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A look at the last generation of killer dinosaurs, carnivores that took killing to a new level. By the end of the Cretaceous period - 75 million years ago - these gigantic and specialised hunter-killers had spread throughout the globe. In the southern continents it was the powerful and muscular abele.....
白垩纪晚期（约 7500 万年前）全球顶级掠食者的进化巅峰与捕猎策略 。
白垩纪晚期（约 7500 万年前）全球顶级掠食者的进化巅峰与捕猎策略 。
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AnimalsTranscript
00:05we're living through the golden age of dinosaur discoveries from all over the
00:11world a whole new generation of dinosaurs has been revealed from the
00:18biggest giants and the deadliest killers to the weird and the wonderful
00:30from the Arctic to Africa from South America to Asia
00:41using the latest evidence for the first time we have a truly global view of
00:49these incredible animals
01:03in this episode we explore the last generation of killer dinosaurs
01:10carnivores that took killing to a new level
01:14at the end of the Cretaceous period 75 million years ago
01:18these hunter killers had spread throughout the globe
01:24in the southern continents
01:26it was the powerful and muscular abelisaurus that reigns supreme
01:34whereas in the north it was the famous tyrannosaurs that dominated
01:4475 million years ago the dinosaur park formation in Canada
01:49was home to two of the largest tyrannosaurs
01:52the biggest and heaviest was desplatosaurus
01:59in 2009 medical scanners were used to look inside the brain cases of these killers
02:07of all the dinosaur groups tyrannosaurs were discovered to have one of the largest areas devoted to smell
02:14something that would give them a clear hunting advantage
02:24back then Cretaceous Alberta
02:26was a vast coastal river plain covered in forests
02:32the perfect hunting grounds for daspletosaurus
02:38at nine meters and three tons
02:41it's the dominant predator in these forests
02:46here it relies on its acute sense of smell and hearing
02:50as much as its sight to hunt its prey
03:03casmosaurus
03:04a rhino-sized behemoth bristling with defensive horns
03:08and an opponent befitting a killer like desplatosaurus
03:13serenius
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03:34Let's go.
03:59Of all the Tyrannosaurs, T-Rex might be the most famous.
04:04But the evolutionary blueprint for these predators was laid down 10 million years earlier with Desplatosaurus.
04:15Tyrannosaurs' effectiveness as killers is clear from their anatomy.
04:19They're massive, with huge strong skulls and powerful muscular necks.
04:25Forward-facing eyes make tracking moving prey easy.
04:30They've famously short arms, but with these giant Tyrannosaurs, it's all about the bite.
04:37They had the most powerful bite of any dinosaur,
04:41with teeth that, unlike the thin, flesh-tearing blades of Carnosaurs,
04:45are thick and strong, easily able to crush bone and kill.
04:54However, this Desplatosaurus has lost the element of surprise.
05:20The odds are now stacked in the Chasmosaur's favor.
05:26Even the most deadly predators fail more often than they succeed.
05:36Tyrannosaurus appeared locked in a deadly evolutionary arms race with the horned dinosaurs.
05:42As one got bigger, so did the other.
05:45It's a predator-prey relationship that endured for more than 65 million years.
05:54Most striking are the head frills of the horned dinosaurs.
05:58The imposing frill of Chasmosaurus is actually made of thin bone
06:04and wouldn't stop the bite of a Tyrannosaur.
06:08But by making it look much bigger, it had the desired effect.
06:13The horns and frills of these dinosaurs acted as visual deterrents,
06:18even if they offered little physical protection.
06:22It meant that a fully grown Chasmosaurus would usually be safe from most predators.
06:34This Desplatosaurus is just a youngster.
06:44Even two Desplatosaurus pose little threat.
07:00In 2005, a remarkable discovery was announced.
07:04In the two-medicine formation of Montana,
07:08a new dig had unearthed something quite extraordinary.
07:12A collection of Desplatosaurus fossils,
07:16all buried at the same place at the same time.
07:30The implication is that Desplatosaurus hunt in gangs.
07:44Tyrannosaurs like Desplatosaurus were so successful
07:48that by the late Cretaceous,
07:50they were the apex predator across virtually all of North America and Asia.
