Stuff You Should Know - SYSK Selects: How Fossils Work

Episode Date: December 29, 2018

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. Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

I'm Munga Shatikler and it turns out astrology is way more widespread than any of us want to believe. You can find it in Major League Baseball, International Banks, K-Pop groups, even the White House. But just when I thought I had a handle on this subject, something completely unbelievable happened to me and my whole view on astrology changed. Whether you're a skeptic or a believer, give me a few minutes because I think your ideas are about to change too.

Just a Skyline drive on the iHeart Radio app, Apple Podcast, or wherever you get your podcasts. Hey everyone, it's me, Josh, and for this week's S-Y-S-K Selects, I've chosen How Fossils Work, which actually is one of the most scientifically interesting, amazing, mind-bending episodes that we've ever done. And I just listened to it and it still holds up. So I hope that you enjoy it, and as they say, on with the show. Welcome to Stuff You Should Know from HowStuffWorks.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, isn't it? No, I like it. Okay. I'm a paleontologist. Well, it'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 is really interesting stuff. It really is. And you can tell that Tracy Wilson, our esteemed head of the writing editor. I think she's site director now for HowStuffWorks. You can tell that she was very, very excited.

She took her time and really doled this one out. I think savor is the right word. You can feel it, her smiling through the keyboard. Yeah. She's very happy to write how fossils work and we're happy to do it because it's one of those very comprehensive articles on the site that you just, it has everything you need. Sedimentary rock, flat bones versus round bones, leaf impressions, it has it all.

Unless you're an intrepid paleontologist, then we'll get an email saying, it actually wasn't very comprehensive. You guys royally screwed this up. Just wait until we get into a punctuated versus gradual evolution. Chuck, you've heard of Lucy, right? The Australopithecus? Yeah. Okay.

Well, she was, I think 3.2 million years old. That's one old lady. It really is. The earliest hominid we've found as far as I know. But there is a part of her foot missing. It's always been missing that we've never found before. So this thing, this bone was 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. Wow. 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-drager. She may have hopped.

We didn't know. Okay. So some people from the University of Missouri or Missouri, depending on whether or not you live in the state, found the group of foot bones needed to show what kind of walker Lucy was. And she walked upright. How was her gait? Upright.

Upright. Just like a human. Did she have a hitch in her get along? She had a pep in her step. Okay. Good. Possibly. She was in love.

She knew she'd be famous one day. Yeah. With Tuck Tuck. But consider this, right? Okay. 3.2 million year old foot bones were found. And we could tell from them how she walked. This is the state of the field that you remember, paleontology.

Pretty cool. This is how advanced it is. And yet, it's really just kind of using common sense to figure out what old bones mean. Yeah. Common sense in science. Fossils. Go. Okay.

Let's talk about it, Chuck. What are some of the different kinds of fossils? Well, one of my favorite kinds is a trace fossil. Yeah. That's actually one of my favorites too. It's like that Jesus footprint thing. Yeah. Footprints in the sand?

Yeah. Yeah. It sort of is, Josh. That is when it's actually not part of the organism at all, but it's like a tooth marks in a chunk of wood from a saber tooth tiger. Or footprints? Or footprints. Or trackways, as Tracy calls them.

Yes. Footprints, trackways. It's just unnecessary, but it has a pleasant tone. You know science. Yeah. They're like, they're not footprints. They're trackways. I'm bored in Ethiopia.

Let's call them trackways. So trace fossils is one. Of course, there's bone fossils, right? The most famous fossils. Yeah, those are great too. They got nothing on trace fossils though. Actually bone fossils, that's what you really want. If you're going to reconstruct a dinosaur for your museum, you can't do it with footprints.

No, you can't. You need the bones. You do. And the bones are of course the most famous ones, and the dinosaur bones are the most famous of all the bone types, right? So there's something that I think is often missed by lay people such as myself. 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.

Yeah, it's not like you find a bone buried in your yard that was an animal from like, you know, 35 years ago. You could, but that's not a fossil. Well, no, it's still bone. A fossil is a bone or a piece of once living organic material that's undergone a transition from an organic state to an inorganic state. That's what a fossil is. It's gone 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? Yeah. Which is awesome. Yeah, it's pretty easy too. We've talked about the Earth's core and layers when I think we talked about earthquakes and maybe some other stuff.

