0:00:02 > 0:00:06I've been making natural history films for over 60 years
0:00:06 > 0:00:10and in the process, I've been to some very interesting places.
0:00:10 > 0:00:14But every now and again, I've been allowed to make a film
0:00:14 > 0:00:18about my other enthusiasms, about the history of exploration,
0:00:18 > 0:00:22about tribal objects or the life of a great scientist.
0:00:22 > 0:00:25You could call them my passion projects.
0:00:56 > 0:01:01After about 40 years of making programmes about living creatures
0:01:01 > 0:01:04that populate our world, I wondered whether I might try
0:01:04 > 0:01:08to make some programmes about the ones that had disappeared.
0:01:08 > 0:01:11They were the creatures that first interested me
0:01:11 > 0:01:13in the natural world - fossils.
0:01:14 > 0:01:17But how can you make programmes about animals and plants
0:01:17 > 0:01:19that no longer exist?
0:01:19 > 0:01:21Well, I thought we'd have a go.
0:01:23 > 0:01:26It's always seemed to me that fossils
0:01:26 > 0:01:30are some of the most romantic things on this planet.
0:01:30 > 0:01:36I mean, if you came across a pebble, like this, for example, and you
0:01:36 > 0:01:38just happened to knock it with your geological hammer,
0:01:38 > 0:01:40which happened to be around at the time...
0:01:40 > 0:01:42But if you just hit it with a hammer
0:01:42 > 0:01:46and split it and it opened like that,
0:01:46 > 0:01:49wouldn't you think that was remarkable?
0:01:49 > 0:01:55And that hasn't seen the light of day for 400 million years.
0:01:55 > 0:01:58And you're the first person ever to clap eyes on it.
0:01:58 > 0:02:02Isn't that the most romantic thing ever? I certainly find it so.
0:02:02 > 0:02:06Where I lived in Leicester, when I was a boy,
0:02:06 > 0:02:10we didn't find trilobites like that, but you did find things like this.
0:02:10 > 0:02:12This actually comes from Kimmeridge,
0:02:12 > 0:02:14but they're ammonites.
0:02:14 > 0:02:18And I collected them like mad, I would be off on my bicycle
0:02:18 > 0:02:22and sitting around in disused iron quarries, just knocking rocks.
0:02:23 > 0:02:28And they come in all different kinds and sizes and actually,
0:02:28 > 0:02:30this particular piece as well is
0:02:30 > 0:02:31interesting, because if you turned
0:02:31 > 0:02:33it over, you'll see the outside
0:02:33 > 0:02:36of the shell of a simply enormous one!
0:02:36 > 0:02:40That these others somehow or other have got stuck inside it.
0:02:40 > 0:02:45So fossils, for me, have always been thrilling.
0:02:45 > 0:02:50And I don't make these programmes out of some kind of proselytising
0:02:50 > 0:02:52view that people ought to be interested,
0:02:52 > 0:02:56I do it because I'M interested in them and it gives me a huge pleasure
0:02:56 > 0:02:59and I think other people can get pleasure from it, too.
0:03:01 > 0:03:03RUMBLE OF THUNDER
0:03:56 > 0:03:59Animals and plants flourished on this earth
0:03:59 > 0:04:02for millions of years before human beings appeared on it.
0:04:02 > 0:04:06And the direct evidence of that comes from one source only -
0:04:06 > 0:04:09from their remains that can be found in rocks.
0:04:09 > 0:04:10From fossils.
0:04:12 > 0:04:17Some are spectacular and dramatic, complete skeletons of huge reptiles.
0:04:23 > 0:04:26Others are the merest trace of imprints,
0:04:26 > 0:04:30left by such insubstantial creatures as jellyfish.
0:04:40 > 0:04:45Many are the remains of creatures quite unlike any that exist today,
0:04:45 > 0:04:49and fossils can be found all around us if we know where to look.
0:04:54 > 0:04:56The South of England, the Dorset coast,
0:04:56 > 0:04:59and a world-famous fossil site.
0:04:59 > 0:05:03Heavy rains have drenched the clay-and-limestone cliffs,
0:05:03 > 0:05:07the rocks are slipping, new surfaces are being exposed,
0:05:07 > 0:05:10fresh fossils could have been revealed overnight.
0:05:10 > 0:05:14Peter Langham regularly patrols this coast, searching for them,
0:05:14 > 0:05:18and he knows that the day after a storm is the very best time
0:05:18 > 0:05:21for finding something interesting.
0:05:21 > 0:05:23This looks like a couple of likely looking bits of stone.
0:05:23 > 0:05:26Why? They look like all the rest to me!
0:05:26 > 0:05:27THEY LAUGH
0:05:27 > 0:05:29Really, if we see this from the right horizon...
0:05:29 > 0:05:33'It takes a lot of experience to be able to judge which out of the many
0:05:33 > 0:05:37'boulders in a cliff like this is likely to have a fossil inside it,
0:05:37 > 0:05:41'but then, Peter has been doing this for years.'
0:05:41 > 0:05:43Let's see what happens.
0:05:46 > 0:05:47- There we go.- Oh, gosh!
0:05:49 > 0:05:55That is one of the most well-known ammonites.
0:05:55 > 0:05:57That's beautiful.
0:06:06 > 0:06:11Fossils don't always appear every time you hit a nodule of rock
0:06:11 > 0:06:12with a hammer.
0:06:12 > 0:06:15But they do so surprisingly frequently
0:06:15 > 0:06:18if you can recognise the right sort of nodule
0:06:18 > 0:06:20and know where to find it.
0:06:29 > 0:06:33I used to come to these old ironstone quarries
0:06:33 > 0:06:36in Leicestershire as a boy to look for them.
0:06:36 > 0:06:39The moments of success when the rock fell apart
0:06:39 > 0:06:44and revealed a shell that hadn't seen the sun for 200 million years
0:06:44 > 0:06:48and that I was the first human being to see, seemed to me then,
0:06:48 > 0:06:52as, to be truthful, it still seems to me now, to be moments of magic.
0:06:58 > 0:07:01It's a beguiling business.
0:07:01 > 0:07:04For you know that even if you've not found anything much so far,
0:07:04 > 0:07:06the very next blow of your hammer
0:07:06 > 0:07:09may suddenly reveal something amazing.
0:07:17 > 0:07:19That's not bad but if I keep looking,
0:07:19 > 0:07:22I should be able to do rather better than that.
0:07:22 > 0:07:25Slowly you begin to get your eye in and soon you will start
0:07:25 > 0:07:27to recognise the particular glint,
0:07:27 > 0:07:30the telltale curve, the slight change in colour
0:07:30 > 0:07:34that indicates the tip of a fossil sticking out from the rock.
0:07:37 > 0:07:41It doesn't take long to gather quite a varied collection.
0:07:43 > 0:07:47They all seem to be the remains of animals that lived in the sea,
0:07:47 > 0:07:52but the local people, some of them at any rate, refuse to believe that.
0:07:52 > 0:07:53"How could they be?" they would say,
0:07:53 > 0:07:56when here we are in the middle of England
0:07:56 > 0:07:58about as far away from the sea as you could get
0:07:58 > 0:08:02and when these fossils are buried in the rock,
0:08:02 > 0:08:05far below the surface of the earth, how could that be?
0:08:05 > 0:08:08Instead they have their own explanations.
0:08:08 > 0:08:11They said, for example, that...
0:08:11 > 0:08:13these,
0:08:13 > 0:08:17these, they said, were the toenails of the devil.
0:08:19 > 0:08:21And this, these impressive
0:08:21 > 0:08:23bullet-shaped objects
0:08:23 > 0:08:26and there are some actually in this boulder on which I'm sitting...
0:08:26 > 0:08:28Those, they said, were thunderbolts.
0:08:28 > 0:08:31They were made when lightning struck the earth.
0:08:31 > 0:08:34And the most beautiful of them all,
0:08:34 > 0:08:36these ammonites.
0:08:37 > 0:08:42Well those, they said, were snake stones and they came in two kinds.
0:08:42 > 0:08:46Big ones like that, and little ones.
