0:00:02 > 0:00:05If you thought you knew all there was to know about dinosaurs,
0:00:05 > 0:00:08think again.
0:00:08 > 0:00:11This is Planet Dinosaur Files,
0:00:11 > 0:00:13the series that rewrites the prehistory books.
0:00:13 > 0:00:16We're bringing to life the most awesome beasts
0:00:16 > 0:00:21ever to walk the earth with state-of-the-art CGI technology
0:00:21 > 0:00:25that makes you feel like you're right there.
0:00:25 > 0:00:28And I'll be discovering what made these massive,
0:00:28 > 0:00:32lethal and, frankly, bizarre beasts tick.
0:00:32 > 0:00:37I'll be devising demos using air power, big chunks of steel,
0:00:37 > 0:00:40and even calling in the fire brigade.
0:00:40 > 0:00:46This is going to be all about brute strength and crunching power.
0:00:47 > 0:00:51In the last 20 years, scientists have discovered more dinosaurs
0:00:51 > 0:00:55than in all the centuries that have gone before.
0:00:55 > 0:00:58Amazing new discoveries.
0:00:58 > 0:01:03They reveal a jaw-dropping cast list of creatures.
0:01:06 > 0:01:08Bigger,
0:01:08 > 0:01:09weirder,
0:01:09 > 0:01:13deadlier than we had ever imagined.
0:01:13 > 0:01:15And this time, on Planet Dinosaur Files,
0:01:15 > 0:01:20I'm asking the question, which predator was the most powerful?
0:01:29 > 0:01:33You might think you know about dinosaurs,
0:01:33 > 0:01:37like the huge 12-tonne plant-eater, diplodocus.
0:01:39 > 0:01:42Or the mighty tyrannosaurus rex,
0:01:42 > 0:01:46a savage predator who dominated half the planet
0:01:46 > 0:01:49for almost five million years.
0:01:49 > 0:01:52Well, think again.
0:01:52 > 0:01:55Ready to meet the new powerful dinos on the block?
0:02:00 > 0:02:02Like Majungasaurus,
0:02:02 > 0:02:05a super scavenger to match a pack of hyenas.
0:02:05 > 0:02:07A vicious cannibal
0:02:07 > 0:02:10which would fight to the death to fill its own stomach.
0:02:12 > 0:02:15Or the crunching power of Daspletosaurus,
0:02:15 > 0:02:17the grandad of mighty T-Rex,
0:02:17 > 0:02:21with one of the most devastating bites of any dinosaur that's lived.
0:02:23 > 0:02:26And now there is an amazing new discovery
0:02:26 > 0:02:30about that pulverising power house, allosaurus.
0:02:30 > 0:02:34A predator with a very special form of attack.
0:02:35 > 0:02:38So, three ravenous, bruising killers,
0:02:38 > 0:02:42who would strike fear into other dinosaurs.
0:02:42 > 0:02:47I'm going to look at what makes these dinosaurs so powerful.
0:02:49 > 0:02:51First, bite strength.
0:02:53 > 0:02:57Strong jaw muscles were a must for any prehistoric killer.
0:02:58 > 0:03:01Next, size.
0:03:01 > 0:03:05Are the biggest predators also the most powerful?
0:03:06 > 0:03:10And finally, the fear factor.
0:03:10 > 0:03:13Being able to scare other dinosaurs is crucial
0:03:13 > 0:03:16if you want to top my power league.
0:03:16 > 0:03:18Ready to meet the first dinosaur
0:03:18 > 0:03:21competing to be the most powerful of the lot?
0:03:33 > 0:03:36This is allosaurus.
0:03:37 > 0:03:41We've known about allosaurus for over 100 years
0:03:41 > 0:03:46but we've recently found out more about this awesome dinosaur.
0:03:48 > 0:03:52This was a heavily armed, super hunter.
0:03:52 > 0:03:54Nine metres long.
0:03:54 > 0:03:57He weighs 1½ tonnes.
0:03:57 > 0:04:01That's a lot less than many other big meat-eaters.