07:56In Asia, there was Electrosaurus,
07:59Alluremus, and Tarbosaurus.
08:02In America, Albertosaurus,
08:05Gorgosaurus, Desplatosaurus, and T-Rex.
08:09But moving further north,
08:11evidence of Tyrannosaurs becomes increasingly rare.
08:16In Alaska, fossils have been excavated close to the Arctic Ocean.
08:22It's the richest source of dinosaurs that lived in the polar regions.
08:27And it seems, here, a different type of killer dominated.
08:36The most common plant-eater in this region
08:39is the highly social Edmontosaurus.
08:43They're the largest duck-billed dinosaur in North America.
08:55And they are the perfect prey for a very different type of predator.
09:08Trudon may not look as lethal as a Tyrannosaur,
09:11but fossil evidence suggests that these, too, were deadly hunters,
09:15surviving entirely on a diet of meat.
09:24At first sight,
09:26it appears the adult and Montessaurus have little to fear.
09:29Twelve meters in length and weighing three and a half tons,
09:33they physically dwarf this diminutive predator.
09:39Trudon were usually small, two-metre dinosaurs.
09:43But the teeth from the Alaskan Trudon
09:46showed something remarkable.
09:48These Arctic predators
09:50were almost twice as big as normal.
09:57Trudon not only survived here,
09:59they positively thrived.
10:03And that's because their hunting prowess
10:06comes into its own after sunset.
10:17This is a land where, after late summer,
10:21there are more hours of darkness than light.
10:41Trudon famously have the largest brains
10:44relative to their body size of any dinosaur.
10:56Trudon not only are they forward-facing,
10:59making them active hunters,
11:01but they are exceptionally large.
11:04These are predators
11:06that can hunt equally well after dark.
11:16Trudon not only are they forward-facing,
11:18the most likely to be found.
11:19Although the group offers protection,
11:21predators always choose the easiest prey.
11:24So it's the juvenile Edmontasaurs
11:26that are at risk.
11:40Let's go.
12:02Separated from the group, this youngster has made a dangerous mistake.
12:54The Alaskan dinosaur bone beds.
12:57It's a dominated by juvenile and Montessor's remains.
13:01Some show clear evidence of Trudon bite marks.
13:06It seems, despite its small size, Trudon thrived here by exploiting the vulnerability of the juveniles throughout the long, dark
13:15winter months.
13:28With a steady food supply, it means Trudon can survive the harsh Arctic winters.
13:34And in doing so, grew to almost double the size of their cousins further south.
13:41But these were the exception.
13:49Wherever else Tyrannosaurs lived, they were the largest predator, living in groups that consist of both youngsters and adults.
14:13In these deadly packs, youngsters provide the speed, adults the power.
14:20It's a hunting strategy that they use to deadly effect.
14:28No!
14:35No!
14:37No!
14:39No!
14:58But despite appearances, this mob attack isn't carefully planned.
15:06There is no strategy behind the actions of the gang.
15:10It's merely opportunism.
15:13And when the kill has been made, the next battle soon begins.
15:30In many tyrannosaurs, we find holes and gouges on the skulls, injuries which turn out to
15:37be bite marks made by other tyrannosaurs.
15:41In one Desplatosaurus fossil, the tooth marks indicate that an individual had been subject
15:46to several attacks.
15:50In another, the tip of a tooth was left embedded in the bone of its skull.
15:57From this evidence, we can assume that such groups were far from harmonious.
16:05And they certainly aren't democratic.
16:08In this world, the strongest takes all.
16:19Tyrannosaurs' domination of the globe might have been total, had it not been for a strange
16:25quirk in the arrangement of the continents.
16:31In the last ten years, the planet had a clear north-south divide with no physical link between
16:36the parts of the globe.
16:38It meant the tyrannosaurs couldn't spread to the southern continents.
16:43Here, a different type of killer reigns supreme.
16:49These were abelosaurids.
16:55In the last ten years, Madagascar has provided the most comprehensive evidence about these predators.
17:0570 million years ago, Madagascar was already an island.
17:14But its climate was much hotter and drier than today.
17:23In the Cretaceous period, Madagascar was subject to devastating droughts.
17:29And big predators like Majungasaurus are especially vulnerable to starvation.