0:08:46 > 0:08:50Farther north up in Yorkshire near Whitby, where exactly the same
0:08:50 > 0:08:54fossils are found, the people had a detailed explanation
0:08:54 > 0:08:55as how that had come about.
0:08:55 > 0:08:58They said that back in the seventh century,
0:08:58 > 0:09:00an early Christian saint, St Hilda,
0:09:00 > 0:09:02had wanted to found an abbey,
0:09:02 > 0:09:05but discovered that the place was infested by snakes.
0:09:05 > 0:09:08So, miraculously, she turned them all to stone.
0:09:08 > 0:09:11Of course, there's one problem with that explanation.
0:09:11 > 0:09:14None of these so-called snake stones have heads.
0:09:14 > 0:09:19But when the devout pilgrims came to the site of this miracle,
0:09:19 > 0:09:21local craftsmen solved that problem.
0:09:21 > 0:09:26They carved on heads onto the snake stones so that they would look
0:09:26 > 0:09:27rather more convincing.
0:09:28 > 0:09:33But there are some fossils that are so perfectly preserved
0:09:33 > 0:09:37that their animal origin simply cannot be denied.
0:09:39 > 0:09:43These tiny creatures are imprisoned in amber - a hard,
0:09:43 > 0:09:49stony substance that is found in lumps in mudstones and sandstones.
0:09:49 > 0:09:52Who can doubt that these, so complete in every bristle
0:09:52 > 0:09:58and antenna, are truly ants, scorpions and flies?
0:10:04 > 0:10:07But how did they get there?
0:10:07 > 0:10:10Amber was once liquid and sticky.
0:10:10 > 0:10:14Resin trickling down the trunks of trees that grew in swamps
0:10:14 > 0:10:15some 30 million years ago.
0:10:24 > 0:10:28Insects were attracted then as now by its sweet smell
0:10:28 > 0:10:31and flew or crawled towards it,
0:10:31 > 0:10:32with fatal results.
0:10:50 > 0:10:54The resin gradually hardens into solid lumps.
0:11:00 > 0:11:03Eventually, the tree itself died.
0:11:06 > 0:11:11And the long, slow processes that lead to fossilisation began.
0:11:23 > 0:11:26Mud and sand washed in by the sea
0:11:26 > 0:11:30slowly settled on the resin lumps and buried them.
0:11:30 > 0:11:32As millions of years passed,
0:11:32 > 0:11:35the layers of sediment were compressed and compacted
0:11:35 > 0:11:41under their own weight and turned into mudstones and sandstones.
0:11:41 > 0:11:45And then were pushed and buckled by colliding continents
0:11:45 > 0:11:48to form mountains like these in the Dominican Republic
0:11:48 > 0:11:52on the Caribbean island of Hispaniola.
0:11:52 > 0:11:55Since amber is highly valued for making jewellery,
0:11:55 > 0:12:00men today burrow deep into the hillsides to look for it.
0:12:08 > 0:12:13The shafts are steep and may go as much as 100 yards into the mountain.
0:12:16 > 0:12:20The amber miners have to chisel away tonnes of stone
0:12:20 > 0:12:23before they find the particular layer where the lumps
0:12:23 > 0:12:25of resin have accumulated.
0:12:25 > 0:12:30But once they find that seam, they often discover piece after piece.
0:12:30 > 0:12:34- Es que el ambar?- Si.
0:12:39 > 0:12:41Grande, eh?
0:12:48 > 0:12:51It's difficult to tell what's inside pieces like this
0:12:51 > 0:12:52when they've just been dug out
0:12:52 > 0:12:55because the surface is all broken and pitted and dirty
0:12:55 > 0:12:57but when they are polished,
0:12:57 > 0:13:00they may reveal the most extraordinary things.
0:13:06 > 0:13:09Many pieces are quite clear with nothing whatever in them
0:13:09 > 0:13:12and those are the ones that are valued for jewellery.
0:13:12 > 0:13:17But one in every dozen or so has the remains of some kind of creature.
0:13:17 > 0:13:19Backboned animals were mostly strong and large enough
0:13:19 > 0:13:22to pull themselves free from the resin if they touched it,
0:13:22 > 0:13:24but occasionally, they failed,
0:13:24 > 0:13:28and these are the rarest of all amber fossils.
0:13:28 > 0:13:30A tiny lizard.
0:13:30 > 0:13:32And a frog.
0:13:36 > 0:13:41Insects are the commonest and were sometimes caught in action.
0:13:41 > 0:13:43An ant carrying a pupa.
0:13:44 > 0:13:49A bug beside a leaf from which it might have been sucking sap.
0:13:50 > 0:13:53A beetle apparently walking up a twig.
0:13:57 > 0:14:01Flying insects with even their delicate wings undamaged.
0:14:03 > 0:14:07And a whole swarm of ants, so perfectly preserved
0:14:07 > 0:14:11that you can even see the facets in their 30-million-year-old eyes.
0:14:13 > 0:14:19I suppose the most romantic is the ones that are very, very, very old.
0:14:19 > 0:14:23I mean, 550 million years old.
0:14:23 > 0:14:27The Burgess Shales up in the Canadian Rockies.
0:14:28 > 0:14:34The Burgess Shales come from a period when life was suddenly
0:14:34 > 0:14:37burgeoning out into a multitude of different forms.
0:14:37 > 0:14:41It's so old that animals with bones had hardly developed.
0:14:41 > 0:14:46But in the Burgess Shales, the deposit is so fine-grained
0:14:46 > 0:14:50and was developed and put down in such a way that it trapped
0:14:50 > 0:14:53a lot of these soft-bodied creatures -
0:14:53 > 0:14:56jellyfish, slug-like creatures -
0:14:56 > 0:15:00that they left only the faintest impression
0:15:00 > 0:15:03in this very, very fine-grained rock.
0:15:04 > 0:15:07When it was discovered, it was a revelation,
0:15:07 > 0:15:09that suddenly you saw there were forms of life
0:15:09 > 0:15:11that people had never dreamed of,
0:15:11 > 0:15:14right at the beginning of the historical record.
0:15:20 > 0:15:23The sun-lit waters of a shallow sea.
0:15:23 > 0:15:27Life here is rich and varied.
0:15:29 > 0:15:33Jellyfish, sea gooseberries and all kinds of larvae
0:15:33 > 0:15:35drift in the dappled waters.
0:15:41 > 0:15:45Creatures like these have a very ancient ancestry.
0:15:45 > 0:15:49They were among the first forms of life to appear on earth
0:15:49 > 0:15:52and they existed for several hundred million years
0:15:52 > 0:15:56before the development of fish - the first animals with backbones.
0:15:58 > 0:16:02But when such creatures with no bones in them die,
0:16:02 > 0:16:04what remains of them?
0:16:04 > 0:16:05Almost nothing.
0:16:05 > 0:16:08Their soft tissues simply disintegrate
0:16:08 > 0:16:10and dissolve in the water
0:16:10 > 0:16:15and there's hardly anything left of them but a little slime in the mud.
0:16:15 > 0:16:18Only a minority, a few molluscs with hard shells,
0:16:18 > 0:16:22leave any signs of their existence after their flesh has vanished.
0:16:23 > 0:16:27This, too, was once mud at the bottom of a sea
0:16:27 > 0:16:30but that was over 500 million years ago
0:16:30 > 0:16:36and now it's mudstone and high in the Canadian Rockies.
0:16:36 > 0:16:39And these rocks too contain the remains of the hard parts
0:16:39 > 0:16:42of sea animals, and very extraordinary animals too.
0:16:42 > 0:16:46They are now totally extinct and we call them trilobites.
0:16:46 > 0:16:48But there's virtually nothing else
0:16:48 > 0:16:49but trilobites in these rocks.
0:16:49 > 0:16:53So, what did the trilobites live on and what hunted the trilobites?
0:16:53 > 0:16:57The answers to questions like those could only be guesswork.
0:16:57 > 0:16:59Until, that is, the year 1901.
0:17:02 > 0:17:06In that year, an American geologist, Charles Walcott,
0:17:06 > 0:17:10was exploring here in the Rocky Mountains of British Columbia.
