When it comes to fossilized remains, plesiosaurs don’t grow on trees.
“These animals are exceedingly rare,” said paleontologist Jeff Person, of the North Dakota Geological Survey. “You never find these things.”
Three separate, single vertebrae were all that existed for examples of the ancient marine reptile in North Dakota, until a find in the 1990s during road construction on federal land in Bowman County. About 10 percent to 20 percent of the animal's skeletal remains came to be recovered, including vertebrae, flipper knuckles and a tooth.
With a bulbous body, short tail and flippers, plesiosaurs are most recognized for their elongated neck, similar to the legendary Loch Ness monster.
“This is the type of animal people usually relate that animal to, is these big, long-necked plesiosaurs,” said Clint Boyd, paleontologist and curator of the state’s paleontology collection.
Cleaned and prepared by the Pioneer Trails Museum in Bowman, the 80 million-year-old remains came to the state’s paleontology collection in the past year. The specimen is undergoing prep work in the weeks ahead for a cast and mural display in the North Dakota Heritage Center’s underwater world exhibit. Installation could come in the first half of 2018, perhaps as a kickoff exhibit to summer.
In a jacket on a table downstairs of the museum are 15 neck vertebrae still in original life position, representing about a quarter of the neck of the 50- to 60-foot elasmosaur, an extreme variety of plesiosaur.
“You’re talking about a very large animal,” Boyd said.
Existing in a warm, shallow seaway between today’s Rocky and Appalachian mountains, plesiosaurs lived alongside mosasaurs, the apex predator of their day, resembling a type of watery Komodo dragon.
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Plesiosaurs had interlocking, X-patterned teeth similar to a Venus fly trap, Person said.
“(Plesiosaurs) are big predators, but compared to their body size, you can see how small their head is, and they have very spindly, pointy teeth that aren’t like the big, robust teeth that mosasaurs have that are designed more for capturing bigger prey and disarticulating the specimens and eating them,” Boyd said. “So these guys are eating a lot of fish and things like that, but they probably weren’t attacking other plesiosaurs or attacking mosasaurs.”
Mosasaurs and ocean fish are more common marine fossils, Boyd said. The plesiosaur to be displayed will be positioned by a mosasaur specimen.
Person said the plesiosaur was identified by its morphology. It could be a styxosaurus, or maybe something entirely new based on its measurements, but the paleontologists don’t have enough of the creature to confirm.
"Down the road, maybe someone will find a more complete specimen and compare it to this and come up with something better," Boyd said. "And for having only a portion of the neck, plus the material collected off the surface, to be able to get it even down to that fine of detail, we got really lucky."
Across the hall in a gleaming storage facility, additional material from the plesiosaur is stored with other fossils from around the state, such as the Pembina Gorge. The facility is controlled on a number of levels, including temperature, humidity, security and pests.
The plesiosaur's other remains, such as paddle knuckles and various fragmentary materials, won’t be for exhibition, Boyd said.
“They’re not as display-y,” he said.