We all know that there's the inner 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. Yes. And most of the rocks in the crust are sedimentary rocks that you've been talking about often on for the past eight minutes. And that's like silty, sandy stuff that hardened over the years. Right.

I mean, the Earth, remember we talked about, oh, what was it, clouds? Sure. I can't remember what podcast it was, but we talked about how much sand is transferred from Africa to South America annually. Yeah, when clouds, but yeah. You remember the one I'm talking about? Yeah. Okay.

So the Earth's biogeochemical process is equal a lot of movement of particulate matter, right? The Earth is dynamic, baby. It is. It's also very fluid too, right? A lot of that matter is at one point as suspended particles in water that's moving around, right? Yeah. So as the water leaves and the 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 winds over it for millions and millions and millions of years revealing the sedimentary rock that's in the Earth's crust. A la Grand Canyon. Exactly. Yeah, I forgot the Grand Canyon part. So you know how I said the Earth was dynamic, baby?

Yeah. 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 unearthed. Things can be moved great distances and pushed to the surface eventually or close enough to where a dig can 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 sedimentary rock is like you said dynamic. It moves around. Sometimes fossils pop up or it becomes exposed all over the Colorado River. And that is where fossils are, right, Chuck? Yes. So let's say that at some point in time there was a dinosaur or a saber tooth tiger or a cyanobacteria. Woolly mammoth.

Woolly mammoth, sure. And it's hanging out around a riverbed and it has a massive heart attack and falls over in the riverbed. And very quickly it becomes covered 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 it would just decompose like everything else and you wouldn't see it anymore. You've just totally betrayed Tracy in the tone she lent to this, 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 this sediment and

silt and it's immediately starting to protect you in a way, not you, but whatever, the woolly mammoth. The woolly mammoth. The thing is that in this sediment, in this silt, you can't really hide from macro bacteria and other forms of life that are basically dedicated to breaking down organic matter, soft tissue, hair, eyeballs, genitalia, all that kind of stuff. It eventually becomes broken down 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 going to break down too. The key here is the inorganic parts of the bone remain intact and it's the other keyword here is porous. Yes. Well, you take calcium, I imagine, for your hips.

Me, who, me? Yeah. Sure. Glucosamine, calcium. Sure. So what you're doing is you're fortifying the calcium that's already in your hips supposedly because the bone is made in large part of calcium, which is a mineral, which is inorganic. So as all the organic stuff dies out, what's left is, like you said, the inorganic 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, other mineral sediment kind of enters into these microscopic pores. Iron.

Right. Carbonate. Yeah. And fortifies this, ultimately turning this, what was once an organic bone, into an inorganic rock in the shape of the bone. Yeah. But for all intents and purposes, it's still the bone. It still has that original calcium.

Yeah. 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, uses a pretty good example. I thought it's like filling a sponge with glue. The sponge is going to keep the shape, but the glue is going to ooze through all the

spots that it can ooze, 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 bones eventually becoming rock. It's not the kind of thing that happens willy-nilly over thousands of years.

Right. It takes a long time. And this isn't just happening by itself. All the surrounding area is being deposited with sediment as well. It's also turning into rock. And then the ultimate test of time for a fossil is that it can withstand the pressure that's mounted by the hardening rock, sedimentary rock, that's growing around it. So it can be crushed.

Is that how? Sure. I imagine a lot of fossils are definitely crushed. Crushed to death. Poor guys. But if it survives and you can find this, you will eventually be able to get to it. And then you 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 $500 for.

On the podcast, Hey Dude, the 90s called David Lasher and Christine Taylor, stars of the cult classic show Hey Dude, bring you back to the days of slip dresses and choker necklaces. We're going to use Hey Dude as our jumping off point, but we are going to unpack and dive back into the decade of the 90s. We lived it and now we're calling on all of our friends to come back and relive it. It's a podcast packed with interviews, co-stars, friends, and non-stop references to the best decade ever. Do you remember going to Blockbuster?

Do you remember Nintendo 64? Do you remember getting frosted tips? Was that a cereal? No, it was hair. Do you remember AOL Instant Messenger and the dial-up sound like poltergeist? So leave a code on your best friend's beeper because you'll want to be there when the nostalgia starts flowing. Each episode will rival the feeling of taking out the cartridge from your Game Boy, blowing

on it and popping it back in as we take you back to the 90s. Listen to Hey Dude, the 90s called on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Mangesh Atikular and to be honest, I don't believe in astrology, but from the moment I was born, it's been a part of my life. In India, it's like smoking. You might not smoke, but you're going to get second-hand astrology. And lately, I've been wondering if the universe has been trying to tell me to stop running

and pay attention because maybe there is magic in the stars if you're willing to look for it. We rounded up some friends and we dove in and let me tell you, it got weird fast. Tantric curses, Major League Baseball teams, canceled marriages, K-pop. But just when I thought I had to handle on this sweet and curious show about astrology, my whole world came crashing down. Situation doesn't look good. There is risk to father.

