-Are you ready to investigate?

-I am ready.

-Let's do it.

-I'm Emily Graslie, and I think geology rocks.

The Moon!

It's a Moon rock!

It's an imaginative science that requires an appreciation of our planet's deep history.

Through geology and paleontology, we can meet the fantastic, unusual creatures that inhabited this world long before we arrived.

-It's a whole adventure of discovery.

-Celebrating Earth's incredible story is what I do as Chief Curiosity Correspondent for the Field Museum in Chicago.

So, is this your first time camping out here?

I've spent years exploring natural history through these vast research collections and sharing my curiosity with people around the world through our YouTube series, "The Brain Scoop."

I'm Emily Graslie!

♪♪ But I know there's more to discover within our own backyards.

[ Horn honks ] So I'm heading back to the area where I grew up in the Northern Great Plains -- the heart of America's fossil country.

We'll come face to face with the diverse prehistoric creatures that called this planet home... Oh, whoa!

I love clams.

Doing a science thing today.

...and meet the people who bring these discoveries to light.

-Everything that we know about the history of life all started here in the ground as a single fossil.

-We'll travel thousands of miles, visiting some of the most active fossil sites in the world.

This is chaos!

But we won't be relying on your typical road map for this journey.

Instead, we'll travel through billions of years along Earth's geologic timeline, from the oldest sites up to today, each stop helping us understand a little more about how we got to where we are now.

Wow!

Together, we'll turn back the pages of Earth's past and reveal the amazing wonders preserved beneath our feet.

So hop in, buckle up, and join me on this "Prehistoric Road Trip."

♪♪ ♪♪ -Like most road trips, our journey begins at home.

I grew up in this area, and with even my basic understanding of geologic time, I knew that we had things that were 66 million years old, from 60 to 40 million years old, and I knew that we had things that were only a few hundred thousand years old.

And I wanted to know, how could we have such a wide diversity of time and organisms represented in a two-hour period of time driving in your car?

♪♪ We're heading to Custer State Park, part of the Blacks Hills of South Dakota and just 45 minutes from where I grew up in Rapid City.

Even though we visited this place a lot when I was growing up, and I appreciated the boulders behind me for their scenic beauty, it wasn't until recently that I really started to understand and appreciate the complex processes that took place over billions of years in order to make this landscape happen.

So I met up with geologist Dr. Mark Fahrenbach to get the basics.

As a geologist, how fun is it to work in the Black Hills?

-It's excellent.

-[ Laughs ] -It's a beautiful place, beautiful place to work, a beautiful place to live.

-Yeah.

How old are these boulders?

-We have rocks that go back to 2.5 billion years old.

-Geologists like Mark chart the earth's rock layers, or formations, which represent periods of time in Earth's history so that the people who study prehistoric ecosystems can paint a better picture of the past.

-Paleontologists, their main focus is on the fossils.

But in order to get as much information you can out of the fossils, you need to know what rocks you are getting these fossils out of.

You need to know the history of these rocks.

The Black Hills is the farthest eastern extent of the Rocky Mountain uplift.

So, about 65 million years ago, the Pacific Plate was actually hitting the North American Plate, crunching the side of the continent.

Well, something's gotta give.

It started to buckle and uplift, and that's what formed the Rocky Mountains.

The Black Hills kind of looks like a bullseye pattern on a map.

And as those rocks were uplifted, you had the oldest at the bottom, and so as those rocks were uplifted, you're going from old rocks to younger rocks to younger rocks to youngest rocks as you move away from the center of the Black Hills.

-It's thanks to this uplift that this area of the country is so unique.

Because, in just a few hours, we can drive through more than 2.5 billion years.

It's like we've discovered a portal through time.

And I'm ready to dive in.

♪♪ What an exciting time to be a geologist.

-Mm-hmm.

It's always an exciting time to be a geologist.

[ Both laugh ] I love that.

I love it.

♪♪ -I have never appreciated rocks this much.

I never realized that the world could open up in this way, that this planet has been here for 4.5 billion years and it has undergone monumental change that's recorded in the rocks.

It's the story that builds the chapters of our earth's history.

We owe it to ourselves to take some time and try and learn that story.

♪♪ [ Horn honks ] ♪♪ We are on our way to see the first fossils on our road trip up here in the Medicine Bow Mountains of southern Wyoming.

And I think a lot of us, when we think of fossils, automatically think of something like a triceratops or a T. rex.

This isn't that.

But at over 2 billion years old, these fossils represent some of the earliest life that grew on our planet.

They might not look like much, but without them, life as we know it might not exist at all.

I'm so excited!

Everyone on the crew has been excited about them.

I mean, it's just really funny when we think about it.

Everyone's just been like, "Fossil bacteria!

Yaaaah!"

♪♪ Our guide for the day is Dr. Kelli Trujillo, who is a geologist and science instructor in nearby Laramie.

And without her, we might miss what we've set out to find.

We're heading to a valley that was once the shore of an ancient sea where some of the earliest life forms on our planet were growing in giant mats just beneath the ocean surface.

-So, you see that?

-Oh, yeah!

-That's starting into some of it there.

-These unassuming rocks, called stromatolites, are what's left behind by colonies of ancient bacteria.

And over the last 2 billion years, they've been thrust to more than 11,000 feet in elevation.

People watching this show are going to see this clip of me huffin' and puffin', and they're gonna be like, "She's real out of shape."

-Wow!

-It's high altitude.

-There's no... -[ Chuckles ] Are all of these stromatolites?

-Everything that you're seeing is either stromatolites or stromatolitic bands.

-And this is a stromatolite?

-And this is a stromatolite.

