A Gorgosaurus neck in a "lasagne of materials."Ed Yong

In 1913, Barnum Brown, the man who discovered Tyrannosaurus rex, unearthed a similar but smaller dinosaur near the Red Deer River in Alberta, Canada. Now known as Gorgosaurus, the dinosaur was half-encased in plaster, and positioned in the classic “death pose” with its head arching backward over its spine. It stayed that way for decades on the wall of the Smithsonian Museum of Natural History’s classic Dinosaur Hall. But now that the hall is entering the final year of its momentous, five-year renovation, the Smithsonian’s staff have to dig Gorgosaurus out all over again.

It currently sits in a cavernous basement room beneath the hall. The petrified bones protrude from a layer of plaster that’s been painted and textured to look like rock. Below that is actual rock, more plaster, chicken wire, and burlap fibers that were part of the field jacket originally used to move the dinosaur from its resting place. And those layers sit atop several wooden beams and steel rods that were used to fix the specimen in place. “It’s a lasagne of materials,” says Kirk Johnson, the museum’s director. “We had to drill it out of the old exhibit.”

The museum’s staff now have several months to “prepare” the dinosaur, which means extricating it from all the gunk that it’s encased in. The same is true for other fossils from the old hall. In the same basement room, there’s a Corythosaurus—a duck-billed dinosaur with a distinctive crest on its head. It also had to be pried out of a wall, and it is also sitting amid a mess of plaster, metal, and burlap. “We have to remove all of that,” says Siobhan Starrs, who is project manager for the renovation.

The dinosaur hall first opened in 1911, when standards for handling fossils were very different. Many specimens, especially those acquired in the early years, weren’t fully excavated. Others were drilled, touched-up, or embedded in plaster or concrete. So for the museum’s preparators, the act of renovating the hall and getting its precious inhabitants up to modern standards is much like organizing a new dig. They are effectively performing re-paleontology, excavating their own dinosaurs from the museum itself.

The process began in April 2014, and it took just over a year to dismantle the old exhibits. Even when fossils were free-standing, they still had to be removed from the supporting metal brackets that acted as skeletons for their skeletons. Every piece was photographed and documented, “just like when you’re researching in the field,” says Starrs. Each fragment was cleaned, tested for cracks or weaknesses, retouched, and housed in bespoke plaster jackets or padded crates.

This isn’t just an aesthetic exercise. Some of the half-prepared dinosaurs are type specimens—the ones that were first used to name and describe their species. These are incredibly important individuals, avatars for their entire kind. They’re the ones to which scientists repeatedly return. But that’s hard to do when a specimen is half-immersed in plaster and stuck on a high wall, as was the case for the Smithsonian’s shovel-snouted Edmontosaurus. “Not only could visitors not get to it, but researchers couldn’t either,” Johnson says. “It does need to be liberated.”

In some cases, the renovation team has made new discoveries. The type specimen of Thescelosaurus, a human-sized plant-eater, had only been prepared on one side; when Starrs’ team exposed the other, they found beautifully preserved tendons and cartilage on its ribs. “Even the curator didn’t know they were there,” she says.

Similarly, the 80-foot-long Diplodocus, which was collected in 1887 and has long stood in the middle of the hall, still had bits of rock around its skull. When the team chipped that away, “suddenly all these amazing pencil-like teeth emerged in its face that weren’t there before,” Johnson says. “It’s a fantastic fossil. They just never finished excavating it.” In the process of exposing the teeth, the preparators also found more fossils—bits of plants, pollens, and other tiny fragments. All of those had to be photographed and described, too.

Once fully prepared, the fossils will be mounted onto new brackets. These are being designed so that individual bones can be snapped in and out, like “when you click a gemstone into the setting on a ring,” says Johnson. That will make them far easier to disassemble in the future, or to use in research. Some of these mounts are being built in the museum’s basement; others, for the larger specimens, are being crafted by the Toronto-based company Research Casting International. They’re one of just three big companies in the dinosaur-building game; a fourth recently went extinct.

In the past, mounts had to be constructed on the fly. “Even in the best cases, you’d end up with something that was a bit like a Frankenstein,” Johnson says. But now, the museum team can scan their skeletons and manipulate them in digital space, to design mounts that display the animals in graceful, biological poses. In the same way that Jurassic Park used digital technology to turn dinosaurs into living, breathing, inspiring animals, so too will the museum use tech to breathe fresh life into their old specimens.

When the hall re-opens in June 2019, a Tyrannosaurus will be dining on a Triceratops. And a Camarasaurus, which was formerly curled up on the ground, will instead rear up on its hind legs and crane its huge neck towards a tree. “People used to miss it because it was a light-colored fossil in a light-colored platform at their feet,” says Starrs. “We’ve re-posed it so it’ll be 20 to 25 feet tall. It’ll be really dramatic.”

It’s not just the dinosaurs that will get a touch of drama. When the hall’s woolly mammoth returns, it will be using its tusks to move snow. An Irish elk will be kneeling, so its 8-foot-wide antlers will be at eye level, accentuating just how big they really are. “People come to see the real things, and if you can mount them in a way that’s beautiful and evocative, it matters,” says Johnson.

The team now has around a year to bring the fossils back, reassemble them, and construct the new exhibits. “This is our first rodeo,” says Starrs, laughing. “We haven’t really done this before.”

The layout of the hall will be very different. Formerly, it was a mish-mash of specimens that had arrived at different times and been shunted into a cramped space without much foresight, like chapters of a book that had been printed in a random order. “There wasn’t any narrative, and a lot of it was disjunct and boring,” Johnson says.

That will change when the hall reopens. Standing in the mostly empty space, Johnson indicates a spiral shape that begins in the far left corner, curves along the right wall, and then loops back across the entranceway towards the left wall. That spiral will follow the evolution of life on Earth, from its very origins, to the age of the dinosaurs, to the recent Ice Age. Notably, it will end in the present day—and beyond.

“In the exhibit, you learn about evolution, extinction, and climate change,” says Johnson. “At the end, you find yourself looