1
00:00:48,127 --> 00:00:50,118
(SPEAKS TUAREG)
2
00:01:01,687 --> 00:01:03,996
We're looking for a dinosaur.
3
00:01:04,047 --> 00:01:09,440
At the time when the dinosaur first appeared,
about 200 million years ago,
4
00:01:09,807 --> 00:01:14,039
all the land on the earth was grouped together
in one supercontinent
5
00:01:14,127 --> 00:01:17,517
and the dinosaurs roamed all over it.
6
00:01:17,687 --> 00:01:22,556
And so today their remains can be found
in the fragments of that supercontinent,
7
00:01:22,407 --> 00:01:28,801
in Australia, in North America,
in Europe and here in Africa.
8
00:01:29,127 --> 00:01:33,757
We're on an expedition
in the southern fringes of the Sahara
9
00:01:33,887 --> 00:01:35,878
and the reason we've come here
10
00:01:36,287 --> 00:01:39,802
is that in a desert
there's very little vegetation to cover the rocks,
11
00:01:39,967 --> 00:01:44,961
so that if there are dinosaurs in them,
we'll be able to see them.
12
00:01:55,527 --> 00:01:59,998
One of the expedition leaders, Dick Moody,
showed me their first find.
13
00:02:00,127 --> 00:02:02,960
I'm sure you'll find this one,
which we haven't touched,
14
00:02:03,487 --> 00:02:05,842
quite a superb specimen, quite exciting.
15
00:02:05,887 --> 00:02:09,721
0h, it is absolutely magnificent.
16
00:02:10,687 --> 00:02:13,485
This is obviously the backbone,
but which way is it lying?
17
00:02:13,887 --> 00:02:18,597
It's running in that direction, we believe,
towards the head and towards the east.
18
00:02:18,687 --> 00:02:22,236
And in this direction, generally,
back towards the tail.
19
00:02:22,527 --> 00:02:24,597
- And the ribs?
- The ribs are running off.
20
00:02:24,727 --> 00:02:29,881
As you can see, they're slightly disarticulated
and slightly broken up,
21
00:02:30,007 --> 00:02:33,761
but they are running
in that general direction down the sand dune.
22
00:02:33,967 --> 00:02:36,686
And how long do you think
the complete animal was?
23
00:02:36,847 --> 00:02:39,122
Between 20 and 30 metres.
24
00:02:39,247 --> 00:02:41,715
- What, that's 90 feet?
- Yes.
25
00:02:41,647 --> 00:02:44,161
- That's enormous.
- It's a large animal, yes.
26
00:02:44,607 --> 00:02:46,677
How complete do you think it might be?
27
00:02:46,527 --> 00:02:51,317
We're hoping to find some skull material
and obviously limb material underneath here.
28
00:02:52,767 --> 00:02:55,440
If we clear these just a little...
29
00:02:55,647 --> 00:02:58,241
The weathered shales
in which the bones were embedded
30
00:02:58,527 --> 00:03:02,076
were so soft that we could
brush them away with our hands.
31
00:03:05,527 --> 00:03:12,126
After only half an hour, we already had some
idea of how much of the animal was preserved.
32
00:03:12,727 --> 00:03:17,437
But it was a further day
before all the bones at this site were exposed.
33
00:03:23,047 --> 00:03:25,481
There weren't as many as we had first hoped.
34
00:03:25,927 --> 00:03:28,839
The base of the tail
and the lower spine was there,
35
00:03:28,807 --> 00:03:32,356
but the legs and most of the body were missing.
36
00:03:34,287 --> 00:03:39,680
But half a mile away, the rest of the expedition
was working on another group of bones.
37
00:03:39,567 --> 00:03:43,685
These were leg bones and probably belonged,
if not to the same animal,
38
00:03:43,887 --> 00:03:47,163
then at least to the same kind.
39
00:03:51,087 --> 00:03:56,719
The huge carcass, whatever it was, had clearly
already been dismembered before it was buried.
40
00:03:56,687 --> 00:03:59,645
Perhaps other scavenging dinosaurs
had pulled it apart.
41
00:04:00,047 --> 00:04:02,197
Perhaps the rotting body had disintegrated
42
00:04:02,247 --> 00:04:05,876
as it lay in the river
that eventually buried it in mud.
43
00:04:06,527 --> 00:04:11,396
The expedition was from the Natural History
Museum and Kingston Polytechnic in London.
44
00:04:11,767 --> 00:04:14,281
Before the bones could be transported back,
45
00:04:14,567 --> 00:04:20,199
they had to be protected by wrapping them
with strips of sackcloth soaked in plaster.
46
00:04:22,687 --> 00:04:28,159
This will harden into a solid jacket
that will hold the whole specimen together.
47
00:04:30,087 --> 00:04:33,602
The expedition dug up and plastered
almost 100 bones
48
00:04:33,447 --> 00:04:35,836
in the four weeks they worked in the Sahara.
49
00:04:36,327 --> 00:04:38,397
But this was only the start.
50
00:04:38,447 --> 00:04:42,235
Indeed, it won't be until the team
gets the bones back to London
51
00:04:42,287 --> 00:04:45,120
and has cleaned them,
studied them and pieced them together,
52
00:04:45,167 --> 00:04:49,797
that they will know for sure
exactly what kind of dinosaur they've got.
53
00:04:56,007 --> 00:05:00,000
But one thing is certain - it's a giant.
54
00:05:04,127 --> 00:05:10,043
These bones, too, in the museum in East Berlin,
came from Africa back in 1912.
55
00:05:09,887 --> 00:05:12,606
When pieced together, they proved to belong
56
00:05:12,767 --> 00:05:16,840
to the most massive land animal
known up to that time.
57
00:05:17,087 --> 00:05:21,524
It was 74 feet, 22½ metres long,
58
00:05:21,887 --> 00:05:26,722
it stood 39 feet, that's 12 metres, high,
59
00:05:26,687 --> 00:05:30,646
and it was estimated to weigh 77 tons,
60
00:05:31,007 --> 00:05:34,841
which is as much as
12 bull elephants put together.