A whole bunch of them, actually, all kind of glumped up into each other here.

-How did these stromatolites form?

I guess its -- We're not really talking about stromatolites, we're talking about cyanobacteria.

-Right.

Yeah.

So, a stromatolite itself is the rock that is left behind, essentially, by bacteria, a colony of a whole bunch of different types of bacteria -- blue-green algae, we call them now, sometimes cyanobacteria -- that photosynthesize.

-Mm-hmm.

-And then sediment would stick to them because they had gooey surfaces.

-Oh.

-And in that process, they would end up burying themselves, and now they can't photosynthesize because they can't see the sun.

-Yeah.

They're like, "Hey!"

-And so they move up.

They can actually move.

These little bacteria can move up and get to a spot where they can see the sun again and now they can recolonize that new surface... -Wow!

-...and start it all over again.

-So it was like kind of a competition.

Like, the mud would, like, stick to the top, and then they would be like, "Oh, no!"

-"No, help!"

And they'd jump up.

-And then bloop-bloop-bloop, and then the process continues.

-Uh-huh.

Over and over and over and over and over and over again.

-Why are these cyanobacteria significant?

-Well, they're significant because we like to breathe oxygen.

-Yeah.

-We think of things from our world of...oxygen-breathing as being normal.

-Yeah.

-But for billions of years on the planet, that was not normal.

The atmosphere was not full of oxygen.

Cyanobacteria in general are, we're pretty sure, responsible for bringing our atmosphere to being oxygen-rich so that other forms of life could start to evolve and utilize it.

-So these tiny bacteria -- these microscopic, early, little hints at life created the oxygen-rich environment that we breathe today?

-Mm-hmm.

Yes.

-That's profound.

I mean, that's amazing.

-We owe everything to these little cyanobacteria.

-Do these bacterial mats, do these cyanobacteria still exist today?

-Cyanobacteria in general, yeah.

They sure do.

They're all over.

They're in our -- in lakes in different places today.

But making these stromatolitic forms, only in rare places today, because we have organisms that eat them.

-Oh.

-So, if you go to these hypersaline bays in Australia, you'll find modern stromatolites, these domes out there.

-Wow!

So this is how life started on Earth.

-Mm-hmm.

Yeah.

-As bacteria.

And you can find it in the rocks.

That's amazing.

And then we get dinosaurs.

-And then we get dinosaurs.

Boom, in the blink and blow.

A billion and a half years later -- 2 billion years later, 3 billion years later, we get dinosaurs.

-That's wild.

-[ Chuckles ] -Geez.

Thank you, stromatolite fossils and cyanobacteria.

♪♪ -The earth is old, man.

-The earth is old!

Those mountains took billions of years to be created.

Bananas!

♪♪ It is completely normal to feel overwhelmed by the concept of deep time.

Let's say you wanted to count to a big number -- say, a million -- and you counted one number for every second, 24 hours a day, and you gave yourself no breaks at all, it would take you 11 days, 13 hours, 46 minutes, and 40 seconds to count from 1 to 1 million.

If you wanted to count to an even bigger number -- say, 1 billion -- it would take you 31 years, 251 days, 7 hours, 46 minutes, and 40 seconds.

So if you wanted to count to the number of the estimated age of our earth -- 4.5 billion years -- you couldn't do it.

It would take you two entire human lifetimes, in about 140 years.

That's unimaginable.

♪♪ So, don't get me wrong, fossil bacteria are awesome, and I am super happy that we can all breathe oxygen now.

But I'm also curious to find fossils that resemble something a little more, well, recognizable.

After the 2.1 billion-year-old stromatolites, We would need to jump way ahead in the geologic record to find our next stop.

Depending on where you are in the world, some areas simply lack huge chapters of our planet's history.

We're diving into an ancient ocean bay that formed more than 300 million years ago close to where the equator is today.

Thanks to continental drift over the last few hundred million years, remnants of the bay are now in central Montana.

Back then, the earth was covered in vast, swampy forests.

The planet reached its highest-ever concentration of oxygen in the atmosphere, and as a result, mega insects and other massive invertebrates dominated the skies and the land, including millipedes that could reach 6 feet in length.

The animals we are seeking to find here are truly astounding -- 150 different species of funky sharks, strange fish, and other early marine life, like squid-like creatures, trilobites, and worms.

Astonishingly, as fossil-rich as this location is, it represents a period of time less than 10,000 years.

[ Pick clinking ] I was invited to join a dig with paleontologists Drs.

Dick Lund and Eileen Grogan.

In the last five decades, they've excavated and studied more than 6,000 specimens from these dramatic cliffs, and I am ready to help them find some more.

You've got to recognize that something has to be really special in order for not just one person but two people to commit their entire lives to studying.

And also, knowing that the work is not done yet.

And so there is a great amount of anticipation and excitement building up to this.

This is a site that, the more you learn about it, the more it's like, you can barely wrap your mind around just how complex the environment was at the time and just how many different species and how many different specimens of fossils have come out of this quarry.

And knowing that this formation spans for miles in every direction and 90 feet up, the potential for this place has been something that I've been really looking forward to seeing.

You do have some examples of some of the things that have been found here?

-Absolutely.

-Wow!

-Look at that.

-The preservation on that is just unbelievable.

-Look at the detail that you can see in the fins.

You can count all of the rays.

You can see the main sensory line going down the body.

This right here... -Is that the eye?

-That's the eye, yeah.

-Wow.

It's astounding that this has survived at all.

-Yeah, but I think that also has a lot to do with, you know, you're in Montana.

This is ranch country, and things aren't being bulldozed right and left.

-There are more of these to be found.

