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Window to the past: North Dakota Geological Survey leads public fossil dig at Medora

Press Photos by Linda Sailer Paleontologist Jeff J. Person with the North Dakota Geological Survey uses a pick to flake away pieces of mudstone from the bone bed at the Medora public fossil dig on Thursday morning. A clam shell can be seen at his right hand.

MEDORA -- Paleontologist Becky Barnes with the North Dakota Geological Survey slowly removed mudstone flakes from her grid at a fossil dig site on Thursday. Working throughout the morning, she uncovered the remnant of a fossilized fish -- identified as an Amia -- that swam in the region's swamps 60 million years ago.

The remnant was part of the frontal lobe of the fish, including the outline of the eye socket.

Barnes padded the fossil with tissue paper and plaster casting so it could be removed from the quarry.

Barnes and fellow paleontologists have been excavating an isolated knoll two miles east of Medora since 2005. They invite the public for yearly digs and this year's program concludes today with a family day. There was a charge of $145 per day per person.

"It's easy for us to dig, but that's not reason we're here -- we're here to let other people enjoy the experience," Barnes said. "Since we've been here, we actually found the largest crocodile tooth to date."

Paleontologists believe the Medora dig site is rich in fossils because it was a lagoon drying up in a swampy area.

"Fish were trapped into one space and the predatory animals moved in to feed there, as evidenced by the coprolite (fossilized poop) lying around," she said.

Edythe Nelsen from Leeds compared the digs to treasure hunts.

"It's amazing to find things that are 60 million years old and still intact and people who can recognize them," she said.

The rugged beauty of the Badlands buttes, junipers and sagebrush provide little hint of the region's prehistoric history. Digging into the Paleocene Sentinel Butte Formation, fossils reveal a time when the Badlands were a swamp -- a quiet, shallow water ecosystem that was teeming with life. Evidence indicates the setting was subtropical, hot and humid, according to research by the paleontologists.

They imagine the Medora swamp would have been a putrid, smelly, disgusting place because of the decaying carcasses, rotting flesh and abundant feces of the animals that fed on them.

The site was discovered in 2004 by Darrell Nodland, who was inspecting an abandoned oil well site for the North Dakota Industrial Commission. The fossil bones he discovered were identified as a champsosaur, a crocodile-like animal that inhabited swamps in North Dakota 60 million to 65 million years ago. It is believed the champsosaur was an underwater predator that fed on fish. As fish swam by, it would lunge off the bottom, propelled by large, powerful back legs.

The largest animals found at the site have been fossils of crocodiles, validated by teeth, vertebrae and limb bones. This Medora wetland existed about 5 million years after the extinction of the dinosaurs and crocodiles were the main predators.

Additional fossils, including soft-shell turtles, fish, amphibians and birds, emerge from a thin bone bed at the site. The site is on Theodore Roosevelt Medora Foundation property. The North Dakota Geological Survey approached the foundation about partnering with the public digs.

"We think the digs are a way to preserve our history -- the Foundation is all about preserving history," TRMF group sales coordinator Jenna Herzig said. "I think it's a fun family learning experience."

The North Dakota Geological Survey conducts research projects to learn more about the kinds of plants and animals that lived in North Dakota in the past, state paleontologist John Hoganson said.

"We provide an educational component to that research as well. Not only through public fossil digs, but we also have established many fossil exhibits around the state," he said.

This year's public digs were delayed by rain showers, but the participants agreed it was worth the wait.

Digging with picks and brushes, the participants uncovered crocodile teeth, a fish tooth and coprolite. Another couple uncovered vertebrae from a Piceoerpeton -- a three-foot salamander considered rare for the region.

Nellie Mahto and her daughter, Marena Mahto from Dickinson, removed several feet of overburden before they hit the bone bed. They found fossilized clam shells. The shells were difficult to remove because they fall apart like chalk.

"I've been interested in digging ever since I was a little kid," Marena Mahto said.

Judy Maier, a West Fargo English teacher, also found clam shells and a specimen that wasn't immediately identified.

Her first trip to a dig, she said, "I love the outdoors -- this has always been an interest of mine."

The participants placed the fossil debris into buckets. The material will be washed at the North Dakota Heritage Center paleontology laboratory in Bismarck to reveal microscopic fossils of teeth and bone.

The Medora site is one of four public digs coordinated by the North Dakota Geological Survey. The others include a site near Marmarth, another at Whiskey Creek northwest of Medora and a fourth at Walhalla.

"We do the public digs to educate the public about why paleontology is important," paleontologist Jeff J. Person said. "We do digs to bolster our collections and to learn more about the history of life in North Dakota. These are non-renewable resources that we have to dig every year."

The digs also are designed to inspire youth to pursue science careers.

"We're learning about the planet, why the rocks look the way they do, what the rocks can tell us about the past and maybe help us see what's coming in the future," Person said.

Nelsen told Person the dig was on her bucket list.

"I think that's true for a lot people -- it's something they've always wanted to do. They think it's exciting, they think it's fun," he said. "It's not as romantic as it's portrayed on television, especially the movies. You definitely need a trained eye -- one of the most common things I hear is 'Oh my God, how did you see that! It looks like a rock to me.'"

The other component is having patience -- the patience to uncover fossils flake-by-flake of mudstone, he added.

Person said the Paleocene rock formations of North Dakota are not exposed in very many places in the country.

"You can't dig in Oklahoma; you can't dig in Texas; you can't go to New York -- you have to come to certain places in the country to dig those rocks," he said.

Besides leading public digs, Person manages the NDGS collections across the state. Examples of their work may be seen at the North Dakota Cowboy Hall of Fame, Medora; the Theodore Roosevelt National Park Visitor Center at the entrance to the South Unit; and at the North Dakota Heritage Center.