0:00:02 > 0:00:03Tyrannosaurus Rex.
0:00:04 > 0:00:08The most terrifying predator that ever stalked the planet.
0:00:08 > 0:00:09What an animal.
0:00:09 > 0:00:13How powerful this predator must have been.
0:00:15 > 0:00:17It's a cultural icon.
0:00:17 > 0:00:19The poster boy of the dinosaurs.
0:00:19 > 0:00:23But for years, we got it completely wrong.
0:00:23 > 0:00:24I fell in love with the dinosaur,
0:00:24 > 0:00:28but it didn't look anything like this.
0:00:28 > 0:00:32I'm Chris Packham, and it's been my lifelong dream
0:00:32 > 0:00:33to meet the real T-Rex.
0:00:33 > 0:00:37And now in the golden age of dinosaur science,
0:00:37 > 0:00:38I've got my chance.
0:00:38 > 0:00:41This is the first time I've been able to
0:00:41 > 0:00:42walk in the footsteps of dinosaurs.
0:00:44 > 0:00:46With the living world as my guide,
0:00:46 > 0:00:48and the latest technological tools,
0:00:48 > 0:00:52I'm going to create the most authentic T-Rex ever.
0:00:54 > 0:00:58On my journey, I'll test its bone-crushing bite...
0:00:59 > 0:01:02When you said pulverised, you weren't joking.
0:01:03 > 0:01:05..its top speed...
0:01:06 > 0:01:09I'm going to get inside its mind.
0:01:09 > 0:01:13..and I'll ask, what did it really look like?
0:01:13 > 0:01:14Really, they were bristled.
0:01:16 > 0:01:20I'm going to reimagine and rebuild T-Rex.
0:01:20 > 0:01:22Oh, love that.
0:01:22 > 0:01:25And finally, bring it back to life.
0:01:33 > 0:01:35HE GROWLS
0:01:40 > 0:01:43As a boy, I was obsessed with dinosaurs.
0:01:45 > 0:01:48I'd take them out into the woods around my house to create these
0:01:48 > 0:01:52little cameos, these little sort of views into the Cretaceous period in
0:01:52 > 0:01:57Cleveland Road in Midanbury.
0:01:57 > 0:02:00And there was absolutely no doubt which one was my favourite.
0:02:00 > 0:02:03Tyrannosaurus Rex.
0:02:03 > 0:02:07The fact that it was big, fierce and most essentially extinct.
0:02:07 > 0:02:11And therefore, I couldn't see it and I would never see it,
0:02:11 > 0:02:13made it my favourite animal.
0:02:13 > 0:02:15And I would wander around the woods around my house,
0:02:15 > 0:02:19wondering if that was the sort of place that Tyrannosaurus would live.
0:02:21 > 0:02:24You see, to me, this animal was as real
0:02:24 > 0:02:26as the grass and the trees.
0:02:26 > 0:02:29And some days I'd even convince myself
0:02:29 > 0:02:32that Rexie was watching me.
0:02:32 > 0:02:36GROWLING
0:02:36 > 0:02:37ROARING
0:02:42 > 0:02:46But how authentic was the creature that lived in my imagination?
0:02:46 > 0:02:49My T-Rex was a product of the imagery
0:02:49 > 0:02:52that I absorbed from the movies and books of the age.
0:02:57 > 0:02:58But since then,
0:02:58 > 0:03:02there's been a radical revolution in our understanding of its appearance
0:03:02 > 0:03:03and its behaviour.
0:03:05 > 0:03:08As it turns out, early scientists
0:03:08 > 0:03:11and popular culture had it all wrong.
0:03:12 > 0:03:16As a child, I'd fallen in love with a fantasy.
0:03:22 > 0:03:26So now, I'm going to put that right.
0:03:26 > 0:03:30I'm on a mission to find the real T-Rex.
0:03:30 > 0:03:34MUSIC: T-Rex, 20th Century Boy
0:03:37 > 0:03:40In the badlands of north eastern Montana,
0:03:40 > 0:03:44the exposed rocks harbour a treasure trove of fossils.
0:03:44 > 0:03:49# Everybody says it's just like rock 'n' roll. #
0:03:49 > 0:03:52They were laid down 65 million years ago,
0:03:52 > 0:03:56when giant dinosaurs roamed the Earth.
0:03:57 > 0:04:00Back when a passing meteorite smashed into our planet,
0:04:00 > 0:04:02wiping them out for good.
0:04:06 > 0:04:09But now these ancient rocks are revealing
0:04:09 > 0:04:12the secrets of that lost world,
0:04:12 > 0:04:15giving me the chance to realise my childhood ambition.
0:04:18 > 0:04:22I've crossed an ocean, come to another continent to see an animal.
0:04:22 > 0:04:26I've done that loads of times before, of course.
0:04:26 > 0:04:28But this one is going to be really special.
0:04:34 > 0:04:39My guide is palaeontologist Doctor Greg Wilson.
0:04:39 > 0:04:40- Chris.- Greg.
0:04:40 > 0:04:41- Good to see you.- Good to see you.
0:04:41 > 0:04:45He's meeting me in the infamous Hell Creek...
0:04:49 > 0:04:52..the Mecca for T-Rex hunters.
0:04:55 > 0:04:57These rocks are filled with fossilised bones
0:04:57 > 0:05:00from the period of the Earth's history known as the Cretaceous.
0:05:07 > 0:05:12Back then, this was a subtropical flood plain teeming with herds of
0:05:12 > 0:05:14majestic plant-eaters.
0:05:22 > 0:05:25And like the wildebeest of the African Savannah,
0:05:25 > 0:05:27where there is prey,
0:05:27 > 0:05:29there are predators who stalk them,
0:05:29 > 0:05:32the king of the dinosaurs.
0:05:34 > 0:05:35Tyrannosaurus Rex.
0:05:39 > 0:05:43We're here in front of a block of this T-Rex specimen
0:05:43 > 0:05:48that has parts of the back of the lower right jaw.
0:05:48 > 0:05:51So this is the articulating surface with the skull.
0:05:51 > 0:05:54- OK.- And so this, from here to here,
0:05:54 > 0:05:57is about the back third of that lower jaw.
0:05:57 > 0:05:59Do you have the material with the teeth?
0:05:59 > 0:06:01We do. We've collected that already.
0:06:01 > 0:06:04That appeared right over here in this space
0:06:04 > 0:06:06and we collected that last year.
0:06:08 > 0:06:10This is a big day.
0:06:10 > 0:06:13Actually it's a very, very big day.
0:06:13 > 0:06:17It's taken me 50 years to get from Southampton to Montana
0:06:17 > 0:06:20to finally meet a T-Rex.
0:06:20 > 0:06:23Not only meet it, but actually reach out and touch it.
0:06:28 > 0:06:30Oh, I can't tell you.
0:06:32 > 0:06:35Now I know it's a fossil, I know it's not a real bone,
0:06:35 > 0:06:37it's the mineralised remains,
0:06:37 > 0:06:38but you've got to allow for
0:06:38 > 0:06:40a little bit of romance in science occasionally.
0:06:40 > 0:06:42And that's our mission here.
0:06:42 > 0:06:44We've got to try and make T-Rex real.
0:06:46 > 0:06:48And I can reach out and use my finger
0:06:48 > 0:06:51to bridge more than 60 million years.
0:06:53 > 0:06:57What we've got to do is to use the very best science
0:06:57 > 0:06:59to bridge that period of time, too.
0:06:59 > 0:07:03To finally produce the real T-Rex.
0:07:06 > 0:07:10It's only when you piece these fossilised bones together
0:07:10 > 0:07:12that you start to get the full picture.
0:07:17 > 0:07:20Here in the Natural History Museum in Berlin,
0:07:20 > 0:07:23a new specimen is on display.
0:07:25 > 0:07:29Complete skeletons are extraordinarily rare.
0:07:30 > 0:07:34Only about 25 good T-Rexes have ever been discovered.
0:07:36 > 0:07:40And this one is an absolute beauty.
