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North Dakota: Legendary. Follow the trail of legends

Backstage Pass to North Dakota History

This blog takes you behind the scenes of the State Historical Society of North Dakota. Get a glimpse at a day-in-the-life of the staff, volunteers, and partners who make it all possible. Discover what it takes to preserve North Dakota's natural and cultural history. We encourage dialogue, questions, and comments!

Osteoderm Fossils: More than Skin Deep

For most people, the first things they think about when they hear the word “fossil” are bones from some ancient creature. Considering the hard parts of animals fossilize more easily than the soft parts, they have good reason to think so. But did you know that skin can fossilize as well? It is rare, but with the right set of circumstances (the animal is buried quickly, and dries out), paleontologists can find patches of skin. Sometimes, like in the case of Dakota the Dinomummy (an Edmontosaurus on display in the ND Heritage Center & State Museum), paleontologists can find a LOT of skin.

Today, I’d like to write talk about something in between. It’s not a skeleton, but it is bone. And it’s not skin, but it helps shape and support the skin. It’s something called an osteoderm — literally “bone skin.” An osteoderm is a deposit of bone material found within the dermis (skin) of some animals, generally covered by a thicker keratin sheath (the same material that makes up your hair or fingernails). The keratin covering is generally called a “scute.” Different animals have evolved osteoderms, from lizards and frogs to dinosaurs. Rather than focus on an obscure group of animals, however, I’d like to use crocodiles as an example, since most people can visualize them a little easier.

Crocodilian leather with osteoderms

I just *happen* to have some crocodilian leather with osteoderms in place.

If you can imagine crocodile skin (or if you can’t, just look at the image above), it is made up of many square scales. Osteoderms are located under the largest of these scales/scutes. Most of the time when crocodile or alligator skin is harvested for use in the clothing industry, those bony plates are removed in order to insure flexible leather, so people don’t really get the chance to feel the natural armor. The scute is left behind, giving us the look of a large scale, without the backing of bone.

Osteoderms are one of my favorite pieces to find on a fossil dig. They’re small, compact, look like Swiss cheese on the top, and clean up well. In 2013, as we wandered through a fossil site after a rainstorm, I let my eyes wander. As my gaze travelled down one of the now-dry rivulets, I saw six squares of white. Fossils, when they sit out in sunlight for a while, may change color or become bleached. I blinked. Sure enough — I was looking at six little osteoderms all in a row!

Erosional rivulet with osteoderms

Erosional rivulet containing osteoderms bleached white from the sunlight.

Bleached osteoderm

Close-up of bleached osteoderm.

Another site we visit on occasion called Whiskey Creek contains dozens to hundreds of osteoderms. Some are small, and others the size of a large belt buckle. If you’re ever out with us when we find these, you may hear us say “scute” instead of “osteoderm.” This isn’t a slip of the tongue; yes, we know that it’s technically an osteoderm. It’s just more fun (and faster) to say scute than osteoderm. Scute scute scute!

Osteoderm in situ

Osteoderms in situ at Whiskey Creek. The smooth side faces inward, and the Swiss cheese side faces the outside of the animal.

Holding a piece of osteoderm

Mid-sized osteoderm, with hand for scale.

Enacting the Emergency Disaster Plan after a Storm

Near the end of June 2018, a storm with strong winds and heavy rain rolled through Bismarck. State Historical Society security received an alarm in the middle of the night for an off-site storage facility. Our security supervisor initially did not see any damage, but he went back in the morning to discover a section of the roof had blown off the building. There was significant water damage to an artifact room on the second floor. He followed protocol and immediately notified the staff members identified in our agency’s Emergency Disaster Plan to respond.

Damage from roof collapse

Part of a roof was damaged during a summer storm at the State Historical Society’s off-site storage facility. Ceiling tiles and water fell on some artifacts and some duct work for the HVAC system was destroyed.

Within a short time, Museum Division staff traveled to the storage facility to assess the situation. First power had to be turned off, since lighting fixtures were down and electrical wiring was exposed to standing water. The room was checked to make sure nothing overhead could fall and harm staff. The next step was to remove debris and wet artifacts from the room. As each artifact was moved to a different part of the building, water was blotted from the artifacts. Items were placed on newsprint near fans to dry quickly in order to prevent mold growth and further damage. A few upholstered pieces were packed with newsprint to help absorb water. Squeegees helped to remove standing water on the floor. Wet ceiling tiles and insulation were removed and thrown away. There was not enough extra space to move all artifacts from the damaged room, so plastic sheeting was put up to protect the remaining artifacts.

Artifacts set out to dry

Artifacts were placed on newsprint to dry. All of the crevices were packed with newsprint to draw out the moisture.

Inventorying artifacts

Staff members Len Thorson and Mark Halvorson inventoried the items being removed from the damaged room. Temporary locations were updated in the database for the displaced artifacts.

The damaged roof was salvageable as a temporary fix. It was secured until a new roof can replace it this fall. Administration staff arranged for a dumpster for debris and contacted insurance company adjusters, roofing contractors to examine the damage, and a heating and cooling company to check on a wet furnace and the destroyed ductwork. After it was deemed safe to do so, the electricity and some of the air handling units were turned on to help dry out the building.

Damage to roof

Temporary repair to roof

Before and after photos of the hole in the roof and the temporary repair.

A few days later, there was another storm with high winds and heavy rain. The plastic sheeting wall protecting the artifacts came down, and more water entered the building through the partially repaired roof. Luckily, no additional artifacts were damaged. The water was cleaned up and all of the artifacts still in the room were covered with plastic sheeting to protect them from future incidents.

Due to the agency’s Emergency Disaster Plan, all employees, from security to museum collections to administration, knew their roles and what they needed to do in such a situation. We did our best to take care of the objects in harm’s way, but there is still more to do. Staff continue to assess artifacts and update necessary reports. The roof and building need further repairs, and objects need to be moved back into storage locations following repairs. We plan to complete the roof and inside repair work in the next few months and are hiring an intern to assist with an inventory of artifacts and new storage solutions. Thanks to an agency staff that understood how to quickly respond because of the plan in place, numerous artifacts were saved and a team came together to smoothly resolve a disaster situation.