[suspenseful music] [dinosaurs roaring] NARRATOR: The bloodiest
battle of the prehistoric era. It happened about
150 million years ago when the earth was much
different than it is now. In what will become
North America, a shallow sea has begun
to split the continent. Increasing oxygen levels
allow dinosaurs to grow taller than a six-story building. It's the late Jurassic period. Sauropods, long-necked
four-legged dinosaurs, and the largest land animals,
grow to giant proportions to reach vegetation
that is 60 feet tall. In what is now Utah,
temperatures soar in the 90s. During their peak, droughts
take their toll on planet Earth, including those that
are receding lakebed. This lake, in
particular, will be the scene of a prehistoric
bloodbath unlike any other. [suspenseful music] [dinosaurs roaring] Fast-forward 150 million years,
30 miles south of Price, Utah, a local herder is
tending to his sheep. Suddenly he sees something
protruding from the soil. A decade would pass before
paleontologists would launch an investigation. Today the site is called
the Cleveland-Lloyd Quarry. And what was found here would
rock the scientific world. Investigators uncovered
one set of remains, then another, then another. Soon they had uncovered
something stunning, thousands of bones matching up
to multiple species. GEORGE BLASING: The
Cleveland-Lloyd Quarry is absolutely one of the
most remarkable fossil sites in the world. Over 15,000 individual bones
have come out of this Quarry. Paleontologists think that
that's not even half the amount of bones that are still
buried in the ground. It's an amazing site. But one of the first
things you have to ask is why are so many bones
from so many different kinds of dinosaurs assembled
in that one location? NARRATOR: Thousands of bones
lay scattered across an area no more than a mile across. Then another revelation. Among all of the bones
found at the site, almost every herbivore
bone recovered showed signs of being
crushed, broken, and bitten. Deep gashes were in some bones. Others had been
somehow pulverized. How did all of these dinosaurs
die at this one site? In order to unravel the
mystery, paleontologists first employed a scientific
approach, called taphonomy. Taphonomy phantom
is basically looking at what happened to a fossil
from the time of death of an animal until it actually
is buried and fossilized. And taphonomy is basically a
technique for understanding what led to the death and burial
of the animal or plant itself. So we can get a tremendous
amount of information just by being careful in
how we excavate our sites, because that gives us clues
about what happens leading up to the death of an animal. NARRATOR: Taphonomy evidence
revealed that the site was once a freshwater lakebed. But why was it filled
with so many bones? GEORGE BLASING: During
times of extreme drought, the water levels in the lake
can shrink pretty rapidly. As they shrink, what happens
is the upper layer of mud sort of becomes dry, when
underneath it remains pretty wet and sticky. So as animals walk out across
this to get to the water and get a drink, they get stuck. Their weight causes them to
crack through the upper crust, and that's when they get
stuck, and you're not going to get out. NARRATOR: It was the
first vital clue. This prehistoric death
trap was once a lakebed. Multiple species would
come to drink here. [thunder crashing] [dinosaur roaring] Then another breakthrough. Investigators identified
one of the dinosaurs. It was one of the
most distinctive of the Jurassic
period, stegosaurus. [low growling] THOMAS HOLTZ: There's
nothing in the world today that looks like a stegosaurus. And it just was so peculiar
with that long, cone-shaped head and this big, curved back
and these short front legs and long back legs. Those plates on the back
and the spikes on the tail, it was just so
different from anything known, past or
present, that it's sort of an icon of the Jurassic. NARRATOR: Its name
means roof lizard with the 17 plates arranged in
a double row along its back. These plates ranged in height
from 4 inches to almost 3 feet and gave stegosaurus
its unique appearance. Their exact function
is still a mystery. SCOTT HARTMAN: Some people
think they look sexy. Perhaps female
stegosaurs really like the look of the plates
on the male stegosaurs. Some people think that
perhaps it played a role in thermoregulation. That is heating up or
cooling down the animal. And, of course, to
some degree, they would have played a
defensive role in the sense that they would've
been very hard to bite, should you try to bite
