1
00:00:15,265 --> 00:00:19,003
We human beings are very
latecomers to the skies,

2
00:00:19,291 --> 00:00:22,647
and although we might think that
we now pretty good at this,

3
00:00:22,774 --> 00:00:27,479
the Natural World, with the help of
several million years of evolution,

4
00:00:27,894 --> 00:00:33,966
has produce a dazzling range of
aeronauts whose talents are far beyond our.

5
00:00:36,172 --> 00:00:41,318
The story of how animals manage to
colonise the air is truly astonishing.

6
00:00:42,626 --> 00:00:45,148
First into the skies were Insects,

7
00:00:45,742 --> 00:00:48,068
they initially had
two pairs of wings

8
00:00:48,149 --> 00:00:52,290
which in due course were modified
in many different ways.

9
00:00:53,976 --> 00:00:58,465
But after having had the skies for
themselves for about 100 million years,

10
00:00:58,607 --> 00:01:01,837
a new group of animals
took to the air,

11
00:01:01,871 --> 00:01:04,874
Vertebrates.
creatures with backbones.

12
00:01:08,992 --> 00:01:13,878
They faced a different challenge, for their
bodies were much bigger and heavier.

13
00:01:15,700 --> 00:01:20,468
But eventually they evolve several
ways of solving that problem.

14
00:01:22,466 --> 00:01:25,516
We will travel the globe
to trace the details

15
00:01:25,551 --> 00:01:30,527
of the extraordinary skills
of the backbone flyers.

16
00:01:33,277 --> 00:01:37,405
English: Bobiko

17
00:01:40,522 --> 00:01:50,968
~ Conquest Of The Skies ~

18
00:01:55,755 --> 00:02:00,738
- RIVALS -

19
00:02:01,323 --> 00:02:03,500
This is Borneo.

20
00:02:04,259 --> 00:02:08,130
And here there are still great
tracks of pristine rainforest.

21
00:02:08,987 --> 00:02:13,081
Forest that is wonderfully rich
in animals of all kinds.

22
00:02:16,289 --> 00:02:19,620
I'm being winch up into
one of the tallest trees here,

23
00:02:20,684 --> 00:02:23,058
in search of a creature
that can give us a hint

24
00:02:23,175 --> 00:02:27,114
of how backbone animals
first took to the air.

25
00:02:41,037 --> 00:02:46,123
Hidden among these leafs of this fern,
high up here in the canopy,

26
00:02:47,101 --> 00:02:51,044
is a very remarkable little frog.

27
00:02:53,330 --> 00:02:58,085
It's a Harlequin Tree Frog,
and it a very-very good climber.

28
00:02:58,527 --> 00:03:03,345
It spend most of its life up here,
clumping around in the branches.

29
00:03:05,402 --> 00:03:08,447
Here it's away from the
numerous predators there are,

30
00:03:08,506 --> 00:03:11,611
that might attack it
down on the forest floor.

31
00:03:12,913 --> 00:03:17,592
But if in fact, a predator were
able to get up here, to hunt it,

32
00:03:18,006 --> 00:03:24,480
a snake perhaps, well, the Tree Frog
has a remarkable trick for defense.

33
00:03:36,908 --> 00:03:39,323
It glides.

34
00:03:39,902 --> 00:03:43,008
It has membranes between
greater elongated toes,

35
00:03:43,194 --> 00:03:47,287
so that each foot becomes a parachute
which slow the frog descent,

36
00:03:47,703 --> 00:03:51,590
and so enable it to make
a relatively safe landing.

37
00:03:58,388 --> 00:04:04,042
The Vertebrates made their first forage
into the air around 260 million years ago,

38
00:04:04,414 --> 00:04:08,827
and it very likely that some of these
pioneers use skinny membranes

39
00:04:08,999 --> 00:04:13,745
to control their falls in much the
same way as this little frog does.

40
00:04:20,914 --> 00:04:24,294
It has to be said that is not a
very good aerial navigator,

41
00:04:24,532 --> 00:04:28,138
it seems that it just jumps
and hopes for the best.

42
00:04:28,674 --> 00:04:32,777
But there are animals up here,
that glide around from tree to tree,

43
00:04:33,048 --> 00:04:35,820
which are very good
navigators indeed,

44
00:04:35,903 --> 00:04:39,845
so good in fact, that they can
go from one tree to another

45
00:04:39,983 --> 00:04:44,019
and never go down to the
ground in their entire life.

46
00:04:49,671 --> 00:04:53,073
One of them is a
little lizard called Draco.

47
00:04:56,815 --> 00:04:59,471
Each male has his own little
territory in the branches,

48
00:04:59,637 --> 00:05:05,624
and tries to attract females and
warn off rivals by flashing his dewlap.

49
00:05:15,090 --> 00:05:18,536
He also spread colored
flaps of skin from his flanks,

50
00:05:18,704 --> 00:05:22,753
that when fully extended do
more or less the same thing.