61
00:05:34,847 --> 00:05:38,442
This is brachiosaurus.
62
00:05:44,567 --> 00:05:48,355
It's head, perched on top
of its immensely long neck,
63
00:05:48,407 --> 00:05:52,116
was comparatively tiny,
less than three feet long,
64
00:05:52,247 --> 00:05:55,557
but it has huge nostrils, high on its forehead
65
00:05:55,607 --> 00:05:59,566
and they led some people to suggest
that this animal lived in lakes,
66
00:05:59,927 --> 00:06:03,078
with its head and nostrils above the surface
67
00:06:03,287 --> 00:06:08,964
while it walked along the bottom
with the water supporting its huge body.
68
00:06:09,047 --> 00:06:12,039
But that, we now know,
would have been impossible.
69
00:06:12,847 --> 00:06:15,680
If its nostrils were open at the surface,
70
00:06:15,727 --> 00:06:19,242
the water pressure
30 or so feet below the surface
71
00:06:19,567 --> 00:06:23,446
would have been so great
that its lungs would've collapsed.
72
00:06:23,407 --> 00:06:28,435
Furthermore, the shape of its legs
and its deep, narrow chest
73
00:06:28,687 --> 00:06:31,121
all suggest an animal that lived on land.
74
00:06:31,567 --> 00:06:34,479
So now, it seems,
we have to think of brachiosaurus
75
00:06:34,447 --> 00:06:40,841
as a kind of gigantic reptilian giraffe,
browsing the tops of the trees.
76
00:06:46,967 --> 00:06:50,721
Brachiosaurus may be the biggest
mounted dinosaur in the world,
77
00:06:50,807 --> 00:06:53,526
but it may not be so for long.
78
00:06:58,007 --> 00:07:02,717
In New Mexico, they've found remains
of an animal that may be even bigger.
79
00:07:03,287 --> 00:07:07,644
They've already given it a name,
seismosaurus, the "earth-shaker".
80
00:07:07,607 --> 00:07:11,725
But the rock in which it is embedded,
unlike the soft shales of the Sahara,
81
00:07:11,687 --> 00:07:13,723
is almost as hard as concrete,
82
00:07:14,087 --> 00:07:18,365
and excavating it is a laborious
and time-consuming business.
83
00:07:20,807 --> 00:07:24,641
The excavation leader, Dave Gillette,
told me the story.
84
00:07:24,527 --> 00:07:28,122
This is where we found
the first set of vertebrae in 1979.
85
00:07:28,367 --> 00:07:30,483
We finally excavated in 1985.
86
00:07:30,767 --> 00:07:32,678
How much of it was showing?
87
00:07:32,687 --> 00:07:34,598
Only the upper part.
88
00:07:34,607 --> 00:07:38,600
It was showing as though it had been carved
out of the rock in bas-relief.
89
00:07:38,927 --> 00:07:41,680
It was perfectly exposed just in this fashion.
90
00:07:41,807 --> 00:07:44,879
- And then?
- Then, when we looked closer in the ground,
91
00:07:45,167 --> 00:07:50,195
we found a total of eight vertebrae along this line,
all in perfect articulation,
92
00:07:50,447 --> 00:07:54,201
and they're from the basal part of the tail,
leading into the pelvic region.
93
00:07:54,287 --> 00:07:57,518
There's another vertebra here.
Then we took out two large blocks,
94
00:07:57,647 --> 00:08:02,960
one here, another here at the base of the tail,
that led right up to the hip region.
95
00:08:02,967 --> 00:08:06,004
- What's that?
- This is a rib, which has been displaced
96
00:08:06,207 --> 00:08:10,325
from the proper anatomical position
when the animal died.
97
00:08:10,607 --> 00:08:13,758
- The rock looks awful.
- It is terribly hard around the bone.
98
00:08:13,967 --> 00:08:18,518
- It takes for ever for us to excavate the bones.
- Does the animal go on in there?
99
00:08:18,767 --> 00:08:23,921
We think the animal continues right into the hill
to the north for another 60 or 70 feet.
100
00:08:23,967 --> 00:08:26,356
- Under the rock?
- About eight feet deep.
101
00:08:26,367 --> 00:08:30,485
We're using sophisticated and experimental
remote-sensing techniques
102
00:08:30,687 --> 00:08:33,679
to try to see those bones before we excavate.
103
00:08:36,447 --> 00:08:40,645
The site is only a few miles
from Los Alamos atomic research station,
104
00:08:40,767 --> 00:08:43,156
and the scientists there, on their days off,
105
00:08:43,167 --> 00:08:46,523
come out to use the most advanced
techniques of nuclear physics
106
00:08:46,527 --> 00:08:50,361
to help Dave locate
his dinosaur bones deep in the rock.
107
00:08:50,807 --> 00:08:54,766
This sledge carries a still-experimental
remote-sensing device,
108
00:08:54,647 --> 00:08:57,115
a kind of radar that looks into the ground.
109
00:09:00,487 --> 00:09:03,399
It's dragged along carefully-plotted tracks
across the rock
110
00:09:03,367 --> 00:09:07,963
and already readings from it are beginning
to confirm the gigantic size of the animal.
111
00:09:08,087 --> 00:09:12,126
I asked Dave how long he thought
seismosaurus might eventually prove to be.
112
00:09:12,487 --> 00:09:17,607
My best estimate is 140 feet in length,
from the snout to the tip of the tail.
113
00:09:17,767 --> 00:09:19,325
How does that compare?
114
00:09:19,207 --> 00:09:22,995
The previous record-holder
was diplodocus at 87 feet.
115
00:09:23,527 --> 00:09:25,518
We're approaching twice that length.
116
00:09:25,447 --> 00:09:29,156
When will you actually know
whether this is a world-beater?
117
00:09:29,287 --> 00:09:33,678
We know now.
We have good confidence in our calculations.