And my whole view on astrology? It changed. Whether you're a skeptic or a believer, I think your ideas are going to change too. Listen to Skyline Drive and the iHeart Radio app, Apple Podcast, or wherever you get your podcasts. When you were a kid, Josh, let me ask you this, did you ever go into the woods on a little nature course from a science center, let's say, and do a plaster cast of an animal footprint? Did you ever do that?

No. Really? Really. I did that. We went and found 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 with trace fossils.

So sediment can act the same way in one of these, let's say, the woolly mammoth makes a footprint in some 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 than the soil that the impressions made in, then yeah, it would preserve that track. Yeah.

And plants can do the same thing. It's not just bones we're talking about. It can also fill in in a different way, I guess, the opposite way to where it makes basically a cast of the foot that made the track. Oh yeah? 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 of not the track but the foot that made the track.

Yeah, yeah. Gotcha. Pretty cool. You know what other, another, my favorite trace fossil is? It's not a trackway. It's copper light. I changed my mind. That is a good one.

That's dung. Fossilized poop. That's right. It can tell you a lot about an animal. It can tell you about its fiber intake. Yeah. It can tell you about what size its poop was. Yeah.

Chuck, you know, in the 80s, the CIA found out much about Gorbachev and his health. They found out he had like cancer or some sort of chronic illness by stealing his poop. Really? He was, when he came on a state visit to the U.S., they took his poop and analyzed it and when Reagan, he was in the U.S., they just grabbed 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 wasn't like... So they had a toilet rigged probably? Yes. Okay. But wherever Reagan went, they had a portable toilet that he used. It was the only one he was allowed to use. Really?

Yeah. So no one could steal his poop? Yep. Wow. Talk about paranoid. Yeah, seriously. When you point one finger, there's three pointing back at you. You know what I mean?

Yeah. Yeah. So Josh, that is sedimentary rock and that's to me one of the cooler ways you can get a fossil. Petrified wood too. Don't leave that one out. Oh, yeah, sure. It's basically the same thing that we just described for bone but for wood.

Yeah. Hard as a rock because it is a rock. Here you go. All right. So like I just said, that was sedimentary rock and that's kind of fun but you can also get a fossil. Why is that funny? Because one dies in a cave that's really dry.

Yeah. Desiccation. Yeah. Desiccation is basically 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. Yeah. It's just natural.

Natural, yeah. Basically it dries out. It's not going to be hydrator so when it's really dry, there's not going to be any place for bacteria to thrive. It's the reason beef jerky is not refrigerated. If you refrigerate your beef jerky, 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. So desiccation actually works so well sometimes that it can preserve the skin and soft tissues as well, which is something that sedimentary rot cannot do. Have you been to the Smithsonian? I have. They have a very cool, I guess a prehistoric cow or a musk ox, I can't remember. But it's the thing's head, much of its back, I guess the cape, two of its legs, the skin's

still there. It's just right there. It's probably, it's tens of thousands of years old and it's just sitting right there. Did they rebuild it or just put the parts up? It's just the parts. But it's laid out so that it gives you the impression of what you're looking at. But its face is still there. It's very cool.

Wow. My favorite kind of fossil though, Josh, is, I'm going to say that every five minutes, is a frozen fossil because if you get trapped, let's say you're a woolly mammoth trapped in ice, not only is that going to keep other vultures and things from picking at your bones and skin, but it's also going to keep it from breaking down and you can get hair fully preserved sometimes, hair and skin and like a big mammoth. Have you seen pictures of Leuba? No.

Leuba is a baby woolly mammoth that was found by a reindeer herder in Siberia. And it weighs 92 pounds or something like that, but it would have gotten up to several tons. It is adorable because it is a fully preserved woolly mammoth baby with the wrinkles in the skin and everything yet. It's spent 45,000 years in the permafrost, but it's like completely intact. 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 tar. Lebrea tar pits. Although that is one of my favorites. Which Lebrea tar pit is actually redundant because Lebrea means the tar, so it's calling it the tar tar pit. And not the tartar. Did I ever tell you about when I shot a commercial there?