51
00:05:27,634 --> 00:05:30,734
But there are predators
among the branches.

52
00:05:32,239 --> 00:05:36,960
Snakes also live up here,
and they hunt Lizards.

53
00:06:08,165 --> 00:06:11,809
But Draco side flaps now
serve another purpose.

54
00:06:16,506 --> 00:06:21,714
He uses them to glide by hinging
forward a specially elongated ribs.

55
00:06:24,161 --> 00:06:27,257
And he so skilled in the air
that he can steer land

56
00:06:27,416 --> 00:06:30,206
on the trunk of his choice.

57
00:06:42,982 --> 00:06:46,882
So, if you live up in the
branches it's less laborious,

58
00:06:46,962 --> 00:06:51,869
and indeed, safer to travel by air,
than to come down to the ground.

59
00:06:52,602 --> 00:06:56,398
But if you want to be a true flyer,
you have to be able to fly

60
00:06:56,451 --> 00:07:01,731
not only downwards but upwards,
you have to have powered flight.

61
00:07:18,116 --> 00:07:21,662
This is another reptile,

62
00:07:21,812 --> 00:07:26,534
and one with even greater flying
abilities than that little gliding lizard.

63
00:07:31,545 --> 00:07:35,508
Today, sadly, it's extinct.

64
00:07:48,751 --> 00:07:53,621
This is Dimorphodon,
we can deduce from its fossils

65
00:07:53,851 --> 00:07:57,744
that he had the muscles
needed to beat its wings.

66
00:07:58,870 --> 00:08:02,540
And computer imagery can show us
what he must was look like.

67
00:08:22,103 --> 00:08:27,122
Dimorphodon was one of the first
large animals ever to travel by air,

68
00:08:27,157 --> 00:08:30,124
200 million years ago.

69
00:08:30,565 --> 00:08:35,630
It belong to a group called the Pterosaurs,
The Winged Reptiles.

70
00:08:39,292 --> 00:08:44,536
It was probably a forest dweller and
it descendant of a tree living glider.

71
00:08:48,880 --> 00:08:53,472
This gliding ancestor might
have had wings like those of Draco,

72
00:08:53,600 --> 00:08:58,761
that was made of skin, and perhaps
extended from its fingers down to its ankles.

73
00:09:00,452 --> 00:09:05,724
But Pterosaurs have evolved larger wings
with a hugely elongated fourth finger.

74
00:09:07,107 --> 00:09:12,496
The wing membrane was strengthen
internally by thin rods of a stiffer tissue.

75
00:09:12,932 --> 00:09:18,380
They were muscles fibers too, that enable
it to modified its contours as it flew.

76
00:09:20,382 --> 00:09:25,119
Looking at the wings insection
revealed a secret of their efficiency.

77
00:09:25,544 --> 00:09:28,912
They have a rounded front edge
and a sharp back edge,

78
00:09:28,996 --> 00:09:32,041
a shape known as an aerofoil.

79
00:09:34,539 --> 00:09:38,842
It's works by forcing the air flowing
above the wing, to speed up.

80
00:09:39,219 --> 00:09:45,535
This faster air has a lower pressure,
and the wing is suck upwards.

81
00:09:46,507 --> 00:09:51,129
The larger the surface area of the wing,
the greater lift it can produce.

82
00:09:54,889 --> 00:09:59,315
So, it seem certain that Pterosaurs
were very competent flyers.

83
00:09:59,751 --> 00:10:02,077
And judging from their teeth,
it's seem likely

84
00:10:02,130 --> 00:10:04,596
that many fed on the
great variety of Insects

85
00:10:04,644 --> 00:10:08,033
that had preceded
them into the air.

86
00:10:09,209 --> 00:10:14,523
Insects have had the skies to themselves
for around 100 million years.

87
00:10:14,808 --> 00:10:17,428
Now, bigger creatures had arrived.

88
00:10:17,491 --> 00:10:20,309
Reptiles.

89
00:10:24,700 --> 00:10:28,034
The Pterosaurs design for flight
proved hugely successful,

90
00:10:28,087 --> 00:10:33,525
and before long they had spread out
of the forest into new environments.

91
00:10:34,032 --> 00:10:37,132
And some became monstrous.

92
00:10:49,334 --> 00:10:54,879
The first large animals to fly
were winged reptiles. Pterosaurs.

93
00:10:55,643 --> 00:10:59,950
They appeared in forests
around 220 million years ago.

94
00:11:00,957 --> 00:11:04,980
As they became more successful,
they ventured into more open countries

95
00:11:05,087 --> 00:11:07,634
and spread around the world.

96
00:11:09,571 --> 00:11:12,762
A great number of them
lived and fed near water.

97
00:11:13,848 --> 00:11:16,029
We know this because
fossils of many species

98
00:11:16,108 --> 00:11:21,529
occur in rocks that was once mud
at the bottom of lakes and shallow seas.

