March 3, 2011 • 35 mins
A fossil is a piece of once-living organic material that has undergone a transition from an organic state to an inorganic state. But what exactly is fossilization? Listen in as Josh and Chuck break down the process of fossilization.
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Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve camera.
It's ready. Are you welcome to stuff you should know
from house Stuff Works dot com. Hey, and welcome to
the podcast. I'm Josh Clark with me as always as
the intrepid paleontologist Charles W. Chuck Bryant. It's terrible, Wasn't
(00:27):
I like it? Okay? I wish I was a Paleontologist's
your new nickname? Or intrepid? At least? Let's just go
with paleontologists. That'd be great. Okay, we're talking fossils today. Dude,
this isn't really interesting stuff? It really is. And um,
you can tell that Tracy Wilson are esteemed head of
the writing editor. I think she's site director director right. Um,
(00:51):
you can tell that she was very, very excited. She
took her time and really dolled this one out. I think, um,
save her is the right word. You can feel it
her smiling through the keyboard. Yeah, she's very happy to
write how fossils work, and um, we're happy to do
it because it's one of those very comprehensive articles on
(01:12):
the site that you just has. It has everything you need.
Sedimentary rock flat bones versus round bones leaf impressions has
it all unless you're an intrepid paleontologist, and we'll get
an email saying it actually wasn't very comprehensive. You guys
royally screwed this up. We just wait until we get
into punctuated versus gradual evolution. Chuck, Um, you've heard of
(01:38):
Lucy right, the austral epithecuss Yeah, okay, Well, Um, she
was I think three point two million years old. That's
one old lady. It really is the earliest hominid we've
found as far as I know. Um, But there's a
part of her foot missing. It's always been missing that
we've never found before. So this thing, this bone, was
(02:00):
so essential that we couldn't tell how she walked until recently.
Why because the missing bone, we couldn't tell how she
walked exactly. We we we can tell so much from
bones that when we don't have the right bones, we
can't tell anything. So she may have been in a
knuckle dragger, she may have hopped, we didn't know. Well. Recently, Um,
(02:22):
some people from the University of Missouri or Missouri, depending
on whether or not you live in the state, UM
found the Uh, the group of foot bones needed to
show what kind of walker Lucy was. And she walked
up right? How was her gate? Upright? Upright? Just like
a human. She had a hitching her get along, she
(02:43):
had a pepper and her step. Possibly she knew she'd
be famous one day with duck. But but consider this, right,
three point two million year old footbones were found and
we could tell from them how she walked. This is
the state of the field that you remember paleontology. Pretty cool.
(03:06):
This is how advanced it is, and yet it's really
just kind of using common sense to figure out what
old bones mean. Common sense and science. Fossils go, let's
talk about it, Chuck. What are some of the different
kinds of fossils. Uh, well, one of my favorite kinds
(03:27):
is trace fossil. Yeah, that's actually one of my favorites too.
It's like, um, that Jesus footprint thing, footprints in the sand. Yeah,
it's sort of this josh um that is when it's
actually not part of the organism at all, but it's
um like tooth marks in a chunk of wood from
(03:49):
a saborite tooth tiger, or footprints or footprints or track ways,
as Tracy calls them. Yes, footprints, it's just unnecessary, but
it has a pleasant tone, you know science. Yeah, they're
not footprints, the track ways I'm bored in Ethiopia, let's
call so trace fossils is one. Of course, there's bone fossils, right,
(04:10):
the most famous fossils. Yeah, those are great too. They
got nothing on trace fossils. So actually, bone fossils, that's
that's what you really want. If you're going to reconstruct
a dinosaur for your museum. You can't deal it with footprints, No,
you can't. You need the bones. And the bones are
of course the most famous ones in the dinosaur bones
are the most famous of all the bone types. Right.
(04:31):
So there's something that I think um is often missed
by lay people such as myself um in in that
when you find a bone, right, so, you find like
a big old dinosaur bone, it's really geologically speaking, it's
not a bone any longer. It's not like you find
(04:52):
a bone buried in your yard that was an animal
from like, you know, thirty five years ago, but that's
not a fossil. That's still bone. A fossil is a
bone or a piece of um, once living organic material
that's undergone a transition from uh, an organic state to
an inorganic state. That's what a fossil is. It's gone
(05:13):
through the process of fossilization. And most of these fossils,
the vast majority of fossils, are found in sedimentary rock.
Before we go any further, we should probably do a
little brief primer on sedimentary rock, right, which is awesome. Yeah,
it's pretty easy to Uh, we've talked about the Earth's core,
um and layers. When I think we talked about earthquakes
(05:35):
and maybe some other stuff. We all know that there's
the inn core, outer core. We got the crust. Crust
is the thinnest layer, and that's where the fossils are.
That's where the goods are. And uh, most of the
rocks in the crust are sedimentary rocks. You've been talking
about off and on for the past eight minutes, right,
And that's like silty sandy stuff that hardened over the right,
(06:00):
I mean, but the the Earth, Remember we talked about oh,
what was it clouds I can't remember what podcast it was,
but we talked about how much sand is transferred from
Africa to South America annually. But if you remember the
one I'm talking about. Okay, so the Earth's geo biogeochemical
(06:21):
processes equal a lot of movement of particulate matter. Right.
The Earth is dynamic, baby, it is. It's also very fluid.
To write, A lot of that matter is at at
one point as suspended particles in water that's moving around, right.
So um as this as the water leaves and the
(06:44):
sediment is deposited, it builds up and up and up.
Over time, it hardens into rock and eventually we have
sedimentary rock which is below our feet. We don't normally
see it unless say, the Colorado River um winds over
it for you know, millions and millions and millions of years,
revealing the sedimentary rocket that's in the Earth's cross Grand Canyon,
(07:08):
exactly what you're talking about. Yeah, I forgot the Grand
Canyon park. So you know how I said the Earth
was dynamic, baby? Yeah? Uh, that's important. I didn't just
throw that in there as a factoid. It's important because
when these plates shift around, that's how fossils are on Earth.
Things can be moved great distances and pushed to the
surface eventually or close enough to where a dig can
(07:29):
unearth it. And it's like just because it's fossilized, doesn't
mean it's stuck in that one spot forever, because Earth
is always moving. So the point of all this is
is sedimentary rock um is like you said, dynamic. It
moves around. Sometimes fossils pop up, or it becomes exposed
all of the Colorado River um, and that is where
fossils are, right Chuck. Yes, So let's say that at
(07:53):
some point in time there was a dinosaur or a
saber tooth tiger or a cyanobacteria wily mammoth, woly mammoth,
sure um, and it's um hanging out around the riverbed
and it has a massive heart attack and falls over
in the river bed and very quickly it becomes covered
(08:14):
with sediment and silt, right yeah, And that's important because
once it starts getting covered up with stuff, it's sort
of being protected from like all of us. Let's just
break the news. All of fossil means is that something
has been protected from the natural decomposition process. Otherwise we
just decompose like everything else and you wouldn't see anymore.
(08:36):
You just totally betrayed Tracy in the tone she went
to this, that the whole drama drawing out suspense. But
that's true. So what you said was right. So you'd
fall over in a riverbed, you start getting covered up
with the sediment and silt, and it's it's immediately starting
to protect you in a way. Um, not you, but whatever,
the wily mammoth, the wooly mammoth. Um. The thing is
(08:58):
the in this sediment, in this still, you can't really
hide from macrobacteria, uh and other forms of life that
are basically dedicated to breaking down organic matter, soft tissue, hair, eyeballs, um, genitalia,
all that kind of stuff. It eventually becomes broken down
(09:19):
and what's left is the hard stuff, the bone, right,
But the bone also has organic material within it as well. Yeah,
and that'll break down. We're talking blood, cells, collagen, fat,
that's gonna break down. To the key here is the
inorganic parts of the bone remain intact. And it's the
other keyword here's porous. Yes. Well, you take calcium, I
(09:41):
imagine for your hips. Yeah, sure, glucosim and calcium. Sure.