0:07:45 > 0:07:50Four metres high at the hip, over 12 metres head to tail,
0:07:50 > 0:07:55and an enormous skull, filled with some of the largest teeth ever seen.
0:07:59 > 0:08:01They call him Tristan.
0:08:02 > 0:08:03Hello, Tristan.
0:08:05 > 0:08:07What an animal.
0:08:07 > 0:08:11How impressive, how powerful this predator must've been.
0:08:12 > 0:08:15But it's just the bones.
0:08:15 > 0:08:16What did it look like?
0:08:16 > 0:08:18How fast could it move?
0:08:18 > 0:08:21What did it do with those jaws?
0:08:21 > 0:08:23I'm going to find the answers on my journey.
0:08:23 > 0:08:27And bring the evidence back here to Tristan piece by piece.
0:08:27 > 0:08:32Driven by the science, I'm going to put the flesh back on these bones.
0:08:32 > 0:08:37And a great place to hunt for the first clues is in modern nature.
0:08:43 > 0:08:44In recent years,
0:08:44 > 0:08:46the study of living animals has revealed
0:08:46 > 0:08:49an enormous amount about the biology,
0:08:49 > 0:08:52biomechanics and the behaviour of the dinosaurs.
0:08:53 > 0:08:56Modern animals really can hold the key to the past.
0:09:01 > 0:09:03The answers are out there.
0:09:03 > 0:09:05And I know exactly where to start.
0:09:21 > 0:09:25These Alabama swamp lands are home to some real old-timers.
0:09:29 > 0:09:31If we want to find out how T-Rex worked,
0:09:31 > 0:09:34to find out how its skull functioned, its teeth functioned,
0:09:34 > 0:09:37then we need to practise a bit of comparative anatomy.
0:09:37 > 0:09:39And to do that there's only really one place to look.
0:09:39 > 0:09:42And that's these guys, the crocodilians.
0:09:42 > 0:09:44This is a North American alligator.
0:09:44 > 0:09:47It's 13 feet long and it weighs a thousand pounds.
0:09:47 > 0:09:51That's more than 450kg, that's half a metric tonne.
0:09:51 > 0:09:55This is as close to a living dinosaur as we're going to get.
0:09:56 > 0:09:58And it's very impressive.
0:09:58 > 0:10:00It's beautiful. Absolutely beautiful.
0:10:03 > 0:10:09Crocodilians have prospered for nearly 250 million years.
0:10:09 > 0:10:12Their ancient ancestors somehow survived
0:10:12 > 0:10:14that deadly meteorite strike.
0:10:16 > 0:10:20And their intimate connection with the world of the dinosaurs
0:10:20 > 0:10:25is helping palaeobiologist Doctor Greg Erickson answer many questions.
0:10:25 > 0:10:27To understand dinosaur palaeobiology,
0:10:27 > 0:10:29we need to understand the biology of living animals.
0:10:29 > 0:10:32I use, basically, the data from these living animals
0:10:32 > 0:10:35as sort of a time machine to go back and try to understand
0:10:35 > 0:10:39what animals such as Tyrannosaurus Rex were doing.
0:10:39 > 0:10:41Come on.
0:10:48 > 0:10:51Greg has been studying the crocodilian jaw
0:10:51 > 0:10:55to see what he can learn about the raw power of the T-Rex bite.
0:10:58 > 0:11:00His team are past masters at
0:11:00 > 0:11:03trapping alligators without harming them,
0:11:03 > 0:11:06but this job is, um, not for the faint-hearted.
0:11:09 > 0:11:12What have we got, Greg, in terms of equipment here?
0:11:12 > 0:11:16Well, I call it dragon slayer. But it's a bite force metre.
0:11:16 > 0:11:18So, I'll tell you what, I'm going to go ahead and test the bite.
0:11:18 > 0:11:20And Wesley is going to help me.
0:11:20 > 0:11:22- Yeah.- And do you want to do the readings for me?
0:11:22 > 0:11:25- I'll do the readings.- Fantastic. - Set this down there.
0:11:30 > 0:11:33- Ready?- Yeah.- Oh, yeah.
0:11:34 > 0:11:36What did we get?
0:11:36 > 0:11:382,058 pounds.
0:11:38 > 0:11:39Wow, over a tonne of bite force.
0:11:39 > 0:11:422,058 pounds!
0:11:42 > 0:11:44My goodness me.
0:11:44 > 0:11:46Greg, let's put that in perspective.
0:11:46 > 0:11:50If we bite down hard, our molars are producing what in pounds?
0:11:50 > 0:11:52About 200 pounds for a human.
0:11:52 > 0:11:56And I read that a big domestic dog, a Rottweiler, about 320, 328.
0:11:56 > 0:11:59And then a hyena, famed for its bone-crushing qualities,
0:11:59 > 0:12:02- 1,100.- Yes.
0:12:02 > 0:12:04Nothing's coming close to the alligator.
0:12:04 > 0:12:07Yeah, crocodilians are today's bite force kings.
0:12:07 > 0:12:12But, you've used these animals to inform reconstructions
0:12:12 > 0:12:14of the T-Rex jaw musculature.
0:12:14 > 0:12:17And what did you come up with for the T-Rex?
0:12:17 > 0:12:20Well, yeah, these are a great model for figuring out the bite forces
0:12:20 > 0:12:22of animals like Tyrannosaurus Rex.
0:12:22 > 0:12:24They have very similar musculature, and with T-Rex,
0:12:24 > 0:12:27we estimate bite forces of 8,000 pounds.
0:12:27 > 0:12:28- 8,000?- Yeah.
0:12:28 > 0:12:308,000.
0:12:30 > 0:12:32So that's a crushing bite of enormous magnitude.
0:12:32 > 0:12:34It's mind-boggling to think about.
0:12:35 > 0:12:39That's the equivalent of being sat on by an elephant.
0:12:39 > 0:12:41So, let's see it in action.
0:12:44 > 0:12:46This is the skull of a cow.
0:12:46 > 0:12:50It's the closest we could get to a typical T-Rex prey,
0:12:50 > 0:12:52a mighty herbivorous dinosaur.
0:12:54 > 0:12:59Greg's using an impact generator to recreate the power of T-Rex's bite.
0:13:00 > 0:13:02Greg, I normally like to keep my skulls
0:13:02 > 0:13:04in perfect condition in my collection.
0:13:04 > 0:13:06But, we're about to bust this one.
0:13:06 > 0:13:09Yeah, well, what we have here is a 25 tonne press,
0:13:09 > 0:13:12and we've got it set to generate four tonnes.
0:13:12 > 0:13:15Just to demonstrate what that kind of force is capable of doing.
0:13:27 > 0:13:30550, 600, 1,500.
0:13:33 > 0:13:38Wow. Oh, Greg. Oh, dear, oh, dear.
0:13:38 > 0:13:41That's T-Rex bite force right there.
0:13:41 > 0:13:44- Remove these pieces. - Look at the carnage.
0:13:46 > 0:13:51So, basically that's bone that's endured the bite force of T-Rex.
0:13:52 > 0:13:54Basically, this is just dust, isn't it?
0:13:54 > 0:13:58- Isn't it amazing?- Nothing survives the bite of T-Rex, does it?
0:13:58 > 0:14:01T-Rex was the ultimate killing machine, in my opinion.
0:14:02 > 0:14:06But how did all of this crushing power work with these massive teeth?
0:14:10 > 0:14:16After all, T-Rex is famed for its colossal set of deadly daggers.
0:14:16 > 0:14:21But Greg shows me that, amazingly, T-Rex's teeth weren't sharp at all.
0:14:21 > 0:14:24There's more than meets the eye here, these are magnificent teeth.
0:14:24 > 0:14:26These are the largest teeth of any dinosaur,
0:14:26 > 0:14:28and they're actually quite blunt.
0:14:28 > 0:14:29It's sort of like a railroad spike,
0:14:29 > 0:14:32or as some of my colleagues call them, lethal bananas.
0:14:32 > 0:14:34And it's kind of what it's shaped like, a banana.
