CHRIS: Hey, everyone, my name is Chris Anderson.

Today on Science Around Cincy, we are going to learn from scientists how they learn about what the earth was like millions of years ago.

(music) Did you know that some of the world's best preserved fossils are right underneath your feet?

The bedrock in Cincinnati is full of trilobite fossils, which geologists have used to learn what the earth was like hundreds of millions of years ago.

Dr. Brenda Hunda is the invertebrate paleontologist at the Cincinnati Museum Center, and she's going to teach us more about these amazing ancient creatures.

DR. HUNDA: My name is Dr. Brenda Hunda.

I'm curator of invertebrate paleontology at the Cincinnati Museum Center.

I am interested in evolution.

I like looking at evolution in the micro realm, what we call micro evolution, which is looking at how organisms change and adapt to their environments as populations through time.

My particular area of interest is going to be on trilobites.

I grew up in a very small family in the middle of nowhere.

My father was in the Canadian Air Force and in radar, I grew up in very small, isolated, guarded Air Force base which meant that I had the run of the place because there was no where I could really go to get in trouble.

So I spent a lot of time outside.

And for me, spending a lot of time in nature and exploring was my favorite thing to do.

And while some people are interested in stuff here and maybe stuff up here, I was interested in what was down there.

And so as a young girl, I would grab my mother's spoons, both wooden and silver, which she would be mad at because I'd bend them all.

And I would dig to see if I could see what was in there.

I just always had a fascination with what was down there.

CHRIS: Hey, Brenda.

DR. HUNDA: Hey.

How's it going?

CHRIS: It's good to see you.

DR. HUNDA: Good to see you.

CHRIS: You love you some trilobites, right?

DR. HUNDA: I do, absolutely.

CHRIS: Tell me what's so great about them.

What are they about?

DR. HUNDA: Well, trilobites are extinct.

There are an extinct group of arthropods.

And when we think about arthropods, you think about things like crabs and lobsters.

You think about arthropods everyday, don't you?

CHRIS: Yeah, constantly.

DR. HUNDA: I mean, our world is surrounded with arthropods, right?

What's one of the biggest groups of arthropods that we have on the planet?

CHRIS: Insects.

DR. HUNDA: Right, exactly.

Now, trilobites are not directly related to insects.

They're arthropods.

They belong to the same phylum, but because trilobites are extinct, we don't have anything like them on Earth today.

CHRIS: So nothing like a trilobite exists today.

DR. HUNDA: That's right.

Trilobites today are most closely related to horseshoe crabs and scorpions.

CHRIS: So when did trilobites live?

They've been gone -- How long have they been gone for?

DR. HUNDA: So the first trilobites appear on the scene 520 million years ago.

And they died out about 250 million years ago in the world's largest mass extinction event, known as the Permian-Triassic extinction event.

CHRIS: OK, so that had lots of impact.

So they lived a really long time ago.

DR. HUNDA: Yes.

CHRIS: And they died out still a long time ago.

DR. HUNDA: Yes.

CHRIS: Then at the same time, they lived for a long time.

How long were they on earth for?

DR. HUNDA: About 270 million years as a class.

CHRIS: Wow.

So what can trilobites teach us about the Earth from millions of years ago?

DR. HUNDA: Because they were around for so long, they diversified into pretty much every latitude and longitude on Earth.

They lived in almost every environment in the ocean.

Of course, we know trilobites were not terrestrial.

They did not fly.

They were all in the ocean swimming.

But within those ocean realms, they occupied every ecological role that you can think of: predators, scavengers, detrital feeders, every kind of lifestyle, swimming, nektonicly, burrowing.

CHRIS: Wow.

DR. HUNDA: And so they can tell us an awful lot about different environments in the ocean and even the chemical conditions of the ocean at that time.

CHRIS: Can you show me a couple trilobite fossils?

DR. HUNDA: Oh, sure.

Absolutely, let's go.

CHRIS: Awesome.

DR. HUNDA: We have thousands of trilobites.

