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00:00We're living through the golden age of dinosaur discoveries.
00:09From all over the world, a whole new generation of dinosaurs has been revealed.
00:16From the biggest giants and the deadliest killers, to the weird and the wonderful.
00:21From the Arctic, to Africa, from South America to Asia, using the latest evidence for the first time, we have a truly global view of these incredible animals.
00:51In this episode, we explore the last generation of killer dinosaurs.
01:09Carnivores that took killing to a new level.
01:13At the end of the Cretaceous period, 75 million years ago, these hunter killers had spread throughout the globe.
01:24In the southern continents, it was the powerful and muscular Abelisaurids that reigned supreme.
01:30Whereas in the north, it was the famous tyrannosaurs that dominated.
01:4375 million years ago, the dinosaur park formation in Canada was home to two of the largest tyrannosaurs.
01:50The biggest and heaviest was Desplatosaurus.
01:58In 2009, medical scanners were used to look inside the brain cases of these killers.
02:06Of all the dinosaur groups, tyrannosaurs were discovered to have one of the largest areas devoted to smell.
02:12Something that would give them a clear hunting advantage.
02:23Back then, Cretaceous Alberta was a vast coastal river plain covered in forests.
02:29The perfect hunting grounds for Dasplatosaurus.
02:38At nine meters and three tons, it's the dominant predator in these forests.
02:45Here, it relies on its acute sense of smell and hearing as much as its sight to hunt its prey.
02:51Chasmosaurus, a rhino-sized behemoth bristling with defensive horns.
03:09And an opponent befitting a killer like Desplatosaurus.
03:12Have you heard a bretasaurus?
03:42of all the tyrannosaurs t-rex might be the most famous but the evolutionary blueprint for these
04:05predators was laid down 10 million years earlier with Desplatosaurus. Tyrannosaurs effectiveness
04:15as killers is clear from their anatomy. They're massive with huge strong skulls and powerful
04:22muscular necks. Forward-facing eyes make tracking moving prey easy. They've famously short arms but
04:31with these giant tyrannosaurs it's all about the bite. They had the most powerful bite of any
04:38dinosaur with teeth that unlike the thin flesh tearing blades of carnosaurs are thick and strong
04:45easily able to crush bone and kill. However this Desplatosaurus has lost the element of surprise.
05:01The odds are now stacked in the Chasmosaur's favor. Even the most deadly predators fail more often than they succeed.
05:31Tyrannosaurus appeared locked in a deadly evolutionary arms race with the horned dinosaurs.
05:40As one got bigger so did the other. It's a predator prey relationship that endured for more than 65
05:49million years. Most striking are the head frills of the horned dinosaurs. The imposing frill of
05:59chasmosaurus is actually made of thin bone and wouldn't stop the bite of a tyrannosaur. But by making it look much bigger it had the desired effect.
06:10The horns and frills of these dinosaurs acted as visual deterrents even if they offered little physical protection.
06:20It meant that a fully grown chasmosaurus would usually be safe from most predators.
06:26This Desplatosaurus is just a youngster. Even two Desplatosaurus pose little threat.
06:46In 2005 a remarkable discovery was announced. In the two medicine formation of Montana a new dig had unearthed something quite extraordinary. A collection of Desplatosaurus fossils.
07:04In the two medicine formation of Montana a new dig had unearthed something quite extraordinary. A collection of Desplatosaurus fossils. All buried at the same place at the same time.
07:16The implication is that Desplatosaurus hunt in gangs.
07:34Tyrannosaurs like Desplatosaurus were so successful that by the late Cretaceous they were the apex predator across virtually all of North America and Asia.
07:53In Asia there was Electrosaurus, Alluremus and Tyrannosaurus. In America Albertosaurus, Gorgosaurus, Desplatosaurus and T-Rex.
08:06But moving further North evidence of Tyrannosaurs becomes increasingly rare.
08:12In Alaska fossils have been excavated close to the Arctic Ocean.
08:19It's the richest source of dinosaurs that lived in the polar regions.
08:24And it seems here a different type of killer dominated.
08:33The most common plant eater in this region is the highly social Edmontosaurus.
08:40They're the largest duck-billed dinosaur in North America.
08:47And they are the perfect prey for a very different type of predator.
08:54And they are the perfect prey for a very different type of predator.
09:06Trudon may not look as lethal as a tyrannosaur, but fossil evidence suggests that these too were deadly hunters, surviving entirely on a diet of meat.
09:16At first sight, it appears the adult Edmontosaurus have little to fear.
09:27Twelve meters in length and weighing three and a half tons, they physically dwarf this diminutive predator.
09:33Trudon were usually small, two meter dinosaurs.
09:40But the teeth from the Alaskan Trudon showed something remarkable.
09:46These Arctic predators were almost twice as big as normal.
09:51Trudon not only survived here, they positively thrived.
09:58And that's because their hunting prowess comes into its own after sunset.
10:06This is a land where, after late summer, there are more hours of darkness than light.
10:21Trudon famously have the largest brains relative to their body size of any dinosaur.
10:44Although what appears more important are their eyes.
10:51Not only are they forward-facing, making them active hunters, but they are exceptionally large.
11:00These are predators that can hunt equally well after dark.
11:06Although the group offers protection, predators always choose the easiest prey.
11:22So it's the juvenile Edmontosaurs that are at risk.
11:26So it's the only thing that they have to be trained.
11:27They're only going to thrive.
11:28So I'm going to die for a while, they are going to die for a while, they are autres.
11:29So it's the juvenile Edmontrons.
11:30Now, you're going to die.
11:31How long have you ever seen a süper like this?
11:32I found out of 10.
11:33What a beautiful thing.
11:34With that kind of amazing distance between the three in the center.
11:36At least in the middle one, am I.
11:37What a beautiful thing is that all those who have to hide in the most?
11:38Well, they're acting at the same place.
11:39텔�ker, but I'm not doing that.
11:40I'm willing to work!
11:43Fire them!
11:45The astuce, the ocean.
11:46The ocean, he's able to die in the future.
11:47What a matter of the most of the characters?
11:48Separated from the group, this youngster has made a dangerous mistake.
12:18The group has been so close to the group, this youngster has been so close to the group, and this is the group that has been a long time.
12:46The Alaskan dinosaur bonebeds are dominated by juvenile Edmontosaurus remains.
13:00Some show clear evidence of Trudon bite marks.
13:05It seems, despite its small size, Trudon thrived here by exploiting the vulnerability of the juveniles throughout the long, dark winter months.
13:16With a steady food supply, it means Trudon can survive the harsh Arctic winters, and in doing so, grew to almost double the size of their cousins further south.
13:40But these were the exception.
13:46Wherever else Tyrannosaurs lived, they were the largest predator, living in groups that consist of both youngsters and adults.
13:57In these deadly packs, youngsters provide the speed that alts the power.
14:19It's a hunting strategy that they use to deadly effect.
14:23The Alaskan dinosaur bone.
14:53But despite appearances, this mob attack isn't carefully planned.
15:05There is no strategy behind the actions of the gang.
15:09It's merely opportunism.
15:12And when the kill has been made, the next battle soon begins.
15:23In many tyrannosaurs, we find holes and gouges on the skulls, injuries which turn out to be bite marks, made by other tyrannosaurs.
15:39In one Desplatosaurus fossil, the tooth marks indicate that an individual had been subject to several attacks.
15:48In another, the tip of a tooth was left embedded in the bone of its skull.
15:53From this evidence, we can assume that such groups were far from harmonious.
16:04And they certainly aren't democratic.
16:07In this world, the strongest takes all.
16:10Tyrannosaurus's domination of the globe might have been total, had it not been, for a strange quirk in the arrangement of the continents.
16:26In the last 10 years, the planet had a clear north-south divide, with no physical link between the parts of the globe.
16:37It meant the tyrannosaurs couldn't spread to the southern continents.
16:41In the last 10 years, Madagascar has provided the most comprehensive evidence about these predators.
16:56Madagascar has provided the most comprehensive evidence about these predators.
16:59Madagascar has provided the most comprehensive evidence about these predators.
17:0370 million years ago, Madagascar was already an island.
17:11But its climate was much hotter and drier than today.
17:22In the Cretaceous period, Madagascar was subject to devastating droughts.
17:28And big predators like Madjungasaurus are especially vulnerable to starvation.
17:34Scavenging is the only way to survive.
17:42We thought Madjungasaurus was the top predator here.
17:47But then, in 2003, some bones of a number of Madjungasaurus were reported gouged with teeth marks.
17:57It appeared there was a bigger, more brutal killer at large.
18:01Madjungasaurus also shares the plains with smaller dinosaurs like Rafa Navis.
18:04Madjungasaurus also shares the plains with smaller dinosaurs like Rafa Navis.
18:05What general tolden anything about the
18:08Madjungasaurus is a big drop prior to a rabbit in the distance
18:13dive-instr saddle of a robot, and the sameinars,
18:14the sameults of outer space.