that part of the stegosaur. Personally, I favor the
sexiness hypothesis. It's kind of more fun to say. NARRATOR: The stegosaurus found
at the site stood 14 feet tall, measured about 28 feet in
length, and weighed 3 tons. Their front legs were
shorter than their rear, making them a slow-moving
dinosaur but far from helpless. JIM KIRKLAND:
Stegosaurs are very much like their armored cousin,
the ankylosaurs in having very small forelegs and
very long hind legs. This allows them to move the
front quarters around, pivoted around a small point, and
use the long legs to move the back end very fast
around that same point to keep the tail pointed toward
what they were attacking. And what a tail they had. They had four spines sticking
out the very end of the tail. In fact, the last
two spines stuck past the point of the tail. NARRATOR: The Jurassic era
was filled with predators. At the watering
hole, stegosaurus would have utilized two
weapons for protection. The first was its tail spikes,
for cone-shaped hell raisers pointing 3 feet high. GEORGE BLASING: Those are the
greatest dinosaur weapons ever found. These spikes are
incredible weapons. By swinging that tail, if
he strikes you with them, you're done for. Those spikes could
penetrate bone, they could penetrate flesh, and
they could cause an injury that would end the attacker's life. SCOTT HARTMAN: It would
be like a big spiked mace, and I don't mean the stuff
you spray on muggers, but rather a more medieval
weapon, a big club with pointy parts on it. I think it's really quite what
it would have been like to have been hit by the end
of the stegosaur tail. NARRATOR: Experts
continue to dig. Then the investigation
took an unexpected turn. Scientists uncovered a
second set of remains near the adult stegosaurus. It was a second stegosaurus,
but this one was a baby. More than one stegosaurus had
been killed at this lake bed. James Masden, Jr. is one of the
original scientists involved in excavating the site. JAMES MADSEN, JR.: There
were probably three or four stegosaurs in there. One that stands out at the
small end of the spectrum is a smaller animal, and
it looks like it's injured. It has a wound of
some kind or another. NARRATOR: Not one, but
two stegosaurus, an adult and a baby, had somehow
died in this deathtrap. Shallow bite marks found
on the hip bones and ribs suggested that the
baby had been attacked by a mid-sized predator. But the wounds were
pale in comparison to what the investigators
were about to find. [dinosaurs roaring] Scientists continued
to investigate. Then a second species
was identified. This one was 100 yards away
from the two stegosaurs. They belong to a titan
of the Jurassic world, a long-neck dinosaur
named camarasaurus. THOMAS HOLTZ: Camarasaurus was
the first dinosaur that showed that there were giant
animals bigger than elephants with these long necks, heads
full of plant-eating teeth, enormous sturdy legs,
and gigantic tails, and that these
things once roamed the earth in great numbers. NARRATOR: They were the most
common long-neck dinosaurs of the late Jurassic period. They could grow to a staggering
20 feet tall at the hips, measured 60 feet in length, and
tipped the scales at 20 tons. That's nine times the
mass of an elephant. Attacking a dinosaur
this size would be like attacking a building. Camarasaurus got that big,
because few dinosaurs were as successful in its environment. THOMAS HOLTZ: Camarasaurus
was very successful, because it could feed
from a variety of ranges. It could feed low at the ground. It could feed at about
its shoulder height, and it may have been
able to rear its head up on this long neck to feed
high up in the trees. By having this big wide
range, it could find food in all sorts of environments. NARRATOR: Camarasaurus
also owed its success to a set of 5-inch-long
spoon-shaped teeth that paleontologists realized
could defoliant entire trees at will. SCOTT HARTMAN: The teeth
of camarasaurus actually interlock. They kind of tongue and groove,
almost, one into each other. They would almost function
like a serrated beak or a single large
cutting surface. So they're probably stripping
vegetation quite effectively. NARRATOR: The remains of three
Camarasauruses found together in Wyoming in 1997 suggested
that these dinosaurs traveled in small herds. But as the lake bed
investigation continued, the mystery deepened. Scientists realized
something intriguing. Very few camarasaurus
bones were found. Why? The answer would
be a vital clue. [dinosaurs roaring] GEORGE BLASING: Really big
animals, like camarasaurus, would have been pretty reluctant
