I had the opportunity this week to witness a unique behind-the-scenes event—the opening of a sealed plaster field jacket, containing dinosaur bones about 75 million-years-old. No one had laid eyes on the fossils since they were collected almost 100 years ago in Alberta. Now that was all about to change.

According to the original field notes, the jacket contains parts of an armoured dinosaur known as an ankylosaur. The jacket was getting this special treatment because it’s the winner in the museum’s recent Dino Idol contest.

View of opened plaster field jacket with exposed rock and fossil.
The opened field jacket of Canadian Club. Two days of work revealed the rock and fossil that had been encased since 1915. Image: Dan Smythe © Canadian Museum of Nature.

It was now time to see what’s really inside, so that our dinosaur researcher Jordan Mallon can study the bones and senior technician Clayton Kennedy can prepare them for eventual display a year or so from now.

Man pulls cart with plaster field jacket on top of it.
Collections technician Alan McDonald moves the plaster field jacket containing the remains of Canadian Club from the collections area to the Heavy Prep lab. Image: Kieran Shepherd © Canadian Museum of Nature.

But before any of that can happen, the plaster encasing the rock and bone inside needs to be carefully removed. Clayton brings the required skill to this process, with about 30 years of experience working with fossils.

The fossil was set up on a pedestal in the museum’s Heavy Prep Lab. Clayton had his tools ready—a large set of pliers, a small brush, a needle-like device called an air scribe and a small bottle of “glue” called Acryloid.

He began by pulling at the exposed, frayed ends of some burlap. As the burlap popped out, pieces of plaster fell to the floor, a smattering of dust accumulating from the effort. Pliers were then used to pull away pieces of plaster.

At one point, he used a pneumatic saw—think of a cast-cutter that surgeons use to remove a cast from a broken leg and you have the idea.

Montage of three images that shows man using pliers to peel plaster from field jacket, man using a small saw to cut away pieces of plaster, and view of the half-opened field jacket.
Top left: Clayton Kennedy uses pliers to remove the plaster. This farrier’s tool, used to put shoes on horses, may have been used by the Sternbergs during fieldwork. Top right: Use of a saw aids in the removal of the plaster shell. Bottom: Pieces of wood used to reinforce the jacket’s structure are revealed after a day’s work. Images: Dan Smythe © Canadian Museum of Nature.

Two hours on and the upper layer of plaster is more-or-less gone. A small history lesson is revealed. There is a dark, brownish-gray layer of plaster and burlap that was underneath the outer layer. It crumbles between the fingers. Turns out this was the original layer applied by Charles H. Sternberg and his team in 1915. It’s a bit mouldy – likely the result of some water damage from decades ago, after which the newer layer of plaster would have been added to protect the contents.

By the end of Day One, some rock and even fossil is popping out. A few pieces of wood rest on top. According to Clayton, the Sternbergs would gather wood from the field and use it to reinforce the jacket for safe transport to the museum in Ottawa.

Day Two—the unveiling process moves along. Within a few hours, the plaster is all gone, and the upper half of the jacket is now exposed revealing gray-brown rock…and fossil. Much of it appears fractured and crumbling, but I am assured this is not unusual.

Close-up of a tool called an air scribe being used to chip away at the rock.
An airscribe is used to chip away at small pieces of rock, revealing the exposed fossil. The vacuum clears away the debris. Image: Pierre Poirier © Canadian Museum of Nature.

Over time, moisture would seep in, with the resulting freeze-thaw process leading to cracking. All in a day’s work for Clayton as he pulls out the Acryloid, a glue-like substance, and applies it in the cracks. When this sets, it will bond the fossil parts together.

Close-up showing glue being applied to cracks in the fossil bones.
Consolidating loose bones is a common step in preparing fossils. Here, Clayton uses Acryloid to bond parts of the ankylosaur bones. This will ensure the fossil remains intact as the rock around it is carefully removed. Image: Pierre Poirier © Canadian Museum of Nature.

Jordan is excited because with the matrix revealed, he knows that the fossil includes the hips of an anyklosaur. This will be something new to the museum’s collections and also allows for better identification of the species. But there’s a hitch—the field notes suggested there might be a tail and its end club so characteristic of an ankylosaur. They do not seem to be in this field jacket. Are they somewhere else? Stay tuned, as more investigation is needed.

So, what’s next? Well, only the surface has been scratched…no pun intended! At least a few months of steady work are now required to remove the rock substrate, consolidate and extract the fossils, and prepare them for study. Then, the bones can be prepared for temporary display.

More blogs to come as the process unfolds!