So what you're doing is, um, you're fortifying the calcium
that's already in your hips supposedly, um, because the bone
is made in large part of calcium, which is a mineral,
which is inorganic, So it's all the organic stuff dies
that out. What's left is, like you said, the inorganic
(10:03):
like calcium, whatever, minerals, and that holds the shape, right. Yeah,
the initial structure is kept intact, right, But like you said,
this bone is also porous. Yeah, that's the key, and
over time, um other mineral sediment kind of um it
enters into these these microscopic pores iron right, carbonate and
(10:25):
fortifies this, ultimately turning this but what was once an
organic bone into an inorganic rock in the shape of
the bone. Yeah, but for all intensive prefaces, it's still
the bone. It still has that original calcium. It's still
the same thing. It's not like a replica of it.
It's just become fossilized. Yeah. And Tracy in the article
(10:46):
uses a pretty good example. I thought, it's like filling
a sponge with glue. The sponge is gonna keep the shape,
but the glue is gonna ouze through all these spots
that it can ouze harden, and there you go. You've
got a hard sponge, a hard sponge, which is basically
what a fossil is. And this takes place Josh over
the course of millions of years, the sediment reinforcing the
(11:07):
bones eventually becoming rock. It's not the kind of thing
that happens willy nilly over thousands of years a long time,
and it's just this isn't just UM happening by itself.
All of the surrounding area UM is being deposited with
sediment as well. It's also turning into rock UM. And
then the ultimate test of time for a fossil is
that it can withstand the pressure of the that's mounted
(11:29):
by the hardening rock sedimentary rock that's growing around it,
so it can be crushed. Is that how? A lot
of fossils are definitely crushed crushed the death um. But
if it survives and you can find this, you will
eventually be able to get to it. And then you
(11:50):
remove the rock from around the fossil, and there's your
bone that you can take to the Natural History Museum
and get at least five dollars for When you were
a kid, Josh, let me ask this, did you ever
go into the woods on a little nature course from
like a science center, let's say, and do a cast
plaster cast of a animal footprint? Do you ever do that? No? Really,
(12:14):
really I did that. We went and found like deer
hoof prints, you fill it with plaster, and there was
some way of doing it where you got an inverse
plaster cast of a deer hoof print. That can happen
actually in a way that with trace fossils, So you can,
you know, sediment connect the same way in one of these.
Let's say the wooly mammoth makes a footprint in some
(12:35):
loose but sturdy soil that fills up with sediment and
creates basically a mold, just like I did as a
kid with the plaster cast. Yeah, as long as the
sediment that fills it in is lighter or thinner, yeah
than the soil that the impression is made in, then yeah,
it would it would, It would preserve that track. Yeah,
And plants can do the same thing. It's not just
bones we're talking about. Um. It can also fill in
(12:58):
in a different way. I guess the was it way
to where it makes a basically a cast of the
foot that made the track. And then so it's like
a kind of like a fossil of a ghost foot
that's not really there, but it makes the foot. It's
like an inverse cast, okay, of not the track, but
(13:19):
the foot that made the track cool. You know what.
Other another my favorite trace fossil is it's not a
track way, it's copper light. I changed my mind. That
is a good one. That's done it poop, fossilized poop,
that's right. I can tell you a lot about an animal.
It can tell you about its fiber intake. It can
(13:39):
tell you about what size it's poop was. Um chuck.
You know, in the eighties the CIA found out much
about Gorbichoff and his health. They found out he had
like cancer or some sort of chronic illness um by
stealing his poop when he was when he came the
(14:00):
state visit to the US, they took his poop and
analyzed it, and when he was in the US they
described it from the toilet. Did he not flush? I
just want more specifics that you probably don't have. As
far as I understand, they probably his hotel room or
wherever he was staying. They were prepared to do this.
This was like toilet rigged. Probably yes, But wherever Reagan
(14:23):
went they had a portable toilet that he used. It
was the only one he was allowed to use. I'm
not kidding. So no one can steal his poop. Talk
about paranoid. Yeah, seriously, when you point one finger, there's
three pointing back at you, you know what I mean. Yeah? Yeah,
Uh so, Josh, that is sedimentary rock and that's to
me one of the cooler ways you can get a fossil.
(14:46):
Petrified wood too. Don't leave that one out. It's basically
the same thing that we just described for bone, but
for wood hard as a rock because it is a rock.
Here you go, alright, So like I just said, um,
that was dementary rock and that's kind of fun. But
you can also uh get a fossil. Has that funny
because one dies in a cave that's really dry. Yeah.
(15:09):
Desiccation Yeah, desiccation is basically, uh, sort of a mummification,
but it's not like we think of with mummification with
the Egyptian tombs or anything like that. Well, that's because
there's no preservation techniques that have been undertaken. Basically, it
dries out. It's like throwing an orange in a dehydrator.
So when it's really dry, there's not gonna be any
(15:30):
place for bacteria to thrive. That's the reason beef jerky
is not um refrigerated. If you refrigerate your beef jerkey,
you're you're doing something wrong. Yeah, that's true. Well, if
you have beef jerky long enough to need refrigeration, then
you're doing something wrong or something really really right. Uh
So desiccation actually works so well sometimes that it can
(15:52):
preserve the skin and soft tissues as well, which is
something that sedimentary rock cannot do. Have you been to
the Smithsonian? I have they have um a very cool
I guess a prehistoric cow or a musk ox I
can't remember, but it's the thing's head, um, much of
its back, I guess, the cape, two of its legs,
and the skin is still there. It's just right there.
(16:14):
Probably it's tens of thousands of years old and it's
just sitting right there. Did they rebuild could they rebuild
it or just put the parts up? It's just the parts,
but it's laid out so that like it gives you
the impression of what you're looking at, but its face
is still there. It's very cool. Uh. My favorite kind
of fossil, though, Josh, is I'm gonna say that, like
every five minutes is a frozen fossil. Because if you
(16:39):
get trapped let's see your wily mammoth trapped in ice.
Not only is that going to keep other like vultures
and things from picking up your bones and skin, but
it's also going to keep it from breaking down. And
you can get hair fully preserved sometimes if you're in
skin and like a big mammoth. Have you seen pictures
of Leuba No? Liuba is a baby wooly mammoth that
(17:01):
was found um by a reindeer herder in Siberia and
um it was pounds or something like that, but it
would have gotten up to several times. It is adorable
because it is a fully preserved wooly mammoth baby with
the wrinkles in the skin and everything, yet spent forty
years in the perma frost. But it's like completely intact.
(17:23):
It's very cute. That's why it's my favorite. It's one
of the cutest dead things you'll ever see. Another couple
of ways you can get a fossil josh, which are
not my favorite, are a tar librea tar pits, although
that is one of my favorites, which librea tar pit
is actually redundant because Librea means the tar, so it's
calling it the tar tart pit, and not the tartar.
(17:46):
Did I ever tell you about when I shot a
commercial there? Have you? Did you go by there in
l A? No? I want to. I forgot about it
when we were there last Well, for those of you
haven't been, it's right in the middle of Los Angeles,
like south of Hollywood on Wilson Bull Levard, and it's um.