18:18Madjungasaurus, a giant nitrogen달icранary disease!
18:23Madjungasaurus also shares the plains with smaller dinosaurs like Rafa Navis.
18:28Madjungasaurus even shares the plains with smaller dinosaurs like Rafa Navis.
18:32Being smaller means Rahu Navis needs less food to survive.
18:50A carcass will attract every big predator for miles around.
19:18A male Majongasaurus attracted to the feast.
19:26It is more than capable of challenging for the carcass.
19:48A male Majongasaurus is more than capable of challenging for the carcass.
19:58A male Majongasaurus is more than capable of challenging for the carcass.
20:06A male Majongasaurus has short arms and can't grasp.
20:36But not with tyrannosaurs, it's all about the bite.
20:47The shape of Majongasaurus skull and teeth suggests a very different biting style to the flesh-tearing dinosaurs.
20:54With a broad, short and muscular skull, it was a dino better adapted to biting and gripping rather than slashing its prey.
21:06This fight is about more than just winning the feeding rights to a carcass.
21:14All right, let's see.
21:39When the bite marks on the mauled Mojongasaurus remains
21:42were studied more closely,
21:46the marks on the bones were found to match
21:48the only large carnivore in the region.
21:52There is no bigger killer in these lands than Mojongasaurus.
21:56This is the first irrefutable evidence of dinosaur cannibalism.
22:04It might seem shocking,
22:06but it's a behavior that clearly shows the most successful killers
22:10will exploit any situation to their maximum advantage.
22:21Das Pletosaurus.
22:22This is the first time we have to do it.
22:33With a bite force unmatched by any other dinosaur in the region,
22:39these are killers in a completely different league.
22:42And this group have congregated to take advantage of an annual event.
22:58In Dinosaur Provincial Park, thousands of bones have been discovered
23:14scattered across the same rock layer.
23:17They belong to the horned dinosaur Centrosaurus.
23:20And they appear to be the bone beds of vast killing fields.
23:29Sites of wholesale slaughter.
23:31This vast herd of Centrosaurus are on the move.
23:48From their nesting sites on coastal lowlands to the east.
23:51Unwittingly, they're moving towards almost certain death.
24:01Seasonal monsoons drives the Centrosaurus inland,
24:05away from coastal flooding.
24:07Seasonal monsoons drives the Centrosaurus in the region.
24:21It's what the Desplatosaurus have been waiting for.
24:37Seasonal monsoons.
24:42Herding behavior protects the many.
24:45But at the expense of the few.
25:07Seasonal monsoons.
25:08Seasonal monsoons.
25:21And things are about to get worse for the Centrosaurus.
25:34With a flooded river ahead.
25:37And the Desplatosaurus behind.
25:40The stage is now set for a massacre.
25:52But despite the rich pickings,
25:54it's not the Desplatosaurus that are responsible for the scale of the slaughter.
26:07There's an even more deadly killer at work here.
26:16There's an even more deadly killer at work here.
26:21There's an even more deadly killer at work here.
26:30Severe monsoon rains have transformed shallow rivers into lethal torrents.
26:36Severe minors.
26:37The Red Boulevard is based on the
26:45geese.
26:45The End
26:46The End
26:47The End
26:49The End
26:50The real killer is the weather itself.
27:20Recent studies of this dense bone bed indicate that 96% of the bones are of a single species,
27:32Centrosaurus, and relatively few of the bones display any bite marks.
27:38The fossil evidence suggests that this was a mass drowning, the result of widespread
27:44seasonal flooding, an event that we have seen repeated in over 20 different sites.
28:00And when the waters recede, new opportunities emerge.
28:07Events like these provide easy pickings for predators.
28:13But even in the fight for rotting flesh, Daspletosaurus authority is absolute.
28:21Tyrannosaurs in the north and Abelisaurus in the south were the supreme killers of their
28:27age.
28:30They dominated every continent where they were found.
28:39And together, they were the last of the killer dinosaurs.
28:47To get more on these prehistoric monsters, go online to bbc.co.uk slash dinosaur.
28:54While over on BBC4 now, they're celebrating cinematic versions of these killer creatures in Rex Appeal.
29:00Next tonight here on BBC1, Richard Maidley uncovers family connections in Who Do You Think You Are?
29:05Time to watch the public.
29:15Yes.
29:16It's all done.
29:17It's all done.
29:18It's all done.
29:19It's all done.
29:20You got it.
29:23And you're done.
29:25It's all done.
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