-Absolutely.

Let's find some fish.

-Alright.

-You're going to first pick up the rock.

-This one?

-Yep.

Now, what you're going to do is look at both sides... -Okay.

-...scan it.

So, now what you want to do is you want to give it a little, gentle tap, see if anything pops out.

Nothing pops out.

If it so happens that you get a fish and it comes out in a thousand tiny, little pieces, anything to scoop it all together, and then this is why we love glue.

-Yeah.

-We'll bring it back.

I'd rather break a fish than to miss the fish.

♪♪ There you go.

♪♪ -It's, like, part of a squid?

-Yeah, straight cephalopod.

-Should I chunk this?

-You can keep it.

Or you could toss it.

-The older you go in the fossil record, the less complete it is for many different organisms.

You know, there are certain animals that fossilized, like mollusks or clams, because they have really hard shells.

But then you start to get into vertebrates, and early vertebrates especially.

I mean, we're talking about hundreds of millions of years ago, and finding complete and abundant fossil records of these kind of organisms is incredibly rare.

You know, you have to imagine, coming closer and closer to present day, the fossil record gets a lot more abundant and a lot more complete.

These organisms haven't been on the planet for as long.

There haven't been as many chances for them to become crumpled up in mountain-building tectonic events that take 100 million years to develop.

[ Strauss' "The Blue Danube" playing ] [ Tools clanking ] ♪♪ This is chaos!

♪♪ Whoops.

Oh, I split it into two.

Whoops.

Oh, geez.

Oh, boy.

There's -- Oh, my goodness.

There's a lot going on here.

♪♪ -That's mineralization there.

-Mm.

-Not even algae.

-What about that?

-Ah, good eye!

That's part of a shell.

-Oh, fun!

-From an invertebrate.

There you go.

There's your first fossil from the Bear Gulch.

-[ Gasps ] -[ Chuckles ] -I'm the winner!

-Now get back to work.

Find a fish.

-Alright, I'll put that one over here.

What's one thing you've found here that was really special or remarkable to you?

-We were working in an area that wasn't as productive as people would have liked.

-Mm-hmm.

-So the morale was getting low.

So I said to Dick, "Let me go back to an old crop that we had abandoned."

I went out to the edge, I pulled this up, flipped it, and said, "Whoa, I see lots of scales."

-Wow.

-I pulled the next one.

By the time I pulled the third one, I had to get on the walkie-talkie to Dick, who was up canyon, and say, "Send me a lot of people.

I've got a fish."

So, turns out it was a shark in the shape of a skate.

-Wow!

-And it was as tall as I am.

-Really?

-Yeah.

It's really cool.

And it's something completely new.

Nobody had ever found something like that before.

-Wow!

-So, think about it this way.

If you find something, yours are the first human eyes to see that evidence of past life.

-Wow!

-Nobody else has seen it before.

Hello!

-What!

-Isn't that cool?

-Yeah!

Does that ever get old?

-No.

No.

Especially when it's a beautiful fish.

-That's amazing.

-Yeah.

-Here, fishy, fishy.

-Well, I haven't been smelling shark yet.

-What is the smell, actually?

-If you know anything about sharks, you realize their liver has a lot of oil.

-Oh!

I can smell the oil.

-See?

-It does smell.

You can smell -- That's ancient shark liver oil?

-That's the shark stuff.

-Wow!

Come on, sharks.

I could smell it.

That's ancient shark smell.

I just smelled a shark from 323 million years ago.

That's amazing.

-[ Humming "Jaws"-like theme ] -Come on, shark.

-I do have to get rid of my whack-and-stack pile.

-Should I throw this?

-Yeah, but don't get too close to the edge.

We don't want you to go bouncing over.

-Well, this is fun, too.

-It can be.

This is how you get your frustration out.

♪♪ -So, Eileen, we gave it a good shot.

No fish today.

-Yeah, they were too fast for us, but we'll find them at another site.

-Yeah.

I'm optimistic.

[ Rock shattering ] ♪♪ -Let's go.

Careful of your step.

So, we've been working in this site for probably about five years.

Alright.

Welcome to Big One.

♪♪ -Chunky.

♪♪ Wouldn't that have been nice?

Just pop it open and, like, a big reveal into the camera?

No.

It didn't happen.

♪♪ So, we found a fish.

Sort of.

[ Laughs ] -Yeah, it's not the prettiest one, but you beat me to it.

That was a great eye, that you picked up on it, and if I put it under the lens and can look at it, I can see details.

There are certain types of scales there.

-Mm-hmm.

-I see parts of fins.

But if there's enough of information, like a head, we can identify what type of bony fish that is.

-Wow.

-It looks like it died, and it kind of bloated and rolled a little bit and then got squished.

Sorry.

-No, that's all right.

He was having a worse day than I am.

[ Both laugh ] -Way to go, girl.

Okay.

Enough of that celebrating.

Let's go find another one.

-Onward.

-A pretty one this time, okay?

-Alright, I'll try.

-We're ramping up.

Did you get the other half?

-It's still here.

-Oh, there we go.

-Yeah.

Hot on the trail.

In pursuit.

You can see part of the fossil right there.

-Yeah, so, we're going to be careful about that layer there.

Let me clear this off a bit more.

-There it is.

Part of it.

-That's part of it, indeed.

And this little bit, as you called it, that's part of it, too.

-Right there.

-Ohhh.

Glue.

-[ Laughs ] That's what you need?

-Glue.

But that's great.

We have evidence of life.

-Yay!

We've spent the last two days just moving mountains -- really excavating rocks, like, turning them over and looking at each of these sheets as though they're a page in a history book that potentially have a story to tell in the form of a fossil.

