position:45% line:89% size:45%
♪ ♪

45:46.566 --> 45:51.133 align:left position:10% line:89% size:80%
Legumes are very special plants.

45:51.133 --> 45:54.466 align:left position:20% line:83% size:70%
Today, there are almost
20,000 species of them,

45:54.466 --> 45:59.333 align:left position:27.5% line:83% size:62.5%
including peanuts,
lentils, and soybeans.

45:59.333 --> 46:03.500 align:left position:25% line:83% size:65%
Their signature pods
are packed with nutrients.

46:03.500 --> 46:07.033 align:left position:45% line:89% size:45%
♪ ♪

46:07.033 --> 46:08.333 align:left position:40% line:83% size:50%
MILLER:
Legumes are like

46:08.333 --> 46:11.200 align:left position:22.5% line:83% size:67.5%
these protein bars for
the mammals on the landscape,

46:11.200 --> 46:16.633 align:left position:10% line:83% size:80%
and at that same moment, we see
all these new and large mammals,

46:16.633 --> 46:18.100 align:left position:35% line:83% size:55%
and we think
that they're taking advantage

46:18.100 --> 46:19.866 align:left position:20% line:89% size:70%
of this new food source.

46:23.300 --> 46:27.100 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Taken together, the many fossils
of Corral Bluffs

46:27.100 --> 46:32.500 align:left position:15% line:83% size:75%
suggest plants were helping
to drive mammal evolution.

46:32.500 --> 46:37.100 align:left position:12.5% line:83% size:77.5%
And a final piece of evidence
reveals how plants, in turn,

46:37.100 --> 46:39.733 align:left position:27.5% line:83% size:62.5%
were being driven
by something else.

46:39.733 --> 46:41.400 align:left position:45% line:89% size:45%
♪ ♪

46:41.400 --> 46:45.733 align:left position:10% line:83% size:80%
Ian uncovers clues to one of the
planet's most powerful forces--

46:45.733 --> 46:48.466 align:left position:40% line:89% size:50%
climate.

46:48.466 --> 46:53.266 align:left position:17.5% line:83% size:72.5%
He zeroes in on the shape
of the leaves he's unearthed.

46:53.266 --> 46:55.266 align:left position:40% line:77% size:50%
MILLER:
The more species you have
with serrations,

46:55.266 --> 46:56.866 align:left position:27.5% line:89% size:62.5%
the cooler it is;

46:56.866 --> 47:00.666 align:left position:10% line:83% size:80%
the more smooth leaves you have,
the warmer it is.

47:00.666 --> 47:03.200 align:left position:12.5% line:83% size:77.5%
And so we can use that to tell
temperature in the past.

47:03.200 --> 47:05.266 align:left position:45% line:89% size:45%
♪ ♪

47:05.266 --> 47:08.433 align:left position:37.5% line:77% size:52.5%
NARRATOR:
The size of the leaves
can reveal rainfall.

47:08.433 --> 47:11.000 align:left position:30% line:89% size:60%
(thunder booms)

47:11.000 --> 47:13.200 align:left position:40% line:83% size:50%
MILLER:
If you've got a really big leaf,

47:13.200 --> 47:15.866 align:left position:15% line:83% size:75%
it means that you're growing
in a world that rained a lot,

47:15.866 --> 47:17.800 align:left position:27.5% line:83% size:62.5%
and so the forest
was really dense.

47:19.633 --> 47:22.700 align:left position:37.5% line:77% size:52.5%
NARRATOR:
Most of the fossil leaves
from Corral Bluffs

47:22.700 --> 47:25.033 align:left position:22.5% line:89% size:67.5%
are smooth and large.

47:27.733 --> 47:31.866 align:left position:12.5% line:83% size:77.5%
Together, they paint a picture
of a very different Colorado

47:31.866 --> 47:34.366 align:left position:22.5% line:89% size:67.5%
65 million years ago.

47:34.366 --> 47:38.700 align:left position:45% line:89% size:45%
♪ ♪

47:40.833 --> 47:44.966 align:left position:40% line:77% size:50%
MILLER:
We're probably looking at a
world that's more like Florida.

47:44.966 --> 47:47.933 align:left position:12.5% line:83% size:77.5%
It's pretty wet, pretty humid,
and pretty darn warm.

47:50.533 --> 47:54.466 align:left position:37.5% line:77% size:52.5%
NARRATOR:
This climate shaped the plants
and the creatures

47:54.466 --> 47:55.800 align:left position:27.5% line:89% size:62.5%
that evolved here.