to walk out to the lake bed. Their sheer mass and
weight makes getting stuck a real possibility. So unless it's an
incredible drought, and that was the only
place to get water, they're probably going
to keep their distance. That's why I think that so
few remains of camarasaurus were found at the
Cleveland-Lloyd site. NARRATOR: As plant eaters, they
were not natural aggressors. When they encountered
a predator, camarasaurus most likely
relied on their sheer mass to act as a
deterrent to a fight. [dinosaurs roaring] SCOTT HARTMAN: Any animal that
weighs 15 to 20 tons is just going to be an absolute
powerhouse to deal with. Just stepping on
potential predators would probably do them in. You want to be very
careful around them. A large African elephant
often weighs in the 5- to 6-ton range. These animals get up to three,
four times that size easily. So we're already talking much
stronger than an elephant. In some ways, perhaps modern
earth-moving machinery is a better analogy for the
type of power they have. GEORGE BLASING: If that's
not enough of a deterrent, and you're still coming in,
then camarasaurus faces you. He's going to wait
till you get too close. And then he's going to
rear up on those hind legs and crush you. If that doesn't work,
and you outflank him, then camarasaurus uses its tail,
which is a defensive weapon. He'll swing that tail
from side-to-side. If he makes a direct hit,
the fight is all but over. He's sending that predator
up into the stands, hits a home run, game over. NARRATOR: Its size, muscles,
and weaponry made camarasaurus immune from most attackers. But the deep wounds and gouge
marks found in the bones at the watering hole prove
that no one was safe. And as investigators
were about to discover, there was a third
monster at this site. And this one wasn't
a plant eater. It was a true killing machine. [dinosaurs roaring] [suspenseful music] Near the town of Price,
Utah, paleontologists uncover one of the richest
bone beds ever found in North America. This was the site of a
prehistoric watering hole, a death trap during
extreme drought. But the discovery of thousands
of pulverized and injured bones suggested something
much more sinister. There were killers
patrolling its shores. Paleontologists must
work to identify who may have been responsible
for the carnage found at this site. To find the answer, they
used the same techniques as modern crime
scene investigators. [suspenseful music] PHILIP CURRIE: When we look
at a dinosaur site, of course, this is representing
something that died 65, 75, 100 million years ago. And a lot of times
your clues are cold. But really, we reconstruct
it the same way a forensic scientist would go
in and reconstruct a mystery surrounding a murder case. NARRATOR: The
investigation continued. Then a third species emerged
from the Jurassic lakebed. And this one was a predator. It was one of the rarest
killers, ceratosaurus. [dinosaur roaring] Its name means horned
lizard, not for the hornlets above its eyes, but rather
for the blade-like appendage on its nose. It's the only predatory
dinosaur known to have this distinctive feature. THOMAS HOLTZ: Those
horns do not protect. They're for display. And if you're going to have a
display structure, that means, at least on occasion,
you get together, and you show off to each
other, say, Look at me. I've got the biggest horn. So at least some of
the time, these guys got together in groups. [dinosaurs roaring] NARRATOR: The ceratosaurus
stood 13 feet tall, measured 20 feet in length,
and weighed 3,000 pounds. That made it a mid-sized
predator in the late Jurassic. Ceratosaurus may
not have been large, but its oversized teeth
meant that they worked much like a meat slicer. GEORGE BLASING: He's got the
most wicked-looking teeth of any predator that
ever walked the earth. He's got two different
kinds of teeth. His upper teeth are immensely
long and very blade-like, while his bottom teeth are a
little stubbier and a little more powerful. What that tells me
is when he grabs you, he uses the muscle in his
jaws to push those lower stubby teeth into you. They're the anchor. Now he brings down the meat
slicer and cuts a chunk of you out. NARRATOR: With a bite like that,
ceratosaurus could compensate for two glaring weaknesses. He wasn't especially fast. And his claws weren't
large or strong, compared to other predators. [dinosaurs roaring] THOMAS HOLTZ:
Ceratosaurus's best hope would be get in there,
take a big chunk of meat out, and get back. It would not have been good
for clamping onto something, for hanging in there
in close combat. Just get in there, strike, and