The main tar pit is uh. Tar pits are fenced off, obviously,
(18:07):
and they have little recreations. It's it's actually the saddest
thing you'll ever see. The recreation they have in there
is of a like I guess it's a mother wooly
mammoth trapped in the tar trying to get out, and
the father and the baby on shore like howling. It's awful.
But it's still active, like all this tars bubbling up
and everything. And shot a commercial there once and I
(18:27):
was on the other side of the property, far away
from the main pit, and I looked down and there
was a little mini tar pit, a little tar puddle
about a foot wide, bubbling right beneath my feet. I
could have scooped it up with my finger if I
had been so inclined. Yeah, Instead, you're like that stinks. Well,
(18:47):
it's just crazy to think that that's still like it's happening. Apparently,
um I looked it up. There's um there's like you said,
main pits that are chained off and that are still
being excavated. But they have them like in neighborhood. It's
all around the area and parks. They're just kind of
all over the place around there. That's like parts of
Stone Mountain popping up all over the place. We used
(19:10):
We had a big chunk of stone Mountain in our
backyard growing up. All right. For those of you don't know,
Stone Mountain is the world's largest exposed piece of granite
and it is right here in our home state. And
it takes like thirty minutes to hike, but you still
get to get to the top and be like I
just hiked a mountain, which I have, Josh. You can
also get a pete. Mossy pete can preserve life forms,
(19:31):
including human beings like tolon Man? Was it? Who was
that Toland Man? I don't know about him? How do
you know? All these people? To people? The first the
first um multi syllable word I could spell with archaeology. Really,
I've always been interested in that I could see that. Yeah,
Tolan Man. Also it doesn't. You can hate archaeology like
(19:52):
some people hate art, and you'll still be interested in
Toland Man. Um, he was He's found in Denmark. He
lived years go and he was murdered. Uh, sacrificially they think,
and cast into the peat bog which pete is just
decomposing moss and lots of it, but it has a tendency.
I think it's anaerobic. So um tissue is preserved really well.
(20:14):
But it's this guy that they dug up and he's
so well preserved that when they found him in the
nineteen fifties they called the cops because they thought they'd
found a murder victim, like a recent one. It looks
kind of funny, but he's got his whiskers are preserved,
he's wearing a cap, he still has this the garrett
around his neck. Um, it's really awesome. So like three
(20:34):
hundred to four hundred BC is one who was killed
and he's wearing a hat. Yeah, sheepskin leather cap. Yeah.
No last chance garage for him. No. Well uh. And
then my favorite way, Josh, that you can get a
fossil h you're joking. Did you say it again? Is amber?
They just keep getting better and better, like the movie
(20:55):
Jurassic Park. Yeah, that's how we get dinosaurs again. Yeah,
dino d NA. So you found something on on whether
or not that's feasible, right, Yeah, because I always wondered.
You know, when you see Jurassic Park, you see the
little video They made it clearly to explain to the
movie going audience how this was done. It's better than
Ellen Page running around. What was that movie inception? Um So,
(21:19):
the mosquito flies and tree resident tree resident eventually becomes
hard as copal than it eventually becomes inert as amber.
You get the little mosquito in there. They extracted the
dino DNA from the blood of the mosquito, filled in
the gaps with I think frog DNA, and that was
all there was to it. And at the time I thought, yeah,
(21:40):
at the time, I thought that seems plausible, and it
sort of is. But I did look up today and
there was a researcher that was interviewed at the or
closer to that time. I think that basically debunked it
and said we could potentially maybe get some DNA even
though it's really fragile and loses his signature really quickly.
Even if you could get the in a he said
(22:01):
that you couldn't construct a dinosaurs just you can't fill
in the blanks like that. There's way too many blanks.
You have a giant frog, yeah, with little tiny arms
forearms that Steven Spielberg made us believe when you saw
those dinosaurs walk across that field. That guy can make
me believe in anything, that aliens came to the American Southwest,
(22:22):
that there was a World War two. That um home,
yea good stuff. Uh, where are we here? Chuck it.
We're kind of painting this picture where if like you
just stick a shovel anywhere on the Earth, you're gonna
yield like all sorts of bones and fossils. No, it's
not um. First of all, a mere fraction that I
(22:45):
don't think could possibly be calculated because we rely on
the fossil record to show us what existed back when,
and it's incomplete. Therefore we've entered to catch twenty two.
But there's just a mere fraction of all of the
species organisms that's ever lived that become fossilized UM Like. Basically,
(23:05):
a perfect storm of chance has to occur for a
fossil to be created. As we've seen, even when it
is created, it can still be crushed into oblivion. Um.
And so there are few and far between to begin with.
What we have to figure out where to find them? Well,
then you got to find that. That's the other problem,
(23:26):
and the way we find it is by identifying rock
that will likely have the type of fossil that we're
looking for. Yeah, so if you want something that from
that year. So if you know that this animal, yeah,
if you if you know this this animal lived, you know,
thirty million years ago, you're gonna go find rock that
you know is thirty million years old and start poking
(23:46):
around and you know, looking this sort of a very
chance thing. And we know that, um, we know, like
say a layer of rock or strata of rock is
thirty million years old because of the technique we have
called radiocarbon dating. Right, Yeah, you want to do this one? Well, sure,
(24:07):
Carbon fourteen dating is what a lot of people toss
around because that's probably the most well known, but that
can only take you back sixty thousand years and we're
talking millions and billions of years, so they need to
uh study isotopes like potassium forty and uranian two thirty eight,
because that goes back millions of years evidently. The half
life yeah, and the half life is where an atom
(24:30):
loses half of its life isotopes to decay. Yeah, okay,
and these the this um radioactive decay takes place at
a predictable rate depending on the atom, the type of atom. Right, Yeah,
that's how I understand it. So if we find the
type of atom missing x number of isotopes, we can say, well,
(24:51):
this is roughly thirty million to thirty one million years
old or thirty million to thirty million and three hundred
years old. I'm not sure what window we can date
it to, right, but I think it's enough so that,
you know, we have a rough estimate of of you know,
when this fossil lived in the sediment was buried around it. So, Josh,
let's say that you're lucky enough and skilled enough as
(25:15):
an intrepid paleontologist to come across your fossil. What do
you do? Well, as I said, you dig it up
and take it to the museum and sell it for
five d SIMOLEA. Well, I don't know about that, but
you should call a museum. Even if you think you
know what you're doing, you're probably gonna need some help.
(25:36):
If it's something major. I think you should probably go
on the assumption that you don't know what you're doing
unless you're a trained paleontologist. Um. Part of the problem
is is we assume that these fossils, being rocks, are sturdy.
That's not always the case, and so there's a lot
of danger of damage um in a just an average
(25:57):
joe trying to excavate him. Also, if you just pull
a bone up and walk away with it, uh, it
immediately loses context. Yeah, it's like removing a piece of
evidence from a crimesy almost exactly. Can't do that, well,
you're not supposed to. Uh. So you know, they have
these huge cranes and uh, digging tools where they can
(26:17):
remove huge slabs of earth, which is a really good
way to do it. And sometimes if they're you know,
if it's something that could be fragile, they will remove
the entire slab, cast it in plaster and just go
ahead and ship that thing off to a facility to
handle it from there. And the cool thing is is
even though rock has formed around this bone, Yeah, that's right,
(26:38):
up right, all up on it, all up in it.