And so, Eileen and I have really been in search of some of the fish that they anticipated finding here.

And then we didn't find very many.

But that's okay.

But what's really cool is that this is just the beginning of this adventure.

I mean, we have hundreds of millions of years to go and so many other fossils to see.

I am so excited to get back out there.

♪♪ All of this talk of fossilization makes me wonder, how does this process work, anyway?

Well, the first thing to know is that there are different kinds of fossils -- bones and exoskeletons, like shells; petrified wood; and even trace fossils, like footprints and coprolites -- fossil poop.

The stromatolites we saw are another example of a trace fossil.

But when it comes to figuring out how fossils form, that's a question we need an expert to help answer.

And lucky for me, I know where to go to find one.

[ Horn honks ] ♪♪ We're on our way to the South Dakota School of Mines and Technology in Rapid City to meet with Dr. Sarah Keenan.

Hey, Sarah!

It's nice to see you!

-Great to see you.

-Are we going to go check out some dead animals?

-Yeah, let's go.

-Alright!

Dr. Keenan specializes in taphonomy, a branch of paleontology that studies the different aspects of the fossilization process.

She invited us to join her on an excursion to her field site, where she's collecting soil samples for an ongoing experiment.

Sarah, how did you get interested in taphonomy?

-There was never really a discussion of how you actually have bones preserved as fossils.

-Hmm.

-So, one of the first steps to try to figuring that out is to watching things decompose today in nature.

-That's interesting.

It's, like, the big, unanswered question.

Like, "Okay, there are fossils here.

But how did they get to become a fossil?"

-Yeah, exactly.

-Part of the reason why fossils are so rare is because the conditions have to be absolutely perfect in order for an organism to transform into a fossil.

The first step for a plant or animal to become fossilized is, well, it needs to die, and preferably in a depositional environment -- that is, in an area where it can quickly become buried in sediment before it can be consumed or carried away by scavengers.

This is why many fossils are found from ancient river, lake, and ocean ecosystems, and not from ancient deserts.

You are much more likely to find a fossil fish than you will a fossil cactus.

But there are still many other factors to consider for fossilization to occur, and that's what Dr. Keenan is helping to figure out.

♪♪ -As paleontologists, we're left with the hard parts, and we can study those, we can study their chemistry.

We can use the chemistry to reconstruct the depositional environment that the bones were preserved in.

-Wow.

So you are able to extrapolate from your research even more information about the environment in which the animal lived, even if that environment is 30 million or 60 million or 100 million years old?

-Yeah.

Yup.

-What?!

-Yeah, it's pretty cool.

-So, you're like a true-crime detective for fossils?

-Yeah.

-And so, how do you achieve this?

-So, I am able to obtain salvaged animals from nuisance trappers and watch them decompose.

-What is the worst stage of an animal's decomposition?

Is it the bloat or the pancake?

-Definitely the pancake.

Definitely active.

-Really?

-Yeah.

There are just so many maggots that it's, like -- it's disgusting.

I mean, if you ever find roadkill and you're curious, if you see maggots, you should definitely stop and look because they form this, like, pulsating mass, and then as they break down tissues, they excrete the waste and form this foam, so it's like a thriving, writhing mass of foaming maggots.

-Cool.

And that's what we're on our way to go see?

-Yeah, that's what we're going to go check out.

Ready?

-Yeah, I think so.

-Let's do this.

-Here we go.

Yeah!

♪♪ ♪♪ Oh, my goodness!

Oh, you weren't lying when you said it was in the pancake stage.

-Yep, it is in the pancake stage.

-Wow!

-The insects have done a pretty good job.

Yeah, it's a little fragrant.

-Yeah.

-It's a little fragrant still 'cause it rained, so it kind of opened up the scent.

-Yeah.

Perfuming.

-Yes.

-And what are you going to do with this now?

-So, now, we can sample the soil underneath this carcass and quantify the chemistry of the soil, and that can tell us, you know, how much was released from the carcass.

-And how does that help inform the taphonomic process?

-So, this is the first environment that bones are going to be exposed to when an animal dies.

So, all of this change in the chemistry changes things like pH.

So, if you change the pH, you can potentially either enhance the potential for preservation of bone or decrease it.

So all of that is -- you can get from the soil.

-I've never done an experiment in the field.

-Really?

-Yeah.

Sarah, would you say that, um, you are "outstanding" in your field?

-[ Chuckles ] -That was a joke, yes.

-It's a pun.

Get it?

'Cause we're standing in a field...out.

Okay!

-Okay.

So, what I'm going to do, and you can help -- I will auger the soil, and then I need you to pick through it and pick out any grass or rocks or bugs or anything.

-I can do that.

-Can you handle that?

-Yep.

-Okay.

-So, you come out here throughout the course of this thing decomposing, taking various samples and watching that pH number change?

-Yep.

-And then comparing it to samples where there haven't been any dead animals?

-Yep.

-And this just informs the nutrient cycling of how an animal decomposes.

-Yep, exactly.

-How its molecules and particles get back into the earth.

-Mm-hmm.

Oh, a maggot!

-Oh, cool.

-Nice.

-Well, that's...disgusting.

Yeah, I'm gonna put that over there.

You know, just your average day, digging through some dirt.

-Just an average day.

-Yeah.

I think it is really interesting that you can take a dead animal and put it out here in a field and watch it decompose and learn interesting things about how fossils form, and by studying this process, it helps people like Dr. Keenan solve mysteries of what the environment was like for an animal 20 million or 30 million or 100 million years ago.

It's amazing.

All that from just studying one stinky skunk in a field.

