[playful tune] [heavy footsteps] -[Narrator] Few creatures spark the imagination like T Rex.

And Triceratops, [deep bellows] perhaps the most iconic dinosaurs ever to have lived.

[hissing snarl] [deep bellow] They were also amongst the last to walk the Earth.

Today the remains of these giants litter the ground in Eastern Montana, a playground for paleontologists like Eric Lund who wants to learn more about how these icons met their end.

-[Eric Lund] They’re the last vestiges of the dinosaur rule.

They’re making a good go of it and they just got cut short.

-[Narrator] It came from outer space, an asteroid the size of Mount Everest smashing into the Atlantic Ocean off Mexico.

An event often thought of as wiping out the dinosaurs in an instant.

[explosion] [flying dinosaur screeching] But the truth isn’t nearly so simple.

-I’m sure some of them got obliterated, the ones very near the impact but here in Montana we’re far away from where that impact hit so they could have lasted hundreds of years after that impact.

-[Narrator] So what really killed off these giants?

-[Eric] As we walk from the bottom of this formation to the top, we’re going up through time.

There becomes a point where we sort of stop finding fragments, lose the dinosaurs.

-[Narrator] This is the exact spot in the fossil record where Triceratops and T Rex die out.

Eric’s drafted in paleontologist Michael Pittman to help him investigate this 66 million-year-old crime scene.

Michael has built a high-powered laser that highlights different element in rock.

-[Michael Pittman] The laser’s essentially giving us chemical information from the rocks that otherwise we wouldn’t be able to find with existing technologies.

-[Michael] Goggles on.

-[Eric] Yeah goggles on.

[flashlight clicks] -[Narrator] The laser scans across the surface.

While the camera photographs the glowing elements.

-[Michael] It’s actually lighting up a scorpion.

-[Narrator] And in just a few seconds, the image is ready.

-[Michael] So this is the image that we have and you’ll see... notice how there’s this layer.

-[Eric] Wow.

It’s cool to see.

-[Narrator] This faint line is rock rich in iridium.

-[Eric] And iridium doesn’t naturally occur often on Earth.

[explosion] -[Narrator] It was in the days and weeks after the asteroid hit that the deadliest damage occurred.

Several trillion tons of rock were ejected into space.

Rock that rained down on the land below.

Leaving behind a band of iridium that’s now been found in over 100 different locations all around the world.

[somber music] Proof that the asteroids impact affected the entire planet.

But Eric thinks even that wasn’t the full story.

-[Eric] The huge cloud of debris and ash, would have blocked out the sun for maybe many months, maybe years.

Would have been like nuclear winter.

[flames crackling] -[Narrator] The loss of the sun was the real killer.

A planet plunged into darkness.

-[Eric] You block out the sun so you start killing off the plants, you got no plants so you get no plant eaters coz they got nothing to eat and then the meat eaters can’t survive.

Would have been relatively slow process, it wasn’t an instantaneous event.

-[Narrator] Eventually decades after the asteroid struck, over 75% of life on earth was lost forever.

Including those giants of the Cretaceous, T Rex and Triceratops.

-[Eric] It’s possible without that asteroid impact things could have been completely different and dinosaurs could have lived for another 180 million years.

[insects chirping]