[ Woman ] The National Science Foundation, where discoveries begin.
[ Man Narrating ] Beneath the earth we know...
lie other worlds...
hidden from sight...
lost in time.
But sometimes we can glimpse a lost world...
through remnants of the past.
We definitely got a skull. Lower right. What do you think?
It's hard to say.
[ Narrator] This story begins with a discovery of unidentified bones.
Depositional environment?
A team of paleontologists will try to figure out whose bones they are...
and what world they came from.
So we got a time frame. That's a start.
[ Narrator ] They were discovered in Kansas—
mostly farmland today.
But once, Kansas lay beneath a vast sea.
It was 82 million years ago...
during the age ofthe dinosaurs.
[ Roaring ]
But there was anotherworld of giants on Earth...
a submerged world...
where enormous reptiles ruled seas filled with incredible creatures.
These...
were the most dangerous seas ofall time.
No living thing was safe.
The great marine reptiles disappeared long ago...
and time has buried their world.
But any of us might still encounter a sea monster.
- [ Dog Whining ] - Buddy!
[ Whining Continues ]
[ Narrator ] As iffrom nowhere, the distant past returns.
The scientists hope to find notjust the fossil ofan ancient creature...
but a story recorded in its bones.
Grab your tools.
Rain washed some ofthe chalk away and exposed it.
This is great. Okay—
[ Narrator] They recognize it as something special...
a rare Dolichorhynchops—
a dolly, for short.
It was a marine reptile ofthe late Cretaceous...
a little bigger than a dolphin...
and a fast swimmer.
To unravel any story the bones may tell...
the investigators will draw on everything they know about marine reptiles.
Yeah, it looks like Hesperornis.
[ Narrator ] Their fossils have been found around the world over decades.
It could have been over 30 feet long.
The matrix materials we've got in the lab seem to indicate—
[ Narrator ] These finds will help the team piece together the story ofthe dolly...
and picture the moment in time when it swam in the sea.
In many ways, the dolly's world was far different from ours.
The climate was warmer.
Sea levels were higher, and more of Earth was submerged.
This dolly would have lived in a vast inland sea...
that cut North America in two.
Marine reptiles were also found in the waters around Europe...
which was a scattering of islands...
and throughout the world's oceans.
In time they died out...
and sea levels retreated...
exposing vast areas ofseabed.
Fossils from the ancient oceans turned up on every continent.
A discovery in the Australian outback...
offers clues to how the dolly's life may have begun.
It seems to be laying out in a pretty consistent pattern.
95% of the fossils we're finding here are the bones of juveniIes.
[ Narrator] So many small bones in one area...
suggests that marine reptiles gathered in protected shallows to give birth.
And in North America, that's how the story of this dolly...
begins to unfold.
Imagine that one of the creatures in the shallows...
is a pregna nt Dolichorhynchops.
She gives birth to a male...
1 8 inches long and colored like his mother...
and a female...
darker in color with light patches below her eyes.
And it's her life we begin to follow.
She and her brother are air breathers.
Instinct tells them what they have to do in their first minute alive.
From the beginning...
the little female and her brother practice skills they'll need one day...
when they'll have to leave the safety ofthe shallows for the dangerous seas beyond.
If she survives the perils to come...
she'll return here one day and have young of her own.
Already she finds competition for food.
There's the Hesperornis...
a bird that can't fuy and has a beak full of sharp teeth.
And the Styxosaurus...
a distant cousin of the dolly's...
with a supersized neck.
An adult can reach 35 feet in length...
more than half of it neck.
Its shape makes it a slower swimmer...
but it's great for catching fish.
The little dolly soon comes across creatures that move...
by pumpingjets of water from their shells.
They're called ammonites...
and they thrive in the ancient sea.
They have rock-hard armor and perhaps another def ense.
Swim too close, like the little female...
and get a face full of ink.
But that doesn't stop a young Platecarpus...
when it wants a snack.
Ammonites were once abundant.
Their fossils have been uncovered often...
even by a road crew in Texas.
Ammonites. A lot of 'em.
[ Narrator ] There were many kinds of ammonites...
and we know when most of them lived...
so their fossils are like markers in time.
Identify an ammonite and you can date other less common fossils nearby.
That helps place dollies in the long history of marine reptiles.
It began some 250 million years ago...
in the Triassic period...
with land reptiles that moved into the sea.
They developed webbed feet, then fuippers.
Some had elaborate armor.
Into theJurassic, they continued to evolve.
To see at great depths...
some had eyes the size of dinner plates—
top predators who grew immense and powerful...
reaching their peak in the late Cretaceous...
near the end of the dinosaur age...
the very time when the Dolichorhynchops lived .
Months have passed.
The female and her brother are nowjuveniles...
but they're still in the safety of the shallows...
and unaware of the huge predators in the sea beyond.