118
00:09:37,847 --> 00:09:41,965
Dinosaurs certainly include
some gigantic animals.
119
00:09:43,607 --> 00:09:46,280
Stegosaurus, bigger than a rhinoceros.
120
00:09:47,367 --> 00:09:50,598
Allosaurus, tall as a giraffe.
121
00:09:59,847 --> 00:10:03,965
But they weren't all huge.
Some were no bigger than a dog.
122
00:10:14,167 --> 00:10:17,000
Nonetheless, many were very big indeed
123
00:10:17,527 --> 00:10:22,840
and they certainly include some of the most
spectacular animals ever to walk the earth.
124
00:10:27,127 --> 00:10:32,326
They dominated the world
for over 160 million years.
125
00:10:53,527 --> 00:10:58,362
But what did a dinosaur like this
actually look like when it was alive?
126
00:10:58,367 --> 00:11:03,157
Did it have hide like an elephant,
or was it covered in scales like a lizard,
127
00:11:03,167 --> 00:11:05,886
or perhaps hair, like a horse?
128
00:11:06,047 --> 00:11:10,962
The skin, of course, like the rest of the soft parts,
is very rarely fossilised,
129
00:11:11,327 --> 00:11:15,115
but in this exceptional example, it has been.
130
00:11:18,527 --> 00:11:22,486
This is the fleshy pad
on the underside of its foot.
131
00:11:26,287 --> 00:11:30,997
And behind you can still see
the wrinkles in the skin on its belly.
132
00:11:33,527 --> 00:11:38,920
This particular individual was, most unusually,
entombed in the hot sand of a desert,
133
00:11:38,807 --> 00:11:41,275
and although its flesh decayed
and disappeared,
134
00:11:41,687 --> 00:11:45,043
its tough hide was baked and mummified.
135
00:11:44,967 --> 00:11:48,755
You can even see the impressions
of the scales in the skin.
136
00:11:49,767 --> 00:11:51,758
From remarkable specimens like this,
137
00:11:52,167 --> 00:11:55,364
we can deduce that dinosaur skin
was thick and tough,
138
00:11:55,527 --> 00:11:58,599
probably not unlike an elephant's hide.
139
00:11:59,367 --> 00:12:02,962
But was it grey and colourless
like an elephant's?
140
00:12:08,487 --> 00:12:14,403
0r was it, perhaps, brightly coloured,
as are the skins of many reptiles today?
141
00:12:18,567 --> 00:12:20,797
Animal pigments don't fossilise,
142
00:12:20,967 --> 00:12:24,721
so it's anyone's guess as to whether
the dinosaurs were coloured or not,
143
00:12:25,007 --> 00:12:27,965
but it's tempting to think that they were.
144
00:12:34,647 --> 00:12:39,004
But we can go further than simply investigating
the size and appearance of dinosaurs.
145
00:12:41,847 --> 00:12:43,644
What did the dinosaurs eat?
146
00:12:44,247 --> 00:12:48,798
Well, flowering plants didn't develop
until about 100 million years ago.
147
00:12:48,567 --> 00:12:51,923
That means that for most of the time
dinosaurs were on earth,
148
00:12:52,407 --> 00:12:56,525
there were very few of the kinds of plant
that dominate the land today.
149
00:12:56,727 --> 00:13:01,118
There were no oak trees or hazel
in Europe, on which deer feed.
150
00:13:01,047 --> 00:13:05,996
In Africa there was no thorn scrub or acacia,
on which elephant and giraffe browse.
151
00:13:06,327 --> 00:13:12,562
Most important of all, there was no grass,
on which horses or bison or antelope graze.
152
00:13:12,567 --> 00:13:15,798
Instead there were plants like these.
153
00:13:21,207 --> 00:13:22,845
These are cycads.
154
00:13:22,647 --> 00:13:27,163
Today they grow wild in only a very few places,
and mostly in the tropics.
155
00:13:27,447 --> 00:13:31,804
But when the dinosaurs first evolved,
they were spread worldwide.
156
00:13:34,647 --> 00:13:40,438
In addition to these, there were also tree-ferns
and primitive conifers like pines.
157
00:13:40,407 --> 00:13:46,243
But all these plants had tough, fibrous leaves,
almost indigestible, you might think.
158
00:13:50,767 --> 00:13:57,479
To make matters more awkward, the early
dinosaurs were poorly equipped with teeth.
159
00:13:57,967 --> 00:14:01,437
Diplodocus had only these small, peg-like teeth
160
00:14:01,327 --> 00:14:05,081
that could have done little more
than just nip off the fronds.
161
00:14:05,647 --> 00:14:11,563
It certainly couldn't have chewed them.
So how did it avoid terrible indigestion?
162
00:14:19,087 --> 00:14:23,842
Clues to the answer were eventually found
lower down in the skeleton.
163
00:14:23,887 --> 00:14:28,165
Between the ribs of specimens
that had been fossilised more or less complete
164
00:14:28,687 --> 00:14:33,317
are sometimes found great heaps of small,
highly polished pebbles.
165
00:14:33,487 --> 00:14:35,762
It seems these had been swallowed and stored
166
00:14:35,887 --> 00:14:39,084
in a muscular pouch
of the dinosaur's stomach, a gizzard,
167
00:14:39,247 --> 00:14:44,958
which served as a kind of internal mill
to grind up its fibrous meals.
168
00:14:45,967 --> 00:14:48,765
Even so, it must have taken a very long time
169
00:14:48,767 --> 00:14:55,115
for a dinosaur's digestive juices to break down
the woody stems and trunks of plants like these.
170
00:14:55,487 --> 00:14:58,718
If you have to keep your food
in your stomach a long time,
171
00:14:58,847 --> 00:15:03,238
then you need a very big stomach
to serve as a storage vat.
172
00:15:06,527 --> 00:15:10,406
That, in turn, means you need
a very large body to carry it.
173
00:15:10,367 --> 00:15:12,722
So the ancient pastures of tree-ferns
174
00:15:12,767 --> 00:15:19,206
may be one of the main reasons
why plant-eating dinosaurs grew so big.