0:17:10 > 0:17:14He was in his 60th year and coming towards the end of a long
0:17:14 > 0:17:17and distinguished career in which he had made a special study
0:17:17 > 0:17:20of the very ancient fossil-bearing rocks of North America.
0:17:24 > 0:17:28When he got to this precise point on the trail, where this
0:17:28 > 0:17:33slip of loose rocks crosses it, one of his horses stumbled.
0:17:33 > 0:17:37Walcott dismounted to clear the path and when he did so, he hit one
0:17:37 > 0:17:41of the boulders with his hammer as he must've done 10,000 times before.
0:17:41 > 0:17:44Only this time when the boulder fell apart, it revealed
0:17:44 > 0:17:47a fossil, the like of which he had never seen before
0:17:47 > 0:17:49in all his experience.
0:17:49 > 0:17:54To his amazement, he saw that it had its soft parts preserved.
0:17:54 > 0:17:57Tentacles, the head and a row of small legs
0:17:57 > 0:17:59on either side of his body.
0:17:59 > 0:18:03If he didn't do so then, he must have realised very soon afterwards
0:18:03 > 0:18:07that this was the most important discovery of his life.
0:18:07 > 0:18:11So the next season, he and his sons returned to this place to try
0:18:11 > 0:18:14and find out where that boulder had come from.
0:18:18 > 0:18:23They climbed up the rock tip, looking for fossils as they went,
0:18:23 > 0:18:29and knowing that the highest level in which they found any fragments
0:18:29 > 0:18:32with fossils in them must be the place
0:18:32 > 0:18:35from which all the fossils were coming.
0:18:35 > 0:18:39And that proved to be just here.
0:18:39 > 0:18:42And this place has been the site of research ever since.
0:18:50 > 0:18:56A band of these shales just seven foot thick produced all the fossils.
0:18:56 > 0:18:59Walcott came here for the next eight seasons and in that time,
0:18:59 > 0:19:03he collected 61,000 specimens.
0:19:03 > 0:19:08Two thirds of the species that he found proved to be new to science.
0:19:13 > 0:19:17Animals such as these with delicate legs, with tiny gills
0:19:17 > 0:19:21and threadlike antennae, must've been living throughout the seas
0:19:21 > 0:19:24of this very ancient period.
0:19:24 > 0:19:27They had never been seen before because everywhere else,
0:19:27 > 0:19:30being soft-bodied, they had simply dissolved
0:19:30 > 0:19:32and disappeared without trace.
0:19:32 > 0:19:37Only here, for some extraordinary reason, had they been preserved.
0:19:37 > 0:19:40And preserved, what's more, in amazing detail.
0:19:43 > 0:19:46These rocks are known as the Burgess Shales.
0:19:46 > 0:19:49How is it that one thin band of them
0:19:49 > 0:19:51on this particular mountainside preserved signs of life
0:19:51 > 0:19:54that are found nowhere else in the world?
0:19:54 > 0:19:56That was one of the questions that Walcott
0:19:56 > 0:20:00and his successors spent a long time trying to answer.
0:20:00 > 0:20:03The latest group of scientists to work on the site here
0:20:03 > 0:20:07come from the Royal Ontario Museum and are led by Des Collins.
0:20:07 > 0:20:13530 million years ago, this was a muddy sea floor about 400 feet deep.
0:20:13 > 0:20:16It was directly in front of a massive, sheer cliff that you can
0:20:16 > 0:20:19see in this light-coloured material over here.
0:20:30 > 0:20:34The reef front rose in a sheer cliff, about 300 feet high
0:20:34 > 0:20:37and you can see at the top, the bedded rock, which is where the
0:20:37 > 0:20:41animals lived in a lagoon about 100 feet deep or less.
0:20:41 > 0:20:45Every so often, the mud on the top would come down the slump,
0:20:45 > 0:20:48picking up the animals, bringing them down here, killing them,
0:20:48 > 0:20:51burying them and preserving them in the mud.
0:20:53 > 0:20:58This happened at a time when complex animals had only just appeared,
0:20:58 > 0:21:01so the ultimate ancestors of all life today
0:21:01 > 0:21:03must therefore be among them.
0:21:03 > 0:21:06This worm with an internal rod running along its length
0:21:06 > 0:21:09may be the ancestor of all backboned animals.
0:21:10 > 0:21:14And this, with five pairs of claws on its head,
0:21:14 > 0:21:17may be the creature from which scorpions and spiders have
0:21:17 > 0:21:21evolved, for it shares some of their most significant characters.
0:21:23 > 0:21:25By examining the best of these specimens,
0:21:25 > 0:21:29it's possible to deduce from the flattened outlines what it was like
0:21:29 > 0:21:34before it was squashed flat, and to reconstruct it in three dimensions.
0:21:34 > 0:21:37But some specimens are so strange, it's difficult
0:21:37 > 0:21:39to make head or tail of them.
0:21:39 > 0:21:43This, for example, three or four inches long, looks like some
0:21:43 > 0:21:47kind of shrimp, except that none has ever been found with a head.
0:21:49 > 0:21:52And this, rather like a slice of pineapple,
0:21:52 > 0:21:55could this be some kind of jellyfish?
0:21:55 > 0:21:57Though there are still some speculations,
0:21:57 > 0:22:00we now have a picture of a large and varied community,
0:22:00 > 0:22:04but if there were so many of these mud-munchers and filter-feeders,
0:22:04 > 0:22:07there must surely have been some hunter that preyed on them.
0:22:07 > 0:22:09What was that?
0:22:11 > 0:22:14That question troubled a British palaeontologist,
0:22:14 > 0:22:18Harry Whittington, as he worked on some of Walcott's specimens.
0:22:18 > 0:22:21Searching through many thousands of them, he found one in which
0:22:21 > 0:22:25that pineapple slice seemed to be attached to some other structure.
0:22:25 > 0:22:28What is more, there were several other specimens rather like it,
0:22:28 > 0:22:32including one that was not completely cleared of matrix.
0:22:32 > 0:22:36And he started very carefully to investigate it.
0:22:36 > 0:22:39If you think this is the underside of the body, which I did,
0:22:39 > 0:22:42to look and see, well, is there anything perhaps
0:22:42 > 0:22:45attached to the underside that goes down into the rock?
0:22:45 > 0:22:48And there was a little area here,
0:22:48 > 0:22:52and gradually this thing came exposed.
0:22:53 > 0:22:58And I realised that was this thing that had been described many
0:22:58 > 0:23:03years before, Anomalocaris. The "strange shrimp".
0:23:03 > 0:23:06But no whole one had ever been found.
0:23:06 > 0:23:10Now here was one attached under the front end of this animal.
0:23:10 > 0:23:13Was that an accident, having that there?
0:23:13 > 0:23:16If there was one one side, there ought to be one the other.
0:23:16 > 0:23:19And indeed there was a layer in the rock here,
0:23:19 > 0:23:22and I exposed parts of that
0:23:22 > 0:23:26chiselling around here, and
0:23:26 > 0:23:29there exposed is part of the companion one
0:23:29 > 0:23:31that was attached there.
0:23:32 > 0:23:34That predator was revealed.
0:23:34 > 0:23:37The headless shrimps were its claws,
0:23:37 > 0:23:40and the pineapple slice was its muscular mouth.
0:23:40 > 0:23:42This was the terror of the trilobites.
0:23:46 > 0:23:49So now we have an even more complete picture of the life that
0:23:49 > 0:23:52flourished on the sea floor
0:23:52 > 0:23:54530 million years ago.
0:23:54 > 0:23:56We knew that it must have contained the ancestors of all
0:23:56 > 0:24:01subsequent life, but now we have some idea of what they looked like.
0:24:05 > 0:24:09In contrast to the Burgess Shales, which were extremely old,
0:24:09 > 0:24:14one of the most recent deposits of extinct animals
0:24:14 > 0:24:17is in California, outside Los Angeles, where
0:24:17 > 0:24:20there are tar pits, naturally occurring tar pits.
0:24:20 > 0:24:24And these pools, which still form today,
0:24:24 > 0:24:27look like black, shiny water.