I'm going to show you some of my favorites.

CHRIS: Oh, awesome.

Let's see what you've got.

DR. HUNDA: So this cabinet is full of trilobites, along with several others that we have.

CHRIS: And this is just trilobites in here?

DR. HUNDA: Is just trilobites.

CHRIS: Wow.

DR. HUNDA: And if you recall, we have over 20,000 species.

Of course, we don't have every single species here, but we do have a network of museums that we share data with that we can see a lot of trilobite species.

And the first one I want to show you is actually one of my favorite specimens we recently got in, this guy right here.

This is Isotelus Maximus.

It's actually a small one.

It is a little guy.

He's a little guy.

Now, this is the official State of Ohio fossil.

CHRIS: That's the official State of Ohio fossil.

DR. HUNDA: Yeah, Isotelus.

CHRIS: Ok, yeah.

It would fit - - like it's fit in your hand.

DR. HUNDA: Yeah, it would fit in your hand.

But what's really special about him, other than the fact that he's complete, is that he's the first trilobite we have -- actually the first fossil of anything in the Cincinnatian with soft body preservation.

CHRIS: Soft body preservation, so not like bones or shells.

DR. HUNDA: Right.

Actual tissue.

And tissue preservation is very rare and it requires certain conditions to do.

And you can see the black circles here, right?

Those are soft tissue that's been preserved inside by pyrite replacement.

CHRIS: So they like blood vessels or...?

DR. HUNDA: I think that they're probably musculature.

CHRIS: Ok, yeah, that's -- you can you can definitely see that.

DR. HUNDA: You can see it's patterned and they're kind of like serial, which even though the tail of the trilobite is one plate, it belies the original segmentation of the animal, which is part of its ancestry.

CHRIS: Are those its eye tissue?

Are the eye tissues preserved as well?

DR. HUNDA: Yeah.

So the lenses here, I don't think the lenses themselves are preserved, but these are where the lenses would be and that is the eyes of the animal.

Yeah.

Trilobites are fascinating because they're the first fully sighted organisms in the fossil record.

CHRIS: Wow.

So now this particular species, if I can make a hypothesis, would have been kind of on the ground, because the eyes are on the top?

DR. HUNDA: Yes.

CHRIS: Wow.

So it's like sitting there looking around like this.

DR. HUNDA: Yeah, it would have had two antennae coming out here.

It would have had legs squiggling at every segment.

Yeah, under the head and under the tail, yep.

Kind of like what we think of when we think of a Roly-Poly.

CHRIS: Yeah.

DR. HUNDA: And he would have been scurrying on the sea floor probably eating soft body things in the sediment like worms.

Now this guy you mentioned was kind of small.

CHRIS: Yeah.

DR. HUNDA: Right?

Well, we don't stay that way.

Isotelus as a genius of trilobite is the largest trilobites on earth.

CHRIS: Oh, okay.

DR. HUNDA: The biggest one comes out of Canada, but here's one of our big ones.

CHRIS: Whoa!

DR. HUNDA: Yeah.

So this is a cast of a specimen that we actually have currently displayed and this is about 40 centimeters long.

CHRIS: Wow.

That's big.

It's like -- I mean, that's the size of like a like a hubcap.

DR. HUNDA: Yeah.

CHRIS: That's big.

DR. HUNDA: That's a big animal.

And you've got to think back in this time period, things didn't get to be super sized.

Right?

CHRIS: Right.

DR. HUNDA: And so arthropods, this is big for an arthropod at this time.

CHRIS: Yeah, that's big for an arthropod now.

DR. HUNDA: It is.

It is.

CHRIS: I would, I mean, if I found -- if I was swimming and I saw one of these in the ocean, I would be terrified.

[FX camera shutter] So how do you go about finding these fossils?

DR. HUNDA: Well, in Cincinnati, we're actually lucky because they tend to be everywhere.

CHRIS: OK. DR. HUNDA: And I'm going to get to show you some places.

CHRIS: Oh, very cool.

