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02:35wrong. T-rexes may have been good parents, their children may have had feathers, and
02:44some dinosaurs even survived the asteroid apocalypse.
02:48I think one of the things I've learned as a paleontologist is that you never say never.
02:55I find it difficult to believe that all dinosaurs were wiped out in this single event.
03:01The dinosaur revolution has really radically changed our understanding of dinosaurs in
03:05so many ways. T-rex probably had much more complex social behaviors than we gave it credit for
03:11for many, many years.
03:14The T-rex that we understand now is not the one that I grew up with, but quite frankly,
03:20it's a far more impressive creature. No one will ever look at a T-rex the same way again.
03:35I'm sorry.
03:44I'm sorry.
03:45I'm sorry.
03:47I'm sorry.
03:51Montana, the late Cretaceous, a nesting pair of T-Rexes takes the
04:15afternoon off. Youngsters play, even T-Rexes. Like many young animals, they play for a reason,
04:40to perfect their hunting skills.
05:10Youngsters play, even T-Rexes.
05:15They play, even T-Rexes.
05:20Youngsters play, even T-Rexes.
05:25Youngsters play.
05:28Youngsters play.
05:33Oh, my God.
06:03Cannibalism serves a function and is surprisingly common in many modern species.
06:33The
06:37The
06:40The
06:45The
06:46The
06:51The
06:55The
06:58It's a really exciting time to study dinosaurs.
07:11And among these, T-Rex is probably the most exciting field because we are doing more new
07:18techniques and more types of studies on Tyrannosaurus in the last 10 years than we are for any other
07:25dinosaur species.
07:27One thing we have learned is that an apex predator was vulnerable to attack, typically from another
07:34apex predator.
07:37Any dinosaur had a tough life, but a predator like T-Rex had a really tough life.
07:42When we look at the fossil record, we see many skeletons of Tyrannosaurus that show injuries
07:48on the body.
07:50Proof can be found in this upper arm bone of a T-Rex.
07:55Throughout the bone, we can see massive damage, suggesting that the arm had almost been pulled
08:01off.
08:03Most likely by another Rex.
08:07So it may be that, at least at times, a T-Rex was another T-Rex's worst enemy.
08:12A nesting pair of T-Rex loses their children after the attack of a cannibalistic rival.
08:20But life must go on.
08:24As with most dinosaurs, very few T-Rex's survive into adulthood.
08:42The odds have not favored this mother.
08:49The odds have not favored this blood pressure and this may cause time to cause akiem of the
08:57Moon, too, because of course.
08:58So it would be like you, you took to the incident.
09:01I've seen her in a race chase.
09:02Do not be very little.
09:03And they are too close to her.
09:04And they are just at the same time, and now I'm attracted to her.
09:06So, it's a mistake.
09:07So, we've seen her in a row.
09:08So, let's go back.
09:09So...
09:10I'm gonna move her in a row.
09:10But I'm going to find out there.
09:11We're ending up all around the time to do it.
09:12So, you're gonna be necesita in one place.
09:13So, we're gonna be identified.
09:15Now, I'm going to be able to try down the way.
09:16These T-Rexes team up for maximum killing advantage.
09:46This T-Rexes team up for a long time, and this T-Rexes team up for a long time, and this T-Rexes team up for a long time.
10:14This T-Rexes team up for a long time, and this T-Rexes team up for a long time, and this T-Rexes team up for a long time.
10:37The T-Rexes team up for a long time, and this T-Rexes team up for a long time, and this T-Rexes team up for a long time.
10:49I don't know.
11:19I don't know.
11:49I don't know.
12:19I don't know.
12:49I don't know.
13:19I don't know.
13:20I don't know.
13:21I don't know.
13:52I don't know.
13:53I don't know.
13:54I don't know.
13:55I don't know.
13:56I don't know.
13:57I don't know.
13:58I don't know.
13:59I don't know.
14:00I don't know.
14:01I don't know.
14:02I don't know.
14:03I don't know.
14:04I don't know.
14:06I don't know.
14:07I don't know.
14:08I don't know.
14:09I don't know.
14:10I don't know.
14:11I don't know.
14:12I don't know.
14:13I don't know.
14:14I don't know.
14:15I don't know.
14:16I don't know.
14:17I don't know.
14:18I don't know.
14:20I don't know.
14:21I don't know.
