They were the most extraordinary
creatures ever to walk the land.
Some were huge,
some were terrifying,
and some were downright bizarre,
but they all had one thing in common,
they live in our own backyards.
Journey back to a time when
the world was a jungle primeval,
and dinosaurs roamed America.
To most New Yorkers, the hustle and
bustle of downtown Manhattan is where
the action is, but 225 million years ago,
this was no-man's land.
Smack in the middle of nowhere.
All the continents were joined together in one giant super-continent, called Pangaea.
Now it was breaking up.
North America was tearing away from Africa along a rift parallel to the present-day East Coast.
As the rift widened, it gave birth to the
Atlantic Ocean, and created a string of
freshwater lakes scientists call the
Newark supergroup.
Back then, an evening on planet Earth looked like a scene out of science fiction.
On the surface, an eerie gloom pervades
the atmosphere.
About 20 million years earlier,
evidence indicates an asteroid crashed to Earth.
The collision triggered the Permian
extinction,
which wiped out over 90 percent of all living things.
Out of the disaster, a new world was born.
It's the Triassic period.
After millions of years of evolution, 
conditions are ripe for something new,
something different,
the dinosaurs.
A freshwater lake is the local watering
hole,
but the customers don't always mix.
For Coelophysis, danger lurks just below
the surface.
Rutiodon is quick, but Coelophysis is
quicker
The Triassic period is the heyday of the reptiles.
To exploit the vacuum left by the Permian extinction,
reptiles evolved into
a variety of different species.
Now they come in all different shapes and
sizes.
Some are docile plant eaters,
others, like Coelophysis, are predators.
Coelophysis may look like your average
reptile, but it's not, it's unusually fast
on its feet, curious, and alert.
Icarosaurus is the first reptile to learn how to glide.
A hungry dinosaur will try anything once.
Traversodon is a mammal-like reptile.
To improve its chances for survival
it feeds at night and sleeps all day in
a burrow.
Desmatosuchus is a docile plant-eater. It
uses its snout to nip ferns and root out
tubers. The armor is for protection, even
its belly is plated. The spikes on its
shoulders are a foot and a half long,
for good reason.
At 20 feet Rutiodon is one of the largest predators around.
Its legs are short and project outward
from its body, which inhibits speed.
Desmatosuchus is fair game for a
worthy predator,
but it's too much for Coelophysis
Insects have been around for over a
hundred million years and some are huge.
This locust can usually fly its way out
of trouble.
Coelophysis is built for speed. Its limbs
are powered by a large muscle that
extends from its thigh bone to its tail.
Its ankle bones are designed to keep its
feet straight while walking or running. A
right-angle hip joint and an open socket
positions its legs under its body, so it
stands upright and moved fully erect.
Its neck is long and shaped like an "S,"
lifting its head above its body for
greater visibility. Its fourth and fifth
fingers are short turning fore-limbs
once used for locomotion into hands
that can manipulate food.
With its long legs and erect gait it can run longer
and faster than any other reptile alive.
Soon the old order will slip away and
the dinosaurs will inherit the earth.
45 million years after the Permian
extinction the earth is once again under siege
Evidence suggests a comet entered
the Earth's gravitational pull and
disintegrated. Hurling a stream of
fragments toward the surface along
latitude 23 degrees. 2 fell on Canada 1
in France
forming a chain some 3,000 miles long. 2
more straight into Minnesota and the
Ukraine. With each impact clouds of
vaporized rock billowed into the
atmosphere, blotting out the Sun.
Here the Triassic period ends and the
Jurassic begins. Now the land belongs to
the dinosaurs and in time they'll be
bigger and better.
This is one of the most dramatic kinds of transitions we
can see in all of Earth history and in
this particular outcrop we actually
have the boundary between the Triassic
down here and the Jurassic up here.