get away as soon as possible. GEORGE BLASING: Its skeletal
design is sort of weak so it's not really
built for full combat. It's really better
designed to sort of slash, grab, rip, and then run away. NARRATOR: The forensic evidence
painted an intriguing picture of how the melee started. [wind howling] [intense music] [low growling] Driven by thirst, a
stegosaurus and its baby have moved out onto
the lakebed to drink. Their compact feet slip easily
through the hardened upper crust, and they
become mired in mud. They are now an easy target. Attracted by the sounds
of the struggling pair, a single ceratosaurus
arrives on the scene. Its long toes and
splayed foot design allow it to move
across the upper crust without breaking through. Its target, the juvenile. GEORGE BLASING: The juvenile
is basically helpless. It normally relies on its mother
to be able to protect him. But she's stuck up to
her shoulders in mud, so she can't use her
main weapon, which is her spiked tail. Like its mother, the
little juvenile has spikes, but he can't move them,
because he's literally exhausted from trying
to get out of the mud. [low growling] NARRATOR: The ceratosaurus
moves in for the kill. He bites the juvenile in one
of his most vulnerable areas, behind the rib cage, directly
in front of her hind legs. [dinosaurs roaring] The mother looks on helplessly
as this ceratosaurus tears open a large gash in the
juvenile's flank. We now know that by
the late Jurassic, ceratosaurus was fast
becoming extinct, desperate for easy prey. [dinosaurs roaring] The discovery of a
ceratosaurus skeleton made it clear that it
hunted the lakebed for food. But there was a
piece of the puzzle that experts couldn't answer. Of the tens of thousands
of fossil remains, only a single
ceratosaurus was found. This mid-sized predator did not
have the power or the weaponry to cause the extreme damage to
the tens of thousands of bones. So what had happened? The answer? Another killer, even bigger,
was keeping them away. The theory, as it turned
out, would gain momentum with the discovery of a
fourth set of remains. And this one was a much
larger, more lethal predator, allosaurus. [dinosaur roaring] GEORGE BLASING: Allosaurus was
the most common dinosaur found in the Cleveland-Lloyd site. It's a massive animal,
so it was more than capable of crushing bones and
ripping apart the skeleton. NARRATOR: Allosaurus was the
first giant predatory dinosaur to stalk North America. It predates T-Rex by
some 80 million years and was the biggest
carnivore of its time. THOMAS HOLTZ: When the first
big skeletons of allosaurus were uncovered,
people finally saw that there were
meat-eating dinosaurs that were as big as a killer
whale with powerful claws on its hand, truly fearsome
meat-eaters, a terror from the Jurassic period. NARRATOR: Of the thousands
of bones excavated at the prehistoric lake, 2/3
of them are from allosaurus. It stood about 16 feet tall,
measured 38 feet in length, and weighed up to 4 tons. In addition to its
size, allosaurus possessed two lethal weapons
that made it a top predator. But first was its trio of 6-inch
claws extending from each hand. THOMAS HOLTZ: The
claws of allosaurus would have been like
an eagle on steroids. They're long, they're curved. They're actually very similar
to eagle claws in shape, but backed by huge muscles. Allosaurus's second
lethal weapon was its combination of
powerful jaw muscles and serrated teeth
2 to 4 inches long. [dinosaur roaring] SCOTT HARTMAN: The teeth of
allosaurus were not like T-Rex. They weren't bone-crushing. They seem to be more blade-like. They're more slashing teeth,
and that's probably more of what it was doing when it attacked. It was making a slash, not
holding on, trying to bleed it. And in some ways, that's the
way sharks actually attack. They'll go up, and they'll
bite something and bleed it and allow that to
weaken the animal. NARRATOR: But the
dinosaur investigators then had to wonder if
the teeth of allosaurus were not capable
of crushing bone, then why did the dinosaurs
found at the watering hole show signs of being crushed? The answer? 8,000 pounds of allosaurus
actually stomped on them. GEORGE BLASING: This
was the site of one of the most gruesome and
barbaric acts ever recorded in the fossil record. The bodies were piled
on top of each other, and the earth literally
ran red with blood. In order to keep from
sinking into the mud, I think the allosauruses
were actually standing on their victims
while they ripped them apart, and that's why so many of the
bones were crushed and broken. NARRATOR: But if the allosaurus