99
00:11:23,270 --> 00:11:28,307
This one shows the skeleton of little
animal that 150 million years ago

100
00:11:28,376 --> 00:11:32,095
fell to the bottom
of a shallow lagoon.

101
00:11:32,802 --> 00:11:39,597
This is its head, here is
its backbone, tail, hind legs,

102
00:11:40,427 --> 00:11:47,250
and here stretching from these long
extended finger bones are its wings.

103
00:11:47,594 --> 00:11:50,011
And this fossil is
particularly remarkable,

104
00:11:50,432 --> 00:11:54,415
because it show an impression of the
membrane in extraordinary detail.

105
00:11:54,499 --> 00:11:58,108
You can see every
little tiny fold.

106
00:11:59,001 --> 00:12:02,809
You can judge how an
animal lived by its skull.

107
00:12:03,346 --> 00:12:06,431
And this one,
have these long jaws,

108
00:12:07,106 --> 00:12:11,452
with forward pointing teeth,
and we think that this indicates

109
00:12:11,489 --> 00:12:15,192
that it lived by skimming
across the surface of the lagoon,

110
00:12:15,309 --> 00:12:20,284
and snatching up fish
with impaled on those teeth.

111
00:12:25,427 --> 00:12:29,464
The Pterosaurs diversified into
a huge variety of forms.

112
00:12:31,975 --> 00:12:35,397
Many seem to been particularly
skilled at soaring and gliding

113
00:12:35,461 --> 00:12:38,704
over the oceans,
looking for fish.

114
00:12:39,094 --> 00:12:42,868
Some developed huge head crests
that were probably colored

115
00:12:42,921 --> 00:12:46,366
and use for display
during courtship.

116
00:12:48,220 --> 00:12:51,500
And a few became very big indeed.

117
00:12:53,559 --> 00:12:59,010
This species had a wingspan
of over 20 feet, 7 meters.

118
00:13:03,050 --> 00:13:06,983
But not all Pterosaurs lived
in the forests or near water.

119
00:13:07,564 --> 00:13:10,962
An open arid landscape like
this one, was the likely home

120
00:13:10,989 --> 00:13:14,135
of one of the most extraordinary.

121
00:13:14,904 --> 00:13:18,906
Around 70 million years ago
a pterosaur appeared

122
00:13:18,976 --> 00:13:23,144
that was of truly
colossal proportions.

123
00:13:48,505 --> 00:13:51,700
That was one of the largest
creatures that had ever flown,

124
00:13:51,749 --> 00:13:58,367
it was in the size of a small aeroplane,
and it was called Quetzalcoatlus.

125
00:14:06,485 --> 00:14:10,334
Its immense wingspan allowed it
to ride on the currents of warm air

126
00:14:10,382 --> 00:14:13,234
that rise up from
sun heated land.

127
00:14:14,585 --> 00:14:18,706
It could then glide great
distances, searching for food.

128
00:14:22,479 --> 00:14:26,636
Small creatures like lizards, or the
dead bodies of much larger ones,

129
00:14:26,743 --> 00:14:29,721
Dinosaurs.

130
00:14:45,311 --> 00:14:48,289
But the Pterosaurs, with their
wings of toughen skin

131
00:14:48,336 --> 00:14:53,440
weren't the only group of reptiles
to make it into those ancient skies.

132
00:14:53,744 --> 00:14:59,093
About 150 million years ago,
another reptilian group appeared

133
00:14:59,124 --> 00:15:02,347
on the Planet that also flew.

134
00:15:05,829 --> 00:15:08,538
Like most reptiles,
including Pterosaurs,

135
00:15:08,571 --> 00:15:12,612
these creatures began
their lives inside an egg.

136
00:15:20,508 --> 00:15:24,945
But they had evolved a
revolutionary new design for flight.

137
00:15:25,312 --> 00:15:30,211
One that would usher in a remarkable
fresh chapter in our story.

138
00:15:32,552 --> 00:15:36,930
And unlike the Pterosaurs,
they still with us today.

139
00:15:48,785 --> 00:15:51,852
There are of course the Birds.

140
00:15:59,945 --> 00:16:04,204
Some today can provide clues
about how their ancestors

141
00:16:04,369 --> 00:16:07,396
manage to get into the air.

142
00:16:12,487 --> 00:16:16,044
This is the chick of a bird found
in farmyards everywhere.

143
00:16:18,293 --> 00:16:20,872
A Bantam Hen.

144
00:16:33,873 --> 00:16:38,988
And at this very early stage in its life,
it can show us something very interesting

145
00:16:39,169 --> 00:16:43,505
about the origin of that crucial
piece of flying equipment.

146
00:16:44,227 --> 00:16:47,029
A feather.

147
00:16:47,691 --> 00:16:52,933
Its feathers are downy, that to say
they made up of simple filaments,

148
00:16:52,970 --> 00:16:57,634
and their function is not for flight,
but insulation,

149
00:16:57,723 --> 00:17:00,320
to keep this little
creature warm.