This layer these layers especially this
white layer and this little black layer
which is a coal extent for miles around
in this area. Within this white layer we
found elevated amounts of the element
iridium which is relatively rare in the
Earth's crust, but relatively more
abundant in asteroids and comets. My
colleagues and I have concluded that
this white layer is evidence of an
impact of a giant asteroid on Earth. There are very
few places in the world you can see
anything like that and it makes this
spot absolutely unique.
A group of flesh eaters is on the prowl.
This is Syntarsus, at 10 feet from head to
tail, they're about the same size as
their forerunners in the Triassic, but
these guys aren't chasing bugs. They're
stalking dinosaurs.
Anchisaurus is a plant eater. Although it walks on all
fours it, spends most of its time on its
hind legs browsing in the trees. A claw
on its thumb is its only protection.
Syntarsus and Anchisaurus may look
similar now, but in the future they'll go
their separate ways. Anchisaurus will evolve into
sauropods, the largest plant eaters of
all time. Its leaf shape teeth are well
suited for plucking vegetation. Its neck
is long for reaching into trees, and the
claw on its foot is ideal for digging
are pulling down branches.
Syntarsus will evolve into Allosaurus and T. rex. iIs jaw is designed to
absorb the stress of struggling prey.
Its wishbone only found in birds, helps make
its arms more flexible and its 3-toed
feet allow for faster running than the
plant eaters.
Anchisaurus is clearly outclassed.
Only one thing intimidates a predator: a
bigger one.
Dilophosaurus towers over its
competitors and its prey.
This is no ordinary predator,
It's a triple threat, it can slash, bite, and run.
A meal comes all too soon when there's a
hungry mouth to feed.
But there's no time to relax when a
stranger is sneaking around.
The carcass of Anchisaurus is too large
for one sitting.
The dinosaurs will eat their fill, then they'll be back,
This is one of the most amazing slabs of
footprints I've ever seen.
The tracks are raised because it's the
mud that filled in the tracks rather
than push down as it would be if they were
were the actual tracks, but more abundant
on this slab are various different sizes
of dinosaur footprints. Particularly
theropod dinosaur footprints .There are
small individuals like this one here you
can see three toes right there. It was a
carnivore you can see from the very
sharp and large claws. This is about as
large as Late Triassic dinosaur
footprints get. Not all that much bigger
than the palm of my hand. When we get
over the Triassic-Jurassic boundary
however, we see an immediate and abrupt
increase in the maximum size of theropod
dinosaur tracks. We get up to the size of
truly large carnivorous animals. There
aren't many other kinds of footprints
around. Gone are tracks of things like
this Desmatosuchus and in their place is an
almost completely uniform assemblage of
various sizes of theropod dinosaur
footprints. Basically large and small
versions of this.
The rules of the forest are simple kill
or be killed, or steal.
Syntarsus may be a hunter, but it's also an opportunist.
Ironically, Dilophosaurus and Syntarsus
are family.
They're both ceratosaurs, but you'd
never know it.
Dilophosaurus is still a primitive
dinosaur. In the future carnivores will
have three fingers instead of four. Their
heads will grow larger, their bodies more
massive, and the crests will disappear.
Dilophosaurus may be top dog for now,
but when predators get bigger, so does
the prey. The descendants of Anchisaurus
have nowhere to go, but up.
Salt Lake City Utah lies nestled in a
valley at the foot of the Wasatch Range,
but a hundred and fifty million years
ago, these snow-capped mountains didn't exist.
Instead the climate was warm and
seasonal, and the land was a vast savanna
that stretched from Canada, south to New
Mexico, and from Idaho East to Nebraska.
It's the dry season.
As far as the eye can see, the once
burdened plane has shriveled to a few
scattered trees and drought resistant
plants. An empty stream bed is a highway to nowhere.
No rain has fallen for months and the
heat is relentless.
In times of drought dinosaurs, like Dryosaurus, flocked to their favorite river.
Here, water usually flows year-round, but
now it's gone dry, and the ponds have
turned to salt.
This Stegosaurus is
looking for a seep.
Like African elephants digging for water sometimes pays off.
But scratching out a living in the dry
season is hard on the dinosaurs, big and little.