0:24:27 > 0:24:30And any animal that came there to drink would find that
0:24:30 > 0:24:34suddenly it's trodden into this sticky stuff, which actually
0:24:34 > 0:24:39holds them tight and eventually pulls them down and they die.
0:24:39 > 0:24:43And then other animals come along, see a dead wolf or something
0:24:43 > 0:24:47and think there's a meal, and comes in to take the trapped animal
0:24:47 > 0:24:49and then gets stuck itself.
0:24:49 > 0:24:53And amongst the most dramatic of these, of the predators that
0:24:53 > 0:24:56come there, are the sabre-toothed tigers. But who would think you'd
0:24:56 > 0:25:00get that sort of insight into animals that lived 40,000 years ago?
0:25:00 > 0:25:03Well, the La Brea tar pits enable you to do that.
0:25:07 > 0:25:09Los Angeles, in America.
0:25:09 > 0:25:11Hardly world-famous for its fossils,
0:25:11 > 0:25:13but it should be, for right
0:25:13 > 0:25:17in the very heart of this most modern of cities is a site
0:25:17 > 0:25:20that gives another, wholly exceptional picture
0:25:20 > 0:25:21of a vanished world.
0:25:21 > 0:25:23BIRDS SQUAWK
0:25:25 > 0:25:2940,000 years ago, this was the appearance of the land
0:25:29 > 0:25:32on which hotels and freeways now stand.
0:25:32 > 0:25:35And firm evidence for every single detail in this most detailed
0:25:35 > 0:25:40painting comes from a small park close by one of the city's
0:25:40 > 0:25:42main avenues - La Brea.
0:25:44 > 0:25:47In one corner of it, through the harmless grass,
0:25:47 > 0:25:50oozes a substance that kills - la brea.
0:25:50 > 0:25:52Tar.
0:25:57 > 0:26:01It wells up from the ground here to form these black pools.
0:26:01 > 0:26:04When it rains, water lies on top of it
0:26:04 > 0:26:07and it looks like a place where you might get a drink.
0:26:07 > 0:26:09But any animal that came down here to do so
0:26:09 > 0:26:12would be lucky to escape alive.
0:26:12 > 0:26:15Feet sink into the tar, feathers get entangled in it
0:26:15 > 0:26:18and the animal is fatally trapped.
0:26:18 > 0:26:21That's been happening for 40,000 years and more.
0:26:21 > 0:26:23And it's still happening today.
0:26:33 > 0:26:37Tar, like oil, is derived from the bodies of animals
0:26:37 > 0:26:39and plants that accumulated in swamps.
0:26:39 > 0:26:42The sand that was deposited on top of them squeezed their
0:26:42 > 0:26:47remains so that droplets of oil were expelled from their tissues.
0:26:47 > 0:26:51That accumulated in basins within the texture of the porous sandstone,
0:26:51 > 0:26:53and then where there is a fault,
0:26:53 > 0:26:56this substance is forced up to the surface.
0:26:58 > 0:27:02The earlier flows of tar, containing the most ancient animals, have
0:27:02 > 0:27:04now been covered by later flows,
0:27:04 > 0:27:08so to reach them, you have to dig down into the tar pit.
0:27:08 > 0:27:12And excavations which started back at the beginning of the century
0:27:12 > 0:27:15are now being carried on some 30 feet down.
0:27:15 > 0:27:18The work is supervised by trained scientists,
0:27:18 > 0:27:22but most of the team is made up of local volunteers.
0:27:22 > 0:27:25- OK, this is ready to go. You got the bag?- Yes, I do.- OK.
0:27:26 > 0:27:29- That's a sabre-toothed cat femur. - Right or left?
0:27:29 > 0:27:32That's a right.
0:27:32 > 0:27:36- I'll bag up this ulna uncovered here.- What's it lying on top of?
0:27:36 > 0:27:40Well, it's laying right across a sabre-toothed cat skull.
0:27:40 > 0:27:43The finds have been put on display in a museum that has recently
0:27:43 > 0:27:46been built on the site, and very spectacular they are.
0:27:58 > 0:28:01In addition to this magnificent imperial mammoth, the biggest
0:28:01 > 0:28:05of all the prehistoric elephants that lived in North America,
0:28:05 > 0:28:09there were extinct horses and camels which grazed on these plains.
0:28:11 > 0:28:15These dire wolves were about the same size as living wolves,
0:28:15 > 0:28:17but with more massive heads.
0:28:17 > 0:28:20Struggling trapped animals were obviously something
0:28:20 > 0:28:22they couldn't resist. For wolves, in fact,
0:28:22 > 0:28:25are the commonest of all the victims of the tar pits.
0:28:28 > 0:28:31The most frequently trapped grass eaters were the bison,
0:28:31 > 0:28:34so there were probably big herds of them.
0:28:34 > 0:28:37But again, the pits contain more bones of the animal
0:28:37 > 0:28:40that preyed on them, the American lion.
0:28:40 > 0:28:42ROARING
0:28:45 > 0:28:48The females were about the same size as African lions,
0:28:48 > 0:28:51but the males were 25% bigger.
0:28:55 > 0:28:59And there was an even more impressive cat, the sabre-tooth.
0:29:00 > 0:29:03At one time it was thought that these extraordinary teeth
0:29:03 > 0:29:05were daggers for stabbing.
0:29:05 > 0:29:07But now it's believed that they were used to slit open
0:29:07 > 0:29:09the belly of the prey.
0:29:09 > 0:29:12You might wonder how on earth the animal managed even to
0:29:12 > 0:29:16close its jaws, and I asked a scientist at the museum,
0:29:16 > 0:29:19George Jefferson, to explain.
0:29:19 > 0:29:20As you can see,
0:29:20 > 0:29:24the incisors actually interlace between each other.
0:29:24 > 0:29:26Allowing the jaw to fully close.
0:29:26 > 0:29:30I'm surprised to see how much space there is between those huge
0:29:30 > 0:29:32sabre teeth and the lower jaw.
0:29:32 > 0:29:34That gap is the same gap
0:29:34 > 0:29:37as between the meat-slicing teeth
0:29:37 > 0:29:39here on the side of the face.
0:29:39 > 0:29:43What that meant is the animal would disengage the incisors,
0:29:43 > 0:29:48drop the jaw down, move it slightly sideways and guide the slicing
0:29:48 > 0:29:52blades here by running the inside of this flange
0:29:52 > 0:29:55against the canine tooth.
0:29:55 > 0:29:57- Is that a new discovery?- It is.
0:29:57 > 0:30:01In fact, we didn't know that this gap was that way
0:30:01 > 0:30:03until we found this particular specimen.
0:30:03 > 0:30:05ROARING
0:30:14 > 0:30:18The sheer abundance of the dire wolf skulls also yields information.
0:30:18 > 0:30:20They're not, of course, all the same,
0:30:20 > 0:30:24and the differences are not all due to age.
0:30:24 > 0:30:28The lumps and distortions here that are apparent, compared to the
0:30:28 > 0:30:30smooth forehead on this animal, indicate there was
0:30:30 > 0:30:34an infection in the frontal sinuses of the forehead.
0:30:34 > 0:30:37- Probably the result of being kicked in the face.- OK.
0:30:37 > 0:30:41May have been kicked by a bison, may have been kicked by a camel.
0:30:41 > 0:30:45This animal was obviously going after its prey and getting injured.
0:30:45 > 0:30:48We also see injuries in the sabre cats.
0:30:50 > 0:30:56In this hip, we have a fairly normal hip socket here, but on this side,
0:30:56 > 0:31:00you can see a lot of knobbly bone,
0:31:00 > 0:31:02a distortion and break.
0:31:04 > 0:31:06We think it may have been butted by a bison,
0:31:06 > 0:31:10hit very hard or even possibly by a mammoth elephant.
0:31:10 > 0:31:13- So, he's really a cripple. - He really is, yes.
0:31:13 > 0:31:15It's astounding it lived as long as it did.
0:31:15 > 0:31:20Some researchers believe that this is evidence that the injured
0:31:20 > 0:31:23and infirmed were being tolerated within the population
0:31:23 > 0:31:27- and possibly cared for.- So, social behaviour amongst the sabre cats?
