But first, cave sharks in Kentucky.

Now, that may sound like a wild urban myth or the plot of a really bad movie, but scientists say it's the real deal.

Recent shark discoveries have been made deep in the caverns of Mammoth Cave.

Now, these aren't sharks that are swimming around today.

Researchers have discovered the fossilized remains, more specifically the teeth, of ancient species completely new to science that roamed the shallow seas of this area hundreds of millions of years ago.

From these teeth and other fossils, we're able to learn a wealth of knowledge about how these sharks lived, hunted, and interacted with the world around them.

[music playing] At this time, sharks were ruling the world.

Many of the main fish throughout the ocean were sharks.

Three hundred fifty million years ago, we would have been standing on a ocean floor.

All of this would have been water column, and the water may have been 30, 40, 50 feet deep.

We would see those crinoids and corals and things around us.

And over time, we're seeing these stacked layers of the sand coming in around us, and eventually this is all compressed to make this limestone and allows us to stand here and see the fossils that were originally deposited on the floor of that sea.

And all sorts of critters were living in this sea, things you'd recognize, things that looked like corals, things that looked like clams, and sharks.

One of the interesting things about the shark's teeth is many of the shark's teeth will fluoresce in ultraviolet light, in black light.

And so we use this as a tool in trying to find the shark teeth.

[music playing] So, you can see that that tooth fluoresces very nicely yellow under this UV light, and that is very characteristic of what we see here at Mammoth Cave on our shark's teeth and cartilage.

Much of it will fluoresce in that color.

This is the business end, this flat part here.

This would have been up in the root.

This might have been the front of the tooth.

It's a shark called Psammodus.

Psammodus would have been a shyer animal, one that's sort of laying on the ground, staying out of the way.

It's eating invertebrates.

It's not out actively swimming, chasing other fish.

Right here, we have an example of one of our smaller, a smaller shark and a smaller shark's tooth.

So, this is a shark called Chomatodus.

It had these sets of blades.

Again, with blades, you're now looking at more of an active predator eating softer material like squid, octopus, anything that doesn't have the hard shell on the outside, something that you're just cutting up to eat.

So, that's Chomatodus.

[music playing] These sharks were obviously not the only animals swimming around in this ocean.

And a lot of this would have been analogous to a modern coral reef.

And some of the big players would be things like crinoids.

This is a piece of crinoid stem here.

The stem is made up of pieces that look like little washers, little circular things.

So, those crinoids were incredibly important and very, very diverse and very abundant in this area.

And that's why you have those Psammodus with the crushing teeth, because there's a wonderful food source.

It's like on the prairie, somebody's gonna eat the grass because there's so much of it.

Somebody's gonna eat the crinoids because there are so many of them.

It was a very diverse neighborhood and these sharks were part of that ecosystem.

[music playing] This is a jaw of a shark called Saivodus.

The shark itself, this is the front end, the very front end of the jaw.

This is the back end of the jaw.

This is some pieces possibly out of the gill area.

So, this shark had a jaw, two feet long, and this individual was probably right up in a great white shark size.

This is a tooth.

It was actually found not very far away from the Saivodus, Troglocladodus trimblei.

Troglocladodus, Troglo, being cave.

So, it's the cave shark found by Barclay Trimble, who is the superintendent of the park.

So, it's named for the superintendent because he was the person who found it and said, "Hey, is that a shark tooth?"

[music playing] We're here to look at a very interesting fossil.

It's this piece right here.

And it is a special fossil because again, it's a piece of shark, but in this case, it is a piece of shark cartilage.

It's a softer material and it tends to degrade.

Most sharks, we don't have a lot of information on.

These Mississippian sharks, most of them are known just from teeth.

So, when we find these cartilage pieces, especially when we find these cartilage pieces associated with teeth, so we can tell what shark they came from, they can be incredibly important.

With tourism being off limits to this portion of Mammoth Cave, it's allowed researchers to uncover more than 75 species of fish and shark, three of which are new to science, with many more waiting to be discovered.

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