was the apex predator, why then were so many allosaurus
bones found in the lakebed? Investigators believe that while
feeding, many of them became stuck themselves. But one question remained-- why would so many allosaurs
gather in the same place at the same time? LAWRENCE WITMER: Interesting
that with allosaurus, we find, in some cases,
large accumulations of allosaurus bones. And so when we see
large accumulations, it makes us wonder
what's going on. Did these animals
live in large groups? You might even call them flocks,
considering they're closely related to birds. Or were they together
for some other reason? An interesting parallel that
is compelling in many ways is what we see at the La
Brea Tar Pits in California. Many of the fossils that we find
there are of predatory animals, of wolves and predatory
birds and things like that. La Brea Tar Pits, we
regard as a baited trap. Animals get stuck in there,
and the predators are lured in. NARRATOR: Hundreds of
allosaurus skeletons, but only a single ceratosaurus. There is no doubt which predator
ruled this Jurassic lakebed. Based on this new information,
what does the evidence say happened when allosaurus
came on the scene? GEORGE BLASING: First, we
look at whatever evidence we do have. And then we look at the
behavior of modern animals and apply that to those
prehistoric creatures. By doing this, it gives
us a realistic version of things with science
to help back it up. NARRATOR: A trapped
baby stegosaurus is being eaten alive
by the ceratosaurus. The smell of fresh blood drifts
downwind, perfectly in the path of a team of
approaching allosaurs. GEORGE BLASING:
These allosaurs hunt in packs, because it allows them
to bring down much larger prey. They use their
incredible sense of smell like a prehistoric
homing device. Their keen sense
of smell tells them that there is an adult
and juvenile stegosaurus about 100 yards ahead. But they also pick up
the very distinct scent of a ceratosaurus. And this is the hated
enemy of allosaurus. NARRATOR: One
allosaurus moves off to flank the unsuspecting
ceratosaurus. The remaining allosaurs
head towards the scene. The ceratosaurus is outnumbered. And scientists now know
it was also outsmarted. THOMAS HOLTZ: It was sort of an
earlier model of meat eaters. It doesn't have the
more sophisticated brain that we see in some of its
contemporaries, like allosaurs. So although it
was pretty strong, it didn't have the claws,
it didn't have the brains, and it also didn't have the size
of some of the other giant meat eaters of its environment. NARRATOR: It's a
face-off, one that's about to see a colossal
monster join the fight. [dinosaur roaring] A single ceratosaurus faces
off against two allosaurs. The prize, a helpless
stegosaurus and her young. From the top of the
food chain, allosaurus goes into killing mode. GEORGE BLASING: If he's up
against somebody bigger, allosaurus is going
to be cautious. He's going to stand back. He's going to really
size up the prey. And he's going to focus on
his adversary's weak points. If he's fighting somebody
smaller, the battle changes. Now he's interested in rushing
in and beating the crud out of his opponent. I don't care about weighing
your strengths and weaknesses, brother. I'm bigger than you. I'll rip your head off. [dinosaur roaring] NARRATOR: There's a new clue. Scientists have found allosaurus
bones around the world. They all show signs
of serious trauma. We know this dinosaur was
hardwired to kill or be killed. THOMAS HOLTZ: There's been a lot
of allosaurus specimens found that have wounds on them, damage
from having their foot crushed by another dinosaur or holes
punctured in their tail from the spikes
of a stegosaurus. But these are healed wounds. These dinosaurs survived
these attacks long enough for the bones to heal over. They lived in tough times,
but they were tough, and they could take it. [dinosaur roaring] [low growling] [dinosaur bellowing] NARRATOR: Having
identified their adversary, the allosaurs moved down the
hill towards their intended target. GEORGE BLASING: Allosaurs
are cooperative hunters. So as two of them moved down
to take on their adversary head-on, the third moves
off in a different direction in an effort to outflank
the ceratosaurus. We see this sort of ambush
maneuver in modern lions and sometimes wolves. If you can keep your
opponent's attention focused in one direction, it allows for
surprise attack from the other. NARRATOR: One of them takes
advantage of the stegosaur's vulnerable position and
uses him as a platform. The ceratosaurus begins to
