In Arizona, paleontologists are shifting their focus to microfossils
AYESHA RASCOE, HOST:
Petrified Forest National Park in northern Arizona is famous for enormous crystalized trees and dinosaur bones dating back to the Triassic period. The park's hills are also full of tiny bones. Paleontologists are taking a close look at these microfossils and say they, too, hold the secrets of the past. Member station KNAU's Melissa Sevigny reports.
MELISSA SEVIGNY: The colorful hills of Petrified Forest hide all kinds of hidden wonders. And paleontologist Adam Marsh is headed out to find them.
ADAM MARSH: Seven hundred, 402.
SEVIGNY: There is not a speck of green in this landscape, but dark banded layers in the hillsides mark what used to be the bottom of Triassic ponds, fringed with ferns and conifers. Marsh parks his truck not far from one of his field sites.
MARSH: It's a hop, skip and a jump over that ridge to where we're going.
SEVIGNY: Oh, my gosh.
These hills are full of microfossils from 200-million-year-old frogs, lizards and other small animals. Marsh says park paleontologists never used to pay attention to the little things, too busy digging up dinosaurs and crocodile-like creatures. He says that changed about a decade ago.
MARSH: It was sort of a happenstance of preparing large fossils and finding the small stuff inside and then kind of switching focus to realize, oh, we're missing most of the story of diversity through time by focusing on the large stuff.
(SOUNDBITE OF PICKAXE STRIKING)
SEVIGNY: At the field site, Marsh digs his pickaxe into the hillside. A shower of tiny fossils falls out.
MARSH: So here's this - I just put my pick through the site, through the layer. See how this is a coprolite. These are all little coprolites and teeth.
SEVIGNY: Coprolites are what's left over after Triassic beasts use ponds and rivers as bathrooms. Studying these small roundish blobs is the specialty of park intern Isaiah McKinney.
ISAIAH MCKINNEY: I had that dinosaur phase as a kid that I never really grew out of.
SEVIGNY: Coprolites might not be as glamorous as dinosaurs, but McKinney says their various shapes - spiral or pancake flat - give clues to the anatomy of animals long since extinct.
MCKINNEY: Every part of the puzzle tells a story. And really, it's our goal as paleontologists to try to put that story together, even if it means looking at the not-so-pleasant stuff.
SEVIGNY: But how to find, say, a hip bone the size of an eyelash? The team brings buckets of soil back to the museum laboratory at the Petrified Forest Visitor Center. There, Adam Marsh soaks the dirt in water until it turns to sludge.
MARSH: So what we're going to do, we'll take one of these buckets, and we'll go outside.
(SOUNDBITE OF DOOR SQUEAKING)
SEVIGNY: Outside is an old cattle trough filled with water.
MARSH: So you stick your box in your trough and then you pour it in.
(SOUNDBITE OF WATER POURING)
SEVIGNY: The sludge splashes onto a screened box that's submerged inside the trough.
MARSH: And then is the fun part. You basically agitate this to get the mud and the water to go through the bottom of the box, leaving bigger chunks of mud and hopefully all of your fossils in the box.
SEVIGNY: Bones and teeth are picked out and cleaned up with tiny air hoses and paint brushes. Broken pieces are jigsawed back together with tweezers under microscopes, plus dabs of superglue so small they could fit on the end of a human hair. Ben Kligman is working on a reptile jaw.
BEN KLIGMAN: It's one of the big satisfying aspects is when you do find a fit like that, that really opens a whole new world of understanding this animal.
SEVIGNY: This ability to find and reassemble tiny, broken bits of bone is a new step in paleontology, and it's turning up all kinds of new species, like minuscule frogs and toothed worms, that still have descendants today. Even more exciting, Kligman says, are the bones they can't identify.
KLIGMAN: There's still a huge amount of the anatomy of all these animals that's a mystery and will be probably unraveled over the next century. People will slowly figure out bit by bit what all these different bones we're finding are.
SEVIGNY: The scientists say one drawer of microfossils can hold a career's worth of data, and now that they know how to look, they're finding Triassic troves not just in Petrified Forest, but in other places throughout North America - small wonders that have been overlooked until now.
For NPR News, I'm Melissa Sevigny. Transcript provided by NPR, Copyright NPR.
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