0:04:02 > 0:04:04But - and it's a big but -
0:04:04 > 0:04:08just look at those bulging forearms with the big claws,
0:04:08 > 0:04:13those teeth, like saw blades, and those powerful upper legs.
0:04:13 > 0:04:16This is no lumbering giant
0:04:16 > 0:04:19but a sleek, muscular killer with a speciality.
0:04:19 > 0:04:21Ambush.
0:04:21 > 0:04:25Here, he's hoping to turn plant-eating qantassaurus
0:04:25 > 0:04:27into dinner.
0:04:29 > 0:04:32Allosaurs and qantassaurs lived 150 million years ago,
0:04:32 > 0:04:36roughly where the USA is today.
0:04:36 > 0:04:40And these rocky, scrubby plains are the perfect place
0:04:40 > 0:04:42for a surprise attack.
0:04:42 > 0:04:45There's a lot of cover for the allosaurus to use
0:04:45 > 0:04:48so he can sneak up on the qantassaurus.
0:04:53 > 0:04:58You can still see this kind of hunting going on in Africa today.
0:04:58 > 0:05:03Here, this cheetah has got its eye on a tasty meal of gazelle.
0:05:03 > 0:05:06He's creeping up on his target.
0:05:06 > 0:05:08He needs to get close enough to have a chance
0:05:08 > 0:05:13of using his incredible speed to catch the nimble gazelle.
0:05:14 > 0:05:17This time he just misses out.
0:05:24 > 0:05:27Rewind 150 million years
0:05:27 > 0:05:32and this allosaurus is closing in on its prey, a lone qantassaurus.
0:05:32 > 0:05:36Like the gazelle, the qantassaurus has very alert senses
0:05:36 > 0:05:39so he's alive to possible danger.
0:05:39 > 0:05:41And that's just as well.
0:05:41 > 0:05:44Firstly, because at three-quarters of a tonne
0:05:44 > 0:05:48and six metres in length, he's much smaller than the allosaurus.
0:05:48 > 0:05:53And, secondly, he's on his own and that makes him vulnerable.
0:05:53 > 0:05:56And if allosaurus can get within striking range
0:05:56 > 0:06:01undetected by the qantassaurus, he can spring his ambush.
0:06:04 > 0:06:08That's an incredible explosion of speed by allosaurus.
0:06:08 > 0:06:12He was off his blocks like Usain Bolt.
0:06:12 > 0:06:16An allosaurus could reach a speed of 25mph,
0:06:16 > 0:06:18amazing for a beast that size.
0:06:18 > 0:06:24But the qantassaurus can run too, with long distances a speciality.
0:06:24 > 0:06:30It's his stamina versus the allosaurus' sprinting power.
0:06:30 > 0:06:32This time, it's speed that wins out,
0:06:32 > 0:06:37and now those terrifying jaws go into action.
0:06:48 > 0:06:52Time to go to the Planet Dinosaur Files workshop.
0:06:58 > 0:07:03Obviously, a dinosaur's jaws are what's scary about these beasts
0:07:03 > 0:07:07but what I want to know is just how powerful those jaws are.
0:07:07 > 0:07:11To do that, I've built my own dinosaur jaws.
0:07:11 > 0:07:13This is my allosaurus.
0:07:13 > 0:07:18And this is what's driving the bite of the allosaurus.
0:07:18 > 0:07:20It works of compressed air like this.
0:07:20 > 0:07:23I'm using air to force my jaws shut
0:07:23 > 0:07:28by squeezing it into this rubber tube at high pressure.
0:07:28 > 0:07:31At the moment I've got to set to what dinosaur experts reckon
0:07:31 > 0:07:35is the muscle strength in an allosaurus' jaw.
0:07:35 > 0:07:40I figure a good test to see how powerful a bite these fellas had
0:07:40 > 0:07:43is to stuff something in its jaws,
0:07:43 > 0:07:46get them to clamp down with full biting strength
0:07:46 > 0:07:49and then see what it takes to wrestle the jaws open.