-Okay.

-I don't know why I smelled it.

It smells like dirt.

This is how science happens!

It's cool!

I don't know, I don't even mind the smell, to be honest with you.

It's like the smell of success.

It's the smell of unanswered questions and the smell of a new scientific voyage into a frontier yet undiscovered.

That's what it smells like to me.

In my heart of hearts.

We're leaving Sarah on the farm with her decomposing skunk and departing with a renewed appreciation for the rigors of scientific experimentation.

Oh, there's one.

It's the Gros Ventre Rock Formation.

It's 500 million to 600 million years old.

That is what I love about riding on this road in Wyoming and a lot of Wyoming highways, is that they have these road signs that point out the age of the rock that you're driving by.

Just amazing.

You're driving through hundreds of millions of years of geologic time.

Cool!

Our road trip now moves us further ahead on the geologic timescale and into more familiar territory as we close in on dinosaur country.

Tunnel time!

Whoo!

Do you hold your breath going through tunnels?

It's good luck.

You make a wish.

[ Inhales sharply ] ♪♪ [ Exhales ] ♪♪ We're jumping ahead to explore fossils that preserve the Late Jurassic world from 157 to 148 million years ago.

They're from the Morrison Formation, which is huge.

Exposures of rocks from this age can be found in seven states.

Some of the earliest dinosaur discoveries in North America happened in this formation.

Elmer Riggs, founding paleontologist at Chicago's Field Museum, excavated the first ever brachiosaurus fossil in the Morrison Formation of northern Colorado.

At the time, it was one of the largest dinosaurs ever discovered.

There are many other early Morrison Formation dinosaur finds, made famous by the so-called "Bone Wars."

In the mid-to-late 1800s, two paleontologists -- Edward Drinker Cope of the Academy of Natural Sciences of Philadelphia, and Othniel Charles Marsh of Yale University -- waged a decades-long, competitive, embittered fossil-hunting battle against one another, each trying to out-compete and out-publish the other.

Needless to say, it wasn't paleontology's finest moment, but it did put the Morrison Formation on the map.

The Morrison has been studied by paleontologists ever since.

We know from looking at Morrison fossils that the Jurassic world was lush and green, home to early mammals, pterosaurs, crocodiles, armored dinosaurs, meat-eaters, like allosaurus -- even frogs, salamanders, and fish.

♪♪ And it has continued to produce more dinosaur fossils than any other rock formation in the United States.

[ Horn honks ] In fact, so many fossil bones have been discovered that one man in Wyoming was inspired to create a roadside stop out of them.

In the 1930s, a local man named Thomas Boylan took advantage of the abundant fossils found in this area to build this fossil cabin out of nearly 5,800 dinosaur bones in order to attract roadside travelers to stop at his gas station.

Unfortunately, the fossil cabin has fallen into disrepair in recent years.

But, luckily, the museum in the nearby town of Medicine Bow has raised money in order to physically move and restore the building.

They're bringing it into town so that it can be appreciated by tourists for generations to come.

♪♪ [ Engine starts ] After a quick stopover in Medicine Bow, I was ready to go find a dino from one of the Morrison Formation's historic quarries known as Como Bluff.

This is crazy cool up here.

-The Como Bluff site is one of the first sites ever found in the West, and it was found in 1877 by two railroad workers who were stationed at Como Station.

Previously, the only dinosaurs known in North America was from New Jersey.

-Melissa Connely is a geology professor at Casper Community College and an expert on the region's geology and history.

She's part of a group from the Tate Geological Museum that carries on this century-old tradition of excavating Morrison Formation dinosaurs for research and education.

And you all are heading out to a dig that you've been working on for a while now, excavating another kind of long-necked dinosaur?

-Yes.

So, you know, there are several long-necked dinosaurs in the Morrison Formation.

Apatosaur is one of our favorites, but we also have camarasaur and possibly a haplocanthosaur, so that's what we're looking for.

-So, maybe we can go find a dinosaur.

-Well, let's do it.

I bet we can.

-What day is it today?

-Today is the first day of summer.

[ Laughter ] -Yes, you'll notice we're all dressed in our... -Summer finest.

-...what I call North Slope Alaska gear.

-Yeah.

-The plan, boys and girls -- get some digging tools, which are over there in the buckets.

-Okay.

-Let's go get you some tools.

-This bucket... -Hey, Pickles, you want to help?

-Digging tool.

-Thank you.

-Scooping tool.

-Thank you.

J.P., the museum's chief fossil preparator, welcomed a small group of dino enthusiasts from around the country who are assisting the Tate crew for the week.

They're working on excavating the bones of a diplodocus, a long-necked, whip-tail dinosaur.

-We've only been out here an hour now, but that's the bone of the day so far.

-Oh, really?

-Yeah.

-This was found just today?

-Yeah.

-Okay.

-This is one of the, what I call, final spinals.

-Neat.

-Maybe.

It could also be someone's metatarsal.

-Uh-huh.

-And the more I look at it, it might be that, too.

You will find bones if you just walk around a little bit.

-Really?

-You might not find anything exciting, but you can find chunkosaurs.

Let's see what's at our feet.

-Yeah.

-Oh, look at this one!

I already stepped on it.

Look, there's a piece of bone randomly distributed right here.

-How do you know it's a dinosaur bone?

What are the features you look at?

-It tastes like one.

-[ Laughs ] -I'm looking at bone texture.

-Yeah?

-I mean, texture wise, you have these canals running through this thing, and it's also a bluish-gray, which is fairly typical of the bones around here.

Once they sit on the surface for a little while, they turn bluish-gray.

