-It's not, uh, soft, [sniffs] smells like stone, it's hard as a rock and uh... [camera shutter clicks] -[Narrator] This man just put his tongue on some poop.

-...you put your tongue on it.

-[Narrator] On purpose, but it's okay because it's all in the name of science.

George Frandsen is on the hunt for fossils.

But not the bones, claws or teeth you might imagine when you think of a dinosaur fossil.

He's specifically looking for fossilized dinosaur poop.

-I thought that was one, but it turns out just to be, turns out to be bone.

-[Narrator] Luckily, he doesn't have to wait too long.

And the licking part makes sense too.

-Put your tongue on it, it sticks because it's porous.

And that's one of the ways you can tell it's a coprolite.

-[Narrator] Fossilized poop, known as a coprolite, which literally means dung stone, provides a wealth of information to paleontologists seeking to understand more about the lifestyle, behaviors, and eating habits of dinosaurs, as well as the surrounding ecosystem.

-[George] They're kind of the joke fossil, but they really have enormous scientific information.

-[Narrator] George Frandsen is the latest in a long line of scientists bewitched by the secrets nestled inside of some ancient dino dung.

Famed fossil hunter Mary Anning was the first to observe them in 1824.

Breaking them open, she'd regularly find fossilized bones inside the coprolites.

But others weren't as interested in the dinosaur aspect.

In the mid-19th century, the phosphate found in ancient poop helped revolutionize agriculture by launching the artificial manure industry.

By World War I, that phosphate was in demand for a different reason.

Concerned by German attacks on its supply, the British government turned to fossilized poop to provide phosphate for munitions.

[rapid firing] But most scientists have been captivated by just how much a single poop can tell us about the ancient world.

It's thanks to fossilized poop that we now know about an extinct, never-before-seen beetle that was found preserved in a 230-million-year-old turd.

But for all this, every coprolite discovery starts with the same mystery.

A classic whodunnit.

And it's not very easy to determine the culprit.

The first clue is the size.

The bigger the poop, the bigger the dinosaur that laid it.

-[George] Most of them that you find are just really tiny.

They're, you know, a quarter of an inch, half an inch long.

You know, where most people think, "Oh, there gotta be dinosaur poop, so they’re these big things."

And really, the bigger they are, the more rare they are.

-[Narrator] And in George's collection is the largest fossil poop ever found.

-[George] The biggest one I have in the collection is 26 and a half inches by about just over six inches wide.

-[Narrator] The size alone rules out smaller dinosaurs.

But there are other clues, too.

Analyzing what's actually in the dung can also tell us whether it was laid by a meat-eater or an herbivore.

-[George] Most coprolites that are discovered are from carnivorous animals.

Because they make poo with a lot of phosphorus and calcium, that helps the mineralization process.

-[Narrator] The bulk of that calcium phosphate will have come from carnivores crunching the bones of their prey.

[ground rumbles] And there's no more famous bone cruncher than the T. Rex.

And all these bones also transform the shape of a fossil feces.

-[George] Carnivorous animals, when they poop, most times it's very cylindrical.

And when they fall and they hit the ground or hit a hard surface, they bend.

So, a straight classic turd turns into almost like a little L shape.

-[Narrator] The final clue that this gigantic coprolite came from a mighty T. Rex is the angle.

The bend indicates it might have fallen to the ground from about 8 feet, the approximate height of a T. Rex's behind.

-[George] A coprolite is like a time capsule that tells all about that moment in history where that poop was made.

[snarls] We can tell how it digested.

We can tell about the acidity in their, their stomach.

We can tell what it ate.

-[Narrator] What may seem silly at first, is in fact a fascinating insight into the biochemical ecosystem millions of years ago.

-It's not gross.

I think that's the big misconception.

Once people get over that, it's not too far until they're all in about fossilized poop.

They are fans.

They're with it.