0:07:49 > 0:07:52Chris, do you want to give that full allosaurus strength?
0:07:54 > 0:07:59It has now clamped down on my trusty broom. Can I get it back?
0:08:02 > 0:08:03No.
0:08:03 > 0:08:06It turns out that there is no way
0:08:06 > 0:08:09an 11-stone bloke
0:08:09 > 0:08:14can get the jaws of an allosaurus open once it has bitten down.
0:08:14 > 0:08:16What about two blokes?
0:08:19 > 0:08:23Out in the wild, that would be a very dangerous manoeuvre!
0:08:23 > 0:08:26Right, let's see if we can get this open.
0:08:35 > 0:08:39It's not easy. That is an incredibly powerful bite,
0:08:39 > 0:08:44but two full-grown blokes can just about wrestle open the jaw
0:08:44 > 0:08:47of a full-grown allosaurus.
0:08:48 > 0:08:52That might seem like pretty amazing jaw strength
0:08:52 > 0:08:55but the way that Chris and I can just about open them
0:08:55 > 0:08:58shows that, for a dinosaur that size, allosaurus' jaws
0:08:58 > 0:09:01weren't actually that strong
0:09:01 > 0:09:05and this is where the new discovery bit comes in.
0:09:10 > 0:09:16In 2001, dinosaur experts investigated allosaurus' jaw power.
0:09:16 > 0:09:20They discovered that while the jaw muscles were quite weak,
0:09:20 > 0:09:24its skull had incredible strength.
0:09:26 > 0:09:31In fact, a much smaller animal like a lion has stronger jaws,
0:09:31 > 0:09:35but now we know that allosaurus made up for that
0:09:35 > 0:09:37by using its head, literally.
0:09:37 > 0:09:41By swinging down with its powerful neck muscles like a giant axe,
0:09:41 > 0:09:44it smashed its jaws into its prey.
0:09:44 > 0:09:48So this new discovery shows that allosaurus
0:09:48 > 0:09:50didn't need very powerful jaws.
0:09:50 > 0:09:55By swinging his neck, head and jaws together like an axe...
0:09:57 > 0:10:01..it was easily able to rip off large chunks of flesh.
0:10:02 > 0:10:07Which means this poor qantassaurus doesn't stand a chance.
0:10:17 > 0:10:20That's allosaurus, then.
0:10:20 > 0:10:24This beast was explosively fast and muscle-bound.
0:10:24 > 0:10:27Its bite strength gained extra power
0:10:27 > 0:10:31by using its head and neck like a giant axe.
0:10:31 > 0:10:36Size-wise, at nine metres and 1½ tonnes, it was no lightweight.
0:10:36 > 0:10:38And its fear factor?
0:10:38 > 0:10:41Well, that combination of surprise and speed
0:10:41 > 0:10:44was a great way of terrifying its prey.
0:10:46 > 0:10:50But getting enough food to survive in the prehistoric world
0:10:50 > 0:10:53wasn't always about hunting and fighting.
0:11:00 > 0:11:05Meet Majungasaurus, king of the scavengers.
0:11:06 > 0:11:10Another mighty meat-eating dinosaur.
0:11:10 > 0:11:13This monster lived 70 million years ago,
0:11:13 > 0:11:16weighing in at well over a tonne.
0:11:16 > 0:11:18And seven metres long.
0:11:18 > 0:11:22You would have found Majungasaurus on the island of Madagascar,
0:11:22 > 0:11:24off the east coast of Africa.
0:11:25 > 0:11:27It's a lush and green place now
0:11:27 > 0:11:31but when Majungasaurs roamed this land,
0:11:31 > 0:11:34it was much hotter and much drier.
0:11:34 > 0:11:38That meant droughts and droughts meant less food to go round
0:11:38 > 0:11:42so a hungry dinosaur could not afford to be choosy.
0:11:44 > 0:11:49This is an adult Majungasaur - a mother with two youngsters.
0:11:49 > 0:11:52Mum's looking for a meal for her kids
0:11:52 > 0:11:55and all that's on offer is this rotting carcass.
