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Jeff Person, a paleontologist with the North Dakota Geological Survey, points out tooth sockets on the jaw of a mosasaur fossil discovered on Mike Johnson's land in rural Larimore, N.D., on Monday, April 28, 2014, at the North Dakota Heritage Center in Bismarck. Photo by Mike Nowatzki / Forum News Service

Bones of ancient 50-foot sea monster found on ND farm

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News Fargo,ND 58102
Bones of ancient 50-foot sea monster found on ND farm
Fargo ND 101 5th Street North 58102

LARIMORE, N.D. – A big backbone found 10 years ago by an arrowhead hunter led to a puzzle about to be pieced together by North Dakota’s state paleontologist as a giant marine lizard that swam the sea that covered North Dakota 80 million years ago.


State Paleontologist John Hoganson and his staff members have collected about half of the fossilized bones from the 50-foot sea monster from the past found on the farm of Mike and Jennifer Johnson northwest of Larimore in Grand Forks County.

The remaining bones are waiting in the Johnsons’ garage.

Once he gets them, he figures to have most of the complete skeleton of the beast, Hoganson said this week.

“This mosasaur is a very important fossil because it’s the only fossil of this kind of mosasaur that’s been found in North Dakota,” Hoganson said. “It probably was at least 40 feet to 50 feet long. The teeth are huge.”

Like land-based dinosaurs, mosasaurs were a general category of several species of sea-going reptiles, mostly huge and predatory with big, sharp teeth, flippers and long tails.

Back in the day, 90 million to 70 million years ago, the Pierre Sea – named after the shale rock first found by scientists near South Dakota’s capital – covered the Plains states, connecting what now is the Gulf of Mexico with the Arctic Sea, Hoganson said.

“It was a shallow-water ocean, maybe 500 feet deep,” stretching to the Rocky Mountain area on the west, he said. “This mosasaur cruised around and was what we call cosmopolitan. He lived all over the world and would swim like a whale would, migrate around.”

It is probably most closely related to the monitor lizards of today, such as the Komodo dragon, he said.

“We think it was a tylosaur,” he said of the more specific type of mosasaur the skeleton came from. “Although we are not 100 percent certain about that. We really need to examine the entire fossil.”

That’s why getting it all back together is important, he said.

Important find

The Johnsons themselves hadn’t seen any fossils but their work digging out a water hole and small dam for their cattle helped expose the fossil, Jennifer Johnson said.

It was the spring of 2004 when Kieth Lieberg of Grand Forks was looking for arrowheads in the pasture, he said recently. He had hunted the area for years for deer and waterfowl and also is an avid arrowhead collector, he said. The newly dug bank of the steep coulee looked a likely spot.

He found no arrowheads but instead a big chunk of several fossilized vertebrae embedded in shale. The backbone pieces were “about 8 inches across,” far larger than anything from a cow or buffalo, Lieberg said.

That summer, he hauled the rock around in his van, showing it to experts, including a paleontologist at the University of North Dakota who told him it was something important.

In 2005, he finally tracked down the Johnsons, and they contacted Hoganson.

In 2006, Hoganson and his assistants came to begin their own hunting and gathering of what clearly was a prehistoric relic.

He and others have found smaller mosasaurs near Pembina and Cooperstown and other parts of the state.

“But to find one fairly complete skeleton is really kind of remarkable,” Hoganson said. “So this one is very important.”

From gnaw marks on some bones and the fact he can’t find the smallest bones from the creature’s flippers, Hoganson figures the creature died, sank to the bottom, where its carcass was scavenged by little sharks.

This summer, Hoganson will pick up the remaining fossilized bones in the Johnsons’ garage. They were encased in plaster in the pasture, a way of protecting them until they can be extracted under lab conditions in Bismarck, Hoganson said.

Preserving the past

This work illustrates North Dakota’s special commitment to the long ago past.

Utah and Maryland are the only other states with official paleontologists and North Dakota’s leaders have given unparalleled support, Hoganson said. In 1989, the Legislature created the state fossil center and several years ago authorized hiring two more paleontologists in the state’s geological survey office.

Hoganson’s office actually is part of the state’s department of mineral resources, which regulates the oil and gas industry.

Fossils, when found, are the property of the landowner, Hoganson said.

“The landowner has to make that decision about what they want to do with it,” he said.

 “A few years ago, a triceratops dinosaur skeleton was found out by Bowman (in southwest North Dakota) and it ended up being sold at auction in Paris, France,” Hoganson said. “We hope people decide to donate to museums or to keep them in museums. But there are private collectors out there.”

Fossil owners also can receive tax deductions for the value of a fossil when donating it to a museum or exhibition facility, he said. The Johnsons also can have a say in where this mosasaur’s skeleton will be displayed, Hoganson said.

It will take about a year to get this tylosaur ready for such an exhibit, perhaps in the Heritage Center in Bismarck, newly renovated for $52 million.

But his office already has such exhibits in about two dozen other sites around the state, including in museums near Pembina and Cooperstown where mosasaur fossils have been found.

That means the Larimore or Grand Forks area might remain a place of rest for this beast from the past if the right setting is found, Hoganson said.

“I personally feel we really should try to exhibit a lot of these fossils in the areas where they are found.”