DR. HUNDA: About where the fossils are.

But we work off of the research of previous scientists.

So there's hundreds of years of research in the Cincinnati area about the fossils in this region.

So lucky for us in the Cincinnatian, any cut in the hill that you see driving around the 275 or the I-75, I-71, the cut in the hill, full of fossils.

CHRIS: Well, let's go check it out.

DR. HUNDA: Sounds good to me.

CHRIS: Awesome.

CHRIS: Look at all this stuff in here.

DR. HUNDA: It's crazy packed, it's basically the limestone around here is made up predominantly of little bits of mud off the bottom of the floor and then shells and exoskeletons of fossil organisms.

If you were to cut this and look at it in thin section, it'd be nothing but mud and shells.

CHRIS: And shells.

DR. HUNDA: Yeah.

CHRIS: Well, you can even see the little bits of shells here.

So what are these little circles here?

DR. HUNDA: So those are the columns, the columinals of Crinoid stems.

CHRIS: Ok, so those are the things that like stuck in the ground.

DR. HUNDA: Yeah, like a flower.

CHRIS: Like a flower, but they weren't plants.

DR. HUNDA: No, no, they were animals.

They're related to starfish.

CHRIS: OK. DR. HUNDA: This is a big chunk of Isotelus trilobite.

CHRIS: So this is a piece trilobite right here.

DR. HUNDA: Yeah.

CHRIS: We found a trilobite.

DR. HUNDA: We found a piece of one.

CHRIS: We found a piece of trilobite.

DR. HUNDA: Yeah, they're usually kind of chocolate brown.

Then this is part of the Flexicalymene head of the trilobite right there, a little piece there.

CHRIS: Oh, wow.

DR. HUNDA: These are its free cheeks on the side of the head.

And so there's pieces of Flexicalymene and cryptanalysis and Isotelus throughout this entire slab.

CHRIS: So there's a whole bunch of different -- there's a ton of ancient species just in this one rock.

DR. HUNDA: At least three trilobites, Crinoids, there's Bryozoan.

CHRIS: But there's tons of individual saved here.

DR. HUNDA: Yeah, yeah, yeah.

CHRIS: That's -- I mean, so this ocean that was above Cincinnati was just full of life.

DR. HUNDA: Full, full.

CHRIS: So this is a really weird ocean.

It would be something that we wouldn't even -- couldn't even imagine without the science here.

DR. HUNDA: Right.

And what's interesting in part is that even though we're missing some critical pieces that we're familiar with today, like vertebrates in the ocean, many of these guys all looking different, are representatives of a lot of the specimens that we have in modern oceans.

CHRIS: OK. DR. HUNDA: So I don't have trilobites anymore, but we have crabs and lobsters and shrimp.

CHRIS: Right.

DR. HUNDA: You know, we don't have Crinoids anymore, well, we do actually have Crinoids, but they're a small part of the fauna.

But most people are more familiar with, you know, Echinoids: sand dollars, starfish.

So there are major representatives of all of these groups, they just look a little bit different.

CHRIS: They just look different.

That's cool.

So, Brenda, trilobites were here for hundreds of millions of years.

How come they're not here anymore?

DR. HUNDA: Well, the Permian- Triassic mass extinction event is the largest one of the big five that we have on Earth.

It wiped out 96% of all marine species.

CHRIS: That's almost everything.

DR. HUNDA: Almost everything CHRIS: If you round up, it's everything.

DR. HUNDA: Right.

And so they're just one of many, many, many, many groups that went extinct at that time.

CHRIS: Well, thank you so much for bringing me out here.

I really appreciate it.

I love the idea of like we can just come out and find fossils, like, right under our feet here in Cincinnati.

DR. HUNDA: Yeah, it's one of our treasures.

CHRIS: Yeah.

DR. HUNDA: That tells us about our important natural history.

This area is huge not only in the science, but in the history of science and scientific endeavors.

And it also is right beneath our feet, one of our greatest natural resources.

And doesn't it just smell great out here?