0:11:55 > 0:12:00That's how we think Majungasaurus would have got lots of its food -
0:12:00 > 0:12:02by scavenging.
0:12:06 > 0:12:12But scavenging for food is what lots of animals have to do to survive.
0:12:12 > 0:12:15This is the body of a dead humpback whale,
0:12:15 > 0:12:19washed ashore on the coast of Alaska in the USA.
0:12:19 > 0:12:23There's so much meat that it attracts all kinds of animals
0:12:23 > 0:12:25looking for an easy meal.
0:12:25 > 0:12:27First, a black bear fills up.
0:12:29 > 0:12:31Then an eagle.
0:12:31 > 0:12:34And finally, a pack of hungry wolves.
0:12:34 > 0:12:38All these animals are perfectly capable of killing prey,
0:12:38 > 0:12:42but why go to the effort when dinner turns up on your doorstep?
0:12:47 > 0:12:52Rewind 70 million years to the parched land of Madagascar.
0:12:52 > 0:12:56Our Majungasaurs haven't got that carcass to themselves.
0:12:56 > 0:13:01Free food like this will attract every beast for miles around,
0:13:01 > 0:13:05including other Majungasaurs,
0:13:05 > 0:13:09like this big, hungry male.
0:13:09 > 0:13:13The female's youngsters sense the danger.
0:13:13 > 0:13:15This male wants their dinner.
0:13:15 > 0:13:18This could get really nasty.
0:13:22 > 0:13:26Both male and female adults have very powerful jaws
0:13:26 > 0:13:31and their hunger makes them even more aggressive.
0:13:31 > 0:13:35The female is not giving up easily.
0:13:45 > 0:13:49A sudden savage attack takes the male off guard.
0:13:49 > 0:13:52She gets that crucial first big hit in.
0:13:53 > 0:13:56Majungasaurus jaws are lethal in this situation.
0:13:56 > 0:13:59They're designed for biting and gripping.
0:14:01 > 0:14:04The male is badly wounded.
0:14:15 > 0:14:18Meanwhile, back in the dinosaur workshop,
0:14:18 > 0:14:21time to test out the Majungasaurus jaws.
0:14:21 > 0:14:24I've got the same powerful artificial muscle
0:14:24 > 0:14:27but I've slightly reduced the head size.
0:14:27 > 0:14:30These animals were a little bit smaller than the allosaurus
0:14:30 > 0:14:33but they had a powerful reputation.
0:14:33 > 0:14:36Jaws are set to Majungasaurus strength.
0:14:36 > 0:14:39Although ordinarily a vicious meat-eater,
0:14:39 > 0:14:44it's time the Majungasaurus had one of its five-a-day.
0:14:50 > 0:14:52I think it quite likes them.
0:14:53 > 0:14:59Our allosaurus jaws were shifted with the weight of two blokes.
0:14:59 > 0:15:04What will it take to prise open the mouth of a Majungasaurus?
0:15:04 > 0:15:05Ready?
0:15:13 > 0:15:17It's slightly mad, just how hard that bite is.
0:15:17 > 0:15:22There's absolutely no way both of us are getting that open.
0:15:22 > 0:15:25I think this need something a bit more than human.
0:15:25 > 0:15:30When man power fails, maybe van power will succeed.
0:15:30 > 0:15:32Good. Start taking that away.
0:15:39 > 0:15:41Have you got any more?
0:15:44 > 0:15:47Yes, you've got it, you've got it!
0:15:50 > 0:15:53There we go, the Majungasaurus, too much for a man,
0:15:53 > 0:15:55about right for a man and a van.
0:16:03 > 0:16:06Rewind 70 million years
0:16:06 > 0:16:10and this adult male Majungasaurus has had it.
0:16:14 > 0:16:16With the male dead,
0:16:16 > 0:16:20the female shockingly starts to feed off its body.
0:16:22 > 0:16:25Eating one of your own kind seems pretty drastic
0:16:25 > 0:16:30so how sure can we be that three Majungasaurus were cannibals?