When times are tough and life is under
stress, anything can happen.
Fnding water is critical for Dryosaurus. Her offspring are less than a
year old. They've never experienced a
drought.
Today is a lesson in survival.
They don't know they're being watched.
Ceratosaurus is the last of its kind, but
more dangerous than ever.
Dryosaurus is too small to defend her
brood against a hungry predator.
All they can do is run for their lives.
Dryosaurus' extra long legs make for
speed,
but one of her offspring lags behind.
Now the only hope is to find cover.
In the Jurassic world, there's something even bigger than Ceratosaurus.
The Jurassic river-bottom preserved here
at Dinosaur National Monument contains
an extraordinary diversity of dinosaurs.
There are four kinds of sauropod
dinosaurs, three kinds of meat-eating
dinosaur, there are two kinds of bipedal
plant-eating dinosaurs, and of course
there's Stegosaurus the great plated
dinosaur. Now these animals when we look
at their carcasses, we can see they're of
the same condition of preservation. This
suggests they all died pretty close to
the same time. Well what brought all these
animals here? Most bone beds are just one
species. We believe that this was a
location where there was a perennial
river flowing through the savanna of the
Upper Jurassic of Western North America
and it dried up. Animals would come to
this place during the dry season where
seeps would bring water to the surface
where everywhere else was dry, but on one
particularly bad year the river dried up
completely. The animals not wanting to
leave their only known source of water,
stayed until they finally died. We're
looking at the deaths of the predators,
the prey, young, and old animals alike.
This is truly an extraordinary dinosaur deposit.
Like a caravan in the desert, a group of
Camarasaurus lumbers towards an oasis,  a grove of conifer trees.
Long ago, the
plant-eaters found a way to coexist with nature and each other.
When it comes to food, they live in a
vertical world.
Dryosaurus is tagging along.
Without rain, the pickings are slim,
but where the big sauropods go,
Dryosaurus knows a feast is in the making.
Camarasaurus thrives on the boughs of
evergreens. High in the trees their
strong teeth and powerful jaws literally
rip the branches off.
To reach them, Camarasaurus can do something most other
sauropods can't.
The vertebrae in its neck are strong yet hollow, which makes
them lightweight. A network of cable like
ligaments helps Camarasaurus hold its
head in an almost vertical position.
Sauropods don't chew their food, they
gulp it. To digest it, they swallow
stones called gastroliths, which grind
the food in their stomach. Because
Camarasaurus consumes large quantities of
vegetation faster than it can process it,
its belly is huge.
The Dryosaurus
makes short work of the scraps. They chew their food to speed digestion.
A sauropod is a virtual bulldozer. They
can wipe out a forest in no time by
uprooting trees and plants.
In the days to come, herds of sauropods will scour the landscape, but for now it's one tree at a time..
Two other local residents, a male,
and a female Stegosaurus, are also
scrounging for food.
For an animal the
length of a bus and the weight of a rhino, its snout is small and toothless.
Still, it's the largest dinosaur of its
kind in the world. The plates on its back,
and its tail bristling with four-inch
spikes, are designed to repel the most
aggressive attackers.
Flush with victory the male Stegosaurus
begins to strut, his back plates are like
feathers to a peacock. They're priceless
when it comes to mating,
The female's not ready.
For the male,
there's always tomorrow.
The dry season is now in its fourth
month, but a change is in the wind.
Storm clouds bring the promise of needed
rain.
The monsoon will last for days.
By storms
and the landscape is transformed.
Torrents of water cascade from the hills
and rivers begin to flow.
Seasonal lakes and ponds magically
reappear, their muddy banks are a maze of
footprints left by thirsty dinosaurs.
Large and small, both predator and prey
running helter-skelter
together,
but the coming of the wet season
ushers in more than just rain.
Apatosaurus has arrived.