175
00:15:19,487 --> 00:15:23,480
As millions of years passed, however,
evolution brought changes.
176
00:15:23,807 --> 00:15:29,564
The first flowering plants appeared,
and so did new kinds of plant-eating dinosaurs.
177
00:15:29,567 --> 00:15:34,038
These are hadrosaurs. They had no teeth
at all in the front of their jaws.
178
00:15:34,367 --> 00:15:39,282
Instead, the rounded bone was almost certainly
covered with a horny sheath.
179
00:15:39,167 --> 00:15:44,366
With this, they could have done little more
than just nip off leaves and twigs.
180
00:15:48,287 --> 00:15:53,042
But inside the mouth, at the back of the jaws,
they had an enormous battery of teeth,
181
00:15:53,087 --> 00:15:54,884
row upon row.
182
00:15:55,007 --> 00:15:57,965
This particular jaw had over 200.
183
00:15:58,367 --> 00:16:03,395
As these crushed and ground the tough fibres,
they were inevitably worn down.
184
00:16:03,647 --> 00:16:08,721
But new ones grew in the bone of the jaw
beneath and moved up to replace the old ones.
185
00:16:08,927 --> 00:16:11,885
But could they use them to chew?
186
00:16:11,607 --> 00:16:16,601
Mammals like this camel can chew
by moving their lower jaw from side to side,
187
00:16:16,887 --> 00:16:21,039
so they are able to break down
the toughest of plant foods.
188
00:16:21,447 --> 00:16:25,235
The dinosaurs were reptiles,
and no reptile can do that.
189
00:16:25,287 --> 00:16:31,283
They can only move their jaws up and down,
and that puts a real limit on what they can eat.
190
00:16:32,927 --> 00:16:36,761
The hadrosaurs dealt with that problem
in a most remarkable way.
191
00:16:36,807 --> 00:16:40,482
The highlighted upper jaw
could actually hinge outwards.
192
00:16:40,647 --> 00:16:42,797
When a hadrosaur's skull is examined closely,
193
00:16:43,047 --> 00:16:48,440
it reveals an elastic joint between
the upper jaw and the roof of the snout.
194
00:16:51,207 --> 00:16:55,917
This means that as the lower jaw moves up,
it pushes aside the upper jaw,
195
00:16:56,007 --> 00:17:01,035
in effect, chewing without any sideways
movement of the lower jaw at all.
196
00:17:13,687 --> 00:17:18,078
The most powerful grinding battery of all
was that possessed by triceratops,
197
00:17:18,007 --> 00:17:20,441
one of the last of the dinosaurs.
198
00:17:20,407 --> 00:17:24,719
This, the product of 100 million years
of development in the technique of chewing,
199
00:17:25,207 --> 00:17:29,837
is perhaps the most powerful chewing device
ever possessed by any animal.
200
00:17:30,007 --> 00:17:32,965
A huge beak in the front served as shears
201
00:17:32,887 --> 00:17:36,084
which could probably
slice clean through a tree trunk.
202
00:17:36,247 --> 00:17:39,125
The branches were then moved
to the back of the mouth,
203
00:17:39,607 --> 00:17:42,963
where the massive grinders
reduced them to pulp.
204
00:17:52,807 --> 00:17:56,436
But these teeth belong
to a very different sort of animal.
205
00:17:56,647 --> 00:17:59,559
These are not thin pegs
for nipping off bits of leaves.
206
00:18:00,047 --> 00:18:04,040
These are daggers, finely serrated
along the edge like steak knives,
207
00:18:03,887 --> 00:18:07,675
adapted to slicing through flesh and hide.
208
00:18:08,207 --> 00:18:13,565
In life, much of the empty space in the skull here
would have been filled by massive muscles,
209
00:18:13,487 --> 00:18:17,116
which gave an enormously powerful bite
to these huge jaws.
210
00:18:17,447 --> 00:18:22,237
This is Tyrannosaurus rex,
the biggest of all the meat-eating dinosaurs,
211
00:18:22,247 --> 00:18:26,160
measuring over forty feet long
and weighing about seven tons,
212
00:18:26,567 --> 00:18:30,924
surely the most terrifying hunter
ever to roam the earth.
213
00:18:56,047 --> 00:18:58,959
With long, curved claws and sharp teeth,
214
00:18:59,127 --> 00:19:04,076
the carnivorous dinosaurs must have been
terrifying and highly efficient predators.
215
00:19:04,407 --> 00:19:08,923
But other kinds of dinosaurs evolved
that had no teeth at all.
216
00:19:16,367 --> 00:19:20,280
This one seems to have been
rather like the ostrich of today.
217
00:19:23,567 --> 00:19:27,958
So perhaps, like an ostrich,
this dinosaur, called struthiomimus,
218
00:19:28,367 --> 00:19:33,839
picked up and swallowed anything, animal
or vegetable, it considered remotely edible.
219
00:19:36,047 --> 00:19:39,562
So the bones of dinosaurs,
carefully pieced together,
220
00:19:39,647 --> 00:19:42,559
can tell us a great deal
about how big they were,
221
00:19:43,007 --> 00:19:46,283
what they fed on, and therefore
their relationships with one another,
222
00:19:46,367 --> 00:19:48,483
and how their limbs articulated.
223
00:19:48,767 --> 00:19:50,758
But how fast could they move?
224
00:19:50,687 --> 00:19:54,999
To answer that question,
you have to come to a place like this.
225
00:19:57,967 --> 00:20:01,755
150 million years ago,
there was a mudflat here,
226
00:20:01,807 --> 00:20:04,367
around the margin of a freshwater lake.
227
00:20:04,687 --> 00:20:07,918
The lake filled and eventually
sediments covered the whole area,
228
00:20:08,047 --> 00:20:10,959
and the mudflats turned into mudstones.
229
00:20:10,927 --> 00:20:14,124
In them are preserved huge footprints -
230
00:20:14,287 --> 00:20:16,676
dinosaur footprints.