0:16:30 > 0:16:33Let's take a look at the evidence.
0:16:35 > 0:16:38This is the tailbone of a Majungasaurus,
0:16:38 > 0:16:41discovered on Madagascar in 2003.
0:16:43 > 0:16:45Take a close look.
0:16:45 > 0:16:50There are some shocking marks on it - teeth marks.
0:16:50 > 0:16:54Dinosaur experts discovered these were bite marks,
0:16:54 > 0:16:56another Majungasaur's bite marks.
0:16:58 > 0:17:02But this didn't look like a fight between two angry predators.
0:17:02 > 0:17:06This was one Majungasaurus eating the other.
0:17:11 > 0:17:15So that's Majungasaurus, a truly savage scavenger.
0:17:15 > 0:17:19Its bite strength was better than Allosaurus,
0:17:19 > 0:17:21with that vice-like grip.
0:17:21 > 0:17:25On the size though, it was smaller than Allosaurus,
0:17:25 > 0:17:29at seven metres long and one tonne in weight.
0:17:29 > 0:17:31But for fear factor, it was awesome.
0:17:31 > 0:17:34This beast stopped at nothing to get a meal,
0:17:34 > 0:17:37a totally ruthless killer and a cannibal.
0:17:40 > 0:17:45But is Majungasaurus pound-for-pound our most powerful dinosaur?
0:17:45 > 0:17:49Well, I think there might be an even better contender for that title.
0:17:53 > 0:17:55This is Daspletosaurus.
0:17:55 > 0:17:57His name means frightful lizard,
0:17:57 > 0:18:00and, boy, does he live up to that title.
0:18:03 > 0:18:07This brute ruled by domination and intimidation.
0:18:07 > 0:18:12Daspletosaurs were up to nine metres long and three tonnes in weight.
0:18:14 > 0:18:18They lived 75 million years ago in what, today, is Canada.
0:18:23 > 0:18:26Three tonnes - that's impressive.
0:18:26 > 0:18:29Bigger than both allosaurus and Majungasaurus.
0:18:29 > 0:18:33But that is not what makes this dinosaur stand out for me.
0:18:38 > 0:18:41This monster is the ultimate hunter.
0:18:41 > 0:18:44He's got the weapons, he's got the senses
0:18:44 > 0:18:46that help him lock onto his target.
0:18:46 > 0:18:49He will take on virtually anything.
0:18:51 > 0:18:56Here, he is up against a Chasmosaurus
0:18:56 > 0:18:59a tough opponent with vicious horns like a rhino.
0:19:01 > 0:19:05And he's on guard which means our Daspletosaurus has no chance
0:19:05 > 0:19:07of surprising him.
0:19:23 > 0:19:27Chasmosaurus, with the help of those deadly horns,
0:19:27 > 0:19:30lives to fight another day.
0:19:30 > 0:19:33But Daspletosaurus is persistent. He'll be back.
0:19:36 > 0:19:40Daspletosaurs are part of a famous family of ruthless killers,
0:19:40 > 0:19:42the Tyrannosaurids.
0:19:42 > 0:19:45But 10 million years before T-Rex ruled the earth,
0:19:45 > 0:19:49Daspletosaurus was showing how it should be done.
0:19:52 > 0:19:56This was a seek-and-destroy creature that took killing
0:19:56 > 0:19:58to a whole new level.
0:19:58 > 0:20:01Just like T-Rex, Daspletosaurus had a huge skull,
0:20:01 > 0:20:06bulging neck muscles and a very powerful bite.
0:20:06 > 0:20:10Those forward-facing eyes made tracking moving prey
0:20:10 > 0:20:12a piece of cake.
0:20:16 > 0:20:20And he was especially good at sniffing out a meal.
0:20:21 > 0:20:26How do we know this? By looking at the evidence, that's how.
0:20:32 > 0:20:37Experts have recently studied the skulls of this family of dinosaurs.
0:20:37 > 0:20:41They found that the area of the Tyrannosaurid brain
0:20:41 > 0:20:44that controls how they smell is very large.
