Original subtitles

Over 66 million years ago...

SCREECHING WAIL

..our world...

HIGH-PITCHED CLUCKS

..was ruled...

DEEP SNORT

..by dinosaurs.

DEEP BELLOW

HISSES

The largest animals that have ever walked the Earth.

ROARS

Today, dinosaur experts across the globe

are uncovering the bones they left behind...

..allowing us to imagine how these creatures may have lived...

..so that we can tell their stories, and they...

..can walk again.

Western Canada.

Today, a majestic landscape of snow-capped peaks...

..turquoise lakes...

..and mighty rivers...

..that erode the ancient bedrock.

The perfect conditions for dinosaur-hunting.

Here, on the banks of Red Deer River...

..palaeontologists from the University of Alberta...

..are unearthing the final resting place of a super-predator.

Oh, wow. Yeah, that's really nice.

Looks like a toe claw. Wonderful find.

Albertosaurus - T-rex's deadly cousin.

These are the remains of a teenager.

The team calls her Rose.

Holy cow!

Oh, wow. It keeps going.

Inspired by their discoveries...

..we can imagine her story.

In the Late Cretaceous,

North America is split in two by a vast inland sea.

On its western shores, a sprawling expanse of dense forests

and rugged coastlines.

Laramidia.

A land in crisis.

Atmospheric changes have forced temperatures down by two degrees.

A seemingly small change,

but enough to push the delicate ecosystem out of balance.

SQUAWKS

SHRIEKING CRIES

Food is scarce.

Even...

..for an apex predator.

RUMBLING BREATHS

Standing two-and-a-half metres tall,

and weighing in at one tonne...

..this is Rose...

..the Albertosaurus.

It's been a week since she last ate.

But in her sights...

..an arrhinoceratops,

an older cousin of triceratops.

A chance for Rose to satisfy her hunger.

Rose might just be the fastest land predator on the planet...

..sprinting at up to 30mph.

BELLOWS

ROARS

But Rose has miscalculated.

At two tonnes, her target is twice her weight...

..with horns almost a metre long.

Rose is starving.

But the risk of injury is just too great.

Dinner will have to wait.

71 million years later,

this team of palaeontologists...

Hey, guys, how's it going? Hey, Mark, look at this.

..led by Mark Powers,

is uncovering Rose's secrets...

Found new bones! Whoa, no way!

..piece by piece.

You couldn't ask for better...

No. ..better separation. You really couldn't.

Each day, more remains emerge from the ground.

Ohh! Whoa! Oh, my God.

Yeah! Yeah, clean it off.

There it is!

CHEERING

Today's discovery - Rose's leg bones.

Oh, that's so cool.

Each fossil is exposed and restored,

allowing the team to delve deeper into the story of

this long-lost super-predator.

This is looking really good.

Mark works with limb specialist Christiana Garros

to examine the bones from Rose's shin.

The tibia is not actually that huge,

compared to some of the bigger ones I've seen, at least. No.

Albertosaurus is an older relative of Tyrannosaurus Rex...

It's about 79cm. OK.

Something like that.

..but it's becoming clear she was a very different beast

to her more famous cousin.

So, long limbs, but the ones of T-rex are quite a bit bulkier,

aren't they? Absolutely.

Rose kind of really embodies what Albertosaurus is.

It's a very legsy animal, especially compared to things like T-rex,

which was incredibly huge. Yeah. Incredibly chunky.

Quick, fast, dangerous.

Still has powerful jaws. Yeah.

Maybe the optimal amount of scary for my taste,

that's for sure. Absolutely.

But speed was far from the only weapon

in the Albertosaurus arsenal.

More bones are coming out of the ground.

Oh, that's bone.

But these don't belong to Rose.

It does look like a bone from one of the digits.

And that's definitely Albertosaurus, right?

Yeah, absolutely.

And each bone seems to come from a different-sized Albertosaurus.

This is a huge one.

Dinosaur hunters have discovered

as many as 26 individuals buried here.

To try and say any piece belongs to any one individual

is kind of tough to do, cos there are so many of them.

It's clearly a mass grave of Albertosaurus,

where many individuals died together in this spot.

And if they died together...

..they likely lived together, too.

LOW GROWLING

In the cave Rose calls home,

she's far from alone.

SNIFFS

GRUNTS

Albertosaurus are social animals.

They live and hunt together,

forming strong, intimate bonds.

Rose has paired with this male Albertosaurus the same age.

A source of comfort...

..in times of scarcity.

It's been over a week since the Albertosaurus last made a kill.

And starvation isn't the only threat hanging over Rose.