0:14:34 > 0:14:36They're very dull on the tip,
0:14:36 > 0:14:38but one of the secrets is this animal
0:14:38 > 0:14:40has a serration row called a carina
0:14:40 > 0:14:41on the front and the back here.
0:14:41 > 0:14:44This allowed this animal to basically crack bones,
0:14:44 > 0:14:46tear away those pieces and swallow them.
0:14:46 > 0:14:49And also to cut through flesh at the same time.
0:14:49 > 0:14:51The bones would literally explode when
0:14:51 > 0:14:53T-Rex made a very forceful bite.
0:14:54 > 0:14:59So, how do Rex's bananas combine with that awesome crushing power?
0:14:59 > 0:15:02Greg has made a brass T-Rex tooth to find out.
0:15:06 > 0:15:07- Go.- OK.
0:15:11 > 0:15:16Wow. Wow.
0:15:16 > 0:15:17T-Rex bites again.
0:15:18 > 0:15:20Wow.
0:15:20 > 0:15:22Look at that.
0:15:22 > 0:15:24Destroyed.
0:15:24 > 0:15:27You can see where it initially entered there, Greg.
0:15:27 > 0:15:29Yeah. So, it made a hole, didn't it?
0:15:29 > 0:15:31Yeah, it's like a hot knife going through butter at first.
0:15:31 > 0:15:35But then it basically introduced a crack where this serration edge,
0:15:35 > 0:15:37or carina is, and split the bone apart.
0:15:37 > 0:15:40And that was those ridged edges, the carina.
0:15:40 > 0:15:41Absolutely, that's how it worked.
0:15:41 > 0:15:44- And that was, what, how much bite force?- 2,405.
0:15:44 > 0:15:47- Yeah.- That's like a quarter of what it could have been,
0:15:47 > 0:15:49or capable of doing.
0:15:49 > 0:15:50Yeah, you can imagine,
0:15:50 > 0:15:53it could easily have done this to much larger bones.
0:15:53 > 0:15:56- Yeah.- Maybe even bones from you know, a large duckbilled dinosaur,
0:15:56 > 0:15:58even triceratops.
0:15:58 > 0:16:00- It's amazing, isn't it? - It's amazing.
0:16:02 > 0:16:05T-Rex clearly had a bite like a super crocodilian.
0:16:07 > 0:16:09But, how reptilian was the rest of him?
0:16:13 > 0:16:16I head back to Tristan in Berlin to find out.
0:16:18 > 0:16:20If you inspect his bones,
0:16:20 > 0:16:24there are telltale markings that show where his muscles attached.
0:16:29 > 0:16:33These allow us to reconstruct his immense musculature.
0:16:34 > 0:16:37And as we add the flesh to his bones,
0:16:37 > 0:16:41the prominent muscles behind his head are a clue to his true nature.
0:16:46 > 0:16:49Look at the way that this white-backed vulture is feeding.
0:16:50 > 0:16:53It looks a bit manic, but it's under control.
0:16:53 > 0:16:56And look at the way the bird is using its neck,
0:16:56 > 0:17:00the powerful muscles on the back of its neck, to pull back.
0:17:00 > 0:17:02There, look, you see it now.
0:17:02 > 0:17:05It's found something that is quite tough to get at and it is using that
0:17:05 > 0:17:10neck, bracing itself all the time with its strong feet,
0:17:10 > 0:17:12effectively its hindlimbs.
0:17:16 > 0:17:18We know from the fossil evidence
0:17:18 > 0:17:20that T-Rex's muscles were constructed
0:17:20 > 0:17:22just like those of a carnivorous bird.
0:17:27 > 0:17:30So from what we understand from T Rex's physiology,
0:17:30 > 0:17:33it's very likely that it would have fed
0:17:33 > 0:17:35just like this vulture is feeding now,
0:17:35 > 0:17:38so it was a lot more like a bird than crocodilian.
0:17:39 > 0:17:42Evidence that dinosaurs are related to birds
0:17:42 > 0:17:45has radically changed the study of T-Rex.
0:17:45 > 0:17:49But when I was a kid, experts were still in the dark.
0:17:52 > 0:17:57Tyrannosaurus, king of the tyrant lizards, 20 feet high,
0:17:57 > 0:17:59fiercest creature that ever lived.
0:18:03 > 0:18:07Yes, this was the T-Rex I knew as a boy.
0:18:10 > 0:18:14Early palaeontologists had decided that it should stand erect.
0:18:15 > 0:18:19You see, they'd noted that its skeleton with its large rear legs
0:18:19 > 0:18:23and long, tapering tail was a bit like that of a...
0:18:23 > 0:18:25kangaroo.
0:18:25 > 0:18:29So naturally they decreed that it should stand like one,
0:18:29 > 0:18:32and T-Rex stood tall for over half a century,
0:18:32 > 0:18:36until they realised they'd got it completely wrong.
0:18:37 > 0:18:39I fell in love with a dinosaur,
0:18:39 > 0:18:41but I fell in love with the wrong dinosaur,
0:18:41 > 0:18:44because it didn't look anything like this.
0:18:48 > 0:18:51Today's palaeontologists have made great strides
0:18:51 > 0:18:53correcting the errors of the past.
0:18:57 > 0:18:59Helped by the fact that bones are not
0:18:59 > 0:19:03the only trace left behind by the dinosaurs.
0:19:13 > 0:19:15In Dino Valley State Park in Texas,
0:19:15 > 0:19:17there lies an extraordinary set of
0:19:17 > 0:19:22ancient footprints made by a dinosaur very similar to T-Rex.
0:19:24 > 0:19:28Glenn Cooban has spent years tracing its tracks.
0:19:30 > 0:19:33About 112 million years ago, this was not a riverbed,
0:19:33 > 0:19:35this was an ancient, giant mud flat
0:19:35 > 0:19:37and when the tide would go out,
0:19:37 > 0:19:40it would expose many miles of moist mud.
0:19:40 > 0:19:43When the surface is moist, like after a rain,
0:19:43 > 0:19:46it looks like they walked through five minutes ago,
0:19:46 > 0:19:49and to me it is the next best thing to being beside
0:19:49 > 0:19:50a living, breathing dinosaur.
0:19:51 > 0:19:56This trackway contains clues as to how T-Rex would have walked,
0:19:56 > 0:19:59so I've joined Glenn for a prehistoric paddle.
0:20:02 > 0:20:03That is fantastic.
0:20:05 > 0:20:06I mean, look at that.
0:20:12 > 0:20:14Do you know what? This is the first time
0:20:14 > 0:20:17I've been able to walk in the first steps of dinosaurs,
0:20:17 > 0:20:18quite literally in the footsteps.
0:20:25 > 0:20:27This is a complete trackway, isn't it?
0:20:27 > 0:20:30How many are there in this sequence here?
0:20:30 > 0:20:31Well, if that gravel was removed,
0:20:31 > 0:20:35130 in a row and then there is a scoured area,
0:20:35 > 0:20:38and then 20 some additional tracks
0:20:38 > 0:20:40before they disappear under the bank.
0:20:43 > 0:20:45The prints are incredibly clear,
0:20:45 > 0:20:50but it's the absence of something else that's even more compelling.
0:20:52 > 0:20:54There is no tail swipe at all.
0:20:54 > 0:20:56No. There is no sign of a tail drag here,
0:20:56 > 0:20:58or on any of the other trackways in the park,
0:20:58 > 0:21:00so we can be confident they did not drag their tails.
0:21:02 > 0:21:06The implications of this are pretty fundamental.
0:21:06 > 0:21:11Tyrannosaur-type dinosaurs lifted their tails off the ground.
0:21:16 > 0:21:21That means T-Rex didn't stand tall like a kangaroo.
0:21:21 > 0:21:23It bent forwards.
0:21:23 > 0:21:26Its enormous tail was the counterbalance,
0:21:26 > 0:21:28for its giant, heavy head.
0:21:28 > 0:21:32It turns out that the king of the dinosaurs stooped to conquer.