150
00:17:00,384 --> 00:17:04,528
And back in the Jurassic period,
long before the arrival of True Birds,

151
00:17:04,576 --> 00:17:09,526
very similar looking feathers appeared
on very different animals.

152
00:17:09,574 --> 00:17:14,047
Reptiles.
Dinosaurs if to be precise.

153
00:17:17,069 --> 00:17:19,739
To find evidence for that
astonishing statement,

154
00:17:19,831 --> 00:17:22,461
which not so long ago
was highly controversial,

155
00:17:22,541 --> 00:17:25,651
we heading for China.

156
00:17:29,070 --> 00:17:32,737
And here, I was able to see
the evidence for myself.

157
00:17:33,074 --> 00:17:36,354
Some truly sensational fossils.

158
00:17:55,340 --> 00:17:59,524
Northeast of China Great Wall,
near the borders of Mongolia,

159
00:17:59,631 --> 00:18:03,044
lies the chilly province of Liaoning.

160
00:18:04,920 --> 00:18:08,345
Here, there are great areas of
rocks that was lay down as mud

161
00:18:08,398 --> 00:18:12,073
in the bottom of immense
fresh water lakes.

162
00:18:14,833 --> 00:18:17,744
The bodies of animals that was
swept down into these lakes

163
00:18:17,797 --> 00:18:21,593
was slowly entombed
by the fine grains sediment

164
00:18:21,652 --> 00:18:26,244
that preserved them entire
and in exquisite detail.

165
00:18:28,474 --> 00:18:31,202
And from these rocks
have come specimens

166
00:18:31,250 --> 00:18:35,796
that solve one of the most hotly
debated of evolutionary arguments.

167
00:18:35,863 --> 00:18:38,976
The origin of the Birds.

168
00:18:41,639 --> 00:18:43,547
The key specimens are
now in Beijing,

169
00:18:43,616 --> 00:18:47,769
where they been delicately
prepared under the microscope.

170
00:18:51,044 --> 00:18:55,233
They have been studied here by one
of the world greatest Dinosaurs experts,

171
00:18:55,308 --> 00:18:58,189
professor Xing Xu.

172
00:18:59,561 --> 00:19:02,436
First, he showed me one
of his oldest specimens,

173
00:19:02,475 --> 00:19:05,676
part of a Dinosaur arm.

174
00:19:06,389 --> 00:19:09,351
But thanks to the finest of the
mud of those ancient lakes,

175
00:19:09,414 --> 00:19:12,715
there is more here
than just bones.

176
00:19:13,038 --> 00:19:16,682
You see here, this species
it called a Beipiaosaurus,

177
00:19:16,720 --> 00:19:20,486
So, because this is a very
not like us, two or three meters long,

178
00:19:20,519 --> 00:19:23,630
so quite a big animal.
And here is an arm,

179
00:19:23,656 --> 00:19:26,596
hand, you see here...

180
00:19:27,358 --> 00:19:31,689
dark filamentous structures...
-yes.

181
00:19:31,742 --> 00:19:36,915
along that arms and hand,
they are actually primitive feathers.

182
00:19:37,265 --> 00:19:40,895
And those feathers very simple,
very simple,

183
00:19:42,175 --> 00:19:48,872
so we believed they represent the very
primitive stage for feather evolution.

184
00:19:49,718 --> 00:19:52,614
These simple strands were
made of the same material

185
00:19:52,649 --> 00:19:55,354
as the feathers of today Birds.

186
00:19:55,402 --> 00:19:58,709
They were relatively thick
and must have been quite stiff,

187
00:19:58,725 --> 00:20:02,992
so they would of stuck out
beyond the dinosaur arm.

188
00:20:03,534 --> 00:20:06,958
Behind them, were shorter strands
that covered its all body.

189
00:20:07,602 --> 00:20:11,462
Like the down on the chick,
these might have kept the dinosaur warm.

190
00:20:11,924 --> 00:20:15,808
But those long strands most
likely had a different function.

191
00:20:17,867 --> 00:20:20,233
Clues to what that might
have been can be found

192
00:20:20,268 --> 00:20:23,500
on an even more
extraordinary fossil.

193
00:20:24,254 --> 00:20:29,031
These claws and finger bones belong
to a creature called Caudipteryx.

194
00:20:31,527 --> 00:20:35,500
The long dark shapes around them
are the remains of feathers.

195
00:20:37,518 --> 00:20:40,290
The single strands are here
rather more complex.

196
00:20:42,292 --> 00:20:47,575
They had barbs, thin filaments
attached to either side of a central rod.

197
00:20:47,978 --> 00:20:50,837
This look more like a bird feather.

198
00:20:51,317 --> 00:20:55,827
Caudipteryx had around 26
of them along each arm.

199
00:20:57,396 --> 00:21:01,427
This may look like a wing,
but the feathers were not very long.

200
00:21:03,825 --> 00:21:06,659
And when you compare them
to the size of this creature body,

201
00:21:06,717 --> 00:21:09,711
and its long legs,
it's clear

202
00:21:09,773 --> 00:21:13,437
that they weren't big enough
to enable Caudipteryx to fly.