If you um flake it away properly, if you flake
the surrounding sedimentary rock away, um, you're going to find
that there's what's called the plane of weakness, which is
where the bone and the rock are still on this
very microscopic level, they're not fused together. You're gonna hit
(26:58):
that and the box should chip right away and and
leave the bone. Yeah, And I think sometimes they missed
it with water too, to soften it up and help
the whole process. Another thing too, if they find that
is really brittle, they can actually reinforce the bone with
resin and thin glue. But you need to be careful
there too, which is pretty much helping along the fossilization process. Yeah,
(27:22):
I would think so. I mean it's the same thing.
It's like artifice, forcing it with something sturdy. Well, and
then you can date it using your little mass spectrometer
that's in your pocket and or a cat scan. Sometimes
the use cat scans computer imaging stuff like that. Yeah.
I didn't I didn't get how they were dating it
from cat scan. I don't know if they're dating it
(27:43):
with a cat scan or just sussen. The whole thing out. Gotcha.
I don't think it's a dating situation. Tracy was just
throwing out some extra tools of the trade. Huh yeah, exactly,
gotch So um, chuck, what is all this worth? I mean,
we we have a thirst for knowledge. Obviously people think
bones are very cool, but ultimately, what's the pursuit of
(28:04):
paleontology to to put together the piece of the puzzle
of how we got here? Right? I mean that's what
I think. Yeah, that's my understanding as well. Yeah, you
can learn a lot by not only finding the fossil,
but finding what was with the fossil in that same strata. Ah.
I can tell you like, hey, this is a t
(28:26):
rex bone, and there's also a bit of pine tree,
so we know pine trees were around, and they may
have eaten pine trees. Well not t rex because they
were carnivores, right, um, yeah, they were herbivore. Let's say,
you know what I mean, Abronosaurus sure. Um. And ultimately
all of these fossils come together, plant and well everything
(28:47):
that we can get our hands on to form what
is called the fossil record, right, and this is basically
the record of life on Earth. Uh. It's also used
to support evolution big time. And uh, it's here that
paleontology gets most contentious, right, yeah, sure, because there's um
(29:08):
the the idea that beings evolve if you go far
enough back from a single common ancestor, right, And so
if we can put together a complete fossil record, we
would be able to see how everything alive today evolved
from this common ancestor or common ancestors. Right. Yeah. The
(29:28):
problem is fossil records incomplete, and one of the really
key parts that it's often missing are called transitional fossils. Right,
My favorite kind of fossil, Josh, is a transitional fossil.
And one example Tracy used was the baleen whale. Uh. There,
there's a picture of one actually in the article twenty
five million year old fossil of a baleen whale with
(29:49):
sharp teeth. Um, today's bailing whales don't have sharp teeth,
but we know that once before this had sharp teeth
and legs. So this is a transitional fossil that shows, well,
they used to have legs and sharp teeth, then they
just had sharp teeth, and now they don't have legs
or sharp teeth. They're defenseless, which is why they're bailing whales,
right and not sharks or Megalodon's right. Um, and so
(30:13):
a transitional fossil is one that that pops up between
old and new, and it makes sense. Our understanding of
evolution is that it takes a little while, and UM,
something like teeth aren't just gonna go away in one generation.
It's gonna take more and more and more, and then UM,
we should be able to find them along the way
where maybe the teeth gets smaller. There's fewer and fewer
(30:35):
UM baling whale teeth in the average baling whale mouth,
and you're putting together the puzzle exactly. Um. Again, the
fossil records a little incomplete, and there aren't as many
transitional fossils as I think people would like to UM
have tied all together, right, UM, and then some of
the uh, some of the explanations are probably the most
(30:57):
famous explanation for this is that UM evolution isn't gradual.
I think it's Stephen J. Gould came up with the
idea of punctuated equilibrium, and that is basically that UM
evolution takes place suddenly in these huge quick fits and starts,
which would explain why there's not like teeth don't go
(31:18):
away in a generation, but they go away a lot
faster than we used to suspect. And that's why these
um fossils um accompanied with the idea that not every
animal that's ever died has become fossilized, explained why there's
huge gaps in the fossil record, which will inevitably always
be incomplete. Is that a hypothesis at this point? I
(31:41):
guess it is not a theory yet I don't. I
don't think so. I think it is a hypothesis. I
got one more thing, Okay, I'd like to finish with
my favorite kind of fossil, and that is a living fossil.
And that, Josh, is when you've got a plant or
animal that looks so much like ancient fossils that they
(32:02):
consider a living fossil. Allah, the horseshoe crab, right, apparently
the horseshoe crab has not changed. Didn't need too, It's perfect.
Look at it, it's gorgeous. What else? Oh, genk baloba plants?
And then a word that I don't know of, the
ceila cant. What is that? Uh? It's this horrid looking
fish that they remember that VW commercial where he's like,
(32:26):
it's like the Cela camp and the guys like what
they're looking in the trunk and he's like a full
size spare tire and he's like, it's like a Cela.
Can't They used to think it was extinct. There was
a fish, and then they found it, like in the
nineteen thirties again, but it's this dinosaur looking fish. Oh,
I think I've seen him that they thought was extinct
for millions of years and they called him I think
in South America, off the coast of South America, and
(32:48):
they're still around living Saul and the Horseshoe Crab and
Stephen j. Could in the gek Baloba. Well, it's it
for fossils, right, That's all I have. I think we've
got the point across. That's an overview. A fossil is
a rock. Just remember that, Okay if you want to
learn more about fossils um Seriously, this is one of
the better articles on the site. Tracy did a great
(33:10):
job with it. Type fossils into the search bar a
handy search bar, and how stuff works dot com, which
means it's time for listener mail. Josh. We made a
young girl cry. That's what I'm gonna call this one. Okay,
It's probably happened more than once. Hi, guys and Jerry.
My name is Ali. I'm from Indiana. I was in
(33:32):
the I S s M, a band contest, playing a
difficult marimba solo today. I was pretty nervous, but being
first chair and the only female percussionist in my school
really brought up my confidence. I went in, I choked
and I stumbled through my piece. You get a gold,
silver bronze or a participation medal. Got the bronze, which
(33:53):
is equivalent to a score of an F. I was
really upset. Wait, what is participating that sub f? I
didn't even know they made metals. I thought was is
the ribbon? It's probably a ribbon. I was really upset.
I got home. I was trying to cheer myself up
by listening to your podcast on What's the Deal with Sinkholes.
I really love the show and I've listened almost everyone.
(34:13):
But in the beginning, you guys talked about how much
the bronze medals suck. Remember that. Oh yeah, so we
didn't liftro spirits very much, Josh and Chuck. I just
want to let you know that the two of you
made me cry then from Ali and I has since
written Alie back and apologized, and she said that she's
feeling much better now and uh, it wasn't our fault.
And I told her that I've choked under pressure many
(34:35):
times in my life and it happens, and it will
happen again, and it doesn't mean you don't have the
goods every single time, but you know you pick yourself up.
It sounds like you gave her some good advice choke.
I think so. She seemed receptive to it. It's like
a sweet girl. I think that's an excellent lead in.
If you have a story about choking, not physically choking,
(34:58):
but you there's something you good at and you didn't
do it. Well, say you're a television reporter in Los
Angeles and you're supposed to report on the Grammys like
that to your podcast, and you have to do a
show about the sun to give one too, but we
want to hear about it. You can send it to
us via email. Just type in where it says to
(35:19):
stuff podcast at how stuff works dot com for more
on this and thousands of other topics. Is it how
stuff works dot com To learn more about the podcast,
click on the podcast icon in the upper right corner
of our homepage. The How Stuff Works iPhone app has
a ride. Download it today on iTunes. Brought to you
(35:43):
by the reinvented two thousand twelve camera. It's ready, are
you
Brought to you by the reinvented two thousand twelve camera.