231
00:20:19,927 --> 00:20:22,441
These, nearly a yard across,
232
00:20:22,807 --> 00:20:28,245
can only have been made by a huge plant-eater
like a brontosaur such as diplodocus.
233
00:20:28,367 --> 00:20:30,801
No other had such a huge foot.
234
00:20:30,767 --> 00:20:35,522
Here the animal has trodden on a small shell,
a kind of freshwater mussel.
235
00:20:35,687 --> 00:20:38,838
Molluscs virtually identical to this
still live today,
236
00:20:39,047 --> 00:20:42,084
but only in water
that is less than three feet deep.
237
00:20:42,407 --> 00:20:45,717
So these little shells confirm
that these dinosaurs that day
238
00:20:45,767 --> 00:20:48,486
were splashing through the shallows.
239
00:20:50,567 --> 00:20:55,960
If you can measure an animal's stride from
its tracks, and also know the length of its legs,
240
00:20:56,087 --> 00:21:00,080
it's possible to calculate the speed
at which it was moving.
241
00:21:00,487 --> 00:21:05,481
The brontosaurs had legs that were about nine
feet long, as we know from their skeletons.
242
00:21:05,767 --> 00:21:09,760
But this animal's right hind leg,
which was printed here,
243
00:21:10,087 --> 00:21:15,115
is only about six feet
from the next print in the sequence.
244
00:21:15,367 --> 00:21:20,395
So we can be pretty sure the animal that was
moving along here was moving fairly slowly,
245
00:21:20,647 --> 00:21:23,400
as perhaps you'd expect
if it was just plodding along,
246
00:21:23,527 --> 00:21:26,325
looking for food around the margin of a lake.
247
00:21:26,407 --> 00:21:30,082
But, in fact, although thousands
of these prints have now been found,
248
00:21:30,247 --> 00:21:33,876
not one of them has a stride
longer than 12 feet.
249
00:21:34,087 --> 00:21:39,081
So we can be pretty certain
that these animals were fairly slow-moving.
250
00:21:52,247 --> 00:21:54,886
These prints, though, are very different,
251
00:21:55,127 --> 00:21:58,085
not circular but with three prominent toes.
252
00:21:59,847 --> 00:22:05,922
At the end of each, there is a deep, sharp mark
that can only have been made by a claw.
253
00:22:06,087 --> 00:22:12,606
They match the three-toed feet of theropods,
medium-sized, carnivorous dinosaurs.
254
00:22:12,407 --> 00:22:15,717
From tracks like these,
it's been calculated that some of these hunters
255
00:22:15,807 --> 00:22:19,083
could run at up to 30 miles an hour.
256
00:22:21,567 --> 00:22:24,525
Moving at such speeds
demands a great deal of energy,
257
00:22:24,927 --> 00:22:29,079
and an animal can only produce enough
if it has a warm body.
258
00:22:29,167 --> 00:22:35,037
So did the dinosaurs get their energy
directly from the sun, as reptiles do today,
259
00:22:34,927 --> 00:22:38,886
or could they generate warmth internally,
like birds and mammals?
260
00:22:39,247 --> 00:22:42,159
That is a question of great debate.
261
00:22:44,767 --> 00:22:47,964
This is how Tyrannosaurus rex
may have moved,
262
00:22:48,407 --> 00:22:51,877
in the opinion of one of the new generation
of dinosaur interpreters,
263
00:22:52,087 --> 00:22:54,806
Robert Bakker of the Museum of Colorado.
264
00:22:54,967 --> 00:22:59,199
0K, Tyrannosaurus rex, the most
famous dinosaur, the most popular dinosaur,
265
00:22:59,287 --> 00:23:05,522
and here it is, running at 40 miles per hour,
faster than a rhino, faster than an elephant.
266
00:23:05,527 --> 00:23:08,405
This T. Rex is going faster than a lion.
267
00:23:08,407 --> 00:23:11,319
Yes, but that's your animation. How do you know?
268
00:23:11,847 --> 00:23:15,601
Because of the way the muscles were hung
on those leg bones,
269
00:23:15,687 --> 00:23:18,440
the way the calf muscles were hung on that knee,
270
00:23:18,367 --> 00:23:21,404
and the way the massive thigh muscles
were hung on that ilium.
271
00:23:21,847 --> 00:23:26,443
- But why does that prove it was warm-blooded?
- Let's look at the real one, eh?
272
00:23:28,127 --> 00:23:32,643
Could it really have reared up like that
and lifted its immense length?
273
00:23:32,927 --> 00:23:35,885
Absolutely, and more.
It could jump, it could run fast.
274
00:23:35,807 --> 00:23:40,085
This is a T. Rex, a real one, a cast,
with a bloody big knee, right?
275
00:23:40,607 --> 00:23:44,566
- But why does that make it warm-blooded?
- Actually, it's the other way around.
276
00:23:44,567 --> 00:23:49,925
Unlike the Pentagon, evolution doesn't build
more strength than the animal needs.
277
00:23:50,327 --> 00:23:56,596
This animal is immensely strong. It has a strong
knee and a bloody big drumstick of calf muscle
278
00:23:56,567 --> 00:24:01,277
to run fast, because
warm-bloodedness demands speed.
279
00:24:01,367 --> 00:24:05,485
This animal has to cruise fast
and it needs great bursts of speed
280
00:24:05,687 --> 00:24:08,997
because it has to kill more often
than a cold-blooded animal.
281
00:24:09,047 --> 00:24:13,438
There is no cold-blooded animal today
with this great strength. None.
282
00:24:13,847 --> 00:24:17,362
This is not a scaled-up lizard
or a scaled-up tortoise.
283
00:24:17,207 --> 00:24:22,600
This is an enlarged, five-ton,
meat-eating roadrunner, that's what it is.
284
00:24:23,167 --> 00:24:25,556
And like a roadrunner, it's eating frequently.