0:31:27 > 0:31:29Social behaviour.
0:31:31 > 0:31:34Well, there's no doubt that if you say "fossil, animal",
0:31:34 > 0:31:38an awful lot of people immediately say dinosaur.
0:31:38 > 0:31:41And to make a programme, or make a whole series, about fossils
0:31:41 > 0:31:45and not to mention dinosaurs, well, you couldn't really do that.
0:31:45 > 0:31:49On the other hand, the sort of animations that we had
0:31:49 > 0:31:52in those days to bring dinosaurs to life were really rather clunky.
0:31:52 > 0:31:55They didn't really bring the reality, and I thought it would
0:31:55 > 0:31:58be a bit of a challenge, rather fun,
0:31:58 > 0:32:01to actually do a programme about dinosaurs in which you didn't
0:32:01 > 0:32:05have a single reconstruction, and that you tried to bring the animals
0:32:05 > 0:32:10to life in people's imaginations by simply looking at the bones.
0:32:21 > 0:32:23We are looking for a dinosaur.
0:32:23 > 0:32:27At a time when the dinosaur first appeared, about 200 million
0:32:27 > 0:32:32years ago, all the land and the earth was grouped together in one
0:32:32 > 0:32:37supercontinent, and the dinosaurs roamed all over it.
0:32:37 > 0:32:40And so today their remains can be found in the fragments
0:32:40 > 0:32:42of that supercontinent -
0:32:42 > 0:32:47in Australia, in North America, in Europe, and here in Africa.
0:32:48 > 0:32:53We're on an expedition in the southern fringes of the Sahara,
0:32:53 > 0:32:56and the reason we've come here to look for them is that in a desert,
0:32:56 > 0:33:00there's very little vegetation to cover the rocks, so that
0:33:00 > 0:33:03if there are dinosaurs in them, we'll be able to see them.
0:33:15 > 0:33:19One of the expedition leaders, Dick Moody, showed me their first find.
0:33:19 > 0:33:22I'm sure you'll find this one, which we haven't touched,
0:33:22 > 0:33:25quite a superb specimen, quite exciting.
0:33:25 > 0:33:28Oh, it is absolutely magnificent!
0:33:30 > 0:33:33This is obviously the backbone. Which way does it lie?
0:33:33 > 0:33:36It's running in that direction, we believe, towards the head
0:33:36 > 0:33:38- and towards the east.- Yes.
0:33:38 > 0:33:42And in this direction, generally back towards the tail, obviously.
0:33:42 > 0:33:45- And the ribs, which side?- The ribs are running off, as you can see,
0:33:45 > 0:33:49they're slightly disarticulated and slightly broken up.
0:33:49 > 0:33:52And how long do you think the complete animal was?
0:33:52 > 0:33:57- Well, between 20 and 30 metres. - What, that's 90 feet?- Yes.
0:33:57 > 0:34:00- God, that's enormous.- It's a large animal, yes.
0:34:00 > 0:34:02And how complete do you think it might be?
0:34:02 > 0:34:05We're hoping to find some skull material
0:34:05 > 0:34:08- and obviously limb material underneath.- Yeah.
0:34:08 > 0:34:11Let me clear these just a little.
0:34:11 > 0:34:14'The weathered shales in which the bones were embedded were
0:34:14 > 0:34:17'so soft that we could brush them away with our hands.
0:34:21 > 0:34:23'After only half an hour,
0:34:23 > 0:34:27'we already had some idea of how much of the animal was preserved.
0:34:28 > 0:34:29'But it was a further day
0:34:29 > 0:34:32'before all the bones at this site were exposed.
0:34:39 > 0:34:41'There weren't as many as we had first hoped.
0:34:41 > 0:34:44'The base of the tail and the lower part of the spine was there,
0:34:44 > 0:34:47'but the legs and most of the body were missing.
0:34:49 > 0:34:51'But only half a mile away,
0:34:51 > 0:34:55'the rest of the expedition was working on another group of bones.
0:34:55 > 0:34:58'These were leg bones, and probably belonged,
0:34:58 > 0:35:02'if not to the same animal, then at least to the same kind.'
0:35:06 > 0:35:08The huge carcass, whatever it was,
0:35:08 > 0:35:12had clearly already been dismembered before it was buried.
0:35:12 > 0:35:15Perhaps other scavenging dinosaurs had pulled it apart.
0:35:15 > 0:35:19Perhaps the rotting body had disintegrated as it lay in the river
0:35:19 > 0:35:22that eventually buried it in mud.
0:35:22 > 0:35:24The expedition was from the Natural History Museum and
0:35:24 > 0:35:27Kingston Polytechnic in London,
0:35:27 > 0:35:30and before the bones could be transported back,
0:35:30 > 0:35:32they had to be protected by wrapping
0:35:32 > 0:35:35them with strips of sackcloth soaked in plaster.
0:35:38 > 0:35:41This will harden into a solid jacket that will hold the whole
0:35:41 > 0:35:43specimen together.
0:35:45 > 0:35:49The expedition dug up and plastered almost 100 bones in the four
0:35:49 > 0:35:51weeks that they worked in the Sahara.
0:35:51 > 0:35:54But this was only the start of their work.
0:35:54 > 0:35:57Indeed, it won't be until the team gets the bones back to the museum
0:35:57 > 0:35:59in London and has cleaned them,
0:35:59 > 0:36:01studied them and pieced them together
0:36:01 > 0:36:05that they will know for sure exactly what kind of dinosaur they've got.
0:36:11 > 0:36:13But one thing is certain.
0:36:13 > 0:36:15It's a giant.
0:36:19 > 0:36:23These bones too, in the museum in East Berlin,
0:36:23 > 0:36:25came from Africa back in 1912.
0:36:25 > 0:36:29And when they were pieced together, they proved to belong to the
0:36:29 > 0:36:33most massive land animal known up to that time.
0:36:33 > 0:36:37It was 74 feet - 22½ metres long.
0:36:37 > 0:36:42It stood 39 feet - that's 12 metres high.
0:36:42 > 0:36:47And it was estimated to weigh 77 tonnes, which is
0:36:47 > 0:36:50as much as 12 bull elephants put together.
0:36:50 > 0:36:53This is brachiosaurus.
0:37:00 > 0:37:04Its head, perched on top of its immensely long neck,
0:37:04 > 0:37:06was comparatively tiny -
0:37:06 > 0:37:08Less than three feet long.
0:37:08 > 0:37:12But it has huge nostrils high on its forehead, and they led some
0:37:12 > 0:37:16people to suggest that this animal lived in lakes, with its head
0:37:16 > 0:37:19and nostrils above the surface, while it
0:37:19 > 0:37:24walked along the bottom with the water supporting its huge body.
0:37:24 > 0:37:27But that, we now know, would have been impossible.
0:37:28 > 0:37:31If its nostrils were open at the surface,
0:37:31 > 0:37:34the water pressure 30 or so feet
0:37:34 > 0:37:35below the surface would have
0:37:35 > 0:37:39been so great that its lungs would have collapsed.
0:37:39 > 0:37:43Furthermore, the shape of its legs and its deep,
0:37:43 > 0:37:47narrow chest all suggest an animal that lived on land.
0:37:47 > 0:37:50So now it seems we have to think of brachiosaurus
0:37:50 > 0:37:53as a kind of gigantic reptilian giraffe,
0:37:53 > 0:37:55browsing the tops of the trees.
0:37:58 > 0:38:03In New Mexico, they found remains of an animal that may be even bigger.
0:38:03 > 0:38:07They've already given it a name, seismosaurus, the earth shaker.
0:38:07 > 0:38:10But the rock in which it is embedded, in contrast to the
0:38:10 > 0:38:12soft shales of the Sahara,
0:38:12 > 0:38:14is almost as hard as concrete,
0:38:14 > 0:38:18and excavating it is a laborious and time-consuming business.
0:38:21 > 0:38:24The excavation leader, Dave Gillette, told me the story.
0:38:24 > 0:38:27This is where we found the first set of vertebrae that were
0:38:27 > 0:38:31discovered in 1979, and we finally excavated in 1985.
0:38:31 > 0:38:34- How much of it was showing when you first saw it?- Only the upper part.