This is Dino of the Flintstones, in the
flesh, all 30 tonnes. With legs the width
of tree trunks and feet almost as big as
bicycle tires Apatosaurus is the
elephant of the Jurassic, only 12 times
heavier. Sauropods, like Apatosaurus and
Camarasaurus, are the largest land
animals the world has ever seen. this is
the most complete sauropod dinosaur
ever found.
It's a Camarasaurus, about two years old
and already about 19 feet long.
The sauropod dinosaurs are the kind of thing
we always think about when we hear the
word dinosaur. I grew up with
Brontosaurus now correctly called
Apatosaurus. If we look around the world in
the Upper Jurassic, sauropods are the
dominant dinosaur. In fact, in North
America in any particular dinosaur
quarry we find, we usually see as many as
4 different types. Some feeding high in
the trees, some feeding low grazing on
the surface.  They're an immense part of
the fauna, very important to the
ecosystem. You would think we'd know a
lot about these dinosaurs, however, young
and their eggs are virtually unknown. In
fact, in all of Western North America,
extending from Canada down to central
New Mexico, we have not found a single
sauropod egg shell fragment in the
Morison basin. If we look at eggs from
South America or from Europe, we see the
sauropods laid eggs as big as soccer
balls, with eggshell about a quarter inch
thick. Well in western North America in
the Morison we do get dinosaur eggs, some
of which are only 2 millimeters thick. So,
you would certainly think we'd be
finding sauropod eggs here at all.
This tells us that these animals were
migrating into and out of the basin.
Perhaps they were nesting in the
lowlands of the mountains to the west, or
perhaps to the north and Canada along
the coast of the sea.
Certainly they weren't nesting and
reproducing within the Rocky Mountain
region.
When Apatosaurus moves, the earth begins
to tremble.
Like elephants, these sauropods migrate
long distances following the rainy
season. Along the way they graze on ferns
and low-lying plants. To accommodate
their immense size, Apatosaurus has
perfected a way to eat the most amount
of food with the least amount of effort.
Sweeping its neck in an arc from side to
side, it scours the ground like a giant
vacuum cleaner.
Apatosaurus is the length of a tennis
court, its tail alone is 30 feet long and
ends in a whiplash. To carry the weight,
Apatosaurus' backbone has tall
vertebral spines over its hips. Attached
to the spines are ligaments that hold
its neck and tail up. At the front of its
body the spines are forked to brace its
neck when moving it over the ground.
A healthy adult has no enemies, its size
alone protects it, but stalking the herd
is Allosaurus, the most advanced flesh
eater of its day.
This youngster has strayed from the
center of the herd.
Allosaurus is no quitter.
There's plenty
more fish in the sea.
Ceratosaurus has also been stalking the
herd.
Danger has a whole different meaning for
Stegosaurus.
For days, the male has been trying to lure the female into mating.
Now his persistence finally pays off.
A season of sauropods has wreaked havoc
on the land for Apatosaurus it's time to go.
Dinosaurs this big are constantly on the move.
Having
eaten their fill, they head for greener pastures.
Felled by a broken leg Apatosaurus, is mortally
wounded.
Today, Allosaurus is the victor.
The sauropods will live on and a whole
new generation of titans will leave
their footprints in the mud.
Allosaurus will vanish into extinction.
In Utah the seasons come and go.
Once again the dry spell returns.
Now all that hints at the passage of
time are bones bleaching in the Sun.
Tomorrow, the curtain will rise on the
Cretaceous, and a new cast of characters will appear.
Some are sinister, some are
strange, and some have never been seen before.
Were it not for the Rio Grande River, New
Mexico's largest city would be bone dry
and uninhabitable without a drop of
water to drink, but 90 million years ago,
the land beneath Albuquerque was a
tropical swamp.
During the Cretaceous, sea level began to
rise slowly flooding the interior of
North America. In time the Arctic Ocean
joined the warm waters of the Gulf of
Mexico, creating a shallow Inland Sea
that split the continent in two.
On the southwestern shore of the sea
cool summer breezes and warm winter
rain nurtured the seeds of a different
kind of forest.