-So, you kind of, like, facetiously licked this rock, but, I mean, do paleontologists sometimes, like, lick bones?

-Sometimes they do.

-And why do they do that?

-Because, supposedly, bones will stick to your tongue.

It depends on where they're from.

And generally, this Morrison Formation stuff doesn't, and it's full of uranium, so we don't eat it too much.

-I was going to say, isn't this material somewhat radioactive?

-It's somewhat radioactive.

Yeah, don't try it.

[ Laughs ] -Pickles, a seasoned paleontologist.

-You pick a little, you brush a lot.

You pick a little, you brush a lot.

[ Both laugh ] -One, two, three.

Really quick.

Voilà.

Okay.

♪♪ -I was digging along this cast to try to maybe see if we could flip it later... -Mm-hmm.

-...and as I was digging, I heard a little tink in there... -Yeah, you struck something.

-...and started going under the cast, so, yeah, it's a whole fibula.

-That's exciting.

-And if we're lucky, there will be more bones underneath.

-Oh.

It's exciting.

-[ Chuckles ] It would be a lot of fun to see if there's more.

-Yeah.

-Just 'cause it's small, it doesn't mean it's a negative, discard bone.

-Yeah.

-Melissa just found a crocodile tooth over here.

-Oh, what?

Cool!

-Which, it's one for the boys and girls in the lab to figure out, put back together.

But you can see the striations on it there.

-Yeah.

-There's two halves of a crocodile tooth.

That's the tip of the tooth.

-Geez.

-It's a little dirty.

-Can you identify a species of crocodile just by its teeth?

-Not me.

-But someone can?

-Someone can.

-Okay.

So, are crocodile teeth pretty rare around here?

-Actually, they're the most common teeth we find.

-Oh, okay.

-Turtle teeth -- those are rare.

[ Laughter ] For those who don't know, turtles don't have teeth.

[ Laughter continues ] Put that back in before it blows away.

-Alright, J.P., what are we doing?

-We're going to go... We're going to go plaster some bones.

-Alright.

-I see you come equipped.

-Yeah, I'm ready.

-What is this?

-It's a -- -A dinosaur bucket.

-Tubular.

-Tubular, man.

-Yeah!

-Alright.

We might not need that one.

-Alright -Okay, good.

Let's go this way.

-There we go.

-Okay, a little more.

That should do us.

-Aw, yeah.

-You find an end.

-Alright.

Like this?

-An end.

And then you pass it through my hands while I pray.

-Ooh.

-See I'm praying?

-Yes.

-Okay.

And now I'm begging.

Roll it back down onto me.

-Okay.

Like that?

-That's a little sloppy.

We'll work on that the second time.

Okay.

[ Speaking indistinctly ] -Grab a second one.

-Alright.

-And now I'm going to wrap this around here to protect our bones and not plaster you.

-Alright.

And then do you...?

-And then I'm gonna pray.

-Alright.

-Pull.

-You know what ribbon candy is?

-Yes.

Like this?

-No, you're going to do it ribbon candy down onto my hand.

-Oh, like... [ Chuckles ] Noobie here.

-Now I beg for ribbon candy.

-Okay.

-Oh, look at that.

-Like this?

-Good form.

-Oh, I see.

I see.

Here we go.

Now we're in business.

Now we're talking.

-Alright.

So, this plaster -- I mean, this really just acts as a cast like if you had a broken arm and went to the hospital.

-Exactly, yup.

-And reinforces it.

-Exactly.

It's the same, exact concept.

-How long can a fossil bone stay in a plaster cast?

-If they're outdoors, these things will start decomposing, oh, 10 years?

-Oh, really?

-Yeah.

-What about once you get it to a museum?

How long could they sit in a plaster jacket in a museum's storage?

-100 years.

-What?

-Only 'cause we've been doing this only for 100 years.

-That's amazing.

-We, collectively.

-Yeah, the field of paleontology.

-Yes, exactly.

-Do you do anything with this extra plaster?

-Yeah, you can boop some into some of these gaps.

We call that goop.

-Goop.

-That's the technical term.

Nice job.

-Thanks, J.P.

This was fun.

-Yeah.

-Yeah.

High five.

-High five!

-Oh, that was a bad idea.

-Oh, man!

[ Chuckles ] I knew that was a bad idea, but I was going to let you do it.

[ Both laugh ] -I wanted to know what other incredible discoveries were being made on dinosaurs from the Morrison Formation.

I would love to see a herd of sauropods.

These are animals that are like 70 to 100 feet long.

It's unimaginable how big they were.

Like, I want to hear what it sounded like when they stampeded.

I bet it just, like, shook the earth.

[ Horn honks ] We're on our way to central Montana to meet Cary Woodruff, a paleontologist and sauropod mega-enthusiast.

He's taking us to a quarry where he and a team had excavated bones of another kind of Jurassic sauropod, an apatosaurus.

♪ Lookin' for a dinosaur ♪ Do you ever make up field songs?

-Uh, no.

-Really?

Why not?

-I just don't have a song in my heart.

-[ Laughs ] Oh, no.

Cary is especially interested in how these animals were able to grow to such enormous sizes.

Gah, this quarry's gigantic!

-Yeah.

Big dinosaurs require big holes.

-[ Laughing ] Right.

Cary, you love sauropods.

That's your jam.

-They're the best.

-How did they evolve, when did they evolve, and how long did they live?

-So, we're in the Morrison Formation, so we're in rock that's about 150 million years old.

So, in fact, it's the oldest dinosaur-bearing formation in Montana.

But the Morrison's really what people refer to as like the "Time of the Titans," so this is the time of the sauropods.