0:20:46 > 0:20:49And for a hungry Daspletosaurus,
0:20:49 > 0:20:53a great sense of smell could make all the difference.
0:20:53 > 0:20:57This Chasmosaurus may think he's well hidden from predators
0:20:57 > 0:21:00but he's in for a nasty shock.
0:21:00 > 0:21:06There's no doubt Daspletosaurus has all the equipment you need to be
0:21:06 > 0:21:11a top hunter but there's more to this powerful dinosaur than that.
0:21:11 > 0:21:15Because these killers hunted in gangs.
0:21:16 > 0:21:19When Daspletosaur bones have been found,
0:21:19 > 0:21:23they've often been in groups which makes it likely that
0:21:23 > 0:21:27to increase their chances of getting a meal, they hunted in packs.
0:21:27 > 0:21:31Here, a group of Daspletosaurus of all ages are ganging up
0:21:31 > 0:21:34on this lone Chasmosaurus.
0:21:36 > 0:21:40Younger ones provide the speed.
0:21:40 > 0:21:43The bigger adults, the muscle.
0:21:44 > 0:21:48Working together, they can attack with overwhelming power.
0:21:53 > 0:21:56And once they get close, their lethal jaws get to work.
0:21:59 > 0:22:03The bite of the Daspletosaurus was one of the most powerful
0:22:03 > 0:22:06of any dinosaur that walked the planet.
0:22:09 > 0:22:13Just like Daspletosaurs, today's powerful predators are lethal
0:22:13 > 0:22:16when they work together.
0:22:16 > 0:22:20Just watch these lions bring down this big buffalo.
0:22:23 > 0:22:27And it's the same story for this and unlucky Chasmosaur.
0:22:27 > 0:22:31The Daspletosaurus gang make short work of this kill.
0:22:42 > 0:22:47Time to get back to the dinosaur workshop to find out just
0:22:47 > 0:22:49what those fearsome jaws were like.
0:22:49 > 0:22:51This is my Daspletosaurus.
0:22:51 > 0:22:55Now, even in dinosaur terms, these things were veritable monsters.
0:22:55 > 0:22:58They were like the grandaddy of T-Rex.
0:22:58 > 0:23:02As you can see, it's a much, much bigger animal than either
0:23:02 > 0:23:05the allosaurus or the Majungasaurus.
0:23:05 > 0:23:08In order for us to replicate that bite force with our model,
0:23:08 > 0:23:12we have to take the whole rig right up to maximum.
0:23:12 > 0:23:15Chris, do you want to power it up?
0:23:18 > 0:23:23That's a concrete brick wedged in our Daspletosaur jaws.
0:23:23 > 0:23:26Right, that's down pretty hard.
0:23:29 > 0:23:33Remember, it took two men to shift allosaurus jaws.
0:23:35 > 0:23:39And a van to prise open those of the Majungasaurus.
0:23:39 > 0:23:42Let's see how tough Daspletosaurus is.
0:23:42 > 0:23:45- Jim, shall we try by hand? - OK, ready?
0:23:47 > 0:23:49Right, it's kind of obvious that this thing
0:23:49 > 0:23:53is well beyond the means of human power.
0:23:59 > 0:24:03But the van's not doing the trick either.
0:24:04 > 0:24:06That's pretty shocking
0:24:06 > 0:24:09because we went to great lengths to build this to accurately
0:24:09 > 0:24:13reflect what experts think these dinosaurs were capable of.
0:24:13 > 0:24:17Headline news, you can't even open the jaw of a Daspletosaurus
0:24:17 > 0:24:19with a van.
0:24:20 > 0:24:23I think we need some professional help.
0:24:23 > 0:24:27What I've got is a Daspletosaurus biting down at full power
0:24:27 > 0:24:30and are you sure your little dinosaur is going to be
0:24:30 > 0:24:33more powerful than my big dinosaur?
0:24:33 > 0:24:36- I'd imagine so.- What do you normally use those for?