0:38:34 > 0:38:36It was showing as though it had been
0:38:36 > 0:38:39- carved out of the rock in bas relief.- Wow.
0:38:39 > 0:38:41It was perfectly exposed, just in this fashion.
0:38:41 > 0:38:43And then?
0:38:43 > 0:38:46And then, when we looked closer in the ground, we found a total
0:38:46 > 0:38:50of eight vertebrae along this line, all in perfect articulation.
0:38:50 > 0:38:53And they're from the basal part of the tail,
0:38:53 > 0:38:56leading into the pelvic region. There's another vertebrae here.
0:38:56 > 0:38:58And then we took out two large blocks.
0:38:58 > 0:39:00One here, and another one from here at the base of the tail that
0:39:00 > 0:39:03led right up to the hip region in the skeleton.
0:39:03 > 0:39:05- What's that?- This is a rib,
0:39:05 > 0:39:08which has been somewhat displaced from the proper anatomical
0:39:08 > 0:39:10position when the animal died.
0:39:12 > 0:39:14So, what? Does the animal go on in there, do you think?
0:39:14 > 0:39:17We think the animal continues right into the hill to the north
0:39:17 > 0:39:19and we expect it continues for another 60 or 70 feet.
0:39:19 > 0:39:21What, under the rock?
0:39:21 > 0:39:23Under the rock, about eight feet deep,
0:39:23 > 0:39:26and we're using sophisticated and experimental remote sensing
0:39:26 > 0:39:29techniques to try to see those bones before we excavate.
0:39:32 > 0:39:36The site is only a few miles from Los Alamos Atomic Research Station,
0:39:36 > 0:39:39and the scientists there, on their days off,
0:39:39 > 0:39:42come out to use the most advanced techniques of nuclear physics
0:39:42 > 0:39:46to help Dave locate his dinosaur bones deep in the rock.
0:39:46 > 0:39:49This sledge carries a still-experimental
0:39:49 > 0:39:50remote sensing device.
0:39:50 > 0:39:54In fact, a kind of radar that can look into the ground.
0:39:54 > 0:39:57And already readings from it are beginning to confirm
0:39:57 > 0:39:59the gigantic size of the animal.
0:39:59 > 0:40:01I asked Dave how long he thought
0:40:01 > 0:40:04seismosaurus might eventually prove to be.
0:40:04 > 0:40:07My best estimate just now is 140 feet in length from the tip
0:40:07 > 0:40:08of the snout to the tip of the tail.
0:40:08 > 0:40:10And how does that compare with others?
0:40:10 > 0:40:14Well, the previous record holder was diplodocus at 87 feet.
0:40:14 > 0:40:16So we're approaching twice the length of diplodocus.
0:40:16 > 0:40:20And when will you actually know whether this is a world beater?
0:40:20 > 0:40:24Well, we know now. We have good confidence in our calculations.
0:40:29 > 0:40:32Dinosaurs certainly include some gigantic animals.
0:40:34 > 0:40:37Stegosaurus, bigger than a rhinoceros.
0:40:38 > 0:40:41Ammosaurus, tall as a giraffe.
0:40:43 > 0:40:46But they weren't all huge. Some were no bigger than a dog.
0:40:53 > 0:40:57Nonetheless, many were very big indeed.
0:40:57 > 0:41:00And they certainly include some of the most spectacular animals
0:41:00 > 0:41:02ever to walk the Earth.
0:41:07 > 0:41:11They dominated the world for over 160 million years.
0:41:32 > 0:41:34What did the dinosaurs eat?
0:41:34 > 0:41:37Well, flowering plants didn't develop
0:41:37 > 0:41:39until about 100 million years ago.
0:41:39 > 0:41:41So that means that for most of the time that the dinosaurs
0:41:41 > 0:41:43were on Earth,
0:41:43 > 0:41:47there were very few of the kinds of plant that dominate the land today.
0:41:47 > 0:41:51There was no oak trees or hazel in Europe, upon which deer feed.
0:41:51 > 0:41:55In Africa, there was no thorn scrub or acacia, on which elephant
0:41:55 > 0:41:57and giraffe browse.
0:41:57 > 0:41:58Most important of all, there was
0:41:58 > 0:42:03no grass, on which horses or bison or antelope graze.
0:42:03 > 0:42:05Instead, there were plants like these.
0:42:11 > 0:42:13These are Cycads.
0:42:13 > 0:42:16Today, they grow wild in only a very few places,
0:42:16 > 0:42:18and mostly in the tropics.
0:42:18 > 0:42:22But when the dinosaurs first evolved, they were spread worldwide.
0:42:25 > 0:42:28In addition to these, there were also tree ferns
0:42:28 > 0:42:31and primitive conifers, rather like pines.
0:42:31 > 0:42:34But all these plants had tough, fibrous leaves,
0:42:34 > 0:42:36almost indigestible, you might think.
0:42:38 > 0:42:41And if you have to keep your food in your stomach for a long time,
0:42:41 > 0:42:45then you need a very big stomach to serve as a storage vat.
0:42:49 > 0:42:53That in turn means that you have to have a very large body to carry it.
0:42:53 > 0:42:56So the ancient pastures of tree ferns may be one of the main
0:42:56 > 0:43:00reasons why plant-eating dinosaurs grew so big.
0:43:02 > 0:43:06As millions of years passed, however, evolution brought changes.
0:43:06 > 0:43:08The first flowering plants appeared.
0:43:08 > 0:43:12And so did new kinds of plant-eating dinosaurs.
0:43:12 > 0:43:14These are hadrosaurs. They had
0:43:14 > 0:43:17no teeth at all in the front of their jaws.
0:43:17 > 0:43:19Instead, the rounded bone was almost certainly covered with
0:43:19 > 0:43:21a horny sheath.
0:43:21 > 0:43:24With this, they could have done little more than just
0:43:24 > 0:43:26nip off leaves and twigs.
0:43:29 > 0:43:32But inside the mouth, at the back of the jaws,
0:43:32 > 0:43:35they had an enormous battery of teeth, row upon row.
0:43:37 > 0:43:40As these crushed and ground the tough fibres,
0:43:40 > 0:43:44they were inevitably worn down, but could they use them to chew?
0:43:45 > 0:43:49Mammals like this camel can chew by moving their lower jaw from side
0:43:49 > 0:43:54to side, so they are able to break down the toughest of plant foods.
0:43:54 > 0:43:58The dinosaurs were reptiles, and no reptile can do that.
0:43:58 > 0:44:01They can only move their jaws up and down,
0:44:01 > 0:44:03and that puts a real limit on what they can eat.
0:44:06 > 0:44:10The hadrosaurs dealt with that problem in a most remarkable way.
0:44:10 > 0:44:14The highlighted upper jaw could actually hinge outwards.
0:44:14 > 0:44:16This means that as the lower jaw moves up,
0:44:16 > 0:44:19it pushes aside the upper jaw.
0:44:19 > 0:44:22In effect, chewing without any sideways movement of the lower
0:44:22 > 0:44:23jaw at all.
0:44:29 > 0:44:32The most powerful grinding battery of all was that
0:44:32 > 0:44:36possessed by triceratops, one of the last of the dinosaurs.
0:44:36 > 0:44:39This, the product of 100 million years of development
0:44:39 > 0:44:42in the technique of chewing, is perhaps the most powerful
0:44:42 > 0:44:45chewing device ever possessed by any animal.
0:44:45 > 0:44:49A huge beak in the front served as shears, which could probably
0:44:49 > 0:44:52slice clean through a tree trunk.
0:44:52 > 0:44:55The branches were then moved to the back of the mouth, where the
0:44:55 > 0:44:58massive grinders reduced them to pulp.
0:45:09 > 0:45:12But these teeth belong to a very different sort of animal.
0:45:12 > 0:45:15This is Tyrannosaurus rex,
0:45:15 > 0:45:17the biggest of all the meat-eating dinosaurs,
0:45:17 > 0:45:22measuring over 40 feet long and weighing about seven tonnes.
0:45:22 > 0:45:25Surely the most terrifying hunter ever to roam the earth.