For the first time ancient stands of conifers and palms
were joined by broad-leaf trees like
sycamores, magnolias, and poplars. Along
with a new crop of dinosaurs that had
never been seen before.
This is Zuniceratops, the first
dinosaur with horns and frills to appear in North America
Although they're small
now, about the size of a cow.
In a few million years their descendants
will be four times as big.
Until then, these docile plant eaters
need protection.
Where a herd of Zuniceratops goes, danger can't be far away.
Lurking about are predators, and now
they're more cunning than ever.
Coelurosaurs are too little to be a
threat to Zuniceratops, but nearby
what looks like a flock of weird birds
is actually a band of dromaeosaurs
already lunching on a carcass.
The odor of a fresh kill lures an uninvited guest.
The intruder is a loner out for a free meal.
The carcass is carefully guarded and the
leader of the pack, the alpha male, is in
no mood to share.
Outnumbered three to one,
the intruder knows when to quit.
A dromaeosaur, or "raptor" is the smartest, quickest, and most dangerous dinosaur alive.
Alone or in a pack, it's well equipped to deliver a lethal blow.
The nasty claw in its foot works like a switchblade. A tendon attached to the calf muscle pulls it
into the attack position. Its legs are
strong ,yet lightweight for speed.
Its tail is stiffened by boney rods for
balance.
And its arms and hands are extra-long
for grappling with prey.
Good eyesight, a keen sense of smell, and a big brain make the raptor a dominant predator.
The escape from the pack was a close call. To keep on Ronnie is playing it smart,
but the raptor's not out of the woods yet.
Something's hiding in the bushes, but
it's too large to elude detection.
The raptor's leery.
These are the claws of a carnivore, they look lethal,  but looks can be deceiving.
It may have the claws of a killer, but its long neck and small head belong to a plant eater.
This is Nothronychus.
The raptor's never seen a dinosaur like this before.
Is it a predator, or is it prey?
No other creature in the world looks
like a half-plucked turkey and walks like
a pot-bellied bear.
Still, an oddball can
be dangerous.
Raptors seldom make mistakes, but Nothronychus is rare in North America.
Like Zuniceratops, its ancestors also
migrated from Asia.
Therizinosaurs, such as Nothronychus, were once streamlined predators,
until they evolved into plant-eaters, unlike the raptors.
In 1996, we began to find evidence of dinosaur bones here.
After several months of exploring,
we discovered a little bone bed and it
was in that bone bed we found an animal
that has never been seen in the New World before.
It has claws as you see here and it's fairly nondescript, you'd think it's a meat-eating dinosaur.
They told us we had a therizinosaur. These are amazing animals, only known from Asia.
Very poorly understood,
and we now know they're extremely bird-like dinosaurs.
But unlike the other
bird-like dinosaurs, they're not
meat-eaters they've become plant eaters.
And right behind me here we discovered
this small skull. This little skull
belongs to a small theropod or
meat-eating dinosaur, and we believe it
belongs to a group of dinosaurs called
the coelurosaurs, a brand-new dinosaur
from 90 million years ago. Yeah, at first
when we're looking at the teeth, which're very well preserved here,
we thought we might have a dromaeosaur, or as many people know the raptors. But as we
uncovered the skeleton, we began to
realize we had a more primitive animal:
a basal coelurosaur. This animal may help
unravel the origin of our classic
Cretaceous dinosaurs.
Once a year, come spring, some dinosaurs have more on their minds than food.
For Zuniceratops it's the rutting season, and this young male is in his prime.
The challenge is to entice a female into
mating.
Horns and frills evolved to scare off
predators and discourage rivals,
but to a female they're sexy, if she's impressed.
The female's not interested, but someone
else is.
Only the leader of the herd is allowed to mate with the females and he's not about to relinquish his control.
The object isn't to kill, it's to win by intimidation.
For Nothronychus, the noise is a minor
distraction.
For the raptors, it's a trumpet sounding roll call.
There may be injuries and a wounded Zuniceratops is an easy kill. the
The opportunity is too good to pass up.