Did you go by there in LA? No, I went to. I forgot about it when we were there last. Well, for those of you who haven't been, it's right in the middle of Los Angeles, like south of Hollywood on Wilshire Boulevard. The main tar pit is, tar pits are fenced off, obviously, and they have little recreations. It's actually the saddest thing you'll ever see. The recreation they have in there is of a, I guess it's a mother woolly 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 tar is bubbling up and everything, and I shot a commercial there once and I 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'd been so inclined. Yeah.

Instead, you're like, that stinks. Well, it's just crazy to think that that's still like, it's happening. Apparently, I looked it up, there's, like you said, main pits that are chained off and that are still being excavated, but they have them like in neighborhoods 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. Yeah. We used to have...

Just gotta push it back down with your foot. We had a big chunk of Stone Mountain in our backyard growing up. Yeah. And for those of you who 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 30 minutes to hike, but you still get to get to the top and be like, I just hiked a mountain. Yeah.

Which I have. Josh, you can also get peat, mossy peat can preserve life forms, including human beings. Like tolin man. Uh-huh. Who was that? Tolin man. I don't know about him. How do you know all these people?

Two. These people. Yeah, multi-syllable word I could spell was archaeology. Really? I've always been interested in that. I could see that. Yeah. Tolin man also, it doesn't...

You can hate archaeology like some people hate art and you'll still be interested in tolin man. Yeah. Um, he was... He was found in Denmark. He lived 2,400 years ago and he was murdered sacrificially, they think, and cast into the peat bog, which peat is just decomposing moss and moths of it, but it has a tendency, I think it's anaerobic, so tissues preserve really well.

But it's this guy that they dug up and he's so well preserved that when they found him in the 1950s, they called the cops because they thought they'd found a murder victim. Really? Like a recent one. He looks kind of funny, but... He's got... His whiskers are preserved. Wow.

He's wearing a cap. He still has the garret around his neck. It's really awesome. So what is he dated at? Like 24... Like 300 to 400 BC. That's when he was killed. And he's wearing a hat?

Yeah, a sheepskin leather cap. Really? Yeah. No last chance garage for him? No. Well... And then my favorite way, Josh, that you can get a fossil is... You're joking.

Did you say it again? I did. It's amber. They just keep getting better and better, like the movie Jurassic Park. Yeah, that's how we get dinosaurs again. Yeah. Dino DNA. So you found something 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 clearly to explain to the movie-going audience how this was done. Right. It's better than Ellen Page running around explaining it. What was that movie? An Inception. Inception. So the mosquito flies in tree resin.

Tree resin eventually becomes hard as copal, then 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. Yeah, I think so. Yeah. And that was all there was to it. Yeah.

And at the time I thought- Boomba-da-bing bon jovi. Yeah, 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 its signature really quickly. Even if you could get the DNA, he said that you couldn't construct a dinosaur, it's just you can't fill in the blanks like that.

There's way too many blanks. You'd have a giant frog with little tiny arms, forearms. But 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, that there was a World War II, that E.T., phone home, yeah, please, good stuff though. On the podcast, HeyDude the 90s called David Lasher and Christine Taylor, stars of the cult classic show, HeyDude, bring you back to the days of slip dresses and choker necklaces.

We're going to use HeyDude as our jumping off point, but we are going to unpack and dive back into the decade of the 90s. We lived it, and now we're calling on all of our friends to come back and relive it. It's a podcast packed with interviews, co-stars, friends, and non-stop references to the best decade ever. Do you remember going to Blockbuster? Do you remember Nintendo 64? Do you remember getting frosted tips?

Was that a cereal? No, it was hair. Do you remember AOL Instant Messenger and the dial-up sound like poltergeist? So leave a code on your best friend's beeper, because you'll want to be there when the nostalgia starts flowing. Each episode will rival the feeling of taking out the cartridge from your Game Boy, blowing on it and popping it back in as we take you back to the 90s. Listen to HeyDude the 90s called on the iHeart Radio app, Apple Podcasts, or wherever you

get your podcasts. I'm Mangesh Atikulur, and to be honest, I don't believe in astrology, but from the moment I was born, it's been a part of my life. In India, it's like smoking. You might not smoke, but you're going to get second-hand astrology. And lately, I've been wondering if the universe has been trying to tell me to stop running and pay attention, because maybe there is magic in the stars, if you're willing to look for it.