0:21:36 > 0:21:39But stance is not the only information
0:21:39 > 0:21:41we can glean from these trackways.
0:21:43 > 0:21:46Footprints reveal much more than dinosaur shoe size.
0:21:48 > 0:21:52And using a combination of modern and traditional techniques,
0:21:52 > 0:21:54Glenn gives me the full picture.
0:21:58 > 0:22:02So, Glenn, here we have got one of the photographs and here it has been
0:22:02 > 0:22:05treated with processes of photogrammetry.
0:22:05 > 0:22:08What can this tell us when we have done all of the prints together?
0:22:08 > 0:22:11Well, it is visually stunning and you can immediately
0:22:11 > 0:22:13get an appreciation for the depth of the track
0:22:13 > 0:22:14and things like the pads on the foot.
0:22:14 > 0:22:18If you try to do a conventional map, and even if you record the outlines
0:22:18 > 0:22:20very carefully, you still don't get a good appreciation
0:22:20 > 0:22:23for the depth and the contours that you can with a technique like this.
0:22:23 > 0:22:26OK, so this is going to give us a lot more information
0:22:26 > 0:22:28in terms of the way that this animal was moving.
0:22:28 > 0:22:32The data collected helps to inform the construction
0:22:32 > 0:22:34of precise 3-D models of the dinosaur's feet.
0:22:36 > 0:22:39This is a latex rubber mould that I made,
0:22:39 > 0:22:43and you see more detail often in the mould than the actual track.
0:22:43 > 0:22:44What's interesting about this one
0:22:44 > 0:22:46is that obviously it has put its foot into the mud,
0:22:46 > 0:22:48and then rather than drag it along,
0:22:48 > 0:22:51- it has pulled it out backwards. - Pulling it out backwards, yeah.
0:22:51 > 0:22:53- That is similar to way birds walk, isn't it?- Right, right.
0:22:55 > 0:22:57From muscles to footprints,
0:22:57 > 0:22:59the evidence is stacking up.
0:23:02 > 0:23:05Dinosaurs and birds are very closely related.
0:23:06 > 0:23:09In fact, scientists have proved that modern birds
0:23:09 > 0:23:12evolved directly from small dinosaurs, well,
0:23:12 > 0:23:15the lucky few who made it through the mass extinction event.
0:23:17 > 0:23:21So, if I want to get a sense of T-Rex's athletic prowess,
0:23:21 > 0:23:23I am going to forget about sluggish reptiles.
0:23:23 > 0:23:26I am going to turn to flightless birds.
0:23:30 > 0:23:34An emu or an ostrich can top 30mph.
0:23:35 > 0:23:39So could a sprinting T-Rex reach these kinds of speeds?
0:23:43 > 0:23:46In recent decades, blockbuster movies have portrayed T-Rex
0:23:46 > 0:23:48as a bit of a Roadrunner,
0:23:48 > 0:23:50but there's a real problem with that idea.
0:23:52 > 0:23:56Unlike those long-legged birds,
0:23:56 > 0:23:59T-Rex is carrying a two tonne tail.
0:23:59 > 0:24:02A team from the University of Chile
0:24:02 > 0:24:06recently explored the effects of tails on birds.
0:24:06 > 0:24:09By carefully strapping what looks like
0:24:09 > 0:24:12a modified toilet plunger to a chicken's backside.
0:24:13 > 0:24:15This experimental tail
0:24:15 > 0:24:19totally transforms the bird's posture and gait.
0:24:20 > 0:24:24It begins swinging its legs from the hip rather than the knee.
0:24:25 > 0:24:30This shows us how the tailed T-Rex may have walked.
0:24:30 > 0:24:33But, of course, the bigger question is, could it run?
0:24:36 > 0:24:39One man is on the case.
0:24:39 > 0:24:43Professor John Hutchinson combined trackway data with locomotion in
0:24:43 > 0:24:49flightless birds to unlock the secrets of T-Rex's biomechanics.
0:24:49 > 0:24:52The fossil footprints of a large dinosaur are really useful,
0:24:52 > 0:24:54but they only tell us so much,
0:24:54 > 0:24:57so we use experiments with living animals like an ostrich.
0:25:00 > 0:25:03We can go look at an ostrich, see how an ostrich moves,
0:25:03 > 0:25:06apply that information to the fossil record
0:25:06 > 0:25:08using computer models to help inform us
0:25:08 > 0:25:10about how T-Rex might have moved.
0:25:13 > 0:25:17John has told me there's more to T-Rex's tail than meets the eye.
0:25:18 > 0:25:22And Tristan's musculature can reveal its secret.
0:25:22 > 0:25:25OK, John, so when I am looking at this skeleton,
0:25:25 > 0:25:29and we are making those comparisons to contemporary birds,
0:25:29 > 0:25:32the one thing that I see that is very different
0:25:32 > 0:25:35is this enormous tail out of the back.
0:25:35 > 0:25:37Yes, the tail's enormous,
0:25:37 > 0:25:39more like a crocodile or a lizard's tail.
0:25:39 > 0:25:44And the tail and the thigh are linked by a huge muscle.
0:25:44 > 0:25:48That muscle ran from the tail to the thigh bone, to the femur.
0:25:48 > 0:25:50So this is a tail-to-muscle,
0:25:50 > 0:25:53that helped draw the leg backwards,
0:25:53 > 0:25:56and push a T-Rex forward and upwards.
0:25:56 > 0:25:59So the tail is intrinsically important
0:25:59 > 0:26:01in the locomotion of this enormous animal?
0:26:01 > 0:26:03Yes, and that's really cool.
0:26:05 > 0:26:08John's work has determined that
0:26:08 > 0:26:12T-Rex's tail-leg combo generated incredible thrust.
0:26:15 > 0:26:19But with great power comes perilous instability.
0:26:20 > 0:26:26Something best illustrated by dressing Tristan for a run.
0:26:43 > 0:26:46Let's bring Tristan up to 10mph,
0:26:46 > 0:26:47the speed of a jogging human.
0:26:52 > 0:26:54No problem at all.
0:26:54 > 0:26:58His flexing tail muscles help his legs power along at a steady pace.
0:27:00 > 0:27:05But what happens if we push him up to ostrich speed, 30mph?
0:27:09 > 0:27:12Well, he's powerfully built, he can just about get there.
0:27:13 > 0:27:18But at this speed, he's putting his life into his tiny hands.
0:27:20 > 0:27:23His pounding joints are stressed to the limits.
0:27:24 > 0:27:28And for an animal of this size, the slightest stumble could prove fatal.
0:27:33 > 0:27:35The bigger you are, the harder you fall.
0:27:35 > 0:27:39So, a seven tonne T-Rex falling down would hurt itself.
0:27:39 > 0:27:41And that would be maybe the end of it.
0:27:42 > 0:27:45So, it would be something a T-Rex would try to avoid, actively.
0:27:46 > 0:27:49So, forget ostrich speeds.
0:27:49 > 0:27:51Tristan could barely have outrun a human.
0:27:54 > 0:27:56And this does make sense.
0:27:56 > 0:27:58He didn't need speed.
0:27:59 > 0:28:03He just needed to be fast enough to catch his prey,
0:28:03 > 0:28:07those lumbering herbivores of the Cretaceous flood plains.
0:28:14 > 0:28:17So, now I'm getting much more of an understanding
0:28:17 > 0:28:20of how this magnificent animal moved through his world.
0:28:22 > 0:28:25And we know from living species,
0:28:25 > 0:28:28that to be an effective hunter you need much more than just speed.
0:28:30 > 0:28:33Predators must outsmart their prey.
0:28:34 > 0:28:39They are planners, masters of stealth and killers of precision.
0:28:41 > 0:28:43And none of this fits with my childhood Rex's
0:28:43 > 0:28:45reputation as a lumbering dullard.
0:28:45 > 0:28:50So, have we unfairly underestimated its brainpower?
0:28:54 > 0:28:58To find out, one scientist has called in the medics.
