Home
ログイン
会員登録
学習コンテンツ
Loading...
We're Sending Our Audience Poop. You're Welcome. - Video học tiếng Anh
リスニング練習
リスニング練習
/
Video
/
SciShow
/
We're Sending Our Audience Poop. You're Welcome.
We're Sending Our Audience Poop. You're Welcome.
学習モードを選択:
字幕を表示
単語を選ぶ
単語を書き直す
Highlight:
3000 Oxford Words
4000 IELTS Words
5000 Oxford Words
3000 Common Words
1000 TOEIC Words
5000 TOEFL Words
字幕 (170)
0:00
This April first, have you considered sending your loved ones a piece of old poop in the mail?
0:06
Sure, most people wouldn’t be too thrilled to receive a gift like that.
0:09
But if you happen to know any paleontologists,
0:12
then a petrified poop could be one of the best gifts you could give.
0:16
Because while traditional fossils - shells, bones, teeth - can tell
0:20
us what ancient animals were like when they died, their poop can tell us how they lived.
0:27
[♪ INTRO]
0:30
I should make it clear right from the beginning that I am in no way
0:33
advocating the giving of fresh poop to anyone.
0:37
I’m talking about coprolites, which is the technical term for a fossilized poop.
0:42
Of course, lots of rocks can look like poop.
0:45
Brown, smooth and rounded, kinda grainy,
0:48
maybe even with the occasional chunk of something unidentifiable in them…
0:52
These can all be features of a common beach pebble, too.
0:56
But that doesn’t mean that every pebble on the beach is a poop.
0:59
You’re far more likely to pick up a fresh specimen than a fossilized one on your vacation.
1:04
So instead, scientists look for a bunch of other things to confirm their treasure.
1:09
Some coprolite hallmarks are the same sort of thing you’d expect to see in fresher poop.
1:14
An outer patterning of contraction marks and gas bubbles, and an internal
1:20
structure with pieces of undigested debris can be the telltale signs.
1:24
But one big distinguishing feature is the presence of calcium phosphate inside the rock,
1:30
which can come from the digestion of bones and animal proteins.
1:34
While lab analysis can confirm this, palaeontologists have even been known to
1:39
identify coprolites in the field by using the ‘lick test’.
1:44
Yes, I said, “lick test.”
1:47
Apparently, if you press your tongue against a rock and it sticks a little as you pull it away,
1:52
then chances are you’ve just licked a fossil bone or a fossil poop.
1:58
Lovely!
1:58
It might sound gross, but coprolites are really more
2:02
rock than poop by the time they reach your tongue.
2:05
In order for them to be preserved, fossilization needs to start pretty quickly after being
2:10
… deposited … so that they’re not recycled by hungry bacteria and other decomposers.
2:16
Under the right conditions, the soft, squishy stuff of poop becomes
2:20
completely replaced by hard, durable minerals like that calcium phosphate.
2:25
Carnivores eat all parts of their prey, and make poop that is already full of bone debris, making
2:32
them more likely to be replaced and preserved, compared to the poop of their herbivorous cousins.
2:37
But calcium phosphate can come from other sources,
2:40
and poops from many different creatures have been found in the fossil record.
2:45
The challenge then, is to figure out exactly who pooped your fossil poop,
2:49
which is not always an easy task.
2:52
Occasionally, chemical analysis can find traces of DNA or other
2:56
biological molecules that can pin down the source,
2:59
but since everything is typically replaced with new minerals, this kind of certainty is rare.
3:06
Instead, scientists look at a whole bunch of things to pin down the pooper - like
3:10
the age of the surrounding rocks and the presence of other animal fossils.
3:15
Then, the coprolite’s size and shape can be compared with modern
3:18
examples and the relevant anatomy of the culprit.
3:22
In this way, paleontologists have identified coprolites from trilobites, sharks,
3:27
crocodiles, dinosaurs, hyenas, and many more.
3:30
So once you’ve confirmed your poop-shaped rock really is poop, and you have a decent idea of who
3:36
it belonged to, then you can get to the good stuff: figuring out how your creature lived.
3:42
The first insight is the most obvious one.