47:55.800 --> 47:59.900 align:left position:45% line:89% size:45%
♪ ♪

47:59.900 --> 48:04.033 align:left position:40% line:77% size:50%
GOSWAMI:
No organism evolves or lives
in isolation, right?

48:04.033 --> 48:07.133 align:left position:15% line:5% size:75%
Everything about them really
reflects their interactions

48:07.133 --> 48:08.766 align:left position:20% line:5% size:70%
with their environment,
with other species.

48:08.766 --> 48:13.100 align:left position:15% line:83% size:75%
We really need to understand
those relationships.

48:13.100 --> 48:16.900 align:left position:10% line:83% size:80%
We want to build up a picture of
how life evolved in this period.

48:16.900 --> 48:19.600 align:left position:45% line:89% size:45%
♪ ♪

48:19.600 --> 48:25.300 align:left position:37.5% line:77% size:52.5%
NARRATOR:
In the first two years after
Tyler and Ian made their find,

48:25.300 --> 48:29.266 align:left position:25% line:83% size:65%
their team collected
over 1,000 vertebrate fossils.

48:29.266 --> 48:31.866 align:left position:45% line:89% size:45%
♪ ♪

48:31.866 --> 48:34.166 align:left position:27.5% line:89% size:62.5%
Some 6,000 plants.

48:34.166 --> 48:35.866 align:left position:45% line:89% size:45%
♪ ♪

48:35.866 --> 48:38.200 align:left position:10% line:89% size:80%
And the end is nowhere in sight.

48:38.200 --> 48:43.033 align:left position:45% line:89% size:45%
♪ ♪

48:43.033 --> 48:46.966 align:left position:42.5% line:77% size:47.5%
LYSON:
The discovery at Corral Bluffs
is remarkable for many reasons.

48:46.966 --> 48:49.066 align:left position:15% line:89% size:75%
We have the whole ecosystem,

48:49.066 --> 48:51.066 align:left position:32.5% line:83% size:57.5%
and we have it
at different intervals of time.

48:51.066 --> 48:54.200 align:left position:22.5% line:83% size:67.5%
I mean, we're dealing
with the entire story here.

48:55.666 --> 48:59.000 align:left position:37.5% line:83% size:52.5%
NARRATOR:
So far, that story includes

48:59.000 --> 49:03.166 align:left position:15% line:83% size:75%
16 different mammal species
they've found.

49:03.166 --> 49:07.566 align:left position:15% line:83% size:75%
It's an extraordinary record
that unites plants, animals,

49:07.566 --> 49:09.666 align:left position:27.5% line:89% size:62.5%
climate, and time

49:09.666 --> 49:11.900 align:left position:25% line:89% size:65%
in a single picture.

49:11.900 --> 49:14.933 align:left position:45% line:89% size:45%
♪ ♪

49:14.933 --> 49:19.200 align:left position:40% line:77% size:50%
SHUBIN:
So, what Tyler and Ian have
discovered is a Rosetta Stone.

49:19.200 --> 49:22.000 align:left position:10% line:83% size:80%
And Corral Bluffs is telling us
something very important.

49:22.000 --> 49:25.400 align:left position:10% line:5% size:80%
It's telling us about ourselves,
how we got to be here.

49:28.666 --> 49:30.400 align:left position:25% line:89% size:65%
(rock cracks loudly)

49:30.400 --> 49:33.033 align:left position:45% line:89% size:45%
♪ ♪

49:33.033 --> 49:36.400 align:left position:37.5% line:77% size:52.5%
NARRATOR:
The team's discoveries,
along with other evidence,

49:36.400 --> 49:40.900 align:left position:25% line:83% size:65%
trace the beginning
of the mammals' fateful rise.

49:40.900 --> 49:42.066 align:left position:45% line:89% size:45%
♪ ♪

49:42.066 --> 49:44.233 align:left position:27.5% line:89% size:62.5%
(explosion booms)

49:44.233 --> 49:47.966 align:left position:10% line:89% size:80%
Few survived the impact winter.

49:47.966 --> 49:53.566 align:left position:17.5% line:83% size:72.5%
But as the climate warmed,
plants regained lost ground.

49:53.566 --> 49:58.366 align:left position:20% line:83% size:70%
Small creatures endured,
eating whatever they could find.

