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>> [Background music] It was definitely the biggest adventure
of my life.
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This was the Canadian Arctic.
Hundreds of miles away from any settlement.
We had a narrow summer window of a few weeks,
when the weather cooperates just long enough to let us in.
If we were lucky, we'd reveal a desert landscape
with freshly-exposed rocks.
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Traveled thousands of miles to find fossils from one
of the great transitions of evolution:
the move of vertebrates from water to land.
We were experienced fossil hunters.
>> You gotta go higher Neil.
>> But now, we have to learn to become polar explorers.
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This part of the Arctic has rocks of the right age
and the right type to hold evidence of a great transition,
when our ancient fish ancestors moved from water onto land.
It's hard to believe, when you look at this frozen landscape,
that once this was a warm,
watery world, swimming with life.
This valley, 375 million years ago, was a giant flood plain.
And that flood plain was filled with rivers
that swelled their banks and sometimes shrunk.
But, in those conditions, formed swamps and streams
of all different sizes.
And inside those streams, was diverse life.
And somewhere out there, our distant relatives sank
into muddy graves, which would preserve them
for 375 million years.
At the end of our stay in 2000,
we found a hill loaded with fossils.
And over the next 4 years we dug hoping
to find the fossils we were looking for.
>> Well, it's the second week of July in 2004.
We're all working in series in this hole.
You know, my head is right next to Farrish's feet.
And Farrish's feet is next to Steve [inaudible].
We're digging together.
Steve says, hey guys, what's this?
Ted and I go running over to see what Steve was referring to.
And what we saw was this "V" here,
which was covered with rock.
And as soon as we saw this "V", and we saw these teeth under it,
it became very clear that this little
"V" we're seeing is the tip of a snout.
And that this was a snout of a flat headed fish.
>> Based on other fossils, from slightly younger rocks,
this feature alone suggested we might have a transitional fish.
>> Okay, we get home.
We knew we had a flat headed fish.
But, how much of it did we have?
Then about a month and a half goes by.
And they start to find the orbits, the eyehole.
And then we see the shoulder.
And then we see the fins.
And then we see more and more and more and more
until we see pretty much the entire top side of the body.
So, you can not only say, okay, what did this animal look like?
But, we can begin to ask, you know, how did it work?
How did it move about in these 375 million year old streams?
>> The local Inuit people came
up with the name Taktallik for our fossil.
It means large, fresh water fish.
But, although this creature had the scales and fin of a fish,
it also had the flat head and rotating neck of a land animal.
And when we looked at its fins,
we realized it had the beginnings
of the bone structure that's shared
by all 4-limbed vertebrates today.
It had versions of an upper arm, a forearm,
even parts of a wrist.
This was a fish from a pivotal moment in evolutionary history.
Descendants of fish like Tiktaalik would go
on to spawn reptiles, mammals, and eventually us.
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