203
00:21:15,011 --> 00:21:17,516
So, what were these feathers for?

204
00:21:19,009 --> 00:21:24,072
Microscopic examination has revealed
that they were colored and patent.

205
00:21:24,720 --> 00:21:26,949
So, maybe they were
used for display,

206
00:21:27,006 --> 00:21:31,075
perhaps to wave around during
courtship to attract a mate.

207
00:21:33,008 --> 00:21:37,993
But then is seems that they also
helped the dinosaur in a different way.

208
00:21:40,796 --> 00:21:43,033
We can find a hint of how
they might have done this,

209
00:21:43,054 --> 00:21:47,596
by watching the way some young
birds use their first feathers today.

210
00:21:51,822 --> 00:21:55,082
These are tender old
Pheasant chicks.

211
00:21:55,829 --> 00:21:58,181
Their feathers are not
yet fully developed.

212
00:22:01,405 --> 00:22:06,362
At this stage they are similar in structure to
the feathers on that dinosaur, Caudipteryx,

213
00:22:06,389 --> 00:22:10,399
and going aline along each
arm in much the same way.

214
00:22:13,930 --> 00:22:18,425
But these early feathers are also too
short to enable these creatures to fly.

215
00:22:19,629 --> 00:22:22,284
Nevertheless they very helpful.

216
00:22:23,048 --> 00:22:25,220
Pheasant chicks has to
nest on the ground,

217
00:22:25,298 --> 00:22:29,899
but they soon need to roost high up,
where they are be safe from predators.

218
00:22:38,192 --> 00:22:42,381
Flapping these simple wings
gives the chicks a little extra lift

219
00:22:42,444 --> 00:22:45,679
to help them climb into a tree.

220
00:22:57,112 --> 00:22:59,732
And when the time comes
to return to the ground,

221
00:22:59,802 --> 00:23:03,568
those first feathers
again are a help.

222
00:23:09,073 --> 00:23:11,587
They don't provide a large
air-catching surface,

223
00:23:11,614 --> 00:23:14,760
but they are enough to slow a chick's fall,

224
00:23:14,834 --> 00:23:18,773
and make that landing
just a little softer.

225
00:23:23,102 --> 00:23:26,436
Maybe the feathers that had
initially kept the Dinosaurs warm,

226
00:23:26,511 --> 00:23:29,650
now also help them
to get into the air.

227
00:23:34,158 --> 00:23:36,264
And then,
only a few years ago,

228
00:23:36,280 --> 00:23:41,154
the mudstone of Liaoning produce
yet another extraordinary fossil.

229
00:23:56,132 --> 00:24:02,573
It has been named Microraptor, and it is clearly a small dinosaur.

230
00:24:02,957 --> 00:24:09,499
But this specimen it particularly
exciting, because of its feathers.

231
00:24:10,234 --> 00:24:12,736
Feathers on the forearm there.

232
00:24:12,752 --> 00:24:16,305
Feathers on its hind limbs.

233
00:24:16,339 --> 00:24:21,791
And even feathers right at
the end of its very long tail.

234
00:24:22,177 --> 00:24:24,702
But there is something that
makes these feathers

235
00:24:24,750 --> 00:24:29,440
different from any other feathers
you seen on Dinosaurs before.

236
00:24:30,477 --> 00:24:35,119
They are narrower on one side
of the quill than on the other.

237
00:24:35,183 --> 00:24:38,071
Just like bird feathers.

238
00:24:40,241 --> 00:24:45,873
Microscopic structures within them suggest
that they had flashes of iridescence.

239
00:24:46,836 --> 00:24:50,391
So, these feathers were
probably use for display.

240
00:24:50,740 --> 00:24:55,096
But their asymmetric shape is
characteristic of flight feathers.

241
00:25:02,303 --> 00:25:07,259
The air flowing over the narrow
front of the feather can produce lift.

242
00:25:23,242 --> 00:25:29,409
So, could this strange looking dinosaur
with feathers all over it actually fly?

243
00:25:35,308 --> 00:25:38,379
Some people think that those
feathers on its hind legs

244
00:25:38,431 --> 00:25:42,006
would have made it rather difficult
for it to walk around on the ground,

245
00:25:42,059 --> 00:25:45,207
and that it would had been
more at home climbing.

246
00:25:56,568 --> 00:25:58,748
And those claws on the
fingers and toes

247
00:25:58,808 --> 00:26:03,399
are obviously very helpful
in climbing up tree trunks.

248
00:26:14,050 --> 00:26:17,725
But those aerodynamically shape
feathers certainly suggest

249
00:26:17,806 --> 00:26:21,923
that its arms were
been used as wings.

250
00:26:29,290 --> 00:26:33,443
This four wing dinosaur must had
been a really extraordinary animal.