move away from the stegosaurus. [low growling] [dinosaurs roaring] With the force of a
runaway freight train, the third allosaurus crushes
the unsuspecting ceratosaurus. [body thuds] [dinosaur roaring] We now know that some stegosaurs
could have as many as eight spikes on their tail. [dinosaur roaring] GEORGE BLASING:
The massive weight on the female stegosaurus
causes her body to lean forward. This frees her tail. The moment she feels her
tail has become free, she swings it with every bit
of remaining energy she has, and it lands a direct hit. [dinosaurs roaring] [body thuds] [dinosaurs roaring] NARRATOR: The location of
the bones tells the story. One allosaurus is down. A few steps away, the
body of the ceratosaurus lays motionless. A stegosaurus struggles to
free herself from the jaws of this relentless muddy tomb. Next to her, the lifeless
body of her offspring. 100 yards away, another
dinosaur comes to the lakebed. [dinosaur roaring] [low growling] GEORGE BLASING: A family
of camarasaurus moves down to the lakebed. Leading them is a huge male. Its sheer size is enough
to deter almost any attack. The allosaurus are now faced
with a difficult choice. Do they continue their
attack on the stegosaurus, or do they dare
take on something as huge as a camarasaurus? PHILIP CURRIE: I would say that
under normal circumstances, a camarasaurus was such a big
animal that it didn't really have to worry about
attack very often. We certainly know that sometimes
they get stuck in the mud. And in a situation
like that, if it's isolated from the
rest of the herd, allosaurus may have
taken the chance. [dinosaur roaring] NARRATOR: Allosaurus was
built to move at a good pace, compared to other dinosaurs. Some experts estimate
they could run as fast as 20 miles an hour. But the camarasaurus could
have been 150 years old and wouldn't have
moved as quickly. [dinosaurs roaring] LAWRENCE WITMER: We can look
at the skeletal structure of allosaurus and see it was a
fairly capable moving animal. We could even go
beyond that, though, and look inside the head,
to look at the inner ear. What we see in allosaurus is
the agility of a predator. When we look at the inner ear
of camarasaurus, what we see is an animal that moves
very slowly in a very stately manner. This is an animal for whom quick
movements were not particularly important for this animal. So allosaurus was a relatively
fast-moving, agile animal. Camarasaurus potentially could
have just stood still and faced the music. [dinosaurs bellowing] GEORGE BLASING: Allosaurus
had a very bird-like stance. Having their legs
designed like an ostrich is what gives these
dinosaurs their ability to run so quickly. And like a cheetah,
they use that long tail as a counterbalance to help them
change directions when they're running at top speed. It's the combination of these
features that allows allosaurus to grow huge, yet
move like a sprint. Camarasaurus, on the other
hand, is built like an elephant. But when you're
that big, you aren't in much of a hurry to get to
where you're going anyway. NARRATOR: In fact, a giant
species of allosaurus grew to an even greater
size than its cousin, T-Rex. THOMAS HOLTZ: When you
look at camarasaurus and you look at allosaurus,
the weapons of allosaurus are a lot more obvious. Allosaurus has
blade-like serrated teeth in its powerful jaws. It's got these eagle-like
talons at the ends of his powerful arms. But don't discount
camarasaurus here. It has its size, and
size is a great weapon. On top of that, it's got
a very long, broad tail, which you could use to
swat at an attacker. NARRATOR: CT scans
show that allosaurus was able to strategize more
than the enormous monster. LAWRENCE WITMER: We can
also look at the brain and see differences there, too. When we look at the brain
of allosaurus, what we see is some enlargement of the
forebrain, the cerebrum. On the other hand,
in camarasaurus, we see a very small brain. In particular, the
cerebrum, that same center of higher function,
is really quite small. What that suggests is that
in the heat of battle, the slightly larger brain
size, what we see in allosaur, would have potentially
allowed it to, in a sense, adapt to the changing
battle situation. With camarasaurus, it's
operating purely by instinct. NARRATOR: Experts now know that
the camarasaurus would have sent out a distress call,
which allosaurus would pick up and recognize immediately. [intense music] With the CT scan evidence
and unprecedented insight into predatory
dinosaur behavior, experts now know how the apex
predator took on a monster dinosaur. [heavy footsteps] [dinosaurs roaring] A herd of camarasaurus