285
00:24:25,687 --> 00:24:30,203
There's another message about speed
in the skeleton, not in the legs but in the chest,
286
00:24:30,007 --> 00:24:35,365
because in the chest,
in the first three ribs, in that space,
287
00:24:35,767 --> 00:24:39,806
there is only one organ housed,
the cardiac chamber, the heart.
288
00:24:40,087 --> 00:24:44,080
And in modern cold-bloods,
the heart is very small,
289
00:24:43,927 --> 00:24:48,318
because cold-blooded animals
need only a weak cardiac organ.
290
00:24:48,727 --> 00:24:54,962
But look at this: The first rib, the second rib,
the third rib. Look how long that is.
291
00:24:54,967 --> 00:25:00,041
There was housed in these ribs,
without doubt, a gigantic heart
292
00:25:00,247 --> 00:25:07,244
designed to pump, designed to put out blood flow
at emphatically warm-blooded levels.
293
00:25:16,687 --> 00:25:22,523
So maybe we should get rid of the image
of dinosaurs as slow, lumbering plodders
294
00:25:22,647 --> 00:25:27,516
and think of them instead
as nimble and agile in spite of their size.
295
00:25:27,567 --> 00:25:29,717
(BL00D-CURDLING R0AR)
296
00:25:32,447 --> 00:25:37,601
The truth is almost certainly that some
were warm-blooded and others were not.
297
00:25:38,687 --> 00:25:43,602
A skeleton can not only give clues
about the temperature of an animal's blood,
298
00:25:43,967 --> 00:25:49,678
it can, perhaps even more surprisingly,
reveal something about the animal's social life.
299
00:25:49,727 --> 00:25:52,195
This is the skull of a hadrosaur.
300
00:25:52,127 --> 00:25:57,406
Like all hadrosaurs, it has a rounded front
to its jaws, lacking in teeth,
301
00:25:57,887 --> 00:26:00,606
which in life were probably covered with a horn,
302
00:26:00,767 --> 00:26:05,318
and which give the family as a whole
the name duck-billed dinosaurs.
303
00:26:05,087 --> 00:26:09,000
At the back there is a battery of powerful,
plant-crushing teeth.
304
00:26:09,407 --> 00:26:13,639
In fact, the skulls of all hadrosaurs
are very much the same,
305
00:26:13,727 --> 00:26:18,243
except for one feature - this, a crest.
306
00:26:18,527 --> 00:26:21,325
And this varies amazingly.
307
00:26:21,407 --> 00:26:25,286
This one is thin and forward-pointing,
308
00:26:25,247 --> 00:26:29,763
this one is long and goes right down
the front of the skull
309
00:26:30,047 --> 00:26:35,121
and this one is broad and plate-like
and sits on top of the skull.
310
00:26:35,327 --> 00:26:38,478
So these are three separate species.
311
00:26:38,687 --> 00:26:41,201
But this is almost certainly a male,
312
00:26:41,567 --> 00:26:46,721
because here's another one with very much
the same shape of crest on top of the skull,
313
00:26:46,847 --> 00:26:50,522
but slightly smaller, so it's probably a female.
314
00:26:50,687 --> 00:26:56,080
And there is a third in which the same
shape of crest is only just developing,
315
00:26:55,967 --> 00:26:57,958
so that's probably half-grown.
316
00:27:02,207 --> 00:27:08,476
So crests in hadrosaurs served to proclaim
an individual's sex, age and species.
317
00:27:08,447 --> 00:27:10,597
And since such adornments that do that
318
00:27:10,847 --> 00:27:14,965
elsewhere in the animal kingdom
are very often made more obvious with colour,
319
00:27:15,167 --> 00:27:20,036
we can speculate that the dinosaurs
were indeed quite spectacular-looking animals,
320
00:27:19,967 --> 00:27:24,677
as the character of their scaly skin
has already suggested.
321
00:27:26,687 --> 00:27:30,236
But these crests were more than visual signals.
322
00:27:32,447 --> 00:27:38,283
Inside, there are air chambers, which must have
acted as resonators when the animals bellowed.
323
00:27:40,127 --> 00:27:44,166
Since the air chambers vary in size and shape
as much as the crests,
324
00:27:43,967 --> 00:27:47,721
each species must have had
its own characteristic call.
325
00:27:47,807 --> 00:27:49,798
(GRUNTING)
326
00:28:06,047 --> 00:28:09,403
And they probably roared
in deafening choruses,
327
00:28:09,407 --> 00:28:14,162
for we know that plant-eating dinosaurs
lived in herds, as wildebeest do today.
328
00:28:14,687 --> 00:28:16,917
In Montana, deposits have been discovered
329
00:28:17,087 --> 00:28:21,683
where the bones of hadrosaurs
are piled up in vast numbers.
330
00:28:23,807 --> 00:28:27,402
Jack Horner, the researcher who discovered
the remains of the herds,
331
00:28:27,647 --> 00:28:30,923
has also found in Montana
even more extraordinary evidence
332
00:28:31,007 --> 00:28:33,157
of the social life of dinosaurs.
333
00:28:33,407 --> 00:28:35,875
He's actually found their nests and eggs,
334
00:28:36,247 --> 00:28:40,001
and he showed me where I, too,
could pick up bits of the shell.
335
00:28:40,087 --> 00:28:42,282
(ATTENBOROUGH) Is that anything?
(HORNER) Just eggshell.
336
00:28:42,487 --> 00:28:45,001
(ATTENBOROUGH) What do you mean, just?
337
00:28:44,887 --> 00:28:47,117
(ATTENBOROUGH) Really?
(HORNER) Well...
338
00:28:47,287 --> 00:28:52,964
...when we're looking for a nest,
what we want to see is... Eggshell is important.
339
00:28:53,527 --> 00:28:56,917
- Is it always black?
- Yep.
340
00:28:56,887 --> 00:28:59,606
In this formation it's always black.
341
00:28:59,767 --> 00:29:01,997
In other formations it can be other colours.