RUMBLING GRUNT

The matriarch.

Racked with intense hunger,

she could turn on her own.

And Rose is bottom of the pecking order.

If she hopes to survive,

she'll have to prove herself when it matters most.

It's time to go hunting.

Ready? Let's go.

Mark's teamed up with dinosaur anatomy specialist Henry Sharpe.

They're venturing further up Red Deer River

on the hunt for more giants.

There's some wonderful prospecting rocks up there.

They reach an ancient river system,

dating from the same time period as Rose.

And the first clue...

We got a rib here.

..to what might have fed the Albertosaurus pack.

Given its cross-section and its size, maybe Edmontosaurus.

I'd say Edmontosaurus, yeah.

Edmontosaurus - a plant-eating, duck-billed dinosaur.

Edmontosaurus can get up to 30 feet long.

Ten metres here. Jeez!

Yeah. These things were huge.

But a single Edmontosaurus

wouldn't feed a hungry pack of Albertosaurus for long.

Holy cow!

PANTING: Oh, my God.

At the top of an escarpment...

Look at the size of these honkers!

..more fossils.

Not bone...

..but footprints.

You can see, they got the big front toe

and the two toes on the side.

It's much wider than it is long,

which is classic Edmontosaurus, duck-billed dinosaur.

From the pattern of these prints,

it looks as though these trackways couldn't have been made

by a single creature.

I've got about 16-17 tracks exposed here.

Today, there are just a few footprints.

But when they were created,

there would have been many, many more.

We have lots of footprints from various different individuals,

various different ages all congregating together,

so they definitely moved in herds, lived in herds.

Yeah. You imagine, like, herds of wildebeest,

and these animals were the size of one to two elephants.

These fossilised footsteps suggest

this corner of Canada once played host...

TRUMPETING ROARS

..to one of the most remarkable sights in Earth's history.

A migrating Edmontosaurus herd.

Thousands of plant-eating dinosaurs moving as one.

But an individual adult Edmontosaurus can be

three times the weight of even the largest Albertosaurus.

BIRDSONG

Working as a pack is the only way to take down such colossal prey.

Higher ground will provide the perfect vantage point...

..to mount an attack.

At this time of year,

this area should be teeming with Edmontosaurus...

..but the herds are nowhere to be seen.

LOW GROWLING

ROARS

This is a time of intense geological upheaval.

As the continents move...

..the land buckles and splits.

Lava and ash engulf the landscape...

..forcing this Edmontosaurus herd

to take a much longer route north this year.

They're still many miles away from the starving Albertosaurus.

For the pack, the delay spells disaster.

But on the horizon...

..Rose spots an opportunity.

From the wind-carved rocks by Rose's dig site,

palaeontologist Colton Coppock has made an important discovery.

Yeah.

So, here's a bit of the shaft.

Tiny fragments of finger bone

belonging to one of the most bizarre creatures of the Cretaceous...

And here's the condyle. What?!

So, it looks like it might be from a digit.

There's a condyle? Yeah.

..including a rare condyle, part of the knuckle joint.

Very nice. I'm afraid to touch it.

Yeah. It's just so small and so delicate. Yeah.

You can see the internal structure of the bone right there.

The fossil's paper-thin exterior

tells Mark this bone was built for flying.

But this was no bird.

Even in birds, the bone is usually a lot thicker on the outer surface.

This is very strange.

It can only belong to one creature.

SQUAWKING

A colossal flying reptile with a six-metre wingspan.

Cryodrakon - a giant pterosaur.

They feed on an enormous ammonite washed up on the spring tide.

SQUAWKS

The cryodrakon would make a fine meal for Rose and her mate...

..if they can catch one.

SQUAWKS

Approaching from downwind,

and with the pterosaurs' attention on their meal...

..the youngsters close in.

SQUAWKING

SCREECHES

At last, a chance to feed.

But the pair's absence from the pack...

..hasn't gone unnoticed.

RUMBLING GRUNT

Life in an Albertosaurus pack was fraught with brutality.

And 71 million years later,

this violence is still written in the bones.

Mark and anatomist Dr Greg Funston examine the jawbones of

one of the largest Albertosaurus ever discovered.

We do actually get a few scars along here,

and they're kind of evenly spaced.

Some are raised, and some are deep gouges.

So, could these be bite marks?

An astonishing 65% of Albertosaurus skulls found here

have teeth marks scratched into the bone itself.

Near your finger, there's a little gouge in that one, too.

Look at that. That's deep. Yeah.

It actually looks like the tooth came down from over the top.