It's ready. Are you welcome to stuff you should know
from house Stuff Works dot com. Hey, and welcome to
the podcast. I'm Josh Clark with me as always as
the intrepid paleontologist Charles W. Chuck Bryant. It's terrible, Wasn't
(00:27):
I like it? Okay? I wish I was a Paleontologist's
your new nickname? Or intrepid? At least? Let's just go
with paleontologists. That'd be great. Okay, we're talking fossils today. Dude,
this isn't really interesting stuff? It really is. And um,
you can tell that Tracy Wilson are esteemed head of
the writing editor. I think she's site director director right. Um,
(00:51):
you can tell that she was very, very excited. She
took her time and really dolled this one out. I think, um,
save her is the right word. You can feel it
her smiling through the keyboard. Yeah, she's very happy to
write how fossils work, and um, we're happy to do
it because it's one of those very comprehensive articles on
(01:12):
the site that you just has. It has everything you need.
Sedimentary rock flat bones versus round bones leaf impressions has
it all unless you're an intrepid paleontologist, and we'll get
an email saying it actually wasn't very comprehensive. You guys
royally screwed this up. We just wait until we get
into punctuated versus gradual evolution. Chuck, Um, you've heard of
(01:38):
Lucy right, the austral epithecuss Yeah, okay, Well, Um, she
was I think three point two million years old. That's
one old lady. It really is the earliest hominid we've
found as far as I know. Um, But there's a
part of her foot missing. It's always been missing that
we've never found before. So this thing, this bone, was
(02:00):
so essential that we couldn't tell how she walked until recently.
Why because the missing bone, we couldn't tell how she
walked exactly. We we we can tell so much from
bones that when we don't have the right bones, we
can't tell anything. So she may have been in a
knuckle dragger, she may have hopped, we didn't know. Well. Recently, Um,
(02:22):
some people from the University of Missouri or Missouri, depending
on whether or not you live in the state, UM
found the Uh, the group of foot bones needed to
show what kind of walker Lucy was. And she walked
up right? How was her gate? Upright? Upright? Just like
a human. She had a hitching her get along, she
(02:43):
had a pepper and her step. Possibly she knew she'd
be famous one day with duck. But but consider this, right,
three point two million year old footbones were found and
we could tell from them how she walked. This is
the state of the field that you remember paleontology. Pretty cool.
(03:06):
This is how advanced it is, and yet it's really
just kind of using common sense to figure out what
old bones mean. Common sense and science. Fossils go, let's
talk about it, Chuck. What are some of the different
kinds of fossils. Uh, well, one of my favorite kinds
(03:27):
is trace fossil. Yeah, that's actually one of my favorites too.
It's like, um, that Jesus footprint thing, footprints in the sand. Yeah,
it's sort of this josh um that is when it's
actually not part of the organism at all, but it's
um like tooth marks in a chunk of wood from
(03:49):
a saborite tooth tiger, or footprints or footprints or track ways,
as Tracy calls them. Yes, footprints, it's just unnecessary, but
it has a pleasant tone, you know science. Yeah, they're
not footprints, the track ways I'm bored in Ethiopia, let's
call so trace fossils is one. Of course, there's bone fossils, right,
(04:10):
the most famous fossils. Yeah, those are great too. They
got nothing on trace fossils. So actually, bone fossils, that's
that's what you really want. If you're going to reconstruct
a dinosaur for your museum. You can't deal it with footprints, No,
you can't. You need the bones. And the bones are
of course the most famous ones in the dinosaur bones
are the most famous of all the bone types. Right.
(04:31):
So there's something that I think um is often missed
by lay people such as myself um in in that
when you find a bone, right, so, you find like
a big old dinosaur bone, it's really geologically speaking, it's
not a bone any longer. It's not like you find
(04:52):
a bone buried in your yard that was an animal
from like, you know, thirty five years ago, but that's
not a fossil. That's still bone. A fossil is a
bone or a piece of um, once living organic material
that's undergone a transition from uh, an organic state to
an inorganic state. That's what a fossil is. It's gone
(05:13):
through the process of fossilization. And most of these fossils,
the vast majority of fossils, are found in sedimentary rock.
Before we go any further, we should probably do a
little brief primer on sedimentary rock, right, which is awesome. Yeah,
it's pretty easy to Uh, we've talked about the Earth's core,
um and layers. When I think we talked about earthquakes
(05:35):
and maybe some other stuff. We all know that there's
the inn core, outer core. We got the crust. Crust
is the thinnest layer, and that's where the fossils are.
That's where the goods are. And uh, most of the
rocks in the crust are sedimentary rocks. You've been talking
about off and on for the past eight minutes, right,
And that's like silty sandy stuff that hardened over the right,
(06:00):
I mean, but the the Earth, Remember we talked about oh,
what was it clouds I can't remember what podcast it was,
but we talked about how much sand is transferred from
Africa to South America annually. But if you remember the
one I'm talking about. Okay, so the Earth's geo biogeochemical
(06:21):
processes equal a lot of movement of particulate matter. Right.
The Earth is dynamic, baby, it is. It's also very fluid.
To write, A lot of that matter is at at
one point as suspended particles in water that's moving around, right.
So um as this as the water leaves and the
(06:44):
sediment is deposited, it builds up and up and up.
Over time, it hardens into rock and eventually we have
sedimentary rock which is below our feet. We don't normally
see it unless say, the Colorado River um winds over
it for you know, millions and millions and millions of years,
revealing the sedimentary rocket that's in the Earth's cross Grand Canyon,
(07:08):
exactly what you're talking about. Yeah, I forgot the Grand
Canyon park. So you know how I said the Earth
was dynamic, baby? Yeah? Uh, that's important. I didn't just
throw that in there as a factoid. It's important because
when these plates shift around, that's how fossils are on Earth.
Things can be moved great distances and pushed to the
surface eventually or close enough to where a dig can
(07:29):
unearth it. And it's like just because it's fossilized, doesn't
mean it's stuck in that one spot forever, because Earth
is always moving. So the point of all this is
is sedimentary rock um is like you said, dynamic. It
moves around. Sometimes fossils pop up, or it becomes exposed
all of the Colorado River um, and that is where
fossils are, right Chuck. Yes, So let's say that at
(07:53):
some point in time there was a dinosaur or a
saber tooth tiger or a cyanobacteria wily mammoth, woly mammoth,
sure um, and it's um hanging out around the riverbed
and it has a massive heart attack and falls over
in the river bed and very quickly it becomes covered
(08:14):
with sediment and silt, right yeah, And that's important because
once it starts getting covered up with stuff, it's sort
of being protected from like all of us. Let's just
break the news. All of fossil means is that something
has been protected from the natural decomposition process. Otherwise we
just decompose like everything else and you wouldn't see anymore.
(08:36):
You just totally betrayed Tracy in the tone she went
to this, that the whole drama drawing out suspense. But
that's true. So what you said was right. So you'd
fall over in a riverbed, you start getting covered up
with the sediment and silt, and it's it's immediately starting
to protect you in a way. Um, not you, but whatever,
the wily mammoth, the wooly mammoth. Um. The thing is
(08:58):
the in this sediment, in this still, you can't really
hide from macrobacteria, uh and other forms of life that
are basically dedicated to breaking down organic matter, soft tissue, hair, eyeballs, um, genitalia,
all that kind of stuff. It eventually becomes broken down
(09:19):
and what's left is the hard stuff, the bone, right,
But the bone also has organic material within it as well. Yeah,
and that'll break down. We're talking blood, cells, collagen, fat,
that's gonna break down. To the key here is the
inorganic parts of the bone remain intact. And it's the
other keyword here's porous. Yes. Well, you take calcium, I
(09:41):
imagine for your hips. Yeah, sure, glucosim and calcium. Sure.
