More of the T. rex skull is revealed

October 27, 2017
Burke Museum
The T. rex skull sits nearly fully emerged in the prep lab as visitors look through glass at it

We're making great progress on exposing the T. rex skull!  
Photo: Burke Museum

More of the T. rex skull is being revealed each day in our Testing, Testing 1-2-3 exhibit, and it is truly awe-inspiring!

In the months since we lowered the massive skull into its custom “Rex Rack,” it has gone from being almost fully-encased in sandstone to showing off these incredibly well-preserved teeth…

When we remove a fossil from the field, we keep it encased in a good amount of the matrix—the sediment or rock where it was found—and wrap it in a plaster field jacket to protect it. That way we can save the delicate detail work for preparators back at the museum.

That’s exactly what happened with the T. rex skull when it was collected* by a team of Burke paleontologists and volunteers from the fossil riverbed where it was discovered in the Hell Creek Formation in Montana as part of the Hell Creek Project led by Greg Wilson, Burke Museum curator of vertebrate paleontology. 

Prior to the opening of the T. rex LIVE, our team started cutting into the plaster field jacket, referencing handwritten notes on the cast to avoid hitting any exposed areas of bone. 

Michael cuts through the T. rex plaster jacket with a saw

Michael Holland starts to cut through the T. rex plaster jacket.

Photo: Burke Museum

The team, led by Michael Holland, Burke Museum Hell Creek Preparator and designated “T. rex wrangler,” used an oscillating saw to cut through the plaster in a process similar to how a doctor might cut a cast from a broken arm.

Many of the fossils that we prepare at the museum are surrounded by extremely hard rock, which requires months—or even years—of work to reveal the bone.

Much to the prep team’s delight, most of the sandstone surrounding the T. rex skull is very soft and easy to work with—a lot of the work can be done with small hand tools like what you would find at a dentist’s office. 

The paleontologist's field tools like the brush and awl are featured.

The hand tools used to excavate the T. rex skull.

Photo: Burke Museum 

The paleontologist's field tools like the rock hammer and brush are featured.

The hand tools used to excavate the T. rex skull.

Photo: Burke Museum 

The paleontologist's field notebook from the dig is featured

The hand tools used to excavate the T. rex skull.

Photo: Burke Museum 

In many areas, the sandstone is comparable in texture of the hardened, dried-out brown sugar that you find in the back of your pantry. It’s fairly solid, but can be easily scratched away, returning to granular form. It is this softness that has allowed such remarkably fast progress on the skull.

As an extra bonus, the sand often forms a rind on the surface of the bones that shows a rust-colored stain. When it is encountered, this serves as a warning to preparators that bone is near, and that they may wish to switch to a smaller air scribe or a hand tool. The sandstone is easily removed from the bone, leaving the bone’s intricate textural details intact.

Other areas of matrix include concretions (compact masses of mineral matter) and mudstone pebbles that were carried in with the sand. There are lots of these, but fortunately they do not appear to have compromised the bones in any way. 

Bruce and Primm dig out the right corner of the skull

As they worked down, the top right corner of the skull (postorbital and squamosal bones) began to emerge first and revealed just how incredibly well-preserved the bone was.

Photo: Burke Museum 

Thankfully, these bones are complete and are fully articulated in their correct anatomical position. The texture near the eye that is “textbook T. rex” is beautifully preserved, clearly showing the web of vascular indentations on the surface.  

The top of the T. rex peeks out of the jacket and looks beautifully preserved

The T. rex is beautifully preserved coming out of the jacket.

Photo: Burke Museum 

There were even a few teeth that were peeking out of the rock when they put the plaster jacket on it in the field. 

The first teeth peek out of the skull during the excavation

The first teeth peeking out of the skull!

Photo: Burke Museum

Soon, more of the skull began to appear, and they added a “googly eye” to help orient visitors with where the beast’s eye would’ve been in life. This temporary visual aid got quite a few chuckles out of visitors!

Scientists added the 'googly eye' at the top of the skull to indicate the eye socket

Scientists added a 'googly eye' to indicate the eye socket on the skull.

Photo: Burke Museum 

Recently, the team rotated the skull in the “Rex Rack” to redistribute the weight and begin working on different areas of the skull, including more of the teeth. 

The team digging out the teeth and jaw of the skull.

The team rotated the skull to work on other parts of the skull.

Photo: Burke Museum

Watching the teeth appear was a very exciting process for Michael and paleontology volunteer Jean Primovich—one that we were lucky to capture on video. 

To help remove the sandstone from the teeth, Jean used a small amount of acetone to wet the sandstone, soften it and clump it together. The acetone evaporates quickly and doesn’t get much time to soak into the bone. We don’t use water because we want to avoid getting the fossils wet. (Water can damage the bones and interfere with the consolidants and adhesives used during fossil preparation.)

A close up of the T. rex teeth sticking out

A close-up of the T. rex teeth

Photo: Burke Museum

The result? Check out the serrated edges on these teeth! Serrated teeth were a distinct attribute of theropods—a group of bipedal dinosaurs.

T. rex was a carnivore and used these teeth and its large jaws to eat other dinosaurs like Edmontosaurus and Triceratops. They had more than 60 teeth, which were regularly replaced throughout their lives, like those of crocodilians and sharks.

Digging out the sand from the T. rex skull with a drill tool

We're unveiling more of the T. rex every day! 

Photo: Burke Museum 

We’re uncovering more of the T. rex each day! See our progress for yourself in our Testing, Testing 1-2-3 exhibit!  

*The T. rex skull and other fossils were collected on federal land managed by the Bureau of Land Management (BLM) with permits.

More information about the Hell Creek Project
The project, currently led by Wilson, was founded by Jack Horner and Nathan Myhrvold. Burke paleontologists, volunteers, undergraduate and graduate students from the University of Washington and other universities, and K–12 educators participating in the Burke’s DIG Field School contribute to the project.

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