[JOAN CARTAN-HANSEN] 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 epic. That was about 3 ½ million years ago.

[PHIL GENSLER] This part of Idaho is really unique because we have this large section of geology here it's called the Glenns Ferry formation. That's where we find thousands of fossils. Here in Hagerman we have 4,300 acres of land preserved and we have almost 600 fossil localities there. Every year we get about 3 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.

[JOAN] Many of the fossils found here are examples of the plants and animals that were in idaho before the last ice age.

[PHIL] 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.

[JOAN] Paleontologists from the Smithsonian Institute found fossils of the Hagerman horse first in the 1920's. And paleontologist Phil Gensler continues their work today.

[PHIL] What you see here is one of the large plaster jackets. This is what 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 are 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 these fossil preparators - that's what they are called. They use air scribes which is a little hand held jack hammer and they just slowly - very slowly and very gently work away the rock from the fossil bones.

Sometimes it's really hard to tell the difference and you really need to know what you are 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 casts we're usually looking for horse bones but also inside there are little rodents and fish. And those require a microscope to fine them.

[JOAN] Paleontologists study fossils to learn how animals used to interact or how plants grew. They learn 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.

[PHIL] Paleontologists are people who never really quite grew up. You start digging in the dirt and just enjoy what you find and that's pretty much where I am. I enjoy getting out in the field and finding new fossils. That's the funnest part of it.

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