So what you're doing is, um, you're fortifying the calcium
that's already in your hips supposedly, um, because the bone
is made in large part of calcium, which is a mineral,
which is inorganic, So it's all the organic stuff dies
that out. What's left is, like you said, the inorganic
(10:03):
like calcium, whatever, minerals, and that holds the shape, right. Yeah,
the initial structure is kept intact, right, But like you said,
this bone is also porous. Yeah, that's the key, and
over time, um other mineral sediment kind of um it
enters into these these microscopic pores iron right, carbonate and
(10:25):
fortifies this, ultimately turning this but what was once an
organic bone into an inorganic rock in the shape of
the bone. Yeah, but for all intensive prefaces, it's still
the bone. It still has that original calcium. It's still
the same thing. It's not like a replica of it.
It's just become fossilized. Yeah. And Tracy in the article
(10:46):
uses a pretty good example. I thought, it's like filling
a sponge with glue. The sponge is gonna keep the shape,
but the glue is gonna ouze through all these spots
that it can ouze harden, and there you go. You've
got a hard sponge, a hard sponge, which is basically
what a fossil is. And this takes place Josh over
the course of millions of years, the sediment reinforcing the
(11:07):
bones eventually becoming rock. It's not the kind of thing
that happens willy nilly over thousands of years a long time,
and it's just this isn't just UM happening by itself.
All of the surrounding area UM is being deposited with
sediment as well. It's also turning into rock UM. And
then the ultimate test of time for a fossil is
that it can withstand the pressure of the that's mounted
(11:29):
by the hardening rock sedimentary rock that's growing around it,
so it can be crushed. Is that how? A lot
of fossils are definitely crushed crushed the death um. But
if it survives and you can find this, you will
eventually be able to get to it. And then you
(11:50):
remove the rock from around the fossil, and there's your
bone that you can take to the Natural History Museum
and get at least five dollars for When you were
a kid, Josh, let me ask this, did you ever
go into the woods on a little nature course from
like a science center, let's say, and do a cast
plaster cast of a animal footprint? Do you ever do that? No? Really,
(12:14):
really I did that. We went and found like deer
hoof prints, you fill it with plaster, and there was
some way of doing it where you got an inverse
plaster cast of a deer hoof print. That can happen
actually in a way that with trace fossils, So you can,
you know, sediment connect the same way in one of these.
Let's say the wooly mammoth makes a footprint in some
(12:35):
loose but sturdy soil that fills up with sediment and
creates basically a mold, just like I did as a
kid with the plaster cast. Yeah, as long as the
sediment that fills it in is lighter or thinner, yeah
than the soil that the impression is made in, then yeah,
it would it would, It would preserve that track. Yeah,
And plants can do the same thing. It's not just
bones we're talking about. Um. It can also fill in
(12:58):
in a different way. I guess the was it way
to where it makes a basically a cast of the
foot that made the track. And then so it's like
a kind of like a fossil of a ghost foot
that's not really there, but it makes the foot. It's
like an inverse cast, okay, of not the track, but
(13:19):
the foot that made the track cool. You know what.
Other another my favorite trace fossil is it's not a
track way, it's copper light. I changed my mind. That
is a good one. That's done it poop, fossilized poop,
that's right. I can tell you a lot about an animal.
It can tell you about its fiber intake. It can
(13:39):
tell you about what size it's poop was. Um chuck.
You know, in the eighties the CIA found out much
about Gorbichoff and his health. They found out he had
like cancer or some sort of chronic illness um by
stealing his poop when he was when he came the
(14:00):
state visit to the US, they took his poop and
analyzed it, and when he was in the US they
described it from the toilet. Did he not flush? I
just want more specifics that you probably don't have. As
far as I understand, they probably his hotel room or
wherever he was staying. They were prepared to do this.
This was like toilet rigged. Probably yes, But wherever Reagan
(14:23):
went they had a portable toilet that he used. It
was the only one he was allowed to use. I'm
not kidding. So no one can steal his poop. Talk
about paranoid. Yeah, seriously, when you point one finger, there's
three pointing back at you, you know what I mean. Yeah? Yeah,
Uh so, Josh, that is sedimentary rock and that's to
me one of the cooler ways you can get a fossil.
(14:46):
Petrified wood too. Don't leave that one out. It's basically
the same thing that we just described for bone, but
for wood hard as a rock because it is a rock.
Here you go, alright, So like I just said, um,
that was dementary rock and that's kind of fun. But
you can also uh get a fossil. Has that funny
because one dies in a cave that's really dry. Yeah.
(15:09):
Desiccation Yeah, desiccation is basically, uh, sort of a mummification,
but it's not like we think of with mummification with
the Egyptian tombs or anything like that. Well, that's because
there's no preservation techniques that have been undertaken. Basically, it
dries out. It's like throwing an orange in a dehydrator.
So when it's really dry, there's not gonna be any
(15:30):
place for bacteria to thrive. That's the reason beef jerky
is not um refrigerated. If you refrigerate your beef jerkey,
you're you're doing something wrong. Yeah, that's true. Well, if
you have beef jerky long enough to need refrigeration, then
you're doing something wrong or something really really right. Uh
So desiccation actually works so well sometimes that it can
(15:52):
preserve the skin and soft tissues as well, which is
something that sedimentary rock cannot do. Have you been to
the Smithsonian? I have they have um a very cool
I guess a prehistoric cow or a musk ox I
can't remember, but it's the thing's head, um, much of
its back, I guess, the cape, two of its legs,
and the skin is still there. It's just right there.
(16:14):
Probably it's tens of thousands of years old and it's
just sitting right there. Did they rebuild could they rebuild
it or just put the parts up? It's just the parts,
but it's laid out so that like it gives you
the impression of what you're looking at, but its face
is still there. It's very cool. Uh. My favorite kind
of fossil, though, Josh, is I'm gonna say that, like
every five minutes is a frozen fossil. Because if you
(16:39):
get trapped let's see your wily mammoth trapped in ice.
Not only is that going to keep other like vultures
and things from picking up your bones and skin, but
it's also going to keep it from breaking down. And
you can get hair fully preserved sometimes if you're in
skin and like a big mammoth. Have you seen pictures
of Leuba No? Liuba is a baby wooly mammoth that
(17:01):
was found um by a reindeer herder in Siberia and
um it was pounds or something like that, but it
would have gotten up to several times. It is adorable
because it is a fully preserved wooly mammoth baby with
the wrinkles in the skin and everything, yet spent forty
years in the perma frost. But it's like completely intact.
(17:23):
It's very cute. That's why it's my favorite. It's one
of the cutest dead things you'll ever see. Another couple
of ways you can get a fossil josh, which are
not my favorite, are a tar librea tar pits, although
that is one of my favorites, which librea tar pit
is actually redundant because Librea means the tar, so it's
calling it the tar tart pit, and not the tartar.
(17:46):
Did I ever tell you about when I shot a
commercial there? Have you? Did you go by there in
l A? No? I want to. I forgot about it
when we were there last Well, for those of you
haven't been, it's right in the middle of Los Angeles,
like south of Hollywood on Wilson Bull Levard, and it's um.