So I rounded up some friends and we dove in, and let me tell you, it got weird fast. Tantric curses, Major League Baseball teams, canceled marriages, K-pop? But just when I thought I had to handle on this sweet and curious show about astrology, my whole world came crashing down. Situation doesn't look good. There is risk to father. And my whole view on astrology? It changed.

Whether you're a skeptic or a believer, I think your ideas are going to change too. Listen to Skyline Drive and the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Where are we here? Chuck, we're painting this picture where if you just stick a shovel anywhere on the earth, you're going to yield all sorts of bones and fossils. Not true. No, it's not.

First of all, a mere fraction that I 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 where we've entered at catch 22. But there's just a mere fraction of all of the species and organisms that's ever lived that become fossilized. Basically 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. So they're few and far between.

Yeah, to begin with. We have to figure out where to find them. Well, then you got to find it. That's the other problem. 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 from that year, so if you know that this animal...

Also from 1986. Yeah, if you know this animal lived 30 million years ago, you're going to go find rock that you know is 30 million years old and start poking around and looking. Right. It's sort of a very chance thing. And we know that like say a layer of rock or strata of rock is 30 million years old because of a technique we have called radiocarbon dating, right? Yeah.

You want to do this one? Well, sure. And 14 dating is what a lot of people toss around because that's probably the most well known. Yeah. But that can only take you back 60,000 years. Yeah. And we're talking millions and billions of years.

So they need to study isotopes like potassium 40 and uranium 238 because that goes back millions of years. Evidently the half-life. Yeah. And the half-life is where an atom loses half of its isotopes to decay. Yeah. Okay. So this 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 a type of atom missing X number of isotopes, we can say, well, this is roughly 30 million to 31 million years old or 30 million to 30 million and 300 years old. I'm not sure what window we can date it to. I know. I wonder what that is.

So also that we have a rough estimate of when this fossil lived and the sediment was buried around it. So Josh, let's say that you're lucky enough and skilled enough as 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 500 simoleons. 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 going to need some help 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. Part of the problem is, is we assume that these fossils being rocks are sturdy. That's not always the case. So there's a lot of danger of damage in just an average Joe trying to excavate them. Also, if you just pull a bone up and walk away with it, it immediately loses context. Yeah.

It's like removing a piece of evidence from a crime scene almost. Exactly. Can't do that. Well, you're not supposed to. So they have these huge cranes and digging tools where they can remove huge slabs of earth, which is a really good way to do it. And sometimes 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. Right. And the cool thing is, is even though rock has formed around this bone, right up, right all up on it, all up in it. If you flake it away properly, if you flake the surrounding sedimentary rock away, you're going to find that there's what's called a 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 going to hit that and the rock should chip right away and leave the bone.

Yeah. And I think sometimes they missed it with water too to soften it up and help the whole process. Yep. Another thing too, if they find that it's 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.

I would think so. I mean, it's the same thing. It's like reinforcing 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 they use CAT scans, computer imaging, stuff like that. Yeah. I didn't, I didn't get how they were dating it from CAT scans.

I don't know if they're dating it with a CAT scan or just sussing the whole thing out. Gotcha. I don't think it's a dating situation. And Tracy was just throwing out some extra tools of the trade, huh? Yeah, exactly. Gotcha. So, Chuck, what is all this worth? I mean, we have a thirst for knowledge, obviously, and people think bones are very cool.

But ultimately, what's the pursuit of paleontology? To put together the piece of the puzzle of how we got here, right? I mean, that's what I think it is. 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. It can tell you like, hey, this is a T-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? Yeah, they were. Herbivore, let's say. You know what I mean? Bronosaurus? Sure. And ultimately, all of these fossils come together, plant and, well, everything that we can get our hands on to form what is called the fossil record, right?

Yeah. And this is basically the record of life on Earth. It's also used to support evolution big time. And it's here that paleontology gets most contentious, right? Yeah, sure. Because there's 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 problem is, fossil record's incomplete and one of the really key parts that it's often missing are called transitional fossils, right? Yeah. My favorite kind of fossil, Josh, is a transitional fossil. And one example Trace used was the baleen whale. There's a picture of one actually in the article, 25 million year old fossil of a baleen whale

with sharp teeth. Today's baleen whales don't have sharp teeth, but we know that ones before this had sharp teeth and legs. Right. So this is a transitional fossil that shows, well, they used to have legs and sharp teeth and they just had sharp teeth and now they don't have legs or sharp teeth. They're defenseless. Which is why they're baleen whales and not sharks or megalodons.