49:58.366 --> 50:01.000 align:left position:27.5% line:89% size:62.5%
Forests recovered,

50:01.000 --> 50:05.800 align:left position:27.5% line:83% size:62.5%
and fueled mammals
as they exploded in size

50:05.800 --> 50:09.233 align:left position:20% line:89% size:70%
and took on new forms...

50:09.233 --> 50:12.133 align:left position:35% line:83% size:55%
All in less
than a million years.

50:12.133 --> 50:16.400 align:left position:45% line:89% size:45%
♪ ♪

50:16.400 --> 50:20.700 align:left position:17.5% line:83% size:72.5%
In the ages that followed,
mammals seized empty niches.

50:20.700 --> 50:22.700 align:left position:27.5% line:89% size:62.5%
(large cat growls)

50:22.700 --> 50:27.666 align:left position:10% line:89% size:80%
Our ancestors scaled the trees.

50:27.666 --> 50:30.633 align:left position:20% line:89% size:70%
Others took to the air,

50:30.633 --> 50:35.100 align:left position:12.5% line:89% size:77.5%
or became giants of the seas.

50:35.100 --> 50:38.566 align:left position:35% line:83% size:55%
Mammals rose
to dominate the planet.

50:38.566 --> 50:41.500 align:left position:45% line:89% size:45%
♪ ♪

50:41.500 --> 50:43.833 align:left position:27.5% line:89% size:62.5%
All this diversity

50:43.833 --> 50:47.866 align:left position:25% line:83% size:65%
sprang from the band
of humble creatures

50:47.866 --> 50:50.733 align:left position:10% line:89% size:80%
that emerged from the cataclysm.

50:50.733 --> 50:53.266 align:left position:45% line:89% size:45%
♪ ♪

50:53.266 --> 50:55.933 align:left position:40% line:83% size:50%
JOHNSON:
They inherited a whole world

50:55.933 --> 50:57.600 align:left position:20% line:83% size:70%
and they had the planet
to play in.

50:57.600 --> 51:02.866 align:left position:30% line:83% size:60%
And that moment
of rapid mammal evolution

51:02.866 --> 51:04.700 align:left position:17.5% line:89% size:72.5%
is effectively the trigger

51:04.700 --> 51:06.666 align:left position:22.5% line:83% size:67.5%
to our existence here
on planet Earth.

51:06.666 --> 51:09.433 align:left position:45% line:89% size:45%
♪ ♪

51:09.433 --> 51:13.266 align:left position:37.5% line:77% size:52.5%
NARRATOR:
By unveiling the start
of the mammals' explosion,

51:13.266 --> 51:17.066 align:left position:15% line:83% size:75%
Corral Bluffs seems destined
to join the ranks

51:17.066 --> 51:20.300 align:left position:25% line:83% size:65%
of other celebrated
fossil sites,

51:20.300 --> 51:23.933 align:left position:22.5% line:83% size:67.5%
like Tyler's back yard
in North Dakota.

51:23.933 --> 51:25.833 align:left position:42.5% line:83% size:47.5%
LYSON:
I can trace those same questions

51:25.833 --> 51:28.133 align:left position:22.5% line:83% size:67.5%
that I'm asking today
out on the bluffs

51:28.133 --> 51:31.500 align:left position:12.5% line:83% size:77.5%
all the way back to when I was
six or seven years old,

51:31.500 --> 51:35.566 align:left position:15% line:83% size:75%
running around the badlands
looking for fossils.

51:39.366 --> 51:41.300 align:left position:37.5% line:83% size:52.5%
NARRATOR:
By pursuing those questions,

51:41.300 --> 51:44.633 align:left position:20% line:83% size:70%
Tyler and his colleagues
are helping us understand

51:44.633 --> 51:49.400 align:left position:20% line:83% size:70%
how the planet recovered
from catastrophe.

51:49.400 --> 51:54.766 align:left position:25% line:83% size:65%
They're illuminating
the dawn of a new world.

51:54.766 --> 51:56.966 align:left position:37.5% line:89% size:52.5%
Our world.

51:58.766 --> 52:01.800 align:left position:45% line:89% size:45%
♪ ♪

52:16.933 --> 52:24.466 align:left position:45% line:89% size:45%
♪ ♪

52:28.300 --> 52:35.833 align:left position:45% line:89% size:45%
♪ ♪

52:37.466 --> 52:45.000 align:left position:45% line:89% size:45%
♪ ♪

52:46.633 --> 52:54.166 align:left position:45% line:89% size:45%
♪ ♪

52:59.900 --> 53:07.133 align:left position:45% line:89% size:45%
♪ ♪