Raptors share over 30 anatomical
features with birds,
which is why they look more like birds than primitive reptiles.
Claws to the ready, the raptors are patient.
The old male's been bested. His wound is
minor, but his prides been dealt a
stinging blow, and the excitements not
over yet.
When it comes to survival,
the bonds of kinship transcend a family feud.
The skirmish over the raptors retreat, but they'll be back.
For the once proud leader of the herd, time is running out.
In the lush forests of New Mexico, an
experiment in evolution is underway.
Fleet-footed predators aren't new, but
coelurosaurs are different.
They're on the fast track. Their bones are lighter, which makes them even more agile and quick.
They're also more active and
better coordinated
The primitive feathers are for
insulation. This is the body plan of the future
On the inland sea, the days are
hot and humid, and the atmosphere
unstable, but deep in the forest it's
business as usual.
Deep in the forest, the dinosaurs are unaware a storm is brewing.
Zuniceratops live most of their lives
eating.
They made yearly, they're vulnerable when they're young, and old, or injured.
The encounter with the raptors has taken
its toll on the old male.
Since the attack, the raptors have been stalking the herd.
They're here to finish what they started.
Spooked by the lightning, the herd
scatters and runs,
but the old male lags behind.
The tinder is dry. Within seconds sparks leap through the underbrush setting the forest floor on fire.
Soon the flames leap from tree to tree,
igniting a firestorm.
As it races through the forest, some creatures ignore the peril.
When it comes to food, danger has no meaning for the raptors.
Zuniceratops has been on the run
since the first bolt of lightning struck.
Now what remains of the herd heads for
safety as fast as their legs can carry them.
Nothronychus is not far behind,
but the flames overtake the raptors'
escape route. Now nothing can outrun the fire
In this area here, we have material
coming out of this sediment here.
It's very likely that this material is
actually, was actually produced by a fire.
There are several lines of evidence
including the structure of the coaly
material, but also not far from here we
have an upright charcoalified stump,
that was proudly burned in place. When
you have forest fires, you often have the
roots burning down into the soil, and if
this is the case, this is really exciting
because this is not just a vague time
when the dinosaurs lived.
This is an actual event that would have happened when the dinosaurs were here.
In nature, disaster is a constant
companion, and death comes in many guises.
Dinosaurs not trapped by the fire
flee and panic. Most will survive.
For the creatures that perished the
conflict is over. For those that remain,
what lies ahead is 30 million years of
evolution.
Triggered by unseen forces, the environment will gradually change,
and so will the dinosaurs that live here.
In the distant future, the offspring of Nothronychus will grow bigger, weirder, and even more perplexing.
The raptors will stay small, agile, and quick, but they'll get smarter.
And the kin of Zuniceratops will become one of the most famous dinosaurs in North America
The granite faces of the presidents, on
Mount Rushmore in South Dakota, celebrate
200 years of American history, but not
far from here is another important
landmark. 65 million years old it's some
of the last ground the dinosaurs ever walked on.
During the Late Cretaceous, the great
Inland Sea retreated, causing a dramatic
shift in the environment. Now forests and fields stretch for hundreds of miles in every direction.
Grass has yet to evolve so the plains are covered with ferns and herb-like plants
In the twilight of the Cretaceous,
evolution is in overdrive.
After a hundred and sixty million years,
the size and sophistication of the
dinosaurs is breathtaking, but these
creatures are the last of their kind.
Triceratops is one of the largest
animals on the Northern Plains.
Although it's related to Zuniceratops, time has made a dramatic difference.
These are giants, twice the size of a rhinoceros. Their heads are huge, up to 11 feet long,
and their frills are seven feet wide.
Triceratops are plant-eaters. They roam
the plains in herds, grazing on ferns
and small trees like palmettos, while keeping an eye on their young.
Of all the plant-eaters, Anatotitan
is the most efficient because of the way
it processes food. Members of the
hadrosaur family, they're famous for
their bills which look like a duck's.