342
00:29:02,167 --> 00:29:05,876
If the piece is big enough,
you can see the texture of the egg
343
00:29:06,007 --> 00:29:08,680
and then, with a microscope,
you can see the pores.
344
00:29:09,007 --> 00:29:11,521
Is this the sort of size you get normally?
345
00:29:11,407 --> 00:29:16,083
Well, in a nest where there's babies,
the eggshell will be really tiny
346
00:29:16,527 --> 00:29:19,803
because the babies were in the nest,
they trampled the eggs
347
00:29:19,887 --> 00:29:23,084
and so it gets broken up quite bad.
348
00:29:23,247 --> 00:29:28,002
But if we find a nest that was deserted
after the eggs had been laid,
349
00:29:28,207 --> 00:29:30,198
then we'll find big pieces.
350
00:29:30,927 --> 00:29:34,966
Jack has even discovered
complete clutches of unhatched eggs
351
00:29:35,247 --> 00:29:37,124
which he's taken back to his lab.
352
00:29:38,927 --> 00:29:43,557
Now this nest is actually upside down, isn't it,
because that's the top of the jacket.
353
00:29:43,727 --> 00:29:46,400
And so these are the eggs?
354
00:29:46,607 --> 00:29:48,598
These are the eggs, yeah.
355
00:29:48,527 --> 00:29:51,837
This is the centre egg in the nest.
356
00:29:51,887 --> 00:29:55,118
The centre egg is always laid upright
357
00:29:55,647 --> 00:30:00,402
and then each egg out from the centre
becomes more and more inclined.
358
00:30:00,447 --> 00:30:03,200
- They were laid spirally?
- Spiral, uh-huh.
359
00:30:03,527 --> 00:30:06,519
- This was the first?
- That was the first, I assume.
360
00:30:06,607 --> 00:30:09,440
- Are they loose?
- Yes, this one's loose.
361
00:30:09,607 --> 00:30:15,955
You can see the pointed end of the egg,
and the top of the egg has been smushed down.
362
00:30:15,847 --> 00:30:20,204
- And is there shell on there?
- Yeah, this is all shell.
363
00:30:20,647 --> 00:30:23,719
This whole nest, presumably,
was deserted by the parents.
364
00:30:24,007 --> 00:30:25,998
Apparently so, yeah.
365
00:30:25,927 --> 00:30:28,646
- Do you think there's anything in that?
- Yes.
366
00:30:28,967 --> 00:30:32,403
- I don't think there is, I know.
- How do you know?
367
00:30:32,327 --> 00:30:38,197
They've been x-rayed and CAT-scanned,
and there are indications of little ones in there.
368
00:30:38,567 --> 00:30:43,846
How can you wait? Why don't you
hit it with a spoon and take it out?
369
00:30:43,847 --> 00:30:48,284
I would like to do that.
My preparators tell me I'm not supposed to.
370
00:30:48,647 --> 00:30:52,925
- Have you got an opened egg?
- Yes, we have one from another nest.
371
00:30:54,967 --> 00:30:58,437
- This was a clutch of nineteen eggs.
- Nineteen?
372
00:30:58,807 --> 00:31:03,676
Nineteen, and all nineteen have embryos.
This is one of the better ones.
373
00:31:04,327 --> 00:31:08,479
What you see here is the thigh-bone, the femur,
374
00:31:08,647 --> 00:31:14,836
the tibia and then the ankle joint
with the foot underneath.
375
00:31:14,847 --> 00:31:16,838
Very carefully open it up.
376
00:31:18,087 --> 00:31:22,239
- And what can we see there?
- What we're looking at is the right leg.
377
00:31:22,127 --> 00:31:24,118
There's the left leg, the tibia.
378
00:31:24,527 --> 00:31:27,678
And then between the knees is the skull,
379
00:31:27,887 --> 00:31:30,003
sitting right in here.
380
00:31:30,207 --> 00:31:34,405
So we can see that tiny little teeth
had erupted in the jaw.
381
00:31:34,447 --> 00:31:37,837
(ATTENBOROUGH) So it could give you a nip
as soon as it hatched,
382
00:31:37,807 --> 00:31:41,595
just like young alligators can today.
383
00:31:42,047 --> 00:31:45,119
What about individual bones,
do you ever get them out?
384
00:31:45,407 --> 00:31:46,886
Yeah.
385
00:31:46,847 --> 00:31:52,444
One of the eggs I took completely apart
and just took out this.
386
00:31:53,967 --> 00:32:00,600
It's a humerus, the upper arm-bone
of the embryo.
387
00:32:01,167 --> 00:32:07,003
Just for comparison,
so you get some idea of what it looks like,
388
00:32:06,927 --> 00:32:09,236
here's a sub-adult.
389
00:32:09,327 --> 00:32:14,321
- So you can see, it had a little growing to do.
- Beautiful.
390
00:32:15,607 --> 00:32:17,882
The bones of young a few weeks old
391
00:32:18,007 --> 00:32:21,283
also reveal a great deal
about the hadrosaur's habits.
392
00:32:21,367 --> 00:32:25,645
They are found inside the nest,
implying that the young stayed there.
393
00:32:25,927 --> 00:32:30,364
That means their parents must have
brought back food to the nest to feed them,
394
00:32:30,247 --> 00:32:35,844
and there's confirmation of that in their teeth,
which are already slightly worn.
395
00:32:39,847 --> 00:32:43,886
The hadrosaurs flourished
around 75 million years ago.
396
00:32:44,167 --> 00:32:47,796
In Montana, the climate was much warmer
than it is there today,
397
00:32:48,007 --> 00:32:51,363
and there were swamps fringing an inland sea.
398
00:32:52,807 --> 00:32:56,083
The dinosaurs had reached
the pinnacle of their evolution
399
00:32:56,167 --> 00:32:58,727
and many different kinds
lumbered through the swamps
400
00:32:59,047 --> 00:33:03,916
which, then as now, were also the home
of many other reptiles and birds.
401
00:33:21,887 --> 00:33:28,838
But 64 million years ago, the hadrosaurs
and all the other dinosaurs vanished.
