Dinosaur exhibits can leave a lasting impression on museum goers — but not all dinosaur fossils leave an impression quite like the hadrosaur specimen at the University of Washington’s Burke Museum of Natural History and Culture. This fossil is particularly special because, in addition to the skeleton, it also contains impressions of the dinosaur’s scaly skin. 

With 3D scanning and 3D printing technology, scientists at the Burke were able to recreate the skin and give visitors a chance to feel what it’s like to “pet” a dinosaur. We spoke with the Burke’s Fossil Preparator Michael Holland to get the inside scoop on the technology he uses to bring dinosaurs to life. 

About the specimen

The skin belonged to a juvenile Edmontosaurus, a type of hadrosaur — a group more commonly known as duck-billed dinosaurs — found in the Hell Creek Formation in eastern Montana. 

The Hell Creek Formation is a well-known and heavily-studied geological rock unit dating back 66 million years. It’s famous in the paleontological world for preserving the Cretaceous/ Paleogene boundary, providing a snapshot of the “extinction horizon” — a literal line in the earth that marks the abrupt extinction of the dinosaurs.

“It’s an extraordinary environment because, in addition to having that extinction horizon, it offers some really amazing preservation of everything that was around before and after that time,” explained Holland. “It’s chock full of everything, especially dinosaurs. Some of the most iconic dinosaurs that you can think of — the ones that everybody knows — can be found there. The first T. rex was discovered there in 1902.” 

Hadrosaurs were herbivorous, traveled in large herds, and nested in colonies; they were a common part of the Hell Creek ecosystem. “They were big animals. The largest one I know about was 50 feet from nose to tail,” Holland said. “Ours, mercifully, is only about 18 feet in length.”

But the Burke’s specimen didn’t arrive from Montana at the museum’s onsite lab in Seattle already fit for 3D scanning and printing. It takes fossil preparators like Holland to get the pieces ready. “I have a whole team working with me,” he said, “and we’ve divided it up into different zones.” 

Holland and his team use a range of tools depending on the rock matrix surrounding the fossil. “In some cases, it can be surprisingly soft, barely compacted/consolidated sand or flaky layers of mudstone. In other instances, it can be hard as concrete.” If it’s a softer matrix, Holland uses hand tools, including dental tools: “Anything that’s good for fine detail work.” For the harder stuff, Holland relies on power tools like air scribes, which are pen-sized pneumatic “mini jackhammers” that can pulverize the rock. 

“Along with the removal of the matrix comes the stabilizing and the consolidation of the fossil itself,” Holland went on. “The surrounding matrix is largely what’s holding the pieces together, so as you strip that away, the fossil wants to fall apart.” 

Chemical consolidants are used to keep the fossil together as scientists remove the rock. The solvent-based adhesives (as opposed to reaction adhesives like superglue) are archival-grade, clear, colorless polymers that can be dissolved if needed. “It’s kind of like putting together a puzzle. In instances where the bones have already eroded out of the ground and been collected at the surface, it can be quite challenging, because the pieces are already scattered,” Holland said.  

After all that work, why replicate the fossil with 3D scanning and 3D printing instead of putting the original on display in the museum? Holland emphasized that creating replicas allows scientists to continue their research on valuable specimens while also sharing their findings with the public.  

3D Scanning

Historically, paleontologists would restore and replicate fossils with molds and clay. “I’m not going to say molding and casting is dead, because there are still some instances where that’s really what you need,” Holland explained. “But in many instances, I’m finding that a lot of the work I’m doing now is what I call the hard and soft phases. The hard phase is prepping the bones, and the soft phase is when I bring in the devices and software.” 

Holland relies on two different handheld structured blue light scanners from Artec: the Eva for larger pieces and the Space Spider for more detailed scans. 

According to Ian Sayers — a 3D Scanning Product Manager at Hawk Ridge Systems whom Holland relies on to answer questions about the technology — what makes Artec’s scanners especially unique is their ability to operate without traditional target stickers. “Artec’s handheld structured light scanners are able to generate accurate, full color 3D models with the exquisite level of detail paleontologists are looking for.”

Speaking of detail, in the case of the Burke’s hadrosaur, there’s another consideration: the fossil has both “positive” and “negative” skin prints. In some areas, the skin was pressed into the mud, leaving a negative imprint much like a footprint. But in other areas, sediment filled in that negative imprint, creating a positive rendering. The Space Spider, in particular, can pick up on these minute details down to 0.1 mm resolution.

Once the specimen is scanned, Holland brings it into the digital space to “squish digital clay” using Maxon ZBrush, a digital sculpting software. It’s there that Holland is able to restore the fossil in digital space, filling in gaps if needed. 

3D Printing

With the fossils prepared, scanned, and restored in the digital space, the next step is to bring the replica to life with 3D printing. The Burke museum has multiple 3D printers, but they’re older models; lately, Holland has been using his own machine at home: a brand-new Bambu Labs H2S.

“Bambu Labs has cracked the code on 3D printing in terms of getting a remarkably reliable, consistent machine — at a pretty accessible cost,” Holland said. “In terms of dollars versus performance, it's really impressive.”

Though Holland is printing large specimens (in addition to the hadrosaur project, Holland was also working on printing a 6-foot-long triceratops skull), the printer itself has a build volume of about a 13-inch cube. This means that Holland often prints large bones in multiple sections — a technique he prefers to one massive printer, because, in case of a printing error, it’s easier to fix a small section than to start over on an entire dinosaur. 

Holland prints the fossils using PLA (polylactic acid) filament, a plant-based plastic. While it’s not as tough as other options like nylon or ABS, PLA is cheaper and doesn’t give off as much smell.

Before 3D printing was an option, “Material expenses could be pretty significant. In molding and casting land, the RTV silicone that we use to make molds cost about $100 a gallon,” Holland said. Not only that, the casts are often solid and heavy. 3D printed fossils, on the other hand, have a honeycomb-like structure on the inside; they’re more durable and lighter weight, making them easier to mount in exhibits; and they can be replicated as many times as needed without needing to replace a worn-out mold.

When it comes to displaying the fossil in an exhibit, Holland has been experimenting with 3D printing the mounting armature, too. “With some specimens, the weight is going to be so much that I'm not sure I would want to trust anything other than steel if I’m mounting the real bones,” Holland said, adding that, “I’ve done a few smaller specimens where the armatures are entirely 3D printed.” Holland also sees a future where he could blend both techniques for better fossil mounts: “I think there are going to be some opportunities where I can do steel where it's necessary and then some 3D printed components, too.”

Old and new

Paleontology is at an interesting crossroads in technology, with fossil preparators like Holland using a mix of hand tools and power tools, 3D printing and metalwork. Holland still hand-paints the plastic replicas himself, noting that he’s yet to find a printer that can capture the unique patina-like coloration of real fossils. 

But as the technology evolves, so, too, does Holland’s process. 

For more information: 

Burke Museum

Artec 

ZBrush

Bambu Labs

Lead image: Burke Museum fossil preparator Michael Holland looks at hadrosaur skin impression. Credit: Chris Snyder | Burke Museum of Natural History and Culture

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