251
00:26:33,992 --> 00:26:37,693
Its front wings were broad
enough to enable it to glide,

252
00:26:38,120 --> 00:26:41,869
and its muscles on the chest
were sufficiently strong

253
00:26:41,922 --> 00:26:44,807
to enable it to flap
every now and then,

254
00:26:44,865 --> 00:26:47,310
and help it on its way.

255
00:26:47,467 --> 00:26:52,054
But the wings on the hind legs
were probably not held spread out,

256
00:26:52,124 --> 00:26:56,210
but kept beneath the body
to help the animal to steer.

257
00:27:01,548 --> 00:27:04,684
Now, clearly, these Dinosaurs
were on their way

258
00:27:04,705 --> 00:27:08,254
to joined the Pterosaurs
in the sky.

259
00:27:13,264 --> 00:27:19,922
And then, around 130 million years
ago the True Birds appeared.

260
00:27:21,726 --> 00:27:25,215
And here, on the Lochs in Scotland
are some of the most majestic

261
00:27:25,242 --> 00:27:28,019
of those little around today.

262
00:27:28,687 --> 00:27:31,631
Whooper Swans.

263
00:27:39,006 --> 00:27:42,389
These particular birds were
in contact with human beings

264
00:27:42,448 --> 00:27:44,580
from the very first moment
of their hatch,

265
00:27:44,644 --> 00:27:48,081
so they allow me to get
really close to them.

266
00:27:52,072 --> 00:27:55,966
The small feathers on their bodies are still
essential for keeping their owners warm.

267
00:27:57,004 --> 00:27:59,702
But this one is a wing feather.

268
00:27:59,940 --> 00:28:02,714
It extremely strong,
but very light,

269
00:28:02,758 --> 00:28:07,294
and the filaments on either
side of the quill and the barbs,

270
00:28:07,395 --> 00:28:13,451
zip together to form a continues surface
which will strong enough to hold the air.

271
00:28:14,148 --> 00:28:19,032
But if the air is to support
a wing bird as it flies,

272
00:28:19,091 --> 00:28:22,698
it has to move over
the wing very fast.

273
00:28:23,069 --> 00:28:27,958
And in order for that to happen,
these Swans will move at speed

274
00:28:27,994 --> 00:28:33,193
across the surface of the water like
an aircraft taxiing before take-off.

275
00:29:28,989 --> 00:29:31,692
When you close up to
a flying bird like this,

276
00:29:31,745 --> 00:29:37,074
you can see how a wonderful piece of
complex engineering their wings are,

277
00:29:37,123 --> 00:29:40,723
able to change their shape
and their beat

278
00:29:40,758 --> 00:29:46,438
to respond to every little change in
the currents of the air around them,

279
00:29:46,475 --> 00:29:50,817
and so propelled them forward
and lift them upwards.

280
00:29:59,100 --> 00:30:02,255
So, how the bird wings
actually work?

281
00:30:04,269 --> 00:30:08,176
If we slow them down we can watch
in detail the mini subtle changes

282
00:30:08,208 --> 00:30:11,276
they make as they
move up and down.

283
00:30:12,217 --> 00:30:16,380
The feathers overlap to form
a smooth contoured surface

284
00:30:16,401 --> 00:30:19,355
that extends far beyond
the bones within.

285
00:30:24,308 --> 00:30:28,552
With a curved leading edge of the front,
and a sharp trailing edge of the back

286
00:30:28,574 --> 00:30:33,028
they have a classic aerodynamic
shape that produced lift.

287
00:30:33,789 --> 00:30:36,682
They are aerofoils.

288
00:30:42,718 --> 00:30:46,965
With this downward beat the air
pressure above is reduced,

289
00:30:46,992 --> 00:30:50,213
so that the bird is sucked upwards.

290
00:30:53,335 --> 00:30:58,166
Wings like these consisting of jointed bones
covered with closely fitting feathers

291
00:30:58,204 --> 00:31:01,863
can make very subtle delicate movements.

292
00:31:02,641 --> 00:31:08,061
The feathers slide over one another,
so that when the wing changed its shape

293
00:31:08,088 --> 00:31:11,988
there is no loss of smoothness
on the contour.

294
00:31:17,606 --> 00:31:21,003
When the Swan slightly retract
its wings in between beats,

295
00:31:21,057 --> 00:31:25,958
the sliding feathers ensure that
the aerofoils still produces lift.

296
00:31:31,115 --> 00:31:34,842
And the bird bodies have become
modified in another way.

297
00:31:35,720 --> 00:31:38,857
They become light weight.

298
00:31:40,209 --> 00:31:42,909
The Dinosaurs heavy
bony jaws lined with teeth

299
00:31:42,962 --> 00:31:46,722
have been reduced to a
light weight beak of horn.

300
00:31:48,941 --> 00:31:54,347
The bony tail has shrunk to a stump,
nearly an attachment point for the tail feathers.

301
00:31:57,309 --> 00:31:59,989
And many of the bones within
the body had become hollow,

302
00:32:00,044 --> 00:32:03,069
so reducing weight even further.