0:24:36 > 0:24:40It's a hydraulics spreader, mainly used for car crashes
0:24:40 > 0:24:42so we can rescue people stuck in cars.
0:24:42 > 0:24:46- To get these in, I'm going to have to do a bit of dentistry.- Yes.
0:24:47 > 0:24:49Cleanliness is important in dentistry.
0:24:49 > 0:24:54Don't worry, big fella, this shouldn't hurt at all.
0:24:54 > 0:24:56Stay being brave.
0:24:58 > 0:25:03- Sparky, can you do a job for us? - Yeah, power it up.
0:25:08 > 0:25:12So, will these jaws finally meet their match?
0:25:14 > 0:25:17It's taken that super-powerful firemen's gadget,
0:25:17 > 0:25:21capable of shifting the weight of two double-decker buses,
0:25:21 > 0:25:23to get those jaws open.
0:25:23 > 0:25:25I'm seriously impressed.
0:25:25 > 0:25:28I don't want you to hold you up from fighting fires.
0:25:28 > 0:25:31- Thank you ever so much. - Cheers, thank you.- Thanks.
0:25:31 > 0:25:35Looks like we've finally overcome the Daspletosaurus.
0:25:35 > 0:25:37It appears that although normal people can't do it,
0:25:37 > 0:25:40if a Daspletosaurus bites down on something,
0:25:40 > 0:25:42you've got to call the fire service.
0:25:47 > 0:25:50So that's Daspletosaurus,
0:25:50 > 0:25:55a terrifying gang hunter with jaws that can crush
0:25:55 > 0:25:57virtually any prey into pulp.
0:25:57 > 0:26:00But for all-round power,
0:26:00 > 0:26:04how does this magnificent predator compare to our other contenders?
0:26:07 > 0:26:12There was allosaurus, explosively fast and strong with it.
0:26:12 > 0:26:15On bite strength,
0:26:15 > 0:26:18it gained extra power from that axe-swimming head action.
0:26:18 > 0:26:23For size, a big predator, nine muscle-bound metres long
0:26:23 > 0:26:26and 1½ tonnes.
0:26:26 > 0:26:29And fear factor, a great combination of surprise
0:26:29 > 0:26:32and speed made allosaurus terrifying.
0:26:35 > 0:26:39Then the savage Majungasaurus, a top-class scavenger.
0:26:39 > 0:26:43For bite strength, it was better than allosaurus,
0:26:43 > 0:26:47with that powerful vice-like grip.
0:26:47 > 0:26:52Size? A respectable seven metres long and one tonne.
0:26:52 > 0:26:56Finally, fear factor, well, this was a ruthless,
0:26:56 > 0:26:58anything-goes killer cannibal.
0:27:01 > 0:27:04And lastly, there's Daspletosaurus,
0:27:04 > 0:27:08a superbly evolved hunter with a keen sense of smell
0:27:08 > 0:27:10that locked onto its prey.
0:27:11 > 0:27:15First, bite strength. Those jaw muscles were amazing.
0:27:15 > 0:27:18Three times stronger than Majungasaurus,
0:27:18 > 0:27:21an incredible crunching chomp.
0:27:21 > 0:27:24Size-wise, this was a big predator.
0:27:24 > 0:27:28Nine metres long and weighing in at three tonnes.
0:27:28 > 0:27:31And fear factor, well, the Daspletosaurs
0:27:31 > 0:27:36liked nothing better than attacking a lone victim in a big gang.
0:27:38 > 0:27:42So, for me, there's only one winner.
0:27:42 > 0:27:45That combination of great smell, gang hunting
0:27:45 > 0:27:48and crashing jaws make Daspletosaurus
0:27:48 > 0:27:50my most powerful predator.
0:27:58 > 0:28:01Next time on Planet Dinosaur Files...
0:28:01 > 0:28:05I dive into the wonderful world of marine reptiles.
0:28:05 > 0:28:08And my dinosaur workshop goes under water.
0:28:08 > 0:28:10Subtitles By Red Bee Media Ltd
0:28:10 > 0:28:13Email subtitling@bbc.co.uk