approaches a drying lake. Their skeletal design prohibits
them from lowering their heads to the ground. With their keen
sense of smell, they pick up the scent of an
unusually high number of predators. GEORGE BLASING: Their
sheer size and mass is usually enough to deter
any predator from attacking. But the large number of
predators assembled in this one area puts the camarasaurus
on high alert. NARRATOR: Despite
the threat, quenching their thirst is a priority. The alpha male steps onto
the mud-encrusted shore. As he positions
himself to get a drink, he finds it different
to maneuver. [low growling] GEORGE BLASING: This
puts the dinosaur in a very precarious position
if it happens to get attacked. Unfortunately for
this sauropod, it's unaware of the mud
trap that lies just beneath the cracked
and dry upper crust. NARRATOR: The enormous weight
of this Jurassic titan cracks through the dried mud layer. It's elephant-like
front feet become stuck. Each time it tries to
pull its legs free, it ends up sinking even further. The stuck camarasaurus begins
to panic and bellows a distress call. [dinosaurs bellowing] The allosaurs pick it up
and run 100 yards away. GEORGE BLASING: The allosaurus
make a very wise decision to abandon the stegosaurus
and go for the camarasaurus. That stegosaurus just
freed her tail and killed. They know now she
can defend herself, so the sounds of
the camarasaurus makes it much more
interesting of a target. [low growling] So they move off and decide
that's the thing they're going to attack. Because if they can kill
it, it will keep them fed for three or four days. [dinosaurs roaring] NARRATOR: At the sight
of the allosaurus, the camarasaurus herd turns and
retreats, leaving its leader to face the threat alone. [thudding footsteps] GEORGE BLASING: Camarasaurs
are herding dinosaurs. Their number one priority is to
make sure that the babies make it into the next generation. When two allosauruses
showed up, their priority is to move away from the
danger and take their babies. Unfortunately, that leaves
their leader abandoned and stuck in the mud. [mud squishing] [dinosaurs bellowing] [dinosaur roaring] NARRATOR: The allosaurs
approach carefully, circling to make sure that
the camarasaurus is firmly stuck in the mud. The anatomy of the camarasaurus
shows two weak spots, the flanks and the neck. A deep gouge or bite in
those strategic areas, and the herbivore goes down. GEORGE BLASING: Under
normal conditions, there is no way these two
allosaurus would dare take on a bull camarasaurus. But the fact that
it's stuck in the mud has changed the
whole battle plan. They'll attack him as
long as they can reach one of his vulnerable areas. NARRATOR: Taking up
positions on either side of the giant sauropod, the
allosaurus launch their attack, teeth and claws pry
to bite and slash. GEORGE BLASING:
The allosaurs leap onto the side of the sauropod. They're trying to cut
through the thick flesh. If they can rip open its side,
the lifeblood of that sauropod is going to spill
out on the ground, and that's going to
end the battle quickly with no harm to the allosaurs. NARRATOR: The camarasaurus
strains from the weight of his attackers, but in a
defensive move shakes them off, but not before the allosaurus,
using their large hand claws, inflict deep wounds
in his flanks. But under the intense
heat of the Jurassic sun, scientists say an unseen force
begins to take its toll-- overheating. GEORGE BLASING: The massive
size of these allosaurus makes overheating
a real concern. Almost all evidence
points to these dinosaurs as being warm-blooded
creatures, which means they have no trouble warming
up, but cooling down can be a real chore. And after their fight
with that ceratosaurus, their bodies were
already in high gear. And now with this new
assault on camarasaurus, their temperature
gauges are in the red. [low growling] NARRATOR: Like some
modern-day animals, the allosaurs shut
down momentarily. GEORGE BLASING: Like
modern birds and dogs, the allosauruses
pant in an effort to expel excess body heat. But they also have a special
adaptation that allows the heat to escape through their skull. It's a large opening, called
the antorbital fenestra. It's located directly in
front of the eye socket. Most people looking
at the skull think that that's the actual eye. With only a thin layer
of skin covering it, it's ideal for allowing
excess heat to escape. [dinosaurs roaring] NARRATOR: With their body
temperatures back to normal, the allosaurs are
ready to fight. [dinosaurs roaring] It's two predators
versus camarasaurus on an ancient lakebed. All hell is about