303
00:32:06,421 --> 00:32:10,940
The result is an extremely
efficient light weight flyer.

304
00:32:12,949 --> 00:32:15,956
We are traveling around 30
miles an hour now,

305
00:32:16,008 --> 00:32:21,512
and yet these birds could easily accelerate
and leave us behind if they wanted to.

306
00:32:45,636 --> 00:32:49,419
So feathers, since they're first
appeared on the bodies of Dinosaurs,

307
00:32:49,473 --> 00:32:52,180
have acquired several different functions.

308
00:32:53,388 --> 00:32:56,437
Initially they served to keep
their owners warm.

309
00:32:57,596 --> 00:33:03,377
Then, some grew large and acquired color
and were probably use in courtship displays.

310
00:33:07,055 --> 00:33:09,362
And only then,
after millions of years,

311
00:33:09,405 --> 00:33:12,603
where they used to help their
owners get into the air.

312
00:33:18,632 --> 00:33:23,157
But the Birds were not the last
animals to acquire the ability to fly.

313
00:33:26,008 --> 00:33:28,842
When the Pterosaurs vanished
together with the Dinosaurs,

314
00:33:28,889 --> 00:33:32,717
there was room in the skies
for yet another aeronaut,

315
00:33:32,744 --> 00:33:37,282
And one appeared with yet
another kind of wing.

316
00:33:43,753 --> 00:33:49,476
Animals on our Planet have
flown for over 320 million years.

317
00:33:50,656 --> 00:33:54,849
First came insects, then a group
of winged reptiles, Pterosaurs,

318
00:33:54,869 --> 00:33:57,903
and next, Birds.

319
00:34:02,775 --> 00:34:08,127
Then, around 66 million years ago,
came the global catastrophe

320
00:34:08,162 --> 00:34:14,005
that triggered the disappearance of a vast
proportions of the animal life of this Planet.

321
00:34:21,393 --> 00:34:26,522
An asteroid hitting the Earth was the
most likely cause of this mass extinction.

322
00:34:29,904 --> 00:34:33,639
In the devastation that followed,
the dominants creatures of that age,

323
00:34:33,691 --> 00:34:36,715
the Dinosaurs, disappeared.

324
00:34:37,275 --> 00:34:40,262
The Pterosaurs were completely wipeout.

325
00:34:40,882 --> 00:34:44,125
And only a few of the Birds survived.

326
00:34:46,512 --> 00:34:50,884
The skies for a short period
must have been relatively empty.

327
00:34:54,587 --> 00:34:58,359
But then, a new kind
of flying animal appeared.

328
00:35:00,797 --> 00:35:05,634
Now had a chance for a group of
furry warm blooded little creatures,

329
00:35:05,687 --> 00:35:09,998
that has been scampering around the feet of
the Dinosaurs for several millions years.

330
00:35:10,175 --> 00:35:13,399
They were the mammals.

331
00:35:14,922 --> 00:35:18,428
The first of them to take to the air were, doubtless, gliders.

332
00:35:19,556 --> 00:35:22,439
And one mysterious creature
still alive today,

333
00:35:22,498 --> 00:35:26,385
can give us an idea
of what there were like.

334
00:35:28,333 --> 00:35:33,820
It lives in the rainforests of Borneo,
and it called the Cobego.

335
00:35:36,501 --> 00:35:39,827
It has an enormous blanket
of furry skin that stretched

336
00:35:39,843 --> 00:35:44,036
from the sides of its head right
down to the very tip of its tail.

337
00:35:46,626 --> 00:35:51,902
But to see how he travel through
the air, we must wait until nightfall.

338
00:36:35,543 --> 00:36:38,849
As soon as it lands, it regain the
height it inevitably lost

339
00:36:38,914 --> 00:36:41,701
by clambering up the trunk.

340
00:36:50,663 --> 00:36:53,846
It by far the most skillful
of the forest gliders,

341
00:36:53,889 --> 00:36:58,401
and can travel over a
100 meters in one leap.

342
00:37:12,521 --> 00:37:17,265
It undoubtedly a very ancient animal,
and some believe that it may well

343
00:37:17,312 --> 00:37:21,246
have survived virtually unchanged
from that time long ago

344
00:37:21,278 --> 00:37:25,678
when mammals first took
to the skies as gliders.

345
00:37:41,513 --> 00:37:45,154
But soon, the mammals
deed better than that.

346
00:37:49,810 --> 00:37:56,694
This is a fossil that dates from
about 52.5 million years ago.

347
00:37:56,890 --> 00:38:02,182
Here its head, a very well
develop teeth, backbone and ribs,

348
00:38:02,218 --> 00:38:07,824
a long tail, hind legs,
and most importantly of all,

349
00:38:07,877 --> 00:38:13,266
from our point of view, hands with
enormously elongated fingers.

350
00:38:13,755 --> 00:38:16,841
And there was skin
between those fingers.