14:22I don't know.
14:23I don't know.
14:24It is a reasonable assumption what a dinosaur may have looked like.
14:27So they work with a scientist and they study the the bones and where the muscles all go
14:33and what the skin may have looked like feathers any other covering and then they come up
14:37with an idea of what this creature may have looked like in real life and also putting
14:41it in its environment that it actually lived in.
14:44I've always liked to treat dinosaurs as characters.
14:47When I look at the bone I don't see just this creature.
14:50I see somebody.
14:51I want to know who that is.
14:52When the average person looks at a dinosaur or a T-Rex, they see a T-Rex.
14:58But in the many 40-some skeletons that have been found of T-Rex, you can actually tell
15:05the difference between the skulls, as to who is who.
15:08When I look at a fossil, I want to know who this guy was.
15:12I want to know what his life was like.
15:16I want to see the world through its eyes.
15:19Our concept of dinosaurs has changed dramatically since I was a kid.
15:23Now it's common knowledge that they kind of walked in a horizontal position.
15:28They look less lizard-y now.
15:30They look much more bird-like.
15:33Feathers is totally commonly accepted now.
15:36They're just much more interesting, dynamic, and visually exciting creatures.
15:42In my lifetime, dinosaurs have gone through a big overhaul.
15:47There's a lot more work done on myology, how the skin may have applied or how the muscles
15:53may have been attached.
15:56And then having this clue that they're related to birds now also informs a lot of what their
16:01appearance may have been.
16:02So we're getting a much leaner-looking dinosaur and a much better-informed dinosaur.
16:08It's hard to imagine an anxious T-Rex hovering over a nest unless you are part of the dinosaur
16:17revolution.
16:18Beginning in the 1980s, we started to find more and more nests and eggs of dinosaurs.
16:25We can now say with some confidence that they looked after their young.
16:29In fact, we have evidence.
16:31In the mid-1990s in Mongolia, paleontologists found a skeleton of what's called an oviraptorosaur
16:39sitting on a nest of eggs.
16:41So I think there's very solid evidence that dinosaurs brooded their nests, and probably
16:45quite a bit of evidence that they cared for their young to some degree as well.
16:50We know that crocodiles, which are distant relatives of dinosaurs, have parental care.
16:54And also many birds today have parental care.
16:56So it's certainly very possible that Tyrannosaurus itself may have cared for its young.
17:01A six-ton T-Rex sitting like a bird on a nest of fragile eggs seems improbable.
17:09It's more likely that some protective covering was built.
17:13And that was just the beginning of a perilous journey.
17:18It's really sad to think about, but most baby dinosaurs were born to die.
17:23They were born to die when they were really young.
17:26A mama dinosaur probably laid ten clutches in her life.
17:30And yet in nature, on average, only one baby makes it to adulthood per parent.
17:38Not only could hatchlings be picked off at will by predators, even incubating eggs was
17:44a dangerous process.
17:51The more eggs, the better the odds one will survive.
18:16eggs are easy targets for predators during the many long weeks they lie in the nest.
18:41And nests need to be built from available materials.
19:00For the woods are alive with danger, as creatures who would not dare to attack an adult Rex have
19:13no such reservations towards their young.
19:20eggs are porous, allowing the embryo to breathe through the shell.
19:25rising water can cause drowning.
19:46Ah!
19:47Ah!
19:48to breathe through the shell.
19:51Rising water can cause drowning.
20:18This T-Rex is halfway home, but it is not out of the woods.
20:39The T-Rex is almost out of the woods.
21:09I don't know.
21:39I don't know.
22:09I don't know.
22:39I don't know.
23:09I don't know.
23:39I don't know.
23:40I don't know.
23:41I don't know.
23:42I don't know.
23:43I don't know.
23:44I don't know.
23:45I don't know.
23:46I don't know.
23:47I don't know.
23:48I don't know.
23:49I don't know.
23:50If the T-Rex symbolizes all that is ferocious and predatory, it did share the planet with
23:57creatures that possessed none of these attributes.
24:01Although the old ankylosaur's eyesight is weak, his highly developed sense of smell, once cleared
24:10for action, is his window to the world.
24:14I think he's a great figure.
24:15It's a great game.
24:18I think he'll do it.
24:20He is a great game.
24:22All right.
24:24Let's go.
24:54Let's go.
25:24Let's go.