The main tar pit is uh. Tar pits are fenced off, obviously,
(18:07):
and they have little recreations. It's it's actually the saddest
thing you'll ever see. The recreation they have in there
is of a like I guess it's a mother wooly
mammoth trapped in the tar trying to get out, and
the father and the baby on shore like howling. It's awful.
But it's still active, like all this tars bubbling up
and everything. And shot a commercial there once and I
(18:27):
was on the other side of the property, far away
from the main pit, and I looked down and there
was a little mini tar pit, a little tar puddle
about a foot wide, bubbling right beneath my feet. I
could have scooped it up with my finger if I
had been so inclined. Yeah, Instead, you're like that stinks. Well,
(18:47):
it's just crazy to think that that's still like it's happening. Apparently,
um I looked it up. There's um there's like you said,
main pits that are chained off and that are still
being excavated. But they have them like in neighborhood. It's
all around the area and parks. They're just kind of
all over the place around there. That's like parts of
Stone Mountain popping up all over the place. We used
(19:10):
We had a big chunk of stone Mountain in our
backyard growing up. All right. For those of you don't know,
Stone Mountain is the world's largest exposed piece of granite
and it is right here in our home state. And
it takes like thirty minutes to hike, but you still
get to get to the top and be like I
just hiked a mountain, which I have, Josh. You can
also get a pete. Mossy pete can preserve life forms,
(19:31):
including human beings like tolon Man? Was it? Who was
that Toland Man? I don't know about him? How do
you know? All these people? To people? The first the
first um multi syllable word I could spell with archaeology. Really,
I've always been interested in that I could see that. Yeah,
Tolan Man. Also it doesn't. You can hate archaeology like
(19:52):
some people hate art, and you'll still be interested in
Toland Man. Um, he was He's found in Denmark. He
lived years go and he was murdered. Uh, sacrificially they think,
and cast into the peat bog which pete is just
decomposing moss and lots of it, but it has a tendency.
I think it's anaerobic. So um tissue is preserved really well.
(20:14):
But it's this guy that they dug up and he's
so well preserved that when they found him in the
nineteen fifties they called the cops because they thought they'd
found a murder victim, like a recent one. It looks
kind of funny, but he's got his whiskers are preserved,
he's wearing a cap, he still has this the garrett
around his neck. Um, it's really awesome. So like three
(20:34):
hundred to four hundred BC is one who was killed
and he's wearing a hat. Yeah, sheepskin leather cap. Yeah.
No last chance garage for him. No. Well uh. And
then my favorite way, Josh, that you can get a
fossil h you're joking. Did you say it again? Is amber?
They just keep getting better and better, like the movie
(20:55):
Jurassic Park. Yeah, that's how we get dinosaurs again. Yeah,
dino d NA. So you found something on on whether
or not that's feasible, right, Yeah, because I always wondered.
You know, when you see Jurassic Park, you see the
little video They made it clearly to explain to the
movie going audience how this was done. It's better than
Ellen Page running around. What was that movie inception? Um So,
(21:19):
the mosquito flies and tree resident tree resident eventually becomes
hard as copal than it eventually becomes inert as amber.
You get the little mosquito in there. They extracted the
dino DNA from the blood of the mosquito, filled in
the gaps with I think frog DNA, and that was
all there was to it. And at the time I thought, yeah,
(21:40):
at the time, I thought that seems plausible, and it
sort of is. But I did look up today and
there was a researcher that was interviewed at the or
closer to that time. I think that basically debunked it
and said we could potentially maybe get some DNA even
though it's really fragile and loses his signature really quickly.
Even if you could get the in a he said
(22:01):
that you couldn't construct a dinosaurs just you can't fill
in the blanks like that. There's way too many blanks.
You have a giant frog, yeah, with little tiny arms
forearms that Steven Spielberg made us believe when you saw
those dinosaurs walk across that field. That guy can make
me believe in anything, that aliens came to the American Southwest,
(22:22):
that there was a World War two. That um home,
yea good stuff. Uh, where are we here? Chuck it.
We're kind of painting this picture where if like you
just stick a shovel anywhere on the Earth, you're gonna
yield like all sorts of bones and fossils. No, it's
not um. First of all, a mere fraction that I
(22:45):
don't think could possibly be calculated because we rely on
the fossil record to show us what existed back when,
and it's incomplete. Therefore we've entered to catch twenty two.
But there's just a mere fraction of all of the
species organisms that's ever lived that become fossilized UM Like. Basically,
(23:05):
a perfect storm of chance has to occur for a
fossil to be created. As we've seen, even when it
is created, it can still be crushed into oblivion. Um.
And so there are few and far between to begin with.
What we have to figure out where to find them? Well,
then you got to find that. That's the other problem,
(23:26):
and the way we find it is by identifying rock
that will likely have the type of fossil that we're
looking for. Yeah, so if you want something that from
that year. So if you know that this animal, yeah,
if you if you know this this animal lived, you know,
thirty million years ago, you're gonna go find rock that
you know is thirty million years old and start poking
(23:46):
around and you know, looking this sort of a very
chance thing. And we know that, um, we know, like
say a layer of rock or strata of rock is
thirty million years old because of the technique we have
called radiocarbon dating. Right, Yeah, you want to do this one? Well, sure,
(24:07):
Carbon fourteen dating is what a lot of people toss
around because that's probably the most well known, but that
can only take you back sixty thousand years and we're
talking millions and billions of years, so they need to
uh study isotopes like potassium forty and uranian two thirty eight,
because that goes back millions of years evidently. The half
life yeah, and the half life is where an atom
(24:30):
loses half of its life isotopes to decay. Yeah, okay,
and these the this um radioactive decay takes place at
a predictable rate depending on the atom, the type of atom. Right, Yeah,
that's how I understand it. So if we find the
type of atom missing x number of isotopes, we can say, well,
(24:51):
this is roughly thirty million to thirty one million years
old or thirty million to thirty million and three hundred
years old. I'm not sure what window we can date
it to, right, but I think it's enough so that,
you know, we have a rough estimate of of you know,
when this fossil lived in the sediment was buried around it. So, Josh,
let's say that you're lucky enough and skilled enough as
(25:15):
an intrepid paleontologist to come across your fossil. What do
you do? Well, as I said, you dig it up
and take it to the museum and sell it for
five d SIMOLEA. Well, I don't know about that, but
you should call a museum. Even if you think you
know what you're doing, you're probably gonna need some help.
(25:36):
If it's something major. I think you should probably go
on the assumption that you don't know what you're doing
unless you're a trained paleontologist. Um. Part of the problem
is is we assume that these fossils, being rocks, are sturdy.
That's not always the case, and so there's a lot
of danger of damage um in a just an average
(25:57):
joe trying to excavate him. Also, if you just pull
a bone up and walk away with it, uh, it
immediately loses context. Yeah, it's like removing a piece of
evidence from a crimesy almost exactly. Can't do that, well,
you're not supposed to. Uh. So you know, they have
these huge cranes and uh, digging tools where they can
(26:17):
remove huge slabs of earth, which is a really good
way to do it. And sometimes if they're you know,
if it's something that could be fragile, they will remove
the entire slab, cast it in plaster and just go
ahead and ship that thing off to a facility to
handle it from there. And the cool thing is is
even though rock has formed around this bone, Yeah, that's right,
(26:38):
up right, all up on it, all up in it.