For now, they are mastering the art of catching their f avorite prey—
herring-like fish called Enchodus.
Then one day, everything changes f or the dollies.
Perhaps it's a change of seasons...
t hat causes t he Enchodus to head out to sea on a migration.
The dollies must follow their main source of food.
And that means the young f emale and her brother...
must now set out on thejourney of their lives...
trailing their mother f rom the shallows...
out into the Western Interior Sea.
It's about the size of the Mediterranean...
and only a few hundred feet deep...
but somewhere ahead are enormous predators.
We know because...
where those predators once swam...
the layered earth holds their remains...
as if a vast graveyard.
Exposed to wind and rain...
it gradually reveals what's within.
A remarkable discovery was made by Charles Sternberg and his sons...
pioneering fossil collectors in the American Midwest.
I covered it so nobody else would notice and disturb it.
Ah. Yeah.
SkuIl looks like some kind of tylosaur. Big one.
Levi, be sure to look over there.
[ Narrator ] It was a creature like this...
the dollies might encounter in deeperwater...
waters filled with dangers.
The Tusoteuthis was a massive hunter...
like the giant squid of today...
up to 30 feet long and abundant in the inland sea.
It was too big to be attacked by the Platecarpus...
who settles f or smaller prey.
Platecarpus itself was fierce...
but not in the same league as its larger relative...
the creature the Sternbergs had found.
Few ocean predators ever would compare with the beast they were uncovering.
Think I've got some taiI vertebrae over here.
Could be Iower limb bones. Part of a paddIe.
SkuIl here. Paddle there.
Tail vertebra over there.
This f ella could be giant-sized.
[ Narrator] It was a giant with no enemy...
a great reptile called Tylosaurus...
one of the largest and most ferocious creatures of any age.
A fossil of a closely related beast tells us more.
[ Speaking Hebrew ]
Its eyes were as big as grapefruits.
Cone-shaped teeth filled itsjaws...
and the roof of its mouth perfect for seizing prey.
The tylosaurs were out there...
but there were other predators more easily spotted.
As fish go, Xiphactinus was gigantic...
up to 1 7 feet long.
More than twice the size of the little female dolly...
it was a hunter that could kill quickly...
and this day one did.
♪♪ [ Radio: Country ]
We know what happened from a fossil excavated in the badlands of Kansas...
by Charles Sternberg's son George.
Mr. Sternberg?
I called f rom the newspaper.
There's a lot of talk about what you found out here.
- GIad you couId come. - Well, thankyou.
- Caught a pretty big fish here. - What is it, exactly?
This is a 1 3-foot Xiphactinus. But there's more to it.
As I went through digging out the fossiI...
I noticed something beneath the ribs.
I found some vertebrae, kept on going.
Turned out to be an entire animaI inside.
The victim was a six-foot fish called a Gillicus—
such a mouthful that swallowing it killed the Xiphactinus...
a prehistoric victim of gluttony.
[ Water Splashing ]
Weeks pass, and the dollies are now far from any shore—
venturing into a sea turned magical by night.
Microscopic plankton give off an eerie glow.
Under cover of darkness, the Enchodus rest...
not quite sleeping.
Below, there's a mass spawning of straight-shelled ammonites.
The dollies keep their eyes trained for predators.
And one is about to change their lives.
[ Man ] There's hundreds of sharks' teeth here.
[ Narrator ] After a long day hunting fossils...
two amateur collectors unearthed a wealth of sharks' teeth.
So many have been found around the world...
that it's clear sharks were thriving during the age of the sea monsters.
The Cretoxyrhina is as big and lethal...
as the Great White of our day.
It slices its victims into bite-size chunks, using razor-sharp teeth.
[ Whirring, CIicking ]
[ Speaking Dutch ]
[ Narrator] There is evidence from a Dutch quarry...
that ancient sharks fed on even the largest marine reptiles...
leaving tooth marks on their bones.
The female and her brother are being watched.
But it's their mother who becomes the target.
[ Squealing ]
Their mother is gone, but it isn't over.
A smaller shark goes after the young female.
She's wounded...
but she survives the initial charge.
Perhaps the shark was not as lucky.
Her injury will heal...
though she'll always carry a shark's tooth embedded in her fuipper.
The two youngsters must now continue on their own.
If the f emale and her brother are going to survive...
they'll have to find food and their way...
in this vast inland sea.
Finally, they see something familiar-
a school of Enchodus trailed by other dollies...
and by the flightless Hesperornis.
[ Squawks ]
But nearly anything in the sea—
can be a meal for a tylosaur.
[ Man ] This one died with a full stomach.
Yeah, it looks Iike a, uh, Hesperornis.
Big as a pelican. Maybe bigger.
[ Narrator] The stomach contents ofa single tylosaur...
reveal its enormous appetite.
