One hundred and thirty million years ago, massive marine predators were at the top of the food chain.

Imagine what it would take to feed an animal that has a skull of 2.5 meters long.

It's Tuesday, October 24th, but just like every day, today is Science Friday.

I'm SciFRI producer Kathleen Davis. The Paja formation in Central Columbia has an incredible

amount of fossils from the early Cretaceous period. Many of these fossils are from giant marine reptiles.

They were so huge that there's no modern equivalent.

We'll talk about that story in just a bit.

But first, guest host Swatnakrishna takes us to the mountains of Wyoming,

where trout are evolving quickly.

Wyoming's Wind River Mountain Range is a prime location for outdoor sports, including

backcountry fishing. After some 15 miles of hiking, fishers can reach alpine lakes and find a

variety of big, beautiful trout. But these fish high up in the mountains are not a natural

phenomenon.

Reporter Wilwaukee of Wyoming Public Media and the Mountain West News Bureau reported on the way humans have changed Wyoming's alpine lakes. He joins me now from Laramie, Wyoming.

Welcome to Science Friday. Hi, thank you for having me.

So, Will, tell me about these fish. If they aren't natural, how did they get up into the

Wind River Mountains? Starting in the 1800s, you know, more people are starting to move to the region,

and fishermen started stalking these waters with trout. The idea was, hey, it's good food. They're fun to

catch, and it'll get people visiting the region and going fishing. And so people brought fish by the millions into these lakes.

They really created a fisherman's paradise.

It feels really natural when you're out there fishing.

But it's actually, like you said, it's not a natural phenomenon.

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