If you um flake it away properly, if you flake
the surrounding sedimentary rock away, um, you're going to find
that there's what's called the plane of weakness, which is
where the bone and the rock are still on this
very microscopic level, they're not fused together. You're gonna hit
(26:58):
that and the box should chip right away and and
leave the bone. Yeah, And I think sometimes they missed
it with water too, to soften it up and help
the whole process. Another thing too, if they find that
is really brittle, they can actually reinforce the bone with
resin and thin glue. But you need to be careful
there too, which is pretty much helping along the fossilization process. Yeah,
(27:22):
I would think so. I mean it's the same thing.
It's like artifice, forcing it with something sturdy. Well, and
then you can date it using your little mass spectrometer
that's in your pocket and or a cat scan. Sometimes
the use cat scans computer imaging stuff like that. Yeah.
I didn't I didn't get how they were dating it
from cat scan. I don't know if they're dating it
(27:43):
with a cat scan or just sussen. The whole thing out. Gotcha.
I don't think it's a dating situation. Tracy was just
throwing out some extra tools of the trade. Huh yeah, exactly,
gotch So um, chuck, what is all this worth? I mean,
we we have a thirst for knowledge. Obviously people think
bones are very cool, but ultimately, what's the pursuit of
(28:04):
paleontology to to put together the piece of the puzzle
of how we got here? Right? I mean that's what
I think. Yeah, that's my understanding as well. Yeah, you
can learn a lot by not only finding the fossil,
but finding what was with the fossil in that same strata. Ah.
I can tell you like, hey, this is a t
(28:26):
rex bone, and there's also a bit of pine tree,
so we know pine trees were around, and they may
have eaten pine trees. Well not t rex because they
were carnivores, right, um, yeah, they were herbivore. Let's say,
you know what I mean, Abronosaurus sure. Um. And ultimately
all of these fossils come together, plant and well everything
(28:47):
that we can get our hands on to form what
is called the fossil record, right, and this is basically
the record of life on Earth. Uh. It's also used
to support evolution big time. And uh, it's here that
paleontology gets most contentious, right, yeah, sure, because there's um
(29:08):
the the idea that beings evolve if you go far
enough back from a single common ancestor, right, And so
if we can put together a complete fossil record, we
would be able to see how everything alive today evolved
from this common ancestor or common ancestors. Right. Yeah. The
(29:28):
problem is fossil records incomplete, and one of the really
key parts that it's often missing are called transitional fossils. Right,
My favorite kind of fossil, Josh, is a transitional fossil.
And one example Tracy used was the baleen whale. Uh. There,
there's a picture of one actually in the article twenty
five million year old fossil of a baleen whale with
(29:49):
sharp teeth. Um, today's bailing whales don't have sharp teeth,
but we know that once before this had sharp teeth
and legs. So this is a transitional fossil that shows, well,
they used to have legs and sharp teeth, then they
just had sharp teeth, and now they don't have legs
or sharp teeth. They're defenseless, which is why they're bailing whales,
right and not sharks or Megalodon's right. Um, and so
(30:13):
a transitional fossil is one that that pops up between
old and new, and it makes sense. Our understanding of
evolution is that it takes a little while, and UM,
something like teeth aren't just gonna go away in one generation.
It's gonna take more and more and more, and then UM,
we should be able to find them along the way
where maybe the teeth gets smaller. There's fewer and fewer
(30:35):
UM baling whale teeth in the average baling whale mouth,
and you're putting together the puzzle exactly. Um. Again, the
fossil records a little incomplete, and there aren't as many
transitional fossils as I think people would like to UM
have tied all together, right, UM, and then some of
the uh, some of the explanations are probably the most
(30:57):
famous explanation for this is that UM evolution isn't gradual.
I think it's Stephen J. Gould came up with the
idea of punctuated equilibrium, and that is basically that UM
evolution takes place suddenly in these huge quick fits and starts,
which would explain why there's not like teeth don't go
(31:18):
away in a generation, but they go away a lot
faster than we used to suspect. And that's why these
um fossils um accompanied with the idea that not every
animal that's ever died has become fossilized, explained why there's
huge gaps in the fossil record, which will inevitably always
be incomplete. Is that a hypothesis at this point? I
(31:41):
guess it is not a theory yet I don't. I
don't think so. I think it is a hypothesis. I
got one more thing, Okay, I'd like to finish with
my favorite kind of fossil, and that is a living fossil.
And that, Josh, is when you've got a plant or
animal that looks so much like ancient fossils that they
(32:02):
consider a living fossil. Allah, the horseshoe crab, right, apparently
the horseshoe crab has not changed. Didn't need too, It's perfect.
Look at it, it's gorgeous. What else? Oh, genk baloba plants?
And then a word that I don't know of, the
ceila cant. What is that? Uh? It's this horrid looking
fish that they remember that VW commercial where he's like,
(32:26):
it's like the Cela camp and the guys like what
they're looking in the trunk and he's like a full
size spare tire and he's like, it's like a Cela.
Can't They used to think it was extinct. There was
a fish, and then they found it, like in the
nineteen thirties again, but it's this dinosaur looking fish. Oh,
I think I've seen him that they thought was extinct
for millions of years and they called him I think
in South America, off the coast of South America, and
(32:48):
they're still around living Saul and the Horseshoe Crab and
Stephen j. Could in the gek Baloba. Well, it's it
for fossils, right, That's all I have. I think we've
got the point across. That's an overview. A fossil is
a rock. Just remember that, Okay if you want to
learn more about fossils um Seriously, this is one of
the better articles on the site. Tracy did a great
(33:10):
job with it. Type fossils into the search bar a
handy search bar, and how stuff works dot com, which
means it's time for listener mail. Josh. We made a
young girl cry. That's what I'm gonna call this one. Okay,
It's probably happened more than once. Hi, guys and Jerry.
My name is Ali. I'm from Indiana. I was in
(33:32):
the I S s M, a band contest, playing a
difficult marimba solo today. I was pretty nervous, but being
first chair and the only female percussionist in my school
really brought up my confidence. I went in, I choked
and I stumbled through my piece. You get a gold,
silver bronze or a participation medal. Got the bronze, which
(33:53):
is equivalent to a score of an F. I was
really upset. Wait, what is participating that sub f? I
didn't even know they made metals. I thought was is
the ribbon? It's probably a ribbon. I was really upset.
I got home. I was trying to cheer myself up
by listening to your podcast on What's the Deal with Sinkholes.
I really love the show and I've listened almost everyone.
(34:13):
But in the beginning, you guys talked about how much
the bronze medals suck. Remember that. Oh yeah, so we
didn't liftro spirits very much, Josh and Chuck. I just
want to let you know that the two of you
made me cry then from Ali and I has since
written Alie back and apologized, and she said that she's
feeling much better now and uh, it wasn't our fault.
And I told her that I've choked under pressure many
(34:35):
times in my life and it happens, and it will
happen again, and it doesn't mean you don't have the
goods every single time, but you know you pick yourself up.
It sounds like you gave her some good advice choke.
I think so. She seemed receptive to it. It's like
a sweet girl. I think that's an excellent lead in.
If you have a story about choking, not physically choking,
(34:58):
but you there's something you good at and you didn't
do it. Well, say you're a television reporter in Los
Angeles and you're supposed to report on the Grammys like
that to your podcast, and you have to do a
show about the sun to give one too, but we
want to hear about it. You can send it to
us via email. Just type in where it says to
(35:19):
stuff podcast at how stuff works dot com for more
on this and thousands of other topics. Is it how
stuff works dot com To learn more about the podcast,
click on the podcast icon in the upper right corner
of our homepage. The How Stuff Works iPhone app has
a ride. Download it today on iTunes. Brought to you
(35:43):
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