That would've required tremendous amount of force,

from this diving angle, to actually remove that piece of bone.

Only another Albertosaurus could inflict this injury.

The biggest predator in this ecosystem,

and it's still getting beaten up day to day.

They're maybe tussling for food,

like you see on the savanna today,

where lions will eat in a certain order.

You got two hungry Albertosaurus.

One of them is going to want to eat first.

Only one can.

RUMBLING GROWL

As pack leader...

..the matriarch is eyeing up the youngsters' kill.

GROWLING

Rose is determined to defend her prize.

But the matriarch...

..leaves her in no doubt who's in charge.

GRUNTS

Hungry and badly wounded,

Rose has learnt a painful lesson.

She'll have to play by the rules

if she wants to survive.

But the evidence coming out of the ground suggests

not all of the Albertosaurus behaviour was violent.

Mark and Henry examine one of the most intriguing discoveries.

Rose's tiny, fossilised arm bones.

So, we got the upper arm here, and the forearm down there.

And up here, this is the hand, right?

This is like the palm of the hand.

Nobody's quite sure what Albertosaurus used

its minuscule arms for...

..but the strange positioning has given Mark an idea.

It's quite possible the resting position of the arm

was to have a more flared finger,

sticking outwards rather than, you know, kind of down by the side,

like a chicken wing.

So, if this was my arm, it would kind of be flared out like that?

Yeah, you'd be kind of doing one of these things.

Almost jazz hands. Yeah, exactly.

So, Albertosaurus is clearly using its arms for something.

I mean, modern birds have a wide variety of mating displays

and behaviours. Mm-hm, yeah.

Mark believes these seemingly useless arms may have been

vital tools for bonding.

So, if you're going to live in a group, you've got to have ways

of communicating with one another that go beyond just, you know,

grunting and staring at each other,

so maybe they're using their hands side by side on the flank,

reassuring one another.

Telling each other, "It's going to be OK, it's fine".

A morale boost. Yeah, exactly. Yeah.

SNORTS AND GRUNTS

Starving, shaken, and badly wounded...

..Rose needs comfort.

DEEP GRUNT

The young Albertosaurus take time out together to groom.

A soothing ritual...

SOFT GRUNTS

..that strengthens their bond.

As a new day dawns...

..the pack's luck may be about to change.

The Edmontosaurus have finally made it to

their summer feeding ground.

Not a moment too soon for the starving Albertosaurus.

And despite their young age, Rose, her mate,

and the other youngsters will play a crucial role in the hunt.

The fate of the whole pack depends on them.

Close to Rose's dig site,

a remarkable new fossil is emerging.

Wow.

Very cool.

An Edmontosaurus jawbone.

Maybe this is the dentary going in here?

That could be the back part, yeah.

But this fossil holds another secret.

What have we got up here?

That looks like enamel.

Look here - serrations.

That's incredible.

This is no Edmontosaurus tooth.

This came from a meat-eater.

Albertosaurus tooth?

I think you're right.

And, since we don't have much of the root,

it was probably lost during feeding.

That is an awesome find.

It's clear evidence that the Albertosaurus pack

did feast on Edmontosaurus.

But it doesn't help explain how they bought down such enormous prey...

..and what role Rose might have played in the hunt.

These are Rose's metatarsals from the right leg.

Quite narrow and compact for an animal that people usually

envision as being huge, huh?

Mark and Christiana investigate Rose's foot bones...

They get a heck of a lot bigger.

..comparing them with the outer foot bones of a fully-grown adult.

While they're similar in length, they're a very different thickness.

So, we can see this one is only about

three-and-a-half centimetres in width,

whereas, we look at this one,

we have...almost double that.

So, it's about 6cm in width.

Absolutely a beast - and the same thing can be said

about the other metatarsal.

Rose was almost as tall as the largest Albertosaurus,

but just half the weight.

She was definitely going to be much more agile and quick

than these big individuals,

which probably had a lot more difficulty picking up speed.

Large Albertosaurus were unlikely to reach high speeds

due to their enormous weight.

Meaning Rose and the other youngsters must take on

the most dangerous of jobs.

LOW GROWLING

Rose and her mate split off from the pack.

As the swiftest runners, they must identify a target...

..and separate it from the herd.

But they're a fraction of the weight of the largest Edmontosaurus.

HISSING

Impulsive and inexperienced,

Rose's mate blindly charges into the herd...

BELLOWING

..trying to take down one of these enormous creatures alone.

DISTANT ROAR

DISTANT ROAR SCREECHES

Rose has lost her closest companion.

And each failed hunt brings her and the rest of the pack

closer to starvation.