0:45:38 > 0:45:41So the bones of dinosaurs, carefully pieced together,
0:45:41 > 0:45:44can tell us a great deal about how big these animals were,
0:45:44 > 0:45:45what they fed on,
0:45:45 > 0:45:47and therefore their relationships with one another,
0:45:47 > 0:45:49and how their limbs articulated.
0:45:50 > 0:45:52But how fast could they move?
0:45:52 > 0:45:56To answer that question, you have to come to a place like this.
0:45:57 > 0:45:59150 million years ago,
0:45:59 > 0:46:04there was a mud flat here around the margin of a freshwater lake.
0:46:04 > 0:46:07The lake filled, and eventually sediments covered the whole area,
0:46:07 > 0:46:11and the mud flats turned into mudstones.
0:46:11 > 0:46:14In them are preserved huge footprints.
0:46:14 > 0:46:15Dinosaur footprints.
0:46:17 > 0:46:19These, nearly a yard across,
0:46:19 > 0:46:22can only have been made by a huge plant eater,
0:46:22 > 0:46:25like a brontosaur such as Diplodocus.
0:46:30 > 0:46:32These prints, though, are very different.
0:46:32 > 0:46:35Not circular, but with three prominent toes.
0:46:37 > 0:46:40At the end of each, there is a deep, sharp mark
0:46:40 > 0:46:43that can only have been made by a claw.
0:46:43 > 0:46:46They match the three-toed feet of theropods -
0:46:46 > 0:46:49medium-sized carnivorous dinosaurs.
0:46:49 > 0:46:52From tracks like these, it's been calculated
0:46:52 > 0:46:56that some of these hunters could run at up to 30mph.
0:46:59 > 0:47:02Moving at such speeds demands a great deal of energy,
0:47:02 > 0:47:06and an animal can only produce enough if it has a warm body.
0:47:06 > 0:47:10So did the dinosaurs get their energy directly from the sun,
0:47:10 > 0:47:12as reptiles do today,
0:47:12 > 0:47:16or could they generate warmth internally like birds and mammals?
0:47:16 > 0:47:18That is a question of great debate.
0:47:22 > 0:47:26This is how Tyrannosaurus rex may have moved,
0:47:26 > 0:47:29in the opinion of one of the new generation of dinosaur interpreters,
0:47:29 > 0:47:32Robert Bakker of the Museum of Colorado.
0:47:32 > 0:47:35OK, Tyrannosaurus rex, the most famous dinosaur,
0:47:35 > 0:47:36the most popular dinosaur.
0:47:36 > 0:47:40And here it is, running at 40mph -
0:47:40 > 0:47:42faster than a rhino,
0:47:42 > 0:47:44faster than an elephant.
0:47:44 > 0:47:46This T Rex is going faster than a lion.
0:47:46 > 0:47:47Yes, but that's your animation,
0:47:47 > 0:47:49how do you know it can go as fast as that? HE LAUGHS
0:47:49 > 0:47:53Because of the way the muscles were hung on those leg bones,
0:47:53 > 0:47:56because of the way the calf muscles were hung on that knee,
0:47:56 > 0:47:59because of the way the massive thigh muscles were hung on that ileum.
0:47:59 > 0:48:01But why does that prove it was warm blooded?
0:48:01 > 0:48:03Let's look at the real one, eh?
0:48:06 > 0:48:10Could it really have reared up like that and lifted its immense legs?
0:48:10 > 0:48:13Absolutely, and more. It could jump, it could run, it could run fast.
0:48:13 > 0:48:16This is a T Rex, a real one, a cast.
0:48:16 > 0:48:17With a bloody big knee, right?
0:48:17 > 0:48:20But why does that mean it's got to be warm blooded?
0:48:20 > 0:48:21Actually, it's the other way around,
0:48:21 > 0:48:24because warm bloodedness demands speed.
0:48:24 > 0:48:26This animal has to cruise fast,
0:48:26 > 0:48:29and it has to go into great bursts of speed,
0:48:29 > 0:48:32and it has to kill more often than a cold-blooded animal.
0:48:32 > 0:48:36There is no cold-blooded animal today with this great strength.
0:48:36 > 0:48:37None.
0:48:37 > 0:48:40This is not a scaled-up lizard, this is not a scaled-up tortoise -
0:48:40 > 0:48:45this is an enlarged, five-tonne, meat-eating roadrunner.
0:48:45 > 0:48:46That's what it is!
0:48:46 > 0:48:49And like a roadrunner, it's eating frequently.
0:48:49 > 0:48:51And there's another message, too, about speed in the skeleton,
0:48:51 > 0:48:53not in the legs, but in the chest.
0:48:53 > 0:48:55Because in the chest...
0:48:55 > 0:48:59there was housed in these ribs, without doubt,
0:48:59 > 0:49:02a gigantic heart, designed to pump,
0:49:02 > 0:49:07designed to put out blood flow at emphatically warm-blooded levels.
0:49:11 > 0:49:13ROARING
0:49:17 > 0:49:19So maybe we should get rid of the image of dinosaurs
0:49:19 > 0:49:22as slow, lumbering plodders,
0:49:22 > 0:49:26and think of them instead as nimble and agile
0:49:26 > 0:49:28in spite of their size.
0:49:28 > 0:49:30BELLOWS AND CRIES
0:49:32 > 0:49:36The truth is almost certainly that some were warm blooded,
0:49:36 > 0:49:37and others were not.
0:49:39 > 0:49:41A skeleton can not only give clues
0:49:41 > 0:49:44about the temperature of an animal's blood.
0:49:44 > 0:49:46It can, perhaps even more surprisingly,
0:49:46 > 0:49:50reveal something about the animal's social life.
0:49:50 > 0:49:52This is the skull of a hadrosaur.
0:49:52 > 0:49:56Like all hadrosaurs, it has a rounded front to its jaws,
0:49:56 > 0:50:01lacking in teeth, which in life were probably covered with a horn,
0:50:01 > 0:50:05and which give the family as a whole the name "duck-billed dinosaurs."
0:50:05 > 0:50:09At the back, there's a battery of powerful, plant-crushing teeth.
0:50:09 > 0:50:14In fact, the skulls of all hadrosaurs are very much the same,
0:50:14 > 0:50:16except for one feature.
0:50:16 > 0:50:19This - a crest.
0:50:19 > 0:50:21And this varies amazingly.
0:50:21 > 0:50:26This one is thin and forward-pointing.
0:50:26 > 0:50:30This one is long and goes right down the front of the skull.
0:50:30 > 0:50:33And this one is broad and plate-like,
0:50:33 > 0:50:35and sits on top of the skull.
0:50:35 > 0:50:39So these are three separate species.
0:50:39 > 0:50:41But this is almost certainly a male,
0:50:41 > 0:50:46because here's another one with very much the same shape of crest
0:50:46 > 0:50:50on top of the skull, but slightly smaller, so it's probably a female.
0:50:50 > 0:50:54And there is a third in which the same shape of crest
0:50:54 > 0:50:58is only just developing, so that's probably half grown.
0:51:02 > 0:51:05So crests in hadrosaurs serve to proclaim
0:51:05 > 0:51:08an individual's sex, age and species,
0:51:08 > 0:51:13and since such adornments that do that elsewhere in the animal kingdom
0:51:13 > 0:51:15are very often made more obvious with colour,
0:51:15 > 0:51:18we can speculate that the dinosaurs were indeed
0:51:18 > 0:51:20quite spectacular-looking animals,
0:51:20 > 0:51:24as the character of their scaly skin has already suggested.
0:51:27 > 0:51:30But these crests were more than visual signals.
0:51:30 > 0:51:33DEEP BELLOW
0:51:33 > 0:51:35Inside, there are air chambers,
0:51:35 > 0:51:38which must have acted as resonators when the animals bellowed.
0:51:40 > 0:51:44Since the air chambers vary in size and shape as much as the crests,
0:51:44 > 0:51:48each species must have had its own characteristic call.
0:51:48 > 0:51:56RUMBLING BELLOWS
0:51:57 > 0:52:00And they probably roared in deafening choruses,
0:52:00 > 0:52:03for we know that plant-eating dinosaurs lived in herds,
0:52:03 > 0:52:05as wildebeest do today.