402
00:33:29,687 --> 00:33:33,441
The reign of the dinosaurs had ended.
403
00:33:40,407 --> 00:33:43,717
There are many theories as to why
the dinosaurs finally became extinct.
404
00:33:44,247 --> 00:33:48,126
One of the most recent
is that an asteroid collided with the earth,
405
00:33:48,087 --> 00:33:50,282
creating such an immense explosion on impact
406
00:33:50,487 --> 00:33:54,116
that the skies filled with dust,
blotting out the sun.
407
00:33:54,327 --> 00:33:56,477
In the darkness, the plants all died,
408
00:33:56,727 --> 00:34:00,083
and the dinosaurs,
with nothing to eat, starved to death.
409
00:34:00,087 --> 00:34:02,760
There are two problems
with that or any other theory
410
00:34:02,967 --> 00:34:06,562
which depends upon a single
catastrophe as the explanation.
411
00:34:06,807 --> 00:34:10,766
The first is that the dinosaurs
didn't die out in a year or a decade
412
00:34:10,647 --> 00:34:12,797
but over thousands of years.
413
00:34:13,047 --> 00:34:17,563
The second is that, although the dinosaurs
died out, many other creatures didn't.
414
00:34:21,727 --> 00:34:25,720
These alligators are reptiles,
just as the dinosaurs were.
415
00:34:25,567 --> 00:34:30,436
They evolved on earth long before the
dinosaurs, yet they've survived to the present.
416
00:34:30,847 --> 00:34:34,635
It seems unlikely that they would have
lived through a sudden global catastrophe
417
00:34:34,527 --> 00:34:36,836
in which the dinosaurs perished.
418
00:34:40,807 --> 00:34:46,325
A more likely explanation, to my mind,
is a gradual change in the earth's climate.
419
00:34:46,567 --> 00:34:51,846
Some animals, birds, for example, were better
able to cope with this than the dinosaurs,
420
00:34:52,047 --> 00:34:55,722
with their less-than-perfect control
over their body temperature.
421
00:34:57,527 --> 00:34:59,836
The early birds, like birds today,
422
00:34:59,927 --> 00:35:03,920
were protected by their superbly efficient
insulating coats of feathers,
423
00:35:04,247 --> 00:35:05,760
so they survived.
424
00:35:09,727 --> 00:35:14,278
Small reptiles were able to take refuge
against the cold in nooks and crannies,
425
00:35:14,447 --> 00:35:19,646
and reptiles that lived in water were cushioned
against extreme temperature changes.
426
00:35:23,167 --> 00:35:29,037
So the earth still retains representatives
from all these animal groups.
427
00:35:30,487 --> 00:35:33,524
But for me, the most exciting thing
about the dinosaurs
428
00:35:33,367 --> 00:35:35,756
is not how they died, but how they lived.
429
00:35:36,247 --> 00:35:40,286
Their dynasty, after all,
lasted for nearly 200 million years,
430
00:35:40,567 --> 00:35:44,845
compared with a mere two or three million years
that human beings have been on earth.
431
00:35:44,887 --> 00:35:47,560
When the hadrosaurs
were at the height of their success,
432
00:35:47,767 --> 00:35:52,397
much of North America
was covered with swamps very like these.
433
00:35:54,967 --> 00:35:57,606
In the 64 million years since then,
434
00:35:57,847 --> 00:36:00,680
the shallow seas that covered
much of North America
435
00:36:01,207 --> 00:36:04,199
drained away from the margins of the continent.
436
00:36:04,087 --> 00:36:07,477
Rivers deposited layers of mud
over the fallen trees
437
00:36:07,927 --> 00:36:11,761
and finally the swamps became dry land.
438
00:36:15,127 --> 00:36:22,124
This is the richest dinosaur graveyard
in the world, Drumheller in Alberta, Canada.
439
00:36:27,927 --> 00:36:33,843
This light-coloured rock is composed of sand
that was laid down in a river channel.
440
00:36:34,167 --> 00:36:37,079
The dark layer at the top is the remains of mud
441
00:36:37,047 --> 00:36:40,437
deposited when the whole area
was submerged in a flood.
442
00:36:40,647 --> 00:36:43,445
It's in between these layers
in these particular cliffs
443
00:36:43,527 --> 00:36:47,236
that dinosaur bones are most commonly found.
444
00:36:56,047 --> 00:37:00,882
Almost 500 skeletons of 50 different species
have come from these cliffs,
445
00:37:00,847 --> 00:37:04,635
the remains of a whole community of dinosaurs.
446
00:37:08,047 --> 00:37:11,278
And here, too,
in the Tyrrell Museum of Palaeontology
447
00:37:11,247 --> 00:37:16,526
more of them have been reconstructed and
displayed than anywhere else in the world.
448
00:37:22,567 --> 00:37:25,320
They daily astonish thousands of visitors,
449
00:37:25,447 --> 00:37:28,086
who come both to marvel at the bones
450
00:37:28,327 --> 00:37:33,321
and to learn about the vanished lives
of these spectacular animals.
451
00:37:46,527 --> 00:37:53,797
So today, less than 200 years since
we discovered that these animals even existed,
452
00:37:54,207 --> 00:37:59,600
we've learnt so much about them that we
can almost hear the champ of these huge jaws,
453
00:37:59,487 --> 00:38:04,083
visualise the glint in the eye
that once revolved in this empty socket,
454
00:38:04,287 --> 00:38:09,122
clothe this immense skeleton
with leathery skin and muscles
455
00:38:09,567 --> 00:38:15,324
and picture in our imaginations in almost
as much detail as if they were alive today
456
00:38:15,247 --> 00:38:19,798
these bellowing, battling, browsing,
457
00:38:20,047 --> 00:38:24,006
nesting, courting, scavenging, fighting creatures
458
00:38:24,367 --> 00:38:26,358
that disappeared from the earth
459
00:38:26,287 --> 00:38:30,883
over 50 million years
before mankind appeared upon it.