BIRDS CALL

But Albertosaurus were successful,

even in times of adversity.

They were the dominant predator in Western Canada

for over three million years.

At Rose's dig site,

part of the reason behind their success might be emerging.

This bit right here.

An unassuming fragment of bone.

It looks interesting.

I thought it was a rock, actually.

But it's got a pretty interesting texture.

It looks like Albertosaurus.

And this roughened area looks to me like the border of an eye socket.

Is this a part of Rose's skull?

That is part of the skull.

It's probably an indication that the skull is in several pieces at least,

so we'll have to keep our eyes out for any loose skull bones

that might be scattered about amongst the site.

Whoa!

It's Rose's ghost!

The team estimates Rose's skull would have been about

two-thirds of a metre long.

Big, but not big enough to take down huge prey like Edmontosaurus.

But maybe she didn't have to.

Mark and Colton re-examine the jawbones of one of

the largest Albertosaurus.

Just look how big and robust this jaw is.

It's absolutely crazy.

There's quite a few tooth sockets on this side.

It's the final piece of the puzzle,

revealing the pack's sophisticated hunting strategy.

Altogether, 68 teeth in the jaw.

Lots of points of entry into the body,

so, basically, instead of using the arms to grapple with prey,

it's all about the head.

These jaws were built to apply brutal force.

A bite force that's probably upwards of several tonnes.

There's not much that can, you know, protect itself from that,

once they have their eyes on you. Yeah.

Rose's speed and the bite force of these bigger animals...

..make for a deadly combination.

We could say that Rose was the runner, and this was the muscle.

When Rose got the animals out on their own,

big predator like this probably would've come out

and just finished the job.

LOW GRUNTING

Rose may have lost her mate

but she must now work with the other youngsters

to find the easiest target.

But with one failed hunt already,

the pressure is on.

SNORTS

BELLOWS

Rearing up on their hind legs,

the Edmontosaurus are too powerful.

BELLOWS

But Rose bides her time...

..until she spots an older individual.

One that might be weaker than the others.

BELLOWS

BELLOWS

Rose can't take this Edmontosaurus down alone.

But she can steer her prey...

..right towards the killing jaws

of the matriarch.

BELLOWS SNARLS

But there's still fight in this old bull.

SCREECHES

GROWLS

Rose has played her part to perfection.

Finally, the pack can feed.

And this time...

...Rose gets her share of the spoils.

All right. Who's ready to jacket?

Coming your way!

Grab those.

The team is eager to get their finds back to the lab...

...to learn more about this extraordinary creature.

They carefully wrap their discoveries in protective plaster.

Sorry, everyone in the vicinity is going to receive plaster

on their clothes and body, so...

One, two, three.

Oh-oh-oh...

It's OK, it's OK, there's lots of rock, there's lots of rock.

They flip them, ready for transport back to base.

Perfect. Beautiful.

Now just the third one.

Go! Flip.

Watch your feet, watch your feet.

But some of Rose's remains are too heavy

to carry down the hillside.

So, Mark has called in a little help.

Oh...love that sound.

Hold on to your hats!

One false move, and all the team's work would be destroyed.

With ropes attached...

..Rose soars through the air.

Go, Rose! Yeah!

But these ancient lands hold one final surprise

for the dino hunters.

What have you got there, champ?

Colton has made a once-in-a-lifetime discovery.

Oh, what? What is that?

Wait, hold on, that's a... What?! Whoa.

A tiny jawbone.

What's this a jaw of?

It's an Albertosaurus.

It's so tiny.

This is a baby Albertosaurus.

That's beautiful. Like a baby.

Yeah, probably only about a year old.

Think this is the youngest individual we have.

I mean, I had to put it down for a sec to make sure

I wasn't hallucinating.

CHRISTINA LAUGHS

Just scratch it like a puppy. Yeah. Look.

THEY LAUGH

It's more evidence of the success of the Albertosaurus.

And maybe, the baby belonged to one of the pack females.

Perhaps even Rose herself.

LOW GROWLING

As to how Rose died, we may never know.

Show-and-tell time.

Causes of death rarely fossilise.

So cute! That's awesome.

Wow, the comparison really pulled it together. Yeah.

It's not even as long as the tooth.

Oh, my God!

And, though her death is a mystery...

..now at least, we can tell the story

of how she may have lived.

Rose, the young Albertosaurus...

..earned her rightful place...

..hunting and surviving...

..with her pack by her side.

Next time...

..a toddler makes a perilous journey...

..joining one of the largest dinosaur herds

that ever lived...

..in its fight for survival.