0:52:05 > 0:52:08In Montana, deposits have been discovered
0:52:08 > 0:52:11where the bones of hadrosaurs are piled up in vast numbers.
0:52:15 > 0:52:19Jack Horner, the researcher who discovered the remains of the herds,
0:52:19 > 0:52:20has also found in Montana
0:52:20 > 0:52:24even more extraordinary evidence of the social life of dinosaurs.
0:52:24 > 0:52:27He's actually found their nests and eggs,
0:52:27 > 0:52:30and he showed me where I, too, could pick up bits of the shell.
0:52:31 > 0:52:33- Is that anything? - That's just eggshell.
0:52:33 > 0:52:35What do you mean, just! LAUGHTER
0:52:35 > 0:52:37- Really?- Well...
0:52:38 > 0:52:41We're looking for a nest. What we want to see is...
0:52:43 > 0:52:46- Eggshell is important. - Is it always black?- Yeah.
0:52:48 > 0:52:50- In this formation, it's always black.- Yeah.
0:52:50 > 0:52:53In other formations, it can be other colours.
0:52:53 > 0:52:56- If the piece is big enough, you can see the texture of the egg... - Oh, there's some.
0:52:56 > 0:52:59..and then with the microscope, then you can see the pores in it.
0:53:00 > 0:53:04Jack has even discovered complete clutches of unhatched eggs,
0:53:04 > 0:53:07which he's taken back to his laboratory.
0:53:08 > 0:53:11Now, this is... This nest is actually upside down, isn't it,
0:53:11 > 0:53:12- because that's the top of the jacket.- Right.
0:53:12 > 0:53:17- And so, these... These are the eggs? - These are the eggs, yeah.
0:53:17 > 0:53:19The... This is the centre egg in the nest.
0:53:20 > 0:53:22And the centre egg is always...
0:53:23 > 0:53:27..laid upright, and then each egg out from the centre
0:53:27 > 0:53:29becomes more and more inclined.
0:53:29 > 0:53:32- They were laid spirally? - Spiral, mm-hm.
0:53:32 > 0:53:34This was the first, presumably?
0:53:34 > 0:53:36That was the first one, I assume.
0:53:36 > 0:53:37Are they loose?
0:53:37 > 0:53:41Yes, this one's loose, here. You can see the pointed end of the egg.
0:53:42 > 0:53:43And...
0:53:43 > 0:53:45the top of the egg has been smooshed down.
0:53:45 > 0:53:47And is the shell on there? Yeah, I can see it.
0:53:47 > 0:53:49Yeah, this is all shell.
0:53:49 > 0:53:52- Do you think there's anything in that?- Yes.
0:53:52 > 0:53:54- I don't THINK there is, I KNOW there is.- How do you know there is?
0:53:54 > 0:53:55Er...
0:53:55 > 0:53:57They've been x-rayed and CAT scanned,
0:53:57 > 0:54:00and there are indications of little ones in it, yes.
0:54:01 > 0:54:03How can you... HE CHUCKLES
0:54:03 > 0:54:04How can you wait?
0:54:04 > 0:54:06Why don't you hit it with a spoon and see if you can take it out?
0:54:06 > 0:54:08I would like to do that,
0:54:08 > 0:54:10my preparators tell me I'm not supposed to!
0:54:10 > 0:54:11THEY LAUGH
0:54:11 > 0:54:13Have you got an open egg?
0:54:13 > 0:54:15Yes, we have one from another nest.
0:54:16 > 0:54:17Erm...
0:54:18 > 0:54:21I think this was a clutch of 19 eggs.
0:54:21 > 0:54:23- 19?- 19.
0:54:23 > 0:54:25And all 19 have embryos.
0:54:25 > 0:54:27This is one of the better ones.
0:54:27 > 0:54:30What you see here is the thigh bone, the femur...
0:54:32 > 0:54:33..the tibia, and then the...
0:54:35 > 0:54:38..ankle joint and foot underneath, and then,
0:54:38 > 0:54:40very carefully open it up...
0:54:41 > 0:54:42And what can we see there?
0:54:42 > 0:54:45What we're looking at here is the right leg.
0:54:45 > 0:54:47There's the left leg, the tibia,
0:54:47 > 0:54:52and then between the knees is the skull, sitting in there.
0:54:52 > 0:54:53- Ah!- Right in here.
0:54:53 > 0:54:55So we can see the...
0:54:55 > 0:54:57The tiny little teeth had erupted in the jaw.
0:54:57 > 0:55:00So it could give you a nip just as soon it hatched?
0:55:00 > 0:55:01- Right, mm-hmm.- Yeah.
0:55:01 > 0:55:03- Just like young alligators can today.- Yes.
0:55:06 > 0:55:09BIRDSONG
0:55:09 > 0:55:12But 64 million years ago,
0:55:12 > 0:55:16the hadrosaurs and all the other dinosaurs vanished.
0:55:17 > 0:55:20The reign of the dinosaurs had ended.
0:55:28 > 0:55:30There are many theories as to why the dinosaurs
0:55:30 > 0:55:32finally became extinct.
0:55:32 > 0:55:34One of the most recent is that an asteroid from outer space
0:55:34 > 0:55:38collided with the Earth, creating such an immense explosion on impact
0:55:38 > 0:55:42that the skies filled with dust, blotting out the sun.
0:55:42 > 0:55:44In the darkness, the plants all died,
0:55:44 > 0:55:47and the dinosaurs, with nothing to eat, starved to death.
0:55:47 > 0:55:51Well, there are two problems with that or any other theory
0:55:51 > 0:55:54which depends upon a single catastrophe as the explanation.
0:55:54 > 0:55:56The first is that the dinosaurs didn't die out
0:55:56 > 0:56:00over a period of a year or a decade, but over thousands of years.
0:56:00 > 0:56:04And the second is that although the dinosaurs died out,
0:56:04 > 0:56:05many other creatures didn't.
0:56:09 > 0:56:13These alligators are reptiles, just as the dinosaurs were.
0:56:13 > 0:56:16They evolved on Earth long before the dinosaurs,
0:56:16 > 0:56:18yet they've survived to the present.
0:56:18 > 0:56:20It seems unlikely that they would have lived through
0:56:20 > 0:56:24a sudden global catastrophe in which the dinosaurs perished.
0:56:29 > 0:56:31A more likely explanation, to my mind,
0:56:31 > 0:56:34is that there was a gradual change in the climate of the Earth,
0:56:34 > 0:56:37and some animals, such as birds, for example,
0:56:37 > 0:56:40were better able to cope with this than the dinosaurs,
0:56:40 > 0:56:43with their less-than-perfect control over their body temperature.
0:56:45 > 0:56:47The early birds, like birds today,
0:56:47 > 0:56:50were protected by their superbly efficient
0:56:50 > 0:56:53insulating coats of feathers, so they survived.
0:56:57 > 0:57:00Small reptiles were able to take refuge against the cold
0:57:00 > 0:57:04in nooks and crannies, and reptiles that lived in water
0:57:04 > 0:57:07were cushioned against extreme temperature changes.
0:57:11 > 0:57:14So the Earth still retains representatives
0:57:14 > 0:57:16from all these animal groups.
0:57:21 > 0:57:26So, today, less than 200 years since we discovered
0:57:26 > 0:57:28that these animals even existed,
0:57:28 > 0:57:30we've learned so much about them
0:57:30 > 0:57:33that we can almost hear the champ of these huge jaws,
0:57:33 > 0:57:38visualise the glints in the eye that once revolved in this empty socket,
0:57:38 > 0:57:43clothe this immense skeleton with leathery skin and muscles,
0:57:43 > 0:57:45and picture, in our imaginations,
0:57:45 > 0:57:49in almost as much detail as if they were alive today,
0:57:49 > 0:57:53these bellowing, battling,
0:57:53 > 0:57:55browsing, nesting, courting,
0:57:55 > 0:57:58scavenging, fighting creatures
0:57:58 > 0:58:00that disappeared from the Earth
0:58:00 > 0:58:04over 50 million years before mankind appeared upon it.