0:29:02 > 0:29:04Palaeontologist Dr Larry Witmer
0:29:04 > 0:29:09has spent his career trying to get inside T-Rex's head.
0:29:09 > 0:29:12The latest medical scanning technology enables him
0:29:12 > 0:29:14to conduct a virtual dissection.
0:29:16 > 0:29:18In the past when we tried to understand T-Rex,
0:29:18 > 0:29:20and we were looking at the fossils,
0:29:20 > 0:29:22we could learn only so much from the outside.
0:29:22 > 0:29:25But with the advent of CT scanning,
0:29:25 > 0:29:29it allowed us to peer inside to see what was going on.
0:29:31 > 0:29:34I've joined Larry to see what he's discovered.
0:29:36 > 0:29:41The scan detects minute differences in the densities of the fossil.
0:29:41 > 0:29:43And Larry uses this information
0:29:43 > 0:29:47to create a 3-D model of the inside of the skull.
0:29:48 > 0:29:51Larry, I love it when you can just rotate this skull like that.
0:29:51 > 0:29:56It is an amazing piece of anatomy, but let's delve inside the skull.
0:29:56 > 0:29:58Yeah, we can do that.
0:29:58 > 0:30:02You can just sort of make the skull transparent, so we can peer inside.
0:30:02 > 0:30:06What I've got lit up over here is actually the brain case.
0:30:06 > 0:30:09We can see a lovely brain case here.
0:30:09 > 0:30:14But the real advantage is when we start to run a slice through it.
0:30:14 > 0:30:16The scan is so detailed,
0:30:16 > 0:30:20it can register the volume of the skull's interior.
0:30:20 > 0:30:24And this allows Larry to produce something utterly extraordinary.
0:30:24 > 0:30:28The precise form of T-Rex's brain.
0:30:28 > 0:30:32Larry, this is unquestionably brilliant.
0:30:32 > 0:30:34Absolutely sensational.
0:30:34 > 0:30:37- Honestly.- Well, trying to peer inside the mind of a dinosaur,
0:30:37 > 0:30:39this is the closest we're going to get to it.
0:30:39 > 0:30:42And Larry can make the virtual, physical
0:30:42 > 0:30:44by using 3-D printing.
0:30:44 > 0:30:47And that is the brain of an adult T-Rex.
0:30:47 > 0:30:50Right, right. If you compare something like this
0:30:50 > 0:30:52to the skull that it came from,
0:30:52 > 0:30:55it just seems vanishingly small.
0:30:55 > 0:30:56But really for a reptile,
0:30:56 > 0:31:00this is maybe two or three times what we might expect
0:31:00 > 0:31:03for a reptile that was the body size of T-Rex.
0:31:03 > 0:31:06And that's because it's not a reptilian brain.
0:31:06 > 0:31:08It's a bird brain.
0:31:08 > 0:31:12Bird-brain used to be an insult, now it's actually a compliment.
0:31:12 > 0:31:16In recent years we've discovered that the structure of bird brains is
0:31:16 > 0:31:18entirely surprising.
0:31:18 > 0:31:22Their neurons, their brain cells are actually much smaller and much more
0:31:22 > 0:31:24highly densely packed.
0:31:24 > 0:31:26So maybe when we look at something like T-Rex,
0:31:26 > 0:31:30we have been misjudging its potential cognitive abilities.
0:31:33 > 0:31:38The brain scans allow Larry to bring the behaviour of T-Rex to life.
0:31:40 > 0:31:44When a lot of people look at T-Rex, what they see is a feeding machine.
0:31:44 > 0:31:48When I look at the head of T-Rex, I see a gigantic sensory organ.
0:31:48 > 0:31:51I see, really, the senses of a predator.
0:31:52 > 0:31:56Larry has identified the brain centres responsible for smell,
0:31:56 > 0:31:58sight and hearing.
0:31:58 > 0:32:01And he's found that they are super-sized.
0:32:01 > 0:32:03The olfactory bulbs are larger than what we see
0:32:03 > 0:32:06in, really, other kinds of predatory dinosaurs.
0:32:06 > 0:32:10That means it has a remarkably large sense of smell.
0:32:10 > 0:32:12So with regards to vision,
0:32:12 > 0:32:17we can look at the optic nerves that are bringing information in
0:32:17 > 0:32:19from the retina of the eye.
0:32:19 > 0:32:21And those optic nerves are really large,
0:32:21 > 0:32:24and that suggests to us that there was a really highly developed
0:32:24 > 0:32:29sense of vision, that was very important to these animals.
0:32:29 > 0:32:31Perhaps the most astonishing discovery
0:32:31 > 0:32:34is this tiny pink structure.
0:32:34 > 0:32:38One of the things that can give us a view, potentially,
0:32:38 > 0:32:41at the agility of an extinct animal like T-Rex, is the inner ear.
0:32:41 > 0:32:44And we can see these structures right in here
0:32:44 > 0:32:45that are the key to that.
0:32:45 > 0:32:48These semi-circular canals actually sense
0:32:48 > 0:32:51turning movements of the head in space.
0:32:51 > 0:32:54And what that means is that they can coordinate the movement of
0:32:54 > 0:32:58their eyes with the turning movements of their head and body.
0:32:58 > 0:33:02And the purpose of that is to keep the prey firmly within their sight.
0:33:04 > 0:33:06This is incredible.
0:33:06 > 0:33:09You see, this gyroscopic stabilisation system
0:33:09 > 0:33:13is a remarkable adaptation found in modern predators...
0:33:14 > 0:33:18..from birds of prey to cheetahs.
0:33:20 > 0:33:24And it's proof that T-Rex was built for the hunt.
0:33:29 > 0:33:32It must have been one of the most advanced
0:33:32 > 0:33:35and capable predators ever to walk the planet.
0:33:36 > 0:33:40And its inner ear is also revealing the secrets.
0:33:41 > 0:33:45You can learn what an animal sounds like from what it evolved to hear.
0:33:47 > 0:33:50We can get some of that information by looking at the structure of the
0:33:50 > 0:33:54inner ear. In particular the hearing organ, or the cochlear duct.
0:33:54 > 0:33:58What that suggests in T-Rex is that it actually had a very sensitive
0:33:58 > 0:34:03hearing organ, it was especially sensitive to low frequency sounds,
0:34:03 > 0:34:07potentially frequencies lower than even most of us can hear.
0:34:07 > 0:34:08What we might call infra-sound.
0:34:14 > 0:34:18So what does this mean for T-Rex's iconic roar?
0:34:23 > 0:34:26The most chilling noises in the natural world today
0:34:26 > 0:34:28come from our top predators.
0:34:28 > 0:34:30The howl of the wolf.
0:34:32 > 0:34:33The roar of the tiger.
0:34:35 > 0:34:37But Larry's findings add to the suspicion
0:34:37 > 0:34:39amongst scientists that in reality,
0:34:39 > 0:34:42T-Rex sounded nothing like them.
0:34:45 > 0:34:50If we look at any of the classic dinosaur movies, T-Rex is roaring.
0:34:51 > 0:34:55And the reason we probably thought of this as appropriate
0:34:55 > 0:35:00is that large carnivores today, most of them are mammals,
0:35:00 > 0:35:03and those are sounds that they produce.
0:35:03 > 0:35:04But when we think about T-Rex,
0:35:04 > 0:35:09this is an animal most closely related to birds and alligators,
0:35:09 > 0:35:14and crocodiles. And those animals make very different kinds of sounds.
0:35:17 > 0:35:21Professor Julia Clarke studies dinosaur vocalisation.
0:35:21 > 0:35:24And at this recording studio in Berlin
0:35:24 > 0:35:27she's agreed to help me try to recreate T-Rex's voice.
0:35:29 > 0:35:34Julia, I rather perversely like the fact that T-Rex couldn't roar.
0:35:34 > 0:35:38I know, it's really, you know, it grabs you and makes you think,
0:35:38 > 0:35:39what was this animal really like?
0:35:42 > 0:35:45A good place to start is with our old friends,
0:35:45 > 0:35:47the birds and the crocodilians.