25:54A Rexling is now a teenager.
26:15But he still has a youngster's curiosity, and this new armored toy is irresistible.
26:30Let's go.
26:31Let's go.
26:32Let's go.
26:33Let's go.
26:34Let's go.
26:35Let's go.
26:36Let's go.
26:37Let's go.
26:38Let's go.
26:39Let's go.
26:40Let's go.
26:41Let's go.
26:42Let's go.
26:43Let's go.
26:44Let's go.
26:45Let's go.
26:46Let's go.
26:47Let's go.
26:48Let's go.
26:49Let's go.
26:50Let's go.
26:51Let's go.
26:52Let's go.
26:53Let's go.
26:54Let's go.
26:55Let's go.
26:57Let's go.
26:58Let's go.
26:59Let's go.
27:00Let's go.
27:02Let's go.
27:03Let's go.
27:04Let's go.
27:05Let's go.
27:06Let's go.
27:07Let's go.
27:08Let's go.
27:37Let's go.
28:07Let's go.
28:37Let's go.
28:43The six mile wide asteroid hit on the northern coast of the Yucatan Peninsula at a speed of
28:4812.4 miles per second and blew a hole in the earth nearly 88 miles wide and 19 miles
28:56deep.
28:57The explosive power was the equivalent of 1 billion Hiroshima bombs.
29:03The impact created mega tsunamis reaching hundreds of meters high while superheated
29:10debris ignited wildfires across the northern hemisphere.
29:16Shockwaves from the impact caused massive earthquakes and volcanic eruptions.
29:22Certainly, anything in the pathway of the asteroid would have been incinerated, it would
29:27have been terrible to have been standing at ground zero when this giant rock fell out
29:31of the sky.
29:33For animals and plants that weren't in the immediate area of the impact, it would have
29:37been a slow and painful demise.
29:40This thing blasts a bunch of dust into the sky, that dust gradually encircles the globe.
29:46And before too long, you've got most of the Earth enveloped in a cloud of dust.
29:52The effect of this asteroid impact is the closest the world has seen and let us hope the closest
29:58the world will ever see to nuclear winter.
30:01What scientists predict would be the result of a full on global thermonuclear war.
30:0765 million years ago, Earth is shrouded in ash and darkness.
30:15This darkness devastates the planet's food cycle as vegetation dies from lack of light.
30:23All dinosaurs eat sunlight.
30:26That's kind of strange to think about, because after all, plants feed on sunlight.
30:32Herbivores feed on plants.
30:34And carnivores eat the herbivores.
30:36You cut off the sunlight and you plunge the world into darkness.
30:41And the longer and more protracted the darkness goes, the longer the starvation goes.
30:46The interesting thing about extinctions is it's often the best adapted animals that actually
30:50go extinct.
30:51So if there's a specific type of animals that you need to eat, or a specific type of plant,
30:55or maybe even just a specific part of the ecosystem that you have to be in and that part
31:00is wiped out, well you're going to be the first to go then.
31:03Did it happen overnight, or in a period of days, weeks, or was it years, or was it thousands
31:08or millions of years?
31:09I find it difficult to believe that all dinosaurs, other than birds, were wiped out in this single
31:14event.
31:15One creature in particular may have been one of those last survivors.
31:19If we were to think about the dinosaurs, other than birds, that were around at the end of
31:24the Mesozoic, who would be the most likely to survive the longest in the great extinction
31:30event?
31:31I think it would probably be truodon.
31:34Truodon's a very interesting animal.
31:36It's found all the way from Alaska down to the southern United States.
31:40It is an odd beast because its teeth don't really tell us if it's a full-on carnivore,
31:46and many paleontologists now would say that it probably did both.
31:50Truodon has a number of anatomical adaptations that suggest that it would have been relatively
31:55well adapted to survive after the asteroid impact.
31:58First of all, it has big eyes, so it could probably see in the dark.
32:01Secondly, its teeth suggest that its diet would have been quite varied.
32:05Thirdly, it has feathers, and so it would be insulated from the cold of a nuclear winter.
32:11One of the great advantages of being warm-blooded is that you can be active 24 hours a day.
32:17You don't need the sun to help get you going in the morning.
32:22And if truodon was nocturnal, it's maybe one other indicator that in fact this animal had
32:27elevated metabolic rates and was close to, if not warm-blooded or endothermic, as we say.