This looks like the bone ofa three-to-five foot long teleost fish.
Got a bone here from a smalI mosasaur.
Probably the size ofan alligator.
And it seems like he swaIlowed a shark.
Big eater, this guy.
[ Narrator] For several weeks, the travelers push on.
The female's flipper is slowly healing...
the embedded tooth now surrounded my scar tissue.
The young female is drawn away by a potential meal ofsquid.
One escapes among a colony ofcrinoids—
prehistoric relatives ofsea stars—
perhaps swept up from the bottom by currents.
The female has put herself directly in the sights ofa giant.
Taking the exposed parts ofthe skeleton together-
skull to tail— I make the specimen about a 29-footer.
Yeah.
There's something in the stomach.
[ Narrator ] They had found the monster's last meal...
entombed within its ribs.
Because dollies are fast...
a tylosaur's best bet is to catch one by surprise.
[ Hissing, Roaring ]
The female escapes.
But her brother doesn't see the danger coming.
The Sternbergs had discovered a story locked in time...
oftwo ancient lives intersecting.
But why did the predator die so soon after eating the dolly?
Tylosaurs were likely territorial and aggressive, even with each other.
Perhaps an older tylosaur suddenly appeared.
The younger tylosaur is threatened and tiring...
slowed down by the large meal in his stomach.
The female dolly is forgotten.
[ Bones Snap ]
The younger tylosaur is mortally wounded.
But his story isn't over.
His final fate was recorded in stone.
A shark's tooth lay near the fossil.
Look at this.
The female moves on with the others.
Soon the scavenging will begin.
The young dolly has seen the deaths of her mother and brother...
but she survived.
Each year, marine reptiles gather again...
in the birthing grounds ofthe shallows.
Among them is the dolly with the wounded flipper...
now fully grown.
She's completed herjourney and returned to the waters of her birth.
And after several seasons, she becomes a mother.
Heryoung will grow larger and stronger...
and, one day, set out on their ownjourney through the inland sea.
Day by day, month by month...
life plays out.
She sees several litters of her offspring mature...
and depart on lives oftheir own.
Eventually, a year comes when the mother can't finish the migration.
One quiet day...
when old age has weakened her body...
her life comes to a gentle end.
Millions ofyears' worth ofdays and nights and seasons pass...
as she lies undisturbed.
Sea levels rise and fall.
Around the world, continents shift...
and volcanic activity changes the face ofthe Earth.
New species appear, and old species vanish—
including the last ofthe sea monsters.
Beneath the shifting land, the remains ofthe great ocean reptiles...
are turned by time into rock.
[ Girl ] Buddy!
- And lie hidden until exposed. - Buddy!
This time, by a summer rain.
[ Woman Chattering ]
[ Man ] It might be a compIete specimen.
[ Woman ] How are we gonna take it out?
We may have to plaster the whole thing and take it out in a jacket.
[ Woman ] Hey. Come check this out.
[ Narrator ] There was something unusual about one ofthe rear flippers—
a shark's tooth embedded between the bones.
After 82 million years...
the female DoIichorhynchops has returned to tell her story.
There are countless other creatures still buried within the layers ofthe Earth—
waiting for us to find them...
waiting to tell us stories ofour world when it was theirs.
♪♪ [ Woman Vocalizing ]
♪ Looking for clues, traces and signs ♪
♪ Scraping away the dirt and dust of time ♪
♪ Oh, yes, a long time ♪
♪ Digging out the mud that conceals ♪
♪ Take it away and it reveals ♪
♪ Hidden stories, hidden lives ♪
♪ Hidden stories hidden lives ♪
[ Man ] ♪ These are the marks and scars of time ♪
♪ We're digging at the mud ♪
♪ These are the fragments ofthe long-gone days ♪
♪ We're digging out ofthe mud ♪
♪♪ [ Vocalizing ]
♪ Opening stories ofa diff erent life ♪
♪ Beneath the surface the unknown lies ♪
♪ Stripping away the mark and scars of time ♪
♪ Oh, the mark and scars of time ♪
♪ Scraping away what layers remain ♪
♪ To touch the level that contains ♪
♪ Different stories, different lives ♪
♪ Different stories different lives ♪
♪ These are the marks and scars of time ♪
♪ We're digging at the mud ♪
♪ These are the fragments ofthe long-gone days ♪
♪ We're digging out ofthe mud ♪
♪♪ [ Vocalizing ]
♪ Opening stories ofa diff erent life ♪
♪ These are the marks and scars of time ♪
♪ We're digging at the mud ♪
♪ These are the fragments ofthe long-gone days ♪
♪ We're digging out ofthe mud ♪
♪♪ [ Vocalizing ]
♪ Opening stories ofa diff erent life ♪
♪ Of a different life ♪♪
♪♪ [ Fades Out ]