0:35:49 > 0:35:53Many of them communicate with what's known as closed mouth vocalisation.
0:35:55 > 0:35:57So we're going to kick off our experiment
0:35:57 > 0:35:59with my personal favourite.
0:35:59 > 0:36:00The Eurasian bittern.
0:36:03 > 0:36:06We know these birds from reedbeds in the UK,
0:36:06 > 0:36:08so they live in this dense environment.
0:36:08 > 0:36:11They produce these very low sounds,
0:36:11 > 0:36:12booming we call it.
0:36:12 > 0:36:15Let's see how low frequency they really are.
0:36:15 > 0:36:16Because they're not that large,
0:36:16 > 0:36:18but they're making a low frequency sound.
0:36:18 > 0:36:20So, Fabian, take it away.
0:36:20 > 0:36:22Can we make it louder?
0:36:22 > 0:36:23Yeah.
0:36:23 > 0:36:26BOOMS
0:36:26 > 0:36:30I can see that being eerie in an English countryside.
0:36:30 > 0:36:31- Misty.- Misty.
0:36:31 > 0:36:34Reeds, early-morning, or at night.
0:36:34 > 0:36:35It's a little creepy.
0:36:37 > 0:36:39Even though it sounds really low to us.
0:36:39 > 0:36:40It's not that low, is it?
0:36:40 > 0:36:42It's not that low.
0:36:43 > 0:36:46And so what we're talking about when we talk about what T-Rex would have
0:36:46 > 0:36:47produced, or could have produced.
0:36:47 > 0:36:50- This is nothing, it's much lower than this.- Exactly.
0:36:52 > 0:36:54Of all the living birds, the ostriches
0:36:54 > 0:36:56make one of the deepest calls.
0:36:57 > 0:37:00But they're still only a fraction of the size of a T-Rex.
0:37:02 > 0:37:04So to create the sound of a much bigger bird,
0:37:04 > 0:37:08we artificially drop our bittern call by two octaves.
0:37:11 > 0:37:12- All right.- OK.- Crank it.
0:37:16 > 0:37:19It seems subtle, but you know, it's deep.
0:37:19 > 0:37:21- Yeah.- I can barely hear it.
0:37:21 > 0:37:24But deep doesn't necessarily mean quiet.
0:37:24 > 0:37:25No.
0:37:25 > 0:37:27This is low.
0:37:27 > 0:37:30But we haven't yet hit the infrasonic lows
0:37:30 > 0:37:32that T-Rex's inner ear implies.
0:37:35 > 0:37:37We're going to need to try something else.
0:37:38 > 0:37:41We know that animals use infrasonic sounds
0:37:41 > 0:37:43to communicate across vast distances.
0:37:47 > 0:37:49Elephant rumbles travel miles.
0:37:52 > 0:37:55Blue whale song can be heard across entire oceans.
0:37:58 > 0:38:01But amongst T-Rex's living relatives,
0:38:01 > 0:38:04only the crocodilians share this infrasonic vocal ability.
0:38:07 > 0:38:11So, let's put an alligator call into a T-Rex voice box.
0:38:11 > 0:38:16So, what does it sound like if we take the Chinese alligator,
0:38:16 > 0:38:19and we now move it a couple of octaves lower?
0:38:19 > 0:38:23If we move it three octave lower it sounds like this.
0:38:23 > 0:38:26BOOMS
0:38:26 > 0:38:28Can we get it a little louder?
0:38:28 > 0:38:30- Just crank the fader, please.- OK.
0:38:32 > 0:38:34That's ominous.
0:38:36 > 0:38:37That is very ominous.
0:38:39 > 0:38:41What I really like, Julia,
0:38:41 > 0:38:45is that this could be the first time for 66 million years
0:38:45 > 0:38:48that this sound has been heard on Earth.
0:38:49 > 0:38:50It is pretty incredible.
0:38:50 > 0:38:53I mean, it is a shot in the dark,
0:38:53 > 0:38:56- but we're using the evidence that we've got.- Yeah.
0:38:56 > 0:39:01If it sounds like this, I mean, I feel like this just induces fear.
0:39:01 > 0:39:04You know, I think people think you need to have a roar
0:39:04 > 0:39:06for something to be really scary.
0:39:06 > 0:39:10But isn't that the scariest sound that you've heard?
0:39:10 > 0:39:14Well, it's the scariest sound that I've felt.
0:39:14 > 0:39:16- That's the thing, isn't it?- Yeah.
0:39:21 > 0:39:25Tristan the T-Rex is really taking shape.
0:39:25 > 0:39:30We've fleshed him out, road-tested him, and giving him a voice.
0:39:30 > 0:39:32Now it's time for a little beauty treatment.
0:39:36 > 0:39:40An animal's external appearance is a reflection of its biology,
0:39:40 > 0:39:43its environment and its social world.
0:39:43 > 0:39:45So, what should Tristan look like?
0:39:45 > 0:39:48Well, his repto-birdlike nature
0:39:48 > 0:39:52means we should coat his body in scaly skin.
0:39:52 > 0:39:54But what about the colour?
0:39:56 > 0:40:00We know that some contemporary reptiles are very brightly coloured.
0:40:00 > 0:40:04Think of coral snakes, reds and yellows, blues even.
0:40:04 > 0:40:07Maybe, T-Rex was like that.
0:40:10 > 0:40:13Maybe, but T-Rex was a large predator.
0:40:13 > 0:40:17So, it's fairly obvious that he would've needed camouflage.
0:40:17 > 0:40:20Think of tigers, solitary hunters.
0:40:20 > 0:40:22Hunting in forest.
0:40:22 > 0:40:24Dappled sunlight, stripey.
0:40:24 > 0:40:26So, maybe a stripey T-Rex.
0:40:31 > 0:40:33There are other ways to hide, of course.
0:40:33 > 0:40:35Spotted, like a leopard, perhaps.
0:40:38 > 0:40:40Or maybe such a big,
0:40:40 > 0:40:43obvious hunter would need to hide in the shadows of the night.
0:40:43 > 0:40:46That would need a very different colour scheme.
0:40:46 > 0:40:48Think of all those nocturnal mammals
0:40:48 > 0:40:50that we've got these days that aren't related to one another,
0:40:50 > 0:40:52but have come up with the same solution.
0:40:52 > 0:40:56We've got badgers, you've got skunks, you got raccoons.
0:40:56 > 0:41:00All with very prominent black and white patterning on the head.
0:41:00 > 0:41:02Maybe T-Rex was like that.
0:41:05 > 0:41:07I don't like maybes.
0:41:07 > 0:41:09So, clearly I need to narrow down the possibilities.
0:41:17 > 0:41:19In a lab in Austin, Texas,
0:41:19 > 0:41:24Julia Clark analyses tiny samples of fossilised dinosaurs.
0:41:26 > 0:41:28Like, that one is wet, it's about 1.5...
0:41:28 > 0:41:32So, I've tracked her down again to help me in my quest.
0:41:33 > 0:41:35This is a whole new field of palaeontology, isn't it?
0:41:35 > 0:41:38You're looking at dinosaurs under an electron scanning microscope.
0:41:38 > 0:41:39I know, is kind of ridiculous, right?
0:41:39 > 0:41:43You have these huge animals that you're trying to make sense of,
0:41:43 > 0:41:46but yet, to find some insight into how it would have lived,
0:41:46 > 0:41:48or what it would have looked like,
0:41:48 > 0:41:50we've got to look at its tiniest parts.
0:41:50 > 0:41:53But they might bring out some of the most exciting secrets.
0:41:53 > 0:41:55The colour of dinosaurs.
0:41:55 > 0:41:56Yeah. I love that.
0:41:56 > 0:41:59I absolutely love that. That's fantastic.
0:42:01 > 0:42:05Under an electron microscope, the samples reveal hidden information.
0:42:05 > 0:42:08Structures that contain pigments.
0:42:11 > 0:42:14But it's not looking good for a brightly coloured T-Rex.