CHRIS: It smells great.

It's fresh air.

DR. HUNDA: It's fresh air.

CHRIS: And fossils.

DR. HUNDA: It couldn't get any better.

CHRIS: It couldn't get any better.

Mammoth Cave National Park hosts the largest cave system in the entire world.

It's also home to 130 different species of animals and plants.

It's also a treasure trove of geologic formations, including stalactites, stalagmites, gypsum formations, and underground rivers.

But how did this cave system form?

Let's do some exploring and find out.

The rock around Mammoth Cave is made of limestone that formed around 330 million years ago.

Limestone is a sedimentary rock that's easily dissolved in water, which is how this cave system formed.

Here to tell me exactly how that happened is my friend Rachel Bosch, a geologist at the University of Cincinnati who researches how caves form.

Hey, Rachel, how are you doing?

RACHEL: Hi, Chris.

I'm great.

How are you?

CHRIS: I'm great.

So explain to me, how does water create a cave system like the one we're in?

RACHEL: Well, it takes several steps.

The water is all coming from hundreds of feet up above us when it rains on the surface.

And as that water comes down through the soil, it's picking up little bits of carbon dioxide.

They are animals in the soil.

The animals are breathing in oxygen.

They're breathing out carbon dioxide.

That carbon dioxide combines with the water and makes a weak acid called carbonic acid.

CHRIS: Carbonic acid, okay.

RACHEL: And as the water brings the carbonic acid down through the soil and down into the rocks, it hits the limestone and it reacts with the limestone.

It starts dissolving away the limestone, kind of eating away at it.

And eventually over time, it erodes out larger and larger passages.

And it can start bringing in little rocks and those can bang into the sides and make the passages even bigger, until over thousands and millions of years, you can get passages as big as the ones that we're in today.

CHRIS: So how long has Mammoth Cave been forming?

RACHEL: Mammoth Cave has been forming for about the past 5 million years.

CHRIS: Five million.

So it took 5 million years of water breaking this down to create a cave system this big.

RACHEL: It did.

So the passage we're in right now can show us ways in which it's changing.

There's water flowing in through the ceiling right over here.

And you can see that that little hole there, it gets larger and larger over time as that water just cuts its way back, almost like a waterfall on the surface.

CHRIS: It's just like, yeah, and so over time that's going to move further and further back.

If you sit here long enough, it really makes you want to pee.

(laughs) Now, you said there as we go down to lower levels, there's water flowing through the cave system as we speak, right?

RACHEL: Yes.

CHRIS: Can we go down there and take a look?

RACHEL: Yeah, let's do that.

CHRIS: All right.

Let's do it.

All right.

So, Rachel, where are we now?

RACHEL: So we are at the shores of River Styx, CHRIS: River Styx.

RACHEL: The River Styx.

It sounds ominous, doesn't it?

CHRIS: It does.

RACHEL: So we are in the very lowest level of Mammoth Cave where new passages are forming right now.

So this is the very youngest area of the cave.

CHRIS: So this river here is carving out new parts of the cave as we speak?

RACHEL: Yes.

CHRIS: That is crazy.

RACHEL: Isn't it?

CHRIS: Yeah, it's -- I mean, it's just like any other river, it's just hundreds of feet underground.

RACHEL: Right.

It's just it starts on the surface.

It's a river flowing along the surface.

It goes into a sinkhole and then you have the river underground.

So it's just like a surface river, but it's got a roof.

CHRIS: What is that landscape called and how does that work?

RACHEL: So that's called a karst landscape.

CHRIS: OK. RACHEL: And the one big difference you can see between karst and other humid area landscapes is that in other landscapes and, you know, in the wet eastern United States, you'll have water flowing in a lot of streams on the surface, feeding the main rivers.

So you have the main river and you have its tributaries.

And you can see all these tributaries on the surface, streams and waterfalls.

If you come to then a karst region, like central Kentucky, like most of Tennessee, a lot of West Virginia, these areas don't have those surface streams.

