Nellermoe, Concordia’s biologist-in-residence, just published research about findings from the site in the academic journal Palaios with partners Dr. Paul Ullmann and Dr. Kenneth Lacovara of Rowan University, Glassboro, N.J., and Allen Shaw of Standing Rock Paleontology Department (SRPD), Fort Yates, N.D.
The South Dakota site was originally located by the Rev. Ken Olson, who hunted fossils as a hobby. After discovery of the site in 1993, Nellermoe and Concordia students made annual summer excavations collecting more than 4,000 bones from the area named the Concordia Hadrosaur Site.
“Hundreds of students and volunteers have participated in the excavation of bones over the years,” Nellermoe said. “One summer, 30 people were involved including former student Becky (Gould) Barnes ’04, Carl Bailey ’40, professor emeritus of physics, and Dean Bowman, professor emeritus of art.”
After a six-year gap, annual summer excavations began again at the initiation of the SRPD and in 2012 a collaborative dig took place between Concordia, Drexel University and the SRPD at the renamed Standing Rock Hadrosaur Site (SRHS), which is located on Standing Rock Sioux Reservation land. The 2012 expedition was to give Ullmann and Dr. Kristyn Voegele ’11 the opportunity to explore the bone bed.
The research, titled “Taphonomy of the Standing Rock Hadrosaur Site, Corson County, South Dakota,” presented analyses of this large bone bed of Edmontosaurus annectensor duck-billed dinosaurs. Interpretations were based on the bone bed, the sediment and related factors helping to identify the possible conditions for deposition of this tremendous number of Edmontosaurus bones.
At the site, “bones can be found protruding from the hillside”* about halfway up a bluff where “the Upper Fox Hills and Lower Hell Creek formations are exposed”* in north central South Dakota about 15 miles south of Morristown on the reservation and on private land. Thousands of bones ended up at this location spread out over half a mile. Where the bones were found in the strata, the condition of the bones, the sizes and assortment of bones provided a wealth of information.
Dr. Russ Colson of Minnesota State University Moorhead and his wife, Mary, spent a summer working to describe the sedimentology and Barnes did her master’s thesis identifying the dinosaur species. To complete the circle, they needed to describe the depositional history or taphonomy – how the dinosaurs came to be in that location. That’s when Nellermoe asked Ullmann if he wanted to work with the Concordia collection to describe this deposit.
The study showed the subadult and adult Edmontosaurus died in a mass mortality event and “their bones were buried in a shallow floodplain.”* Evidence from this site and other Edmontosaurus bone beds strongly suggests “gregarious” behavior – that Edmontosaurus may have lived as families. Dinosaurs tend not to be gregarious as most meat eaters, the Triceratops and big plant eaters were mostly individuals. A significant finding supported by this bone bed is that Edmontosaurus traveled in herds.
When asked about what might have caused the mass mortality event, Nellermoe said, “some natural catastrophic event wiped them out like a flash flood or disease.” The location of the bones precludes any thought of something like an asteroid impact.
Fossils were split between Concordia and the paleontology department of the Standing Rock Sioux Reservation in Fort Yates after careful cataloging to determine which bones had been located on the reservation.
“We had this fantastic collection of bones and gave at least 2,000 to Fort Yates,” Nellermoe said.
In 2016, Concordia’s SRHS bone collection was transferred to the North Dakota Heritage Center and State Museum in Bismarck, N.D., where Barnes watches over the Concordia bones as chief preparer.
Currently, students in the bone lab in Concordia’s Riverside Center are working on an Allosaurus species with Rowan University to describe a fossil found near Shell, Wyo. Each Friday, they Skype with Ullmann and Voegele as they work to determine and describe this fossil in hopes of finding something unique.
“It’s really enjoyable working with students on new projects and to culminate field collections,” Nellermoe said.
He said he looks forward to the paper they write upon completion of the research.
*excerpts from the research paper
Photos courtesy of Dave Olson/The Forum
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