17:36Scavenging is the only way to survive.
17:43We thought Madagascar was the top predator here.
17:49But then, in 2003, some bones of a number of Madagascar were reported gouged with teeth marks.
17:59It appeared there was a bigger, more brutal killer at large.
18:17Madagascar also shares the plains with smaller dinosaurs like Rafa Narvis.
18:31Madagascar also shares the plains with smaller dinosaurs like Rafa Narvis.
18:47Being smaller means Rafa Narvis needs less food to survive.
18:51Being smaller means Rafa Narvis needs less food to survive.
19:00A carcass will attract every big predator for miles around.
19:19A male Majungasaurus attracted to the feast.
19:27It is more than capable of challenging for the carcass.
19:30It's more than capable of mixing than the
20:00And now people Über drie 가격 is a little trick.
20:00Let's go.
20:31Majungasaurus has short arms and can't grasp.
20:36Like Tyrannosaurs, it's all about the bite.
20:48The shape of Majungasaurus' skull and teeth suggests a very different biting style to the flesh-tearing dinosaurs,
20:55with a broad, short and muscular skull.
20:59It was a dino better adapted to biting and gripping rather than slashing its prey.
21:07This fight is about more than just winning the feeding rights to a carcass.
21:12The fight is about more than just winning the feeding rights to a carcass.
21:22The fight is about more than just winning the feeding rights to a carcass.
21:40When the bite marks on the mauled Majungasaurus remains were studied more closely,
21:47the marks on the bones were found to match the only large carnivore in the region.
21:52There is no bigger killer in these lands than Majungasaurus.
21:57This is the first irrefutable evidence of dinosaur cannibalism.
22:05It might seem shocking, but it's a behavior that clearly shows the most successful killers
22:11will exploit any situation to their maximum advantage.
22:22Taspletosaurus.
22:35Taspletosaurus.
22:42Taspletosaurus.
23:04And this group have congregated to take advantage of an annual event.
23:12In Dinosaur Provincial Park, thousands of bones have been discovered scattered across
23:17the same rock layer.
23:20They belong to the horned dinosaur Centrosaurus.
23:25And they appear to be the bone beds of vast killing fields, sites of wholesale slaughter.
23:44This vast herd of Centrosaurus are on the move.
23:49From their nesting sites on coastal lowlands to the east.
23:56Unwittingly, they're moving towards almost certain death.
24:03Seasonal monsoons drives the Centrosaurus inland, away from coastal flooding.
24:22It's what the Dysplatosaurus have been waiting for.
24:43Herding behavior protects the many, but at the expense of the few.
25:00Is there something to do with it?
25:06We're not going to do anything to do with it.
25:10We're not going to do anything.
25:12We're not going to do anything at all.
25:22And things are about to get worse for the Centrosaurs.
25:35With a flooded river ahead and the Desplatosaurus behind, the stage is now set for a massacre.
25:53But despite the rich pickings, it's not the Desplatosaurus that are responsible for the
25:58scale of the slaughter.
26:14There's an even more deadly killer at work here.
26:31Severe monsoon rains have transformed shallow rivers into lethal torrents.
26:51The End
27:06The real killer is the weather itself.
27:26Recent studies of this dense bone bed indicate that 96 percent of the bones are of a single
27:32species, Centrosaurus.
27:35And relatively few of the bones display any bite marks.
27:39The fossil evidence suggests that this was a mass drowning.
27:43The result of widespread seasonal flooding.
27:49An event that we have seen repeated in over 20 different sites.
28:00And when the waters recede, new opportunities emerge.
28:08Events like these provide easy pickings for predators.
28:13But even in the fight for rotting flesh, Desplatosaurus authority is absolute.
28:23Tyrannosaurs in the north and Abelosaurus in the south were the supreme killers of their age.
28:30They dominated every continent where they were found.
28:39And together they were the last of the killer dinosaurs.
28:44Tyrannosaurus in the south was the very end.
28:47Tyrannosaurus at the west and Deep North.
28:56And in the north, they were the largest Yoshiochus.
29:09The Music of the Ecstasy at the Centrosaurus.
29:09And in the north, those were the largest disease over the top.
29:14You