Joan Cartan-Hansen, Host: We learn about our future by studying the past.

And how do we do that?

We study fossils.

[MUSIC] Some fossils are bones like these.

When animals and plants from ages past die, their remains are covered by silt or soil.

Over thousands and thousands of years, the bone is replaced by minerals and becomes encased in rock.

Scientists, called paleontologists, dig up fossils and learn more about times past.

Idaho is famous for its fossils, particularly the Hagerman horse.

This zebra-like creature lived near what is now Hagerman, Idaho, in a time period called the late Pliocene epoch.

That was about three and a half million years ago.

Phil Gensler, Paleontologist: This part of Idaho is really unique because we have this large section of geology here.

It's called the Glens Ferry formation.

That's where we find thousands of fossils.

And here in Hagerman, we have 4,300 acres of land preserved, and we have almost 600 fossil localities there.

Every year we get about three to 5,000 new fossils a year, and that's one of the richest sites in the world for this age of fossils that we find.

Cartan-Hansen: Many of the fossils found here are examples of the plants and animals that lived in Idaho before the last ice age.

Gensler: The Hagerman Horse is actually a very common horse from this time range.

It's found throughout the western United States.

It was first discovered in Texas of all places, but here at Hagerman it’s the quantity of horses that makes this place very unique.

Cartan-Hansen: Paleontologists from the Smithsonian Institute found fossils of the Hagerman horse first in the 1920s and paleontologist Phil Gensler continues their work today.

Gensler: What you see here is one of the large plaster jackets.

This is what the plaster jackets will look like when we remove them from the field.

This is to protect them so they don't fall apart.

The second cast you see here is what they look like after we take off one side of the plaster.

You can see the rock is exposed, and in certain areas there's little bits of bone.

This is the first step in identifying where the fossils are, so we know where to work.

What you see here is actually the rib bone to the horse.

If we look over in this direction, there's another small sliver of bone.

The rock that the bones are in is like concrete.

It's very hard.

So we use fossil preparators that's what they're called, and they use air scribes, which is a little handheld jackhammer, and they just slowly, very slowly and very gently work away the rock away from those fossil bones.

Sometimes it's really hard to tell the difference and you really need to know what you're looking at.

So it takes skilled people to do that.

But typically, the bone is a different texture than the rock itself.

With these big casks, we're usually looking for horse bones, but also inside there are little rodents and fish, and those require a microscope to find them.

Cartan-Hansen: Paleontologists don't just look at fossils of animals.

They also look for fossils of plants, even algae.

"These fossils are 15 million years old and there are butter knives down there, and what you want to do is you take 'em and you split 'em and open 'em up like you're opening the pages of a book."

Cartan-Hansen:In a hillside near Clarkia, Washington you can find a snowmobile and dirt bike track and a rich deposit of fossils.

Kenneth Kienbaum: In 1972, when my dad cut this hillside down here, he hit these fossils.

Found it very interesting.

So he called up the University of Idaho and Jack Smiley came out here to see what dad was talking about.

So once Jack Smiley told dad that he says, Mr.

Kienbaum, you must understand one thing.

There's only been two people in the world to have ever seen this.

I'm going to say that you're the second person.

I'm the first one because I'm going to tell you what it is.

Cartan-Hansen: There was once a deep ancient lake here, so the clarkia fossils aren't just impressions.

The sediment contains actual ancient leaves and plant matter that settled into the lakebed.

Dave Tank, Associate Professor, University of Idaho: Here.

Because of how deep this lake was, it had very high sedimentation rates and an anoxic environment.

The preservation is really spectacular and they're actually preserving the leaf tissue itself.

And so as we're opening these up, you're not looking at an impression of the leaf.

You're actually looking at the leaf that fell into this lake 15 million years ago.

"There's a nice fall color in that one right there, which that'll turn black."

“Exciting thing is that that's time in 15 million years that's seen the light of day.

It's been covered up for that long."

Cartan-Hansen: Paleo-botanist Bill Rember has studied Clarkia fossils for years.

He says cracking open a rock and finding a fossil is like looking through a history book.

Bill Rember, Adjunct Faculty, University of Idaho: And I've been a voracious reader all my life, and those are like books and it's a book that nobody else has ever read, and that's pretty exciting.

It's like the physical setting of a novel, whereas the biology, the leaves, you put those on it and that's like the characters in the novel and it tells you a story about what was here 15 million years ago.

Cartan-Hansen: Paleontologists study fossils to learn how animals used to interact or how plants grew.

They learned what the environment was like and how the Earth is changing.

Paleontologists need a lot of patience and a lot of schooling, but according to Phil Gensler, the first thing it takes to be a good paleontologist is a sense of wonder.

Gensler: Paleontologists are people who never really quite grew up.

They start digging in the dirt and you just enjoy what you find, and that's pretty much where I am.

I enjoy getting out in the field, finding new fossils.

That's the funnest part of it.

Cartan-Hansen: If you want to learn more about fossils, check out the Science Trek website.

You'll find it at science trek dot org.

[MUSIC] Announcer: Presentation of Science Trek on Idaho Public Television is made possible through the generous support of the Laura Moore Cunningham Foundation, committed to fulfilling the Moore and Bettis Family legacy of building the great state of Idaho; by the Idaho National Laboratory, mentoring talent and finding solutions for energy and security challenges; by the Friends of Idaho Public Television; and by the Corporation for Public Broadcasting.