CHRIS: So how does physical weathering, like in this river, help form a cave like this?

RACHEL: So the physical weathering part would be the fact that all of these materials in here, we can see, there's a bunch of -- this is a pretty big piece of gravel.

CHRIS: Yeah, it's got a lot of sand, too.

RACHEL: Yeah.

There's got a lot of sand, silt, clays, all these different grain sizes.

These are not dissolving in the cave.

This has traveled from outside of the cave.

CHRIS: Oh, this came from outside the cave.

RACHEL: That came from outside the cave.

That's made out of sandstone.

CHRIS: Okay.

Oh, so this isn't limestone like it is here.

It was transported here by the river.

RACHEL: Yes.

CHRIS: Oh, and I can imagine if, like this tumbling on the bottom of the river, it's going to knock some other things loose.

RACHEL: Exactly.

CHRIS: Interesting.

So as millions of years, over a really long time, all these little rocks and pebbles like this help break down other pieces of rock within the cave, because the river is carrying them and it's kind of using that to kind of bump and shape and carve out a whole cave system.

RACHEL: Right.

Almost like a sandblaster.

CHRIS: Chemical weathering is when air, water or living things break down rock through a chemical reaction.

Here at Mammoth Cave, most of the chemical weathering is done by water.

That's because when it rains, the water absorbs some carbon dioxide from the atmosphere and the soil, making it slightly acidic.

When that rainwater seeps into the ground and comes in contact with the rock, it reacts with it breaking it down.

You can reproduce this reaction at home by placing a few drops of acid like lemon juice or vinegar on some limestone.

That fizzing, you see, is gas being given off by the acid as it reacts with the limestone.

Geologists use this test in the field to test the type of rock they're studying.

If the rock fizzes, it's limestone.

Chemical weathering is a big part of how caves like this form.

Slightly acidic water, reacting with the rock, breaking it down and forming a cave.

Chemical and physical weathering are major factors in how caves are formed and the changing surface of our earth.

Next time you're at Mammoth Cave National Park, or next time you're just outside, see if you can identify some examples of physical and chemical weathering.

So we are here at Sawyer Point, which is home to a geologic time line that stretches back 450 million years.

That's a long time, but our planet is much older than that, around 4.6 billion years ago.

That's a really hard number to visualize, so to help us understand that, we're going to run all the way back to when our planet formed.

Ready?

Let's go.

So here we are, 4.6 billion with a B years ago.

To give you an idea of how long ago that is, the geologic time line at Sawyer Point is around a quarter mile long.

And we are over 2.5 miles away from where we started.

That is a huge number to wrap your head around.

So what was the Earth like 4.6 billion years ago?

In a word, crazy.

The earliest earth was actually molten and it took millions of years for our planet to cool enough for the crust to form.

And even then, there were volcanoes going off everywhere and the surface was constantly being hit by asteroids.

Eventually, things cooled down enough for water to condense and for the oceans to form from the most violent thunderstorms in the history of our planet.

Oh, yeah, and the atmosphere was a mixture of carbon dioxide, methane, ammonia, basically poison.

Not a fun place to be, but eventually things calmed down enough for life to evolve.

Here we are at the beginning of life, about 3.5 billion years ago.

No one knows exactly how life formed, but there was a lot of energy left over from the formation of the planet, which helped form the basic chemical building blocks needed for life.

But it took a long time for these chemical building blocks to come together to make a living thing, almost a billion years.

And even then it was just single celled bacteria living in our oceans.

For almost a billion years bacteria had the planet to themselves.

In fact, geologists call this era the boring billion.

But of course, life didn't stay like that.

Around 2.7 billion years ago, a more complex form of life began to evolve: eukaryotes.

These cells are much more complicated than prokaryotes because they have specialized parts called organelles.

That includes things like the nucleus to hold DNA, the mitochondria to produce energy, and chlorophyll to capture the sun's rays during photosynthesis.

Eukaryotes likely evolved when bacteria were living close together in symbiosis and eventually started to live inside one another.