to break loose. [dinosaurs bellowing] [intense music] During a drought in
the late Jurassic, a receding lake has
become a graveyard. Three allosaurus have
killed a ceratosaurus. A stegosaurus, wielding
his lethal tail spikes, has killed one of the
unsuspecting allosaurus. 100 yards away, the surviving
allosaurs focus their attention on a camarasaurus
stuck in the mud. Using their two key weapons,
sharp teeth and vicious claws, they inflict serious wounds. If they can make the kill, the
predators can feast for days. The camarasaurus, despite
being at a clear disadvantage, wages a strong self defense. [dinosaur roaring] The allosaurs stalk their
prey, looking for a weak spot. GEORGE BLASING: If
one of the allosaurs can get to the soft
skin of the neck, they might be able to
sever a major artery or cut off the air to the lungs. That will absolutely
end this battle and bring down
their behemoth prey. NARRATOR: The allosaurs
circle their prey. They use an anatomical
adaptation to their advantage-- splayed toes. GEORGE BLASING: The
allosauruses don't get stuck in the mud like the
camarasaurus for two reasons. Number one, they
don't weigh as much. But number two, they have
a remarkable adaptation. It's the design of their foot. Like modern birds, their
toes are splayed out in three different directions. This configuration gives
them incredible traction when they're running
at high speeds. But it also gives
them stability. And the weight in the body is
distributed between these three toes and not straight down, as
in the foot of camarasaurus. They work like snowshoes,
keeping the body from breaking through the upper hard
crust, while allowing them unimpeded movement
across the lake. NARRATOR: One of the
allosaurs attacks. The camarasaurus is
quick to respond. GEORGE BLASING: Like
a freight train, the impact crushes the
ribs and splinters the arms of allosaurus and drives its
own humerus deep into its chest. [body thuds] NARRATOR: The
momentum of the tail allows the camarasaurus's
front legs to become free. Using the power in its rear
legs, it raises its body. The other allosaurus darts in. GEORGE BLASING: The
allosaurus can't stop. Its momentum literally drives
it directly under the foot of the massive sauropod. [suspenseful music] [dinosaur roaring] [crushing stomp] NARRATOR: With its
massive weight, the camarasaurus crushes
its last remaining rival. But its victory
would be short-lived. With all of its energy spent
and once again firmly stuck in the mud, the
camarasaurus is condemned to a slow, agonizing death. [dinosaurs bellowing] GEORGE BLASING: The allosaurus
was so focused on the fact that camarasaurus was stuck,
it wasn't in top predator mode. That meant it got in too close. Never in its wildest
imagination would have thought that that camarasaurus
sauce would shift its center of gravity,
free those giant front feet, and crush that allosaurus
like it was a bug. [dinosaurs bellowing] NARRATOR: Camarasaurus may
have triumphed over allosaurus in this fight, but in the
ultimate battle for survival, they, and all the other
dinosaurs at the lake, would lose. [dinosaurs bellowing] GEORGE BLASING: At the end
of the Jurassic period, something big happens, and it
causes the extinction of a lot of different dinosaurs. Allosaurus, camarasaurus,
stegosaurus, and ceratosaurus are victims
to this unknown killer. It appears that global climate
change was the catalyst. When your environment
changes, you've got one of three
choices you can make. You can move to a place
that suits you better, you can adapt to this new
environment, or you die. Today experts still seek to know
more about these monsters who dominated the planet
150 million years ago. SCOTT HARTMAN: For years
now, paleontologists have noticed that
there seem to be different types of allosaurs. The discussion now is are we
truly seeing different kinds of species that lived
alongside each other the way perhaps wolves and coyotes do? Or are we seeing, instead, a
single species that's changing across time as the
environment changes and as the animals change? And that's a really
interesting question if you want to understand
how dinosaurs, in general, respond to the environment. NARRATOR: While the search
for answers continues, this much is known. During the late Jurassic,
at a dry waterhole in what is now Utah, a
colossal battle took place. And unusually high number
of predatory dinosaurs died alongside their prey. Their bones are proof
of a brutal world, where a simple drink of water could
lead to the bloodiest battle. [suspenseful music] [dinosaurs bellowing]