So, these are our long-necked, plant-eating dinosaurs.

So, this is when we have apatosaurus, diplodocus, camarasaurus, brachiosaurus.

Really, some of the biggest dinosaurs that ever roamed North America are living during this time.

-Let's put these titans into context.

This is the largest sauropod that ever roamed the earth, a titanosaur.

It would've weighed about 70 tons when it was alive.

That's more than 10 times larger than an African elephant, the largest land animal on Earth today.

Sauropods like this dominated the planet for nearly 150 million years.

Their bones have been found on every continent, including Antarctica.

-Sauropods are some of our first dinosaurs, and they're some of our last dinosaurs.

-So, they last the entirety of the Mesozoic, from 200 million years through the extinction event that wipes out the rest of the dinosaurs 66 million years ago?

-Yep.

-What?!

-Yep.

-They were really champions.

They were really survivors.

-They are.

And, you know, people, I think, just don't give them enough credit for that.

So, this is a cast, so it's a copy of the femur, so the big thigh bone, of an apatosaurus.

This isn't even a particularly large apatosaurus.

-How were they able to get so ginormous?

-So, there's a whole team of paleobiologists that are trying to figure that out, and the short answer is they were doing a lot of things incredibly well.

-So, they're hatched from an egg.

How big are they when they hatch?

-Oh, so, this is why I always love talking to students.

So, sauropods -- biggest land animals ever.

-Yeah.

-Biggest dinosaurs ever.

So you think they come from the biggest eggs.

-Yeah.

-So, we don't have a lot of sauropod eggs, but the biggest sauropod eggs we have are about the size of a grapefruit to, you know, a cantaloupe in size.

-What?!

-Yeah.

So they're just, like, little guys?

-Little guys.

So, that baby apatosaurus hatches from an egg, and let's just call it -- just round up -- we'll call it, you know, 4 feet.

-Uh-huh.

-And probably within 20 years, it's already -- it's reached its adult body size of the better part of 100 feet long.

-Whoa!

That is mind-boggling.

-Yep.

-How do we know this information?

-So, we know this because of histology.

So, that's actually looking at the inside of the dinosaur bones.

When we actually cut open the bones, we can see the similar things like growth rings in trees.

-Really?

-And each ring, just like a tree, right, you know, is deposited each year.

So you count the tree rings, it tells you how old the tree was.

We can do that with these dinosaurs, as well.

-Are you ever afraid in doing this sort of work, cutting into bone, that you're "destroying" a fossil?

-No.

We can actually tell more about the life history of a particular animal by looking at its inside of its bones than we ever could looking at the outside.

-Really?

Why is that?

-The inside of a bone is kind of like a time capsule.

It records the life history of that animal.

The outside just can show us things like how big it got, the particular dimensions of the bones.

Like, you know, if a bone was broken and rehealed, we could see that on the outside.

We even tell, like, by the shape of its teeth what it was eating, things like that.

But the inside -- all those intimate details of every year of the animal's life and what happened to it while it was growing up.

-The field of paleontology has accelerated its realm of possibilities beyond what we could have imagined just a few decades ago.

As we left Cary in the sauropod quarry, I thought back to the early paleontologists who were working on sauropods from the Morrison Formation.

Could they have imagined how, a little more than 100 years later, we'd be able to look into dinosaur bones and begin solving mysteries about their lives, and looking at the very fossils they collected to do so?

Another major change in the field of paleontology in recent decades is the opportunity for nearly anyone to participate, regardless of one's educational background or level of experience.

We headed to the Wyoming Dinosaur Center in Thermopolis to see how they've opened up their quarries to the public.

Oh, wow!

-Ta-da!

-Here it is.

-Yeah.

-A unique feature of the Wyoming Dinosaur Center mission is to get the public involved with active digs and the other sort of research and work that you're doing here in Thermopolis.

-Well, the great thing about the Dinosaur Center is that was our day-one idea.

It wasn't just to make a museum, because why would you make a museum in a town of 3,000 people in the middle of nowhere, Wyoming, unless you had a really specific idea in mind?

And that was that dinosaurs are inaccessible in a lot of ways.

You're either behind the glass of a museum or you have to get yourself out to remote areas to find these things.

So, why not build a museum that's just 10 minutes away from where you're finding the dinosaurs and invite people to get that experience firsthand?

-In the last 25 years, the Wyoming Dinosaur Center has recovered more than 15,000 bones, largely thanks to their visitors.

And these sites are still producing more fossils?

-Absolutely.

We have anywhere from 80 to 130 confirmed sites on the property, stretched out across three formations primarily.

Mostly in the Morrison Formation, Late Jurassic.

We're finding new things almost every day.

♪♪ -Did you ever think that you'd get to come out here and participate in a dino dig?

-Not at all.

-Sure.

-Yeah?

[ Laughter ] -We're just recently married.

-Oh, really?

-Yeah.

-Oh, congratulations.

-In fact, this is -- this week is our first anniversary.

-Oh, that's so special.

-It is.

-So it's kind of part of an anniversary trip.

-Has this experience made you think that paleontology is an accessible kind of science that anybody could get into it?

-It's been a fascination.

You know, you go to a museum, and you have -- you see the finishing product of this wonderful specimen, really, on display.

But this is just the very beginnings of it.

It's wonderful.

-Yeah.

That's really cool.

-Yeah.

-Well, congratulations on one year.

-Thank you.

-And life's an adventure.

-Yeah.

-Yeah.

-Go dig a dino.

♪♪ We have literally driven through 2.5 billion years of Earth's history.

It's bananas!

And it's even more bananas that, like, geologists have only really been mapping this area for a little over 100, 150 years.