But still, this took a really long time, over 1.2 billion years.

But it's a big deal because almost every living thing you see today, from your dog to the trees, even you are made up of eukaryotic cells.

About 600 million years ago, we finally begin to see the first multicellular animals.

This began when single celled eukaryotes began living together in a colony.

By working together, these colonies could get a lot bigger and obtain more resources.

Now, after a while, the cells in these colonies started to specialize with some cells getting really good at capturing food, while others were good at providing structure.

Now, the first multicellular animals weren't that glamorous.

They were simple organisms like sponges.

But soon afterwards, things really started diversifying.

Scientists call this period the Cambrian Explosion because millions of different species evolved in a very short amount of time, including a lot of species that are alive today.

Finally, after over 4 billion years and 2 miles of running, we finally get back to the beginning of the geologic trail at Sawyer Point, around 450 million years ago.

At this point, Earth's oceans were filled with some of the strangest things you've ever seen, including giant trilobites, weird seashell looking things called brachiopods, and 20 foot cephalopods.

Most of the bedrock in Cincinnati is from this time period.

So you can go out to a creek bed or roadside and find a lot of these fossils.

Now, if you were to get in a time machine and go back to this point, it would have been like a completely different planet.

The atmosphere would look pink because it didn't have as much oxygen in it and there would be no trees or shrubs or rivers on the land, just barren rock and braided streams.

But it didn't stay like that.

Around 360 million years ago we start to see the first land animals.

Our distant ancestors who took the first steps onto dry land looked a lot like giant salamanders.

But the transition wasn't easy.

It's a relatively simple thing to get oxygen and stay hydrated when you're living in the ocean, but it's much more difficult on dry land.

This transition took millions of years, which again is a really long time, but relatively short compared to the total age of the Earth.

But this is a big step because it allowed for a lot of other things to evolve, including dinosaurs.

65 million years ago was the worst day on the history of life on this planet when an asteroid over 6 miles wide slammed into the surface, going at least 44,000 miles an hour.

This vaporized anything within thousands of miles and caused a tsunami over 300 feet tall.

The heat caused by the impact alone lit forest fires that raged on continents on the other side of the planet.

On top of all that destruction, an enormous amount of rock was thrown into the air, which not only rained back down on the earth killing more things, but also blocked out the sun for years, keeping plants from photosynthesizing and destroying food chains.

It's lucky any living thing survived the asteroid impact.

But as the great Dr. Ian Malcolm once said, "Life finds a way."

Birds who were the relatives of dinosaurs survived.

But the biggest winner of all were mammals who took over the Earth.

Which leads us to the last stop on our tour.

Finally, at the end of our trail, we get to us, humans.

Humans have been around for around 500,000 years, which sounds like a long time.

But after 2.5 miles of running, that just accounts for 8 inches.

That's right.

The entire existence of our species is just 8 inches.

In fact, our entire written history, up to about 5000 years ago, accounts for just 1/6 of an inch.

That's it.

Sometimes we humans like to think of ourselves as this incredibly successful species.

And in some ways we are, but we just haven't been around for that long.

Especially when you remember that for 2 billion years, life on earth was limited to single celled organisms.

The Earth is just so old and it's a hard thing to wrap your head around.

So hopefully this video gave you a little bit of perspective on the age of our wonderful planet.

That's our show.

Thank you so much for watching.

We hope you learned a little bit about what the earth was like hundreds of millions of years ago and how it's changed since.

Thank you so much.

We'll see you next time on Science Around Cincy.

Hey, everyone, my name is Chris Anderson and I'm -- >> Actually back to one, I zoomed out too early.

CHRIS: A few drops of -- Science Around Cincy is an independently produced collaboration between educators and students in Cincinnati and Northern Kentucky.

Funding is provided in part by: Northern Kentucky University's College of Informatics and Department of Communication, the Hamilton County Educational Service Center, Outsider Productions, and Fuel Cincinnati.

Stay curious, my friends.

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