Hadrosaurs tend to be big, up to 30 feet long,
but Anatotitan is even bigger. They range up to 40 feet, the length of a bus.
Here size is no accident.
Three million years ago, a monster arrived in South Dakota. Now it's the scourge of the American West:
Tyrannosaurus rex.
T. rex is the consummate killing machine.
Its skull is a lethal weapon.
Although it's 40 feet long, it's not the size of
the animal that makes it deadly, it's the
size of its mouth. The bigger the mouth,
the bigger the bite.
Towards the end of the Cretaceous,
the tyrannosaurs produced their largest
version: an animal called Tyrannosaurus
rex and other families of dinosaurs did
much the same thing. Like Triceratops,
because the inland sea withdrew from
North America, and as it withdrew we had
the introduction of a continental climate.
The summers were hotter, the winters were colder, the days were warmer, and the nights were cooler,
and under this kind of climatic regime, selection tends to
favor large size and animals.
Quetzalcoatlus, the king of the pterosaurs.
Named after an Aztec God, with a wingspan of 40 feet, this is one of the largest animals that ever flew.
A pterosaur has no feathers, its wings are made of a single membrane that stretches from the
elongated fourth finger of its hands, to
its ankles.
Its arm bones are hollow and thinner than a postcard.
Tiny fibers, called actinofibrils, stiffen the membrane to give its wings lift.
Although Quetzalcoatlus can fly under its own power,
more often it glides on thermals, scanning the ground for a meal.
Today, the carcass of a dead dinosaur proves irresistible. Quetzalcoatlus may soar
like an eagle, but on land, it's a fish out of
water.
Nearby, Triceratops is feasting on shrubs.
The last in a long line of horned
dinosaurs, their ancestors migrated from
Asia.
With horns as long as broom handles, and
hides as tough as a rhino's, these
dinosaurs have only one known enemy.
Sensing danger, the group closed ranks.
Head-on, nothing can be more menacing than
the frill and horns of an angry Triceratops.
At 17 feet from tip to tail, this T. rex is a teenager, less than half the size of its parents. The herd can wait.
At a mere 200 pounds, Quetzalcoatlus is hamburger for this youngster.
At a top speed of 30 miles an hour, a young T. rex is one of the fastest dinosaurs around.
Chasing prey for a living is a chancy business. Even carnivores like T. rex are not always successful.
At dusk, the odds
are even poorer. Daylight favors the predators.
As night falls, colors fade, depth perception decreases, and familiar images begin to blur.
Without a kill, this youngster flunked its first test as a solitary hunter.
But in a pack, a family of T. rexes is a force to be reckoned with. The male stands 12 feet tall.
The female is even bigger. A veteran of
the combat zone, she bears the scars of a
hard life. Her leg's been crippled by
painful injury. Still, she rules the roost.
A young T. rex still relies on its
parents for support.
T. rex's skull is huge, over five feet
long, filled with air spaces to
accommodate an elaborate network of
nerves and muscles. Its brain is the size
of a gorilla's. Its teeth are serrated
for shearing meat and its jaw is
powerful enough to crush bone. While its
arms are too short for grasping prey, its
body is massive and robust. Its ribs are
an interlocking array of bones designed
to help it breathe. Equipped with strong sturdy legs, T. rex is braced to spring to the attack.
Tomorrow, the youngsters will learn to
hunt from the deadliest predator of them all.
Discovery of juvenile tyrannosaur
bones led to some surprising changes in
how we think about these animals. First
of all, when we looked at the juveniles,
it turned out that they weren't built
the way we originally thought they were.
They did not look like the adults. The
legs were longer and more slender
compared to their body size. Even now we
know these animals were extremely fast.
This led to some speculation concerning
the behavior of the juveniles in the
pack structure. If we compare those
dinosaurs to modern animals, we have
analogues. When you look at a pride of
lions, the female lions are generally
much faster than the males because
they're lighter weight and very often
they're used to scare up the prey and
chase them back into the jaws the male lion
Tyrannosaurs may have done
something very similar because of their
speed they may have moved into a herd of
duck-billed dinosaurs, scared up an
individual or two, and these came back
into the jaws of the adults who killed them.