So, like, there's still so much more that we don't know.

Every new place that I go, I have an appreciation for the geology and the paleontology.

It adds a whole-new level.

♪♪ [ Horn honks ] We made our way to the Tate Geological Museum in Casper, Wyoming, to drop off the field jackets from our dig with J.P. and talk with Melissa Connely again.

I'd soon come to learn that the Tate was home to some surprises and that Melissa had her own story about the power of an individual to make contributions, not only in science, but in the way paleontology is reflected in pop culture.

Looking at some of the strengths of the collections that you have on display, one thing that I think is really remarkable are these pterosaur tracks.

When we say pterosaurs, we mean some of these flying reptiles.

-Flying reptiles, yeah.

Well, they have very unique morphology.

So, the pterodactyls, so pterosaurs, have a hind foot with four toes, and then the forearm has three fingers, or three digits.

And the fourth digit is the wing.

-Oh!

-So, when you find these tracks, you can see the footprint quite easily that shows both the manus and the pes, which is the hind foot.

So, this is a cast of one of the original tracks that was found.

And what's really cool about tracks is tracks is doesn't represent a dead animal.

-Mm-hmm.

-This is a living animal.

And this is behavior.

So, what we've preserved here or what has been preserved and we're interpreting, is what is the behavior of these animals that died a 145 million years ago?

What's really cool about these is these tracks is what convinced the scientific community that pterosaurs were quadrupedal -- They walked on all four, and they weren't upright like ducks.

-So, before, it was sort of like, you can imagine like a bird with a webbed foot... -Yeah, kind of walking around.

-...maybe waddling or walking.

And then you brought this to the scientific community.

-Yes.

-And has this been reflected in popular media -- this new scientific discovery... -Oh, of course.

Yeah.

-...or this conclusion?

-Well, I mean, "Jurassic Park," you know, the third movie, you can see the pterosaurs walking on all fours, and that's because of these guys.

-[ Screams ] ♪♪ -[ Growls ] [ Hisses ] -Seeing that, like, in popular cinema, what does that mean to you, and how did you react to that?

-Oh, I just cry every time I see it.

-Really?

[ Both laugh ] -Yeah, I totally do.

Because, you know, this was something that we did when I was an undergrad, and so it really showed that a girl in science in Wyoming in a field that's just not known for having girls in there can do something that makes a difference.

-Yeah.

-You know, I can contribute to the scientific community, and we all can.

-I have chills right now.

It's just mind-blowing to me that you can come to those conclusions by really carefully analyzing this material.

-Yeah.

Mm-hmm.

-So cool!

I'm fascinated by the concept of fossils being able to capture the behavior and movement of an organism that lived hundreds of millions of years ago.

In that sense, trace fossils are the closest thing we have to a time machine.

They provide a wonderful, if limited, window into history to give us a look at a few seconds or minutes into the life of a creature that may be unlike anything else on our planet today.

And so we find a way to connect with our earth's past and begin to see ourselves in their world.

We are on our way to the Red Gulch Dinosaur Tracksite.

We're gonna see some dino footprints.

We're gonna see where the dinosaurs walked.

East of the town of Greybull, Wyoming, is the Red Gulch Dinosaur Tracksite, which is the largest tracksite in the state.

We're here!

In 1997, it was first reported to the local Bureau of Land Management office by residents of the nearby town who spotted the tracks while they were out enjoying the scenery.

Here, not just a handful of steps, but an entire dance floor of movements from dozens of three-toed dinosaurs has been preserved, and you can walk with them yourself.

So, there's one, two, three, and four.

Some 167 million years ago, a meat-eating, three-toed dinosaur was walking here in a shallow edge of a sea, and its footprints -- because of the algae that was covering the limestone of the surface -- was preserved.

I think that's absolutely amazing that an everyday life of a dinosaur ends up getting preserved for over 100 million years.

Seeing trace fossils like these make me think about my own movements through the world on a daily basis, from the places that I walk to the things that I eat and to stuff I throw away.

It makes me think of the evidence that I might be leaving behind.

What will future scientists think when they come across traces of our lives?

♪♪ By this point in the geologic record, during the Jurassic period, our planet had already survived several major mass-extinction events.

Countless life forms had evolved, perished, adapted, or been replaced many times over.

But we've only just begun to scratch the surface.

As we continue on our road trip, we'll visit the height of the reign of the dinosaurs.

-Basically, with this, the entire skull is here.

-That's amazing.

Ooh!

And we'll soon come to learn more about the resilience of life on Earth -- as well as its limits.

It's amazing that anything survived at all!

-Next time on "Prehistoric Road Trip"... -Happy fossil dance.

-Oh, yay.

You did a happy dance.

We could be standing on top of a T. rex right now, and we'd have no idea?

-No, we wouldn't.

-This has turned out to be a pretty amazing day.

Aaaaah!

-Whenever you find a new triceratops, it's like meeting a new friend.

It's like, "Oh, hi!"

-I don't know what that is, but somebody does.

Oh, whoa!

Dinos, no dinos.

Happy clamming.

-Let's go.

Happy clamming to you.

-I found an ancient chicken wing.

It doesn't feel like work out here, it feels like we've just been having a good time.

Rah, rah, rah.

[ Laughs ] -We're here in Sylvan Lake in Custer Steak Park -- "Steak Park."

Steak Park!

It's a park of steaks.

♪ It's chilly ♪ ♪ But I'm ready ♪ ♪ To find a dino ♪ ♪♪ -To order "Prehistoric Road Trip" on DVD, visit Shop PBS, or call 1-800-PLAY-PBS.

This program is also available on Amazon Prime Video.