0:42:15 > 0:42:18There are many pigments that are used in nature,
0:42:18 > 0:42:22and some of these pigments create very bright colours.
0:42:22 > 0:42:26But, we don't have any evidence, at present,
0:42:26 > 0:42:28of them in the dinosaur fossil record.
0:42:29 > 0:42:33But the structures they have found contained melanin,
0:42:33 > 0:42:36the same biological pigment that gives us a tan.
0:42:39 > 0:42:42And one group of T-Rex's living relatives
0:42:42 > 0:42:45could provide a perfect colour template.
0:42:45 > 0:42:46The birds of prey.
0:42:47 > 0:42:52What we can say is that living birds that are meat-eaters,
0:42:52 > 0:42:54that are carnivores of some kind,
0:42:54 > 0:42:56have an ecology that is somewhat similar,
0:42:56 > 0:42:59at a very different scale from T-Rex,
0:42:59 > 0:43:01and they do not tend to be brightly coloured.
0:43:08 > 0:43:10According to Julia's research,
0:43:10 > 0:43:14the evidence is that T-Rex's predatory lifestyle,
0:43:14 > 0:43:18puts his colouration squarely in line with these contemporary birds.
0:43:22 > 0:43:27I think that T-Rex would have been coloured in a palette of browns,
0:43:27 > 0:43:31blacks, maybe lighter tones, greys even.
0:43:31 > 0:43:34And, that these colours would have been distributed in patches over the
0:43:34 > 0:43:37body, maybe breaking up the body outline.
0:43:37 > 0:43:39Potentially serving in camouflage,
0:43:39 > 0:43:44but also parts of the body that might be a little more dramatic.
0:43:46 > 0:43:49Colour is often more intense around the eyes.
0:43:49 > 0:43:53And this could help explain another fascinating feature
0:43:53 > 0:43:57that Larry showed me in his analysis of T-Rex skulls.
0:43:57 > 0:44:01So, we look at the skull and we see these area of roughening that is
0:44:01 > 0:44:04almost certainly associated with fleshy display structures,
0:44:04 > 0:44:07so they may have well have used those for colour.
0:44:07 > 0:44:09But also what could be courtship signs.
0:44:09 > 0:44:12They might have communicated information about age,
0:44:12 > 0:44:13males versus females.
0:44:13 > 0:44:17These were the kind of social cues that T-Rex would have used
0:44:17 > 0:44:21to interact with other members of the same species.
0:44:22 > 0:44:27So, with Julia and Larry's findings, let's colour up Tristan.
0:44:31 > 0:44:34Melanin tones, and patterning for the body.
0:44:36 > 0:44:39And a touch of melanic orange around the eyes.
0:44:40 > 0:44:41He's looking good.
0:44:44 > 0:44:47But, if we are using birds as a guide,
0:44:47 > 0:44:50wouldn't Tristan have also had a coat?
0:44:59 > 0:45:02And let's be clear, he wouldn't be the first feathered dinosaur.
0:45:09 > 0:45:12Feathers evolved directly from reptilian scales.
0:45:14 > 0:45:17In fact, we already know that some dinosaurs
0:45:17 > 0:45:22were flying about 80 million years, before T-Rex even existed.
0:45:22 > 0:45:25One of the first was Archaeopteryx,
0:45:25 > 0:45:27and Julia has one of its feathers.
0:45:27 > 0:45:31All right, so you have to look at this.
0:45:33 > 0:45:36So, this is 149 million years old.
0:45:36 > 0:45:38149 million.
0:45:38 > 0:45:41It looks like it was pressed there yesterday.
0:45:41 > 0:45:44Absolutely. So, you see that centre part where the rake is,
0:45:44 > 0:45:47and then branches, which are the barbs.
0:45:47 > 0:45:51And then what locks it together tightly are these barbules,
0:45:51 > 0:45:55that have tiny hooklets that lock the feather into form.
0:45:55 > 0:46:00Just like a modern bird, and yet this is 149 million years old.
0:46:00 > 0:46:02And what colour, can you tell what colour that feather was?
0:46:02 > 0:46:04Well, other groups looked at the
0:46:04 > 0:46:07fossilised malanosomes in this feather,
0:46:07 > 0:46:09and they are consistent with a pretty dark tone.
0:46:09 > 0:46:12So, maybe like a black, or there
0:46:12 > 0:46:15could be some gradations in black,
0:46:15 > 0:46:16some subtle tonalities,
0:46:16 > 0:46:18but overall quite dark in colour.
0:46:18 > 0:46:24And these feathers clearly evolved millions of years before T-Rex.
0:46:24 > 0:46:27- Absolutely.- So, could T-Rex have had feathers like this?
0:46:29 > 0:46:32Well, the short answer is no.
0:46:32 > 0:46:34Right.
0:46:34 > 0:46:39No. T-Rex didn't evolve from these flying dinosaurs.
0:46:39 > 0:46:44But recent discoveries in China have unearthed some of his relatives,
0:46:44 > 0:46:47and they prove that Tyrannosaurs did
0:46:47 > 0:46:51indeed have a simple form of feathering.
0:46:52 > 0:46:56So, if we look at this cassowary that's been checking us out,
0:46:56 > 0:47:00these are much more simple bristle structures.
0:47:00 > 0:47:03They're like the centre part of the feather,
0:47:03 > 0:47:05but without any branching structures to the side.
0:47:05 > 0:47:06So here there are big,
0:47:06 > 0:47:10stiff structures that are on the wing of this cassowary,
0:47:10 > 0:47:11which is really tiny.
0:47:11 > 0:47:12But even around the face,
0:47:12 > 0:47:16we can see simple structures here under the beak,
0:47:16 > 0:47:19and even kind of in the eyebrow zone above,
0:47:19 > 0:47:23that are like single filaments.
0:47:23 > 0:47:27And that's what we find in relatives of T-Rex from China.
0:47:32 > 0:47:36So, what does this mean for Tristan's flamboyant feather coat?
0:47:36 > 0:47:38Well, it certainly didn't look like this.
0:47:46 > 0:47:48For one thing, with so much insulation,
0:47:48 > 0:47:52such a large animal would simply overheat.
0:47:52 > 0:47:56But the evidence suggests that he would have sported a sparse coating
0:47:56 > 0:47:59of these feathery Tyrannosaur bristles.
0:47:59 > 0:48:01Now that's an attractive chap!
0:48:05 > 0:48:09So, we've got the measure of Tristan's hunting style,
0:48:09 > 0:48:10his walking style,
0:48:10 > 0:48:12and his appearance.
0:48:12 > 0:48:15But what can we uncover about his family structure?
0:48:24 > 0:48:28These are the Alberta Badlands, just across the border from Hell Creek.
0:48:35 > 0:48:39There's startling evidence for T-Rex's social structure
0:48:39 > 0:48:41hidden in this landscape.
0:48:43 > 0:48:45Whilst exploring these hills,
0:48:45 > 0:48:49Dr Phil Currie uncovered a game-changing set of bones.
0:48:49 > 0:48:53You see, this spot was the scene of a terrible tyrannosaur tragedy.
0:48:53 > 0:48:57The fossilised remains of 26 Albertosauruses,
0:48:57 > 0:48:58close relatives of T-Rex,
0:48:58 > 0:49:02were found lying in a group side by side.
0:49:02 > 0:49:06They died together, possibly in a cataclysmic storm,
0:49:06 > 0:49:09and never before had so many Tyrannosaurs
0:49:09 > 0:49:11been found in one place.
0:49:11 > 0:49:15Remarkably, they were a mix of young and old.
0:49:15 > 0:49:19The smallest animal we have in here was about two years old,
0:49:19 > 0:49:22and the largest animal was about 24 years old.
0:49:22 > 0:49:27Until this find, Tyrannosaurs were thought to be lone rangers,
0:49:27 > 0:49:31but this discovery gave strength to the idea that, instead,
0:49:31 > 0:49:35they existed in family groups.
0:49:35 > 0:49:36I'd never really thought about
0:49:36 > 0:49:38parental care and tyrannosaurs before,
0:49:38 > 0:49:42because we tend to think that these animals are quite self-sufficient.