Right. So a transitional fossil is one that pops up between old and new and it makes sense. Our understanding of evolution is that it takes a little while and something like teeth aren't just going to go away in one generation. Right. It's going to take more and more and more and then we should be able to find them along the way where maybe the teeth get smaller or there's fewer and fewer baleen whale teeth in the average baleen whale mouth.

Yeah. And you're putting together the puzzle. Exactly. Again, the fossil record's a little incomplete and there aren't as many transitional fossils as I think people would like to have. Yeah. Tied all together. Right.

And then some of the explanations or probably the most famous explanation for this is that evolution isn't gradual. I think it's Stephen J. Gould came up with the idea of punctuated equilibrium and that is basically that evolution takes place suddenly in these huge quick bits and starts which would explain why there's not like teeth don't go away in a generation but they go away a lot faster than we used to suspect. Gotcha. And that's why these fossils 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 guess it is. Not a theory yet. 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 got a plant or animal that looks so much like ancient fossils that they consider a living fossil, Allah, the horseshoe crab. Right. Apparently the horseshoe crab has not changed. Didn't need to. It's perfect.

Yeah, look at it. It's gorgeous. What else? Ginkgo biloba plants and then a word that I don't know. Oh, the sealicanth. What is that? It's this horrid looking fish that they, remember that VW commercial where he's like, it's like the sealicanth and the guy's like, what?

They're looking in the trunk and he's like a full-sized spare tire. He's like, it's like a sealicanth. They used to think it was extinct. There was a fish and then they found it like in the 1930s again, but it's this dinosaur looking fish. Oh, I think I've seen them. That they thought was extinct for millions of years and they caught them, I think in South America, off the coast of South America and they're still around living fossil.

And the horseshoe crab. And Steven J. Gould. And the Ginkgo biloba. Well, that'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, seriously, this is one of the better articles on the site. Tracy did a great job with it. Type fossils into the search bar, the handy search bar at howstuffworks.com, which means it's time for listener mail. Josh, we made a young girl cry. That's what I'm going to call this one.

Okay. It's probably happened more than once. Hi, guys. I'm Jerry. My name is Ali. I'm from Indiana. I was in the ISSMA 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 participation medal. I got the bronze, which is equivalent to a score of an F, 20%, and I was really upset. Wait, what is participation then? That's sub F. I didn't even know they made medals. I thought it was just a 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 have listened to almost everyone, but in the beginning you guys talked about how much the bronze medals suck. Remember that?

Oh, yeah. So we didn't lift our spears very much. Josh and Chuck, I just want to let you know that the two of you made me cry. I met her from Ali, and I've since written Ali back and apologized, and she said that she's feeling much better now, and it wasn't our fault, and I told her that I've choked under pressure many times in my life, and it happens, and it'll happen again, and doesn't mean you don't have the goods with your marimba solo. Every single time.

Yeah. But you pick yourself up. It sounds like you gave her some good advice, Chuck. I think so. She's getting receptive to it. Sounds like a sweet girl. I think that's an excellent lead-in if you have a story about choking. Not physically choking, but there's something you're 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. Something like that. Yeah, so you're a podcaster, and you have to do a show about the sun to give it to you. We want to hear about it. You can send it to us via email. Just type in where it says to stuffpodcastathousestuffworks.com. For more on this and thousands of other topics, visit howstuffworks.com. Want more how stuff works?

Check out our blogs on the howstuffworks.com homepage. I'm Munga Shatikular, and it turns out astrology is way more widespread than any of us want to believe. You can find it in Major League Baseball, international banks, K-pop groups, even the White House. But just when I thought I had a handle on this subject, something completely unbelievable happened to me, and my whole view on astrology changed. Whether you're a skeptic or a believer, give me a few minutes, because I think your ideas

are about to change too. Listen to Skyline Drive on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hey guys, I'm Kaylee Shore. On my podcast too much to say, I share my thoughts on everything from music to martinis, social media to social anxiety, regrets to risky texts, and so much more. I have been known to read my literal diary entries on my show, and sometimes I do interviews with my crazy group of friends.

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