Documentary, Extinct Complete Series 2 Episode 2 - The Sabertooth
#TheSabertooth #Extinct #Sabertooth #ExtinctSabertooth
#TheSabertooth #Extinct #Sabertooth #ExtinctSabertooth
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AnimalsTranscript
00:00You
00:30This fertile wooded valley is a land of giants.
00:55In it, one creature rules above all others.
00:58A highly evolved killer.
01:01For a million years, this top predator has lived unchallenged.
01:05It is Smilodon Fatalis, the sabre-tooth.
01:15But this formidable animal, with no predator to fear and plentiful gain to eat,
01:20is about to disappear forever.
01:2811,000 years later, a city of freeways and skyscrapers has arisen from the valley.
01:39Yet it has not totally obliterated all traces of the sabre-tooth.
01:52Evidence still remains beneath downtown Los Angeles.
01:56The Rancho La Brea tar pits is one of the world's most extraordinary fossil sites.
02:03These pools of tar contain a record of life stretching back into the ice age.
02:11Paleontologists have unearthed millions of fossilized bones.
02:15For Blair Van Volkenberg, it's a gold mine.
02:20Believe it or not, this black swamp that I'm standing in the middle of is a paleontologist's dream.
02:27I mean, it is hard to believe looking at it, but it is chock-a-block with bone.
02:31I mean, from all the tar pits that are in this small area, there are over 4 million specimens that have been found.
02:39Things as small as rodents and as large as mammoths.
02:44This paleontologist's dream is the result of an accident of ancient geology.
02:50Tar seeps from under the earth through cracks caused by California's frequent earthquakes.
02:56Pools of deadly oil formed just below the surface.
03:01Ten thousand years ago, you're a thirsty animal, and you might walk out, approach that water,
03:07and because you're a rather large and heavy animal, you'd find your feet sinking,
03:12and you would struggle, but that would actually probably drive you deeper as you struggle,
03:17and pretty soon you'd be in a position from which you were no longer able to get yourself out of.
03:26It would have been a slow, agonizing death.
03:29And even today, we see things getting stuck.
03:31It's not that this process stopped ten thousand years ago.
03:34It's still happening.
03:35You can see the tar coming up on the surface,
03:37and over here you can see a little yellow-rummed warbler that probably innocently saw some water
03:42or saw a bug on the surface and swooped down to get it and never took off again.
03:47Tar is one of nature's great preservatives.
03:53So even the smallest of bones remain.
03:58Paleontologists can reconstruct the past using the bones of the animals that they find,
04:06especially when they're beautifully preserved as they are at Rancho La Brea.
04:10You can reconstruct the strength of the animal, you can reconstruct the size of the animal,
04:17you can reconstruct its feeding habits from its teeth.
04:20The preservation at La Brea allows us to reconstruct the entire fauna with relative ease.
04:26But Rancho La Brea is famous for reconstructing one creature above all others, the saber tooth.
04:33Over two thousand of them have been recovered.
04:36Now we can probably guess that this might be a female.
04:40It's hard to tell because female and male saber tooth were about the same size.
04:44So we need to really do a lot of detailed measurements to actually figure that out.
04:48And it really illustrates how well the tar preserves these fossils.
04:52There's just no distortion.
04:53The cat is very beautifully preserved and it's very easy for us to think about them moving around the landscape here,
05:00recreating, at least for a paleontologist, it's easy to recreate them in our own mind
05:04and see them roaming the plains of Los Angeles some eleven thousand years ago.
05:19This female saber tooth is nine years old.
05:23She's very similar to a male cat, up to a metre high at the shoulder and the weight of four men.
05:35She's tracking her prey, searching for the scent left by a large game like bison or horses.
05:42The saber tooth is often thought of simply as a lion with big teeth, but it's a very different animal.
05:59She's twice as heavy as a modern lion, built more like a bear with stocky muscular shoulders,
06:05shortened hind legs and a stunted tail.
06:09All designed to deliver power to her killer canines.
06:18So why did the saber tooth evolve its bizarre body and even stranger teeth?
06:27And is there a link between them and the animal's extinction?
06:31Obviously one of the most remarkable things about saber tooth cats are these saber like canine teeth that they have.
06:38And these are the longest canine teeth of any carnivore that ever existed.
06:42At least for the size of the cat, they're definitely the longest.
06:44And they're very sharp actually on the back edge and they're narrow from side to side and knife like in cross section.
06:53Clearly the teeth were vicious weapons, but little is understood about how the saber tooth used them to kill.
06:59To find out means looking at the muscular structure of the entire body.
07:07But there's a problem. The tar pits preserve bone, not muscle.
07:13So one paleontologist has turned to modern cats to investigate this.
07:19The nearest match isn't a speedy runner like a cheetah, but the slower moving jaguar.
07:25This zoo animal died of natural causes.
07:36Now it's helping Virginia Naples to find out how its ancient saber tooth relative actually behaved as a predator.
07:42The biggest mystery about saber tooth cats is how an animal with very long and very sharp, but very thin and brittle teeth could have been able to make a bite without these teeth being broken.
07:56And how were they able to use their muscles in order to generate enough force to make the bite.
08:04Understanding how the jaguar's biting muscles attach to the skull allows Virginia to compare the awesome power of the saber tooth's bite.
08:12The saber tooth cat skull, in addition to being larger than the jaguar skull, is different in shape and you've got much greater space here for this muscle than you do in this animal.
08:25So we can assume this muscle was bigger and therefore could exert more force than the corresponding muscle in the jaguar, which would help to give this animal a stronger bite.
08:37The skull also reveals the mouth could have opened some 30 degrees wider than the jaguar and other modern cats to administer the killing bite.
08:47The shape of the skull and the heavy body both show the creature had evolved to ambush lone animals.
08:55We've got an animal here with very heavy limbs, short legs, it would not have been a sprinter, it would have had to hide in ambush and sneak up on its prey.
09:08This animal was much bigger, relatively speaking much heavier, with even heavier muscles.
09:15If this animal could not run particularly fast, this animal would have been even more dependent upon hiding from its prey and then pouncing on it at the last minute.
09:25A lone bison has moved into the female's hunting ground in search of fresh grazing.
09:41Without the protection of a herd it's exposed to a terrible risk.
09:48The female saber tooth is hungry and she has two new cubs to feed.
09:53Her massive bulk means she can eat around 30 kilograms of meat in one go.
10:04As a slow runner, good cover is vital to the success of her ambush.
10:09If she can pounce she's capable of severing a bison's jugular and crushing its windpipe with a single bite.
10:22Yet even for a predator as deadly as the saber tooth, ambush hunting is a high risk strategy.
10:41She's paid a price for her kill, injuring her back while wrestling the two-ton bison to the ground.
10:49Proof that hunting could take a heavy toll on saber tooth comes from the bones found at La Brea.
11:02Paleopathologist Chris Shaw finds hundreds of similar injuries on saber tooth bones,
11:07many of which he thinks were caused by bringing down large prey.
11:12Being a large vicious carnivore is an awfully risky business no matter where you are in the world.
11:19We have this very nice example of a pelvis of a saber toothed cat.
11:24This side is normally developed, looks and shape is very normal.
11:30On the other side however, we have a very traumatic injury.
11:35What happened here was that the thigh bone itself had dislocated from the joint
11:41and there was complete destruction of cartilage which affected this area by bacteria getting in here and causing a massive infection.
11:52Over 5,000 mangled saber tooth bones have been found at La Brea.
11:58For Chris, they are not only evidence of the high risk hunting strategies saber tooth pursued,
12:04but how group behavior may have evolved to help injured animals.
12:08The incredible thing is that these crippling injuries did not kill these animals.
12:15What killed these animals was the La Brea turpids, getting entrapped in the La Brea turpids.
12:20To me, these injuries indicate that these animals were social animals and being part of a social group affords these really seriously injured individuals the opportunity to feed at group kills and also to be protected by the rest of the group.
12:41Several hours have passed since the kill and the injured female has eaten her fill.
12:51She's joined by her cubs. While they eat, she nurses her wounds.
12:55A male comes along. He's her two-year-old son. She tolerates his presence. In fact, this social behavior helps defend the kill from scavengers.
13:12Until they've all eaten their fill.
13:20The saber tooth thrived as long as there was prey and adequate cover from which to attack it.
13:25But while life seems abundant, this saber tooth family are already facing a threat that will prove decisive.
13:35Around them, their valley home is changing and their reign as the top predator is about to end forever.
13:42Having reigned as top predator for a million years, this saber tooth along with the rest of her species is suddenly facing extinction.
14:00The fossil record at the La Brea Tar Pits reveals that a catastrophe overwhelmed many species.
14:18Not just the saber tooth, but many other animals disappeared too.
14:22About 11,000 years ago, something strange happened and we find no more of these saber tooths anymore in this tar pit or anywhere else in North America.
14:34And lost alongside them are the dire wolves and the mastodons, the mammoths, the camels, the horses, all the things they preyed upon.
14:42In fact, this saber tooth is probably one of the last saber tooth cats that existed in North America.
14:47In this land of giants, many of the largest animals like the mammoth died out.
14:57Dating their remains shows this coincided exactly with the end of the last ice age.
15:03For 100,000 years, global temperatures had been around 10 degrees Celsius colder than today.
15:10But by 11,000 years ago, the climate was warming up.
15:18In Arizona's Sonoran Desert, paleobotanist Julio Bettencourt has discovered compelling evidence,
15:25revealing what conditions were like when the saber tooth ruled,
15:29and the drastic change that was about to overwhelm it.
15:36Today, the Sonoran Desert is very dry, but Julio's discovery reveals that it wasn't always like this.
15:42And evidence for this comes from an unlikely animal, the pack rat.
15:51This seemingly unremarkable rodent reveals a major environmental change was unfolding at the same time as the saber tooth disappeared.
16:00All because of how its ancestors built their nests 12,000 years ago.
16:10Well, here's what all the excitement is about.
16:13This is actually a pack rat nest right here that was occupied by a pack rat, in this particular case, about 12,000 years ago.