0:49:42 > 0:49:47But when you start finding juvenile animals that are living with a large
0:49:47 > 0:49:49number of adults, then you have to start thinking
0:49:49 > 0:49:52about family structure and these things.
0:49:54 > 0:49:58So these animals were definitely together for a reason.
0:49:58 > 0:50:00That reason could not have been mating,
0:50:00 > 0:50:03because that wouldn't make sense to have the juveniles around at that
0:50:03 > 0:50:04- point in time.- Quite, quite.
0:50:04 > 0:50:07And I just think it makes perfect sense that,
0:50:07 > 0:50:09if these animals were moving together,
0:50:09 > 0:50:11that, in fact, they were hunting co-operatively.
0:50:13 > 0:50:16And of course, pack predators aren't unusual.
0:50:16 > 0:50:19Africa's apex predator, the lion,
0:50:19 > 0:50:22lives and hunts in a family unit, the pride.
0:50:23 > 0:50:25And there are plenty of advantages.
0:50:25 > 0:50:28They can protect one another, help raise the young,
0:50:28 > 0:50:30and there's plenty of opportunity for mating.
0:50:35 > 0:50:38But males also fight for dominance,
0:50:38 > 0:50:40often causing deep facial wounds.
0:50:45 > 0:50:50Tantalisingly, adult T-Rex skulls are also scarred.
0:50:53 > 0:50:56These animals were actually biting each other in the face.
0:50:56 > 0:50:58And we know that it must have been T-Rex,
0:50:58 > 0:51:00because no-one else is biting T-Rex in the face
0:51:00 > 0:51:01other than another T-Rex.
0:51:04 > 0:51:08These face biting behaviours may have been part of the mating rituals
0:51:08 > 0:51:10for these animals, we don't really know for sure.
0:51:10 > 0:51:13One thing we do know is that features like these scars
0:51:13 > 0:51:16on their faces show that these animals
0:51:16 > 0:51:19were interacting with each other in routine and regular ways,
0:51:19 > 0:51:21because we see lots of them.
0:51:23 > 0:51:27But the real advantage of living in groups comes with the hunt.
0:51:30 > 0:51:34And Phil believes that lions offer some real clues
0:51:34 > 0:51:36about the social life of Tyrannosaurs.
0:51:37 > 0:51:38Very often what happens,
0:51:38 > 0:51:40it's the young lions and lionesses
0:51:40 > 0:51:44that are the ones that do most of the hunting. They do the running.
0:51:44 > 0:51:47Very often, what they'll do is they'll chase a herbivore
0:51:47 > 0:51:51back towards the jaws of the adults, the ones that have the real power.
0:51:53 > 0:51:58T-Rex packs may have had an extra weapon in their hunting arsenal,
0:51:58 > 0:52:01their fast-moving young.
0:52:01 > 0:52:05We know this because the bones of juveniles show them to be markedly
0:52:05 > 0:52:07different to the adults.
0:52:09 > 0:52:14Tyrannosaurus Rex is an animal that just went through incredible changes
0:52:14 > 0:52:17in its lifetime, and juvenile animals would have had
0:52:17 > 0:52:21very long legs, it would have been very lightly built,
0:52:21 > 0:52:23it would have been fast and agile.
0:52:23 > 0:52:26Even its jaws are very slender,
0:52:26 > 0:52:29and its teeth are quite small compared to the size of the animal.
0:52:31 > 0:52:35Young T-Rex was so different to the adult version,
0:52:35 > 0:52:38that until recently scientists thought they were separate species.
0:52:44 > 0:52:46In his lab in Florida,
0:52:46 > 0:52:50Greg Erickson has been investigating the secrets of this transformation.
0:52:53 > 0:52:56By slicing through fossilised T-Rex bones,
0:52:56 > 0:52:59he's revealed their annular growth rings.
0:53:00 > 0:53:04Ageing a dinosaur like Tyrannosaurus Rex is very much like ageing a tree.
0:53:04 > 0:53:06Dinosaurs put down annual growth lines,
0:53:06 > 0:53:08you can see some of them here.
0:53:08 > 0:53:10And simply by counting up the total,
0:53:10 > 0:53:14we can figure out how old an animal was at the time of death.
0:53:14 > 0:53:18The rings reveal that at about 12 years of age,
0:53:18 > 0:53:22T-Rex began the mother of all adolescent growth spurts.
0:53:25 > 0:53:30The increasing gaps between rings indicates that, in just a few years,
0:53:30 > 0:53:34T-Rex grew three times in height and six times in weight.
0:53:36 > 0:53:38In its teenage years here,
0:53:38 > 0:53:41this animal was putting on about five pounds of weight per day.
0:53:42 > 0:53:43It's mind-boggling.
0:53:45 > 0:53:48This extreme growth gave T-Rex the ability
0:53:48 > 0:53:51to develop its secret weapon in adulthood,
0:53:51 > 0:53:55that almighty head and its massive bite power.
0:53:56 > 0:53:58But it also defined it in another way.
0:54:00 > 0:54:05As its enormous body grew, its forearms were left behind.
0:54:05 > 0:54:08They were effectively the arms of a child.
0:54:16 > 0:54:19Tristan the T-Rex is almost complete.
0:54:20 > 0:54:25Now, we can only speculate on the true extent of his social world,
0:54:25 > 0:54:28but we know this ultimate hunter
0:54:28 > 0:54:30would have borne the marks of a violent life.
0:54:32 > 0:54:35And for me, the idea that he lived and hunted
0:54:35 > 0:54:39in a pride like a modern-day lion, is fascinating.
0:54:42 > 0:54:46And it's this that's encouraged me to add one final,
0:54:46 > 0:54:48yet plausible touch to my dinosaur.
0:54:55 > 0:54:57What about... I like this idea.
0:54:57 > 0:55:01What about if T-Rex had a mane like a lion?
0:55:01 > 0:55:03We know that male lions use those manes
0:55:03 > 0:55:07to communicate to other male lions, and to females.
0:55:07 > 0:55:09So, T-Rex with a mane?
0:55:13 > 0:55:17A spiky crown for the king of the dinosaurs.
0:55:24 > 0:55:29After 65 million years, Tristan is whole again.
0:55:31 > 0:55:32Time to set him free.
0:55:49 > 0:55:52You know, this journey has been a revelation.
0:55:53 > 0:55:57Even as a child I suspected we'd got T-Rex wrong,
0:55:57 > 0:56:00but I'd have been amazed at the progress
0:56:00 > 0:56:01we've made in the last few years.
0:56:05 > 0:56:09What we've discovered about his brain, his appearance,
0:56:09 > 0:56:11his behaviour and his voice
0:56:11 > 0:56:14have enabled me to strip away the myth and put
0:56:14 > 0:56:19real life into that 50-year-old monster at the bottom of my garden.
0:56:21 > 0:56:23Now, where are you, Tristan?
0:56:34 > 0:56:37T-Rex was no tail-dragging dullard.
0:56:39 > 0:56:42He was as real as any animal alive today.
0:56:46 > 0:56:49A clever, agile predator,
0:56:49 > 0:56:51with senses keen enough to track me down.
0:56:59 > 0:57:03He bore the scars of a violent life,
0:57:03 > 0:57:06and the colours and plumes of a social creature...
0:57:09 > 0:57:14..capable of summoning his kind with a stomach-churning rumble.
0:57:40 > 0:57:45When I was a boy, he was the product of my misled imagination.
0:57:45 > 0:57:48But now, he's so much more real.
0:57:51 > 0:57:56He has such clarity, I can almost...
0:57:59 > 0:58:01Well, maybe not.
0:58:10 > 0:58:13We've successfully chipped away at his mystery.
0:58:13 > 0:58:17This wondrous animal is far better understood
0:58:17 > 0:58:19shorn of the errors of the past.
0:58:21 > 0:58:24And I, for one, think he'd be pleased
0:58:24 > 0:58:30that we're finally much closer to the truth about T-Rex.