32:34Of any of the dinosaurs around at the end of the Cretaceous period, I would expect that
32:39Troodon and its close relatives may have had the best shot to survive.
32:44Phi and Troglie
32:48worked by the
33:07but
33:10I don't know.
33:40I don't know.
34:10Catastrophe tends to favor the indiscriminate and the improvisational.
34:36There is strong evidence that like penguins and ostriches, Trudons involve the males in
35:00the child-rearing process.
35:02They may have even sat on the eggs.
35:08But first, there have to be eggs.
35:12These nesting pairs are bonded for life.
35:16Lives that are fast running out.
35:20They may have to be fired.
35:24It's been a fun day.
35:28It's been a fun day.
35:34I don't know.
36:04The female leaves in search of food, the male shields the nest.
36:34The male shields the nest.
37:04The male shields the nest.
37:34The male is a whisper's mate.
37:36But she cannot hear.
37:38She cannot hear.
37:40She cannot hear.
37:42She cannot hear.
37:44She cannot hear.
37:46She cannot hear.
37:48She cannot hear.
37:52She cannot hear.
37:54She cannot hear.
37:56She cannot hear.
37:58She cannot hear.
38:00She cannot hear.
38:02She cannot hear.
38:04She cannot hear.
38:06She cannot hear.
38:08She cannot hear.
38:10She cannot hear.
38:12She cannot hear.
38:13She cannot hear.
38:14She cannot hear.
38:15She cannot hear.
38:16She cannot hear.
38:17She cannot hear.
38:18She cannot hear.
38:19She cannot hear.
38:20She cannot hear.
38:21She cannot hear.
38:22She cannot hear.
38:23She cannot hear.
38:24She cannot hear.
38:25She cannot hear.
38:26She cannot hear.
38:27She cannot hear.
38:28She cannot hear.
38:29She cannot hear.
38:30She cannot hear.
38:31She cannot hear.
38:32She cannot hear.
38:33She cannot hear.
38:34She cannot hear.
38:35She cannot hear.
38:36She cannot hear.
38:37accurately measured, one of the first and only raptor dinosaurs.
38:41That ratio, brain to body size, is quite high in Troodon, one of the highest ratios
38:45of any dinosaur.
38:47Now in the modern world, intelligence generally correlates with brain size to body size.
38:53And so if that held true in the age of dinosaurs, then it's likely that Troodon was one of the
38:57smarter dinosaurs that we've discovered so far.
39:01From stealing eggs, to parenting, and hunting, the Troodon may have exhibited its intelligence
39:11in many ways.
39:14And yet, with all this going for it, Troodon didn't make it.
39:18I personally think it probably lasted the longest of the dinosaurs other than the birds.
39:23But sad to say, the Troodons are no more.
39:31The day of the dinosaur is over, but their night still has a few hours to go.
39:41The former rulers of the planet are now frozen corpses.
39:55In perpetual winter, the last few dinosaurs try to survive.
40:07The moon has a few hours.
40:09It was the fact that I suppose this has been very uncertain.
40:13The moon has revealed.
40:15The moon has been realized.
40:16The moon has advanced magics.
40:18The moon has advanced magics.
40:19The moon has advanced magics.
40:20The moon was discouraged.
40:21The moon has become very cautious.
40:23The moon is also declared.
40:25The moon is confirmed by the moon.
40:30I don't know.
41:00I don't know.
41:30I don't know.
42:00I don't know.
42:30I don't know.
42:38We've seen many things in the dinosaur revolution.
42:41One of the greatest discoveries is that at least some dinosaurs survived one of the worst
42:47events the earth is seen.
42:48And these are birds.
42:50And so in that sense, dinosaurs aren't extinct.
42:54We eat them for Thanksgiving.
42:56And so dinosaurs are all around us.
42:59By any stretch and by any measure, dinosaurs were a success story.
43:06We think that because we're here right now that we're the best.
43:10But that's like criticizing your great-great-grandparents because they're not here anymore and you
43:15are.
43:17Everything dies over time.
43:21Human beings?
43:22Eventually everything goes extinct.
43:28We're the best.
43:29It's like human beings.
43:31I don't know.
43:33You're the best.
43:34I want to know...
43:35You can see from an island.
43:37I've got jealous.
43:38I've got jealous.
43:39You're the best.
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