3:45
Coprolites can tell you what an animal ate.
3:47
Back in 1998, researchers looked in detail at a Cretaceous coprolite so
3:53
large that it could only have been produced by a huge animal, like Tyrannosaurus rex.
3:58
Inside the fossil, which is about as long as a forearm and nearly twice as thick,
4:04
the researchers found bone fragments.
4:06
And not just a few - up to half of the entire coprolite was made
4:10
up of pieces of bone that had been fractured before being swallowed.
4:15
This study, when it came out, turned what we thought we knew about T rex’s feeding on its head.
4:21
Based on how modern predatory reptiles feed, scientists thought that these carnivorous
4:25
giants would have focused mainly on tearing flesh off their victims.
4:29
But the coprolite showed that they were capable of making bigger chomps, ripping
4:33
flesh and crushing the bone of, for example, a triceratops frill, in one devastating movement.
4:40
This revelation helped to change our view of T rex’s behaviour and its physical strength.
4:46
Previously, researchers had doubted that the dino’s teeth were up to the task,
4:51
but this king-sized poop showed definitively that they were.
4:55
Not every dinosaur coprolite tells of devastating predatory strength, though.
5:00
Another study of Cretaceous coprolites, this time thought to be produced by herbivorous Titanosaurs,
5:06
surprised scientists with the range of plants they contained.
5:09
These fossil poops had fragments of cycads,
5:13
related to the modern sago palm, as well as conifers and grasses inside them.
5:18
That last one was a real shocker
5:20
The problem seems to be that grass, without any woody structure to preserve,
5:25
doesn’t leave much of a trace in the fossil record.
5:28
But finding it in these gentle giants’ poops shows that they were not only there,
5:33
but they were already being used as a food source for millions of years before the dino’s demise.
5:39
Coprolites are very good at giving us a glimpse – albeit a mashed, crushed,
5:44
and half-digested glimpse - of what passed through an extinct animal’s gut.
5:49
But they are also surprisingly good at showing
5:51
us what was still in there when the poop was produced.
5:55
If an animal has internal parasites, like worms or single-celled amoebas, then these
6:00
parasites typically reproduce by releasing eggs and protective cysts out with the animal’s poop.
6:07
And when that poop becomes fossilized, the parasite eggs can be too.
6:11
Coprolites provide evidence for some of the oldest parasites found so far in the animal kingdom.
6:17
Clusters of tiny tapeworm eggs, each around a tenth of a millimeter in diameter, have been
6:23
identified in 270-million-year-old shark poop from the Permian period.
6:29
And a sample of Triassic poop, which researchers think was produced by
6:33
something like a crocodile, contains at least five different types of parasite.
6:38
The researchers think this unfortunate animal probably got its parasites from
6:42
feeding on a range of other animals, like fish and amphibians which had the parasites themselves.
6:49
Findings like this not only give a complete picture of an animal’s physiology, but they
6:54
can also help give information about their population density and behaviour.
6:59
For example, scientists have studied the numbers and types of eggs and cysts found
7:04
in ancient human poop, and in places they routinely left their poop, like latrines.
7:09
These show that among ancient humans, the amount of parasitic
7:12
infections increased when they shifted from nomadic to agricultural societies,
7:18
presumably as a result of more people living together and sharing the same space.
7:24
Not only that, but finding particular types
7:26
of parasites can give a clue to how ancient humans lived.
7:30
For example, human coprolites from Peru and Chile, dating to around 5,000 years ago, contain evidence
7:36
of tapeworms and flukes, which today are known to be transmitted by eating raw or undercooked fish.
7:43
Modern inhabitants of these countries can still be infected with these parasites
7:47
from eating the traditional Pacific coastal dish ceviche.
7:51
The fossil parasites are seen by researchers as evidence of this
7:55
traditional dish’s roots extending far back into American prehistory.
8:00
So, coprolites can tell us what an ancient animal ate,
8:04
but they can also give us a clue to how efficiently their bodies worked.
8:08
For instance, in the early 19th century,
8:11
spiral-shaped rock specimens were thought to be the fossils of fir cones.