Contrary to popular opinion, life in a
primeval forest is filled with endless days of boredom.
Moments of terror
are only fleeting.
Anatotitans are peaceful creatures. They'd like nothing more than to be left alone.
Although they're almost as large as Tyrannosaurus rex, they have few defenses against a
hungry predator. Especially when they're
old or sick.
To protect themselves, Anatotitans congregate in herds and post sentries to look out for danger.
Equipped with good eyesight, acute hearing, and a keen sense of smell, they're constantly on alert.
Hadrosaurs seem to prefer a diet high
in fiber,
but unlike sauropods, that rely on stones
and chemicals in their gut to break down vegetation,
Anatotitans have the most sophisticated food processor yet devised by nature.
The front of their muzzles are toothless
and rigid for shearing plants. When
chewing, their jaws moved from side to
side, allowing a battery of hundreds of
tightly packed teeth to grind the food to a pulp.
Hadrosaurs are one of the most
successful dinosaurs that ever lived.
Scores of different species once inhabited North America, from Texas to as far away as Alaska.
From birth a baby Anatotitan clings to its mother for protection.
A behavior passed from
generation to generation.
As adults, hadrosaurs cling to each other,
but it's not always foolproof.
The Anatotitans have walked into a
trap.
The young T. rex leaps like a bird-dog
flushing prey.
The Anatotitans bolt for safety,
unaware a second youngster is lying in wait.
There's one more surprise in store.
Mom.
Tyrannosaurus rex has terrorized the
land for the last time.
An asteroid bigger than Mt. Everest
streaks across the sky,
and slams into Mexico's Yucatan
Peninsula at an angle of about 30 degrees.
The impact gouges out a crater 120 miles
wide, and sends an incandescent plume of
vaporized rock arcing towards the
northwest at speeds close to 10 miles
per second. In minutes everything for
hundreds of miles is incinerated.
In South Dakota, plants and animals
suffer a different fate.
Some are scalded by the heat, others succumb to shock waves generated by the collision.
an hour after impact a cloud of dust and
debris settles over North America
Temperatures drop, and acid rain begins to fall  as nitrogen,
burned by the heat, is washed out of the atmosphere
The Sun won't shine again for months.
First light reveals the devastation.
90% of all leaf-bearing trees and
plants have been obliterated,
and 70% of the animals have vanished.
Most of the dinosaurs are now extinct.
There are many theories that try to
explain why dinosaurs suffered such a
massive extinction 65 million years ago.
The evidence in the rocks here suggests
that 65 million years ago something
major happened.
We have iridium, we have shocked quartz,
we have micro diamonds. Along the Red
Deer River of Alberta though, we have
some of the best evidence anywhere for
showing us what was going on in those
last few years of the dinosaurs rule.
For example as we follow the Red Deer River
upstream, we're literally going up in time.
10 million years before the dinosaurs
disappeared there were 35 species of
dinosaurs living in this area. 5 million
years before the end there was only 20
or 25 species left, and just before the
great extinction event there was only
about half a dozen species of dinosaurs
in this this area.
Not since the great Permian extinction
gave rise to the dinosaurs, had an event
been so catastrophic, and so final,
but life is resilient.
in South Dakota, a turtle angles for a
perch in the Sun. A primitive mammal
comes out of hiding. The only dinosaur
visible a bird soars overhead to remind
us of the giants that are gone.
The dinosaurs are one of life's great success stories. From Alaska to Mexico, Maine to California,
they roamed North America in huge numbers for a staggering hundred and sixty
million years. In their day, they were the
largest, brainiest, and most sophisticated
creatures on Earth.
It's unlikely
anything so huge or captivating will
ever pass this way again, but for a tiny
mammal called Purgatorius, the future
belongs to them. Someday, their children
will walk on the moon,
and think back in awe to a time when
dinosaurs roamed America.