351
00:38:17,485 --> 00:38:20,878
These were wings
and they could flap.

352
00:38:20,913 --> 00:38:25,195
This is the earliest fossil
yet discovered of a bat.

353
00:38:27,932 --> 00:38:30,841
We have new evidence to show
exactly how a bat fingers

354
00:38:30,868 --> 00:38:33,896
first began to lengthen
to support their wings.

355
00:38:35,885 --> 00:38:39,279
But we can understand how
those early bats flew,

356
00:38:39,287 --> 00:38:42,652
by looking on their
modern descendants.

357
00:38:51,609 --> 00:38:54,565
These are some of the largest.

358
00:39:00,108 --> 00:39:03,820
They so big, that they often
called Flying Foxes.

359
00:39:11,060 --> 00:39:14,361
And they have a wingspan
of over a meter.

360
00:39:21,558 --> 00:39:24,080
When you slow a bat
flight down like this,

361
00:39:24,121 --> 00:39:27,954
you can see that its four fingers
are spread wide under down stroke,

362
00:39:27,989 --> 00:39:32,394
keeping the membrane wide and taut,
and then clump together on the up stroke,

363
00:39:32,535 --> 00:39:35,589
with just a thumb
off the top three.

364
00:39:41,259 --> 00:39:47,084
This folding of the wings reduces the
bat air resistance between each beat.

365
00:40:05,845 --> 00:40:09,978
To maximise the size of its wing,
the back edge of the wing membrane

366
00:40:10,052 --> 00:40:12,973
is attached to the ankles.

367
00:40:15,091 --> 00:40:18,331
Bats roost by hanging upside down.

368
00:40:21,307 --> 00:40:24,868
And this is how they tend
to spend their days.

369
00:40:26,722 --> 00:40:29,401
Is thought that the first
mammals were nocturnal,

370
00:40:29,433 --> 00:40:33,385
that doubtless was the best thing
to be out of the way of the Dinosaurs

371
00:40:33,417 --> 00:40:36,206
that were rampaging around
during the day.

372
00:40:37,319 --> 00:40:40,935
So, the bats continue the nocturnal
habit of their ancestors,

373
00:40:40,957 --> 00:40:46,512
and they are also inherited the acute
sensors needed to move around at night.

374
00:40:46,858 --> 00:40:50,712
Eyes specially adapted to
operating well in low light.

375
00:40:50,861 --> 00:40:55,260
And an acute sense of smell that
enable them to find food in the dark.

376
00:40:56,260 --> 00:41:00,442
In any case, Birds already
dominate in the daytime skies.

377
00:41:06,391 --> 00:41:09,191
With their wings of skin
and nocturnal senses

378
00:41:09,234 --> 00:41:13,105
the Bats became a
hugh global success.

379
00:41:14,596 --> 00:41:17,961
Today there are over
1,100 species of them,

380
00:41:17,994 --> 00:41:21,125
that's over a fifth of all mammals.

381
00:41:24,793 --> 00:41:29,841
So, by 50 million years ago,
three groups of large backbone animals

382
00:41:29,846 --> 00:41:33,409
had joined the Insects in the air.

383
00:41:37,925 --> 00:41:40,772
The pioneers were reptiles,
Pterosaurs,

384
00:41:40,798 --> 00:41:44,963
with membrane of skin stretch
from elongated fingers.

385
00:41:52,145 --> 00:41:58,497
Then, came a group of Dinosaurs
that acquired feathers and became Birds.

386
00:42:01,093 --> 00:42:06,327
But when the Pterosaurs and Dinosaurs
were swept away in a global extinction event,

387
00:42:06,423 --> 00:42:10,561
the stage was set for the Birds
and the newly emerge Bats

388
00:42:10,593 --> 00:42:13,914
between them to
take command on the skies.

389
00:42:15,414 --> 00:42:19,977
Each of these two groups had evolved
its on techniques for getting into the air,

390
00:42:20,014 --> 00:42:26,345
and each was destined to bring
theirs skills to astonishing extremes.

391
00:42:27,566 --> 00:42:31,311
Next time, we see how Birds
adapted and diversified

392
00:42:31,364 --> 00:42:35,852
to become the remarkable creatures
we see in our skies today.

393
00:42:40,601 --> 00:42:43,605
Lethal hunters...

394
00:42:47,774 --> 00:42:50,645
formation flyers...

395
00:42:51,153 --> 00:42:54,661
an aerial acrobats.

396
00:42:56,486 --> 00:42:59,756
We explore how the Bats
develop a new super sense

397
00:42:59,799 --> 00:43:03,443
that enable them to hunt in the
pitch-blackness of the night.

398
00:43:05,446 --> 00:43:09,483
And we visit one spectacular place
were the battle for the skies,

399
00:43:09,531 --> 00:43:14,968
between Insects, Bats
and Birds still continues.

400
00:43:16,585 --> 00:43:21,474
English: Bobiko

401
00:43:22,271 --> 00:43:25,665
Written and Presented by
David Attenborough