8:15
But experimental work with modern fish revealed that these snazzy spiral rocks
8:20
are actually produced inside the intestines of fish like sharks,
8:25
making them a kind of internal coprolite: a poop preserved before being pooped.
8:32
And in addition to being cool-looking, these spiral intestine stones tell an important story.
8:38
Because this kind of gut, known as a ‘spiral valve’,
8:41
has evolved to have extra surface area over which nutrients can be absorbed.
8:46
They’re more efficient than the traditional tubular style,
8:49
and a sign of a body and metabolism suited to getting more out of every meal.
8:54
And remarkably, fossils of this kind have been found in rocks dating all
8:58
the way back to the Ordovician, around 450 million years ago.
9:03
In contrast, dinosaur coprolites show that these animals did things very differently.
9:09
In Alberta, Canada, scientists picked apart a perfectly preserved poop that
9:14
probably belonged to a carnivorous tyrannosaurid from the late Cretaceous.
9:18
The internal texture was so finely fossilized that the researchers
9:22
were able to find bundles of undigested muscle fibers from the animal’s last meal.
9:27
Not only that, but a Triassic coprolite from Poland, thought to belong to a
9:31
reptilian dinosaur relative, was scanned with X-rays to reveal whole beetles,
9:37
some of them with their legs and antennae still intact.
9:40
The specimen was so perfect that researchers were able to show
9:44
that the undigested beetles were a new species, previously unknown to science.
9:50
Not only are these impressive feats of preservation,
9:52
but they also say a lot about the gut transit time for these animals.
9:57
For structures as fine as beetle antennae to survive through a dinosaur’s body in one piece,
10:02
then that journey must have been really really quick.
10:06
That suggests that these dinosaurs had fast digestion and high energy requirements,
10:11
favoring quantity over quality when it came to their meals.
10:15
Unlike modern crocodiles, for example, which can sit and digest for days.
10:20
So we’ve seen that coprolites can tell us about an animal’s diet, its parasites, and its digestion.
10:27
But there’s one more insight we can get from these fossil poops,
10:31
and that’s the creature’s role in the wider ecology.
10:35
For example, researchers studied 35 coprolites discovered in a cave
10:39
in New Zealand, dating between 6,400 and about 700 years ago.
10:44
Using DNA analysis, they showed that these coprolites belonged to
10:48
the now-extinct moa - a large flightless bird that was endemic to New Zealand.
10:53
In the fossil poops, they found evidence of 67 separate species of plant,
10:58
including a number of intact, undigested seeds.
11:01
This not only suggests that these birds played an important role in helping to
11:05
disperse plant seeds for reproduction, but it also reveals the extent of that dispersal.
11:11
The variety of plant species in their poops suggested that they browsed widely
11:16
between surrounding forests and grasslands,
11:19
and may have roamed more than 600 meters just to reach certain plants.
11:24
In this way, the cave coprolites are helping to paint a picture of the moa as it lived in
11:29
its environment: it was a generalist herbivore with a wide-ranging impact on the local ecology.
11:35
So whether you want to learn about an animal’s diet, the shape of its intestine,
11:39
or how far it walked for food, coprolites have you covered.
11:43
And we have you covered if you're a SciShow Rocks Box subscriber.
11:48
This month, we’re sending everyone a coprolite from the late Cretaceous of Madagascar.
11:53
If you’re interested in getting authentic fossils and minerals like that in the mail,
11:57
visit Complexly.store/rocks to find out more.
12:02
And do feel free to take my word for it, rather than licking it to test for yourself.
12:08
If you’re a SciShow Rocks Box subscriber, you’re going to love the latest Crash Course.
12:13
It’s finally time for Crash Course Geology!
12:16
The Earth we know is very different than it was two billion years ago… and yet,
12:21
geologic rules and processes remain the same.
12:24
By uncovering these constants, we can reveal our planet’s past,
12:28
learn how to thrive in the present, and prepare for the future.
12:31
In this 25 episode series, you’ll learn the basic principles of geology
12:36
as they guide you on a tour of the Earth’s past, present, and future.
12:40
And you can watch it right now on the Crash Course YouTube channel!
12:45
[♪ OUTRO]