16:20Pack rats use these rock shelters for cover, and they bring in a lot of plant material from about 50 meters, 60 meters away.
16:30The plants the pack rat built its nest from have been preserved in a unique way.
16:36The pack rat oftentimes pees all over these piles of plant remains,
16:41and as the urine evaporates, it crystallizes and holds all of this material together like amber.
16:50But most significantly, the preserved plant remains confirm forests grew here, during the Ice Age when it was colder and wetter.
16:59The beauty of it is that the preservation is actually exquisite.
17:07We see here, for example, that there are the needles or the leaves of a pine.
17:13We also have junipers and oaks.
17:16So we know that there were pine, juniper and oak woodlands covering most of the Sonoran Desert at the end of the last Ice Age before.
17:24Big herbivores and things like saber-toothed tigers became extinct.
17:30But the pack rat evidence from a thousand years later tells a very different story.
17:36The pine and oak forests were disappearing.
17:39The Ice Age was coming to an end, heralding massive environmental changes that continue till this day.
17:45So the overall trend for the southwestern United States and Southern California since the last Ice Age has been towards hotter, drier environments and towards more desert vegetation.
18:00But how could changing vegetation be linked to the extinction of a carnivore like the saber-tooth?
18:09While the change didn't affect the female and her cubs directly, it did affect their food supply in vital ways.
18:17Ironically, paleoecologist Greg McDonald believes it actually increased it.
18:23The biggest mystery that we have to look at is the fact that not everything goes extinct, that you have animals that do survive.
18:32Here in North America you have mammoths, mastodons, horses, they all disappeared.
18:39And yet other groups of animals like the North American antelope, the American bison, a lot of those animals did survive and did quite well, increased in numbers and spread out.
18:50Horses didn't return until Spanish conquistadors reintroduced them a mere 500 years ago.
18:58Scientists must explain their extinction and also why the bison survived and thrived.
19:10To solve this puzzle, Greg must investigate how different animals coped with the changing vegetation.
19:16This is not a job for the squeamish.
19:21Talking about why some animals became extinct and other ones survived,
19:26one of the clues that we can look at is actually in their dung.
19:31If we tear apart the droppings of a buffalo and look at the plant fibers inside,
19:40we can see that they're very fine and that's because they chew their food twice.
19:45If we look at horses, animals with a simple stomach,
19:51you can see that the plant material is much coarser.
19:54What this means is that buffalo, the ruminants, get a lot more nutrition out of the plant material
20:00than what the simple stomached animals like the horse can do.
20:03As the variety and nutritional value of plant life changed,
20:13it now seems the ruminants had an in-built evolutionary advantage.
20:18The variety of plants that's living in an area is changing,
20:23and this probably creates a crisis,
20:25and those animals that are better at getting the nutrients out survive like the bison,
20:32whereas those that are not as good are going extinct like the horse.
20:38But for the saber-tooth, the proliferation of bison means hard times.
20:44Despite the fact she's beautifully designed as an ambush predator,
20:48she's becoming peculiarly vulnerable.
20:50In drier, more open country, there's less cover,
20:55and she'll struggle to hunt using her highly evolved ambush skills.
20:59She'll need to chase down her prey, but she simply isn't built for speed.
21:06Bison farmer Larry Toller appreciates how hard it is to hunt bison.
21:12To kill a bison is damned hard.
21:14They don't like to separate from each other.
21:16They stay as a very close, tight-knit group, and they protect the babies.
21:20To get one separated is almost impossible because the herd doesn't want it to happen.
21:27The ability to hunt successfully, always a tricky business,
21:32was now even more difficult.
21:34Not only was there less cover to ambush from,
21:37fossil discoveries show Greg MacDonald
21:40that the bison were evolving a powerful new defense mechanism.
21:44One of the things that we see happens is they become smaller.
21:46This does have advantages, though, because a smaller animal does not require as much food for survival,
21:52and you can pack more animals into a given area,
21:56which means you can have larger herds,
21:58which has the advantage of more eyes, more animals on the watch out for predators.
22:02The growth of large bison herds was another terrible blow to the saber-tooth's chances of survival.
22:17As the ice age ended, solitary prey is hard to find.
22:21Many prey species have disappeared.
22:23Others, like bison, have safety in numbers.
22:32So while there's plenty of meat on the hoof,
22:35catching it is very hard for an ambush predator.
22:42Despite being beautifully designed to pounce and kill,
22:45now everything is working against her.
22:48In bigger groups, the bison spot danger more easily across the open land.
23:01They've seen her coming, and can easily outrun her.
23:03Superb adaptation to an ice age environment, didn't help the female saber-tooth once that environment changed.
23:24In a different world, the predator at the top of the food chain is even more vulnerable to annihilation.
23:31Starving, the female saber-tooth has had to abandon her cubs.
23:52She'll never reproduce again.
24:04Forced to survive on carrion, the smell of rotting flesh lures her to the deadly tar pit.
24:13Hunger overpowers her sense of caution and drives her to the edge of the black abyss.
24:22Let's go.
24:31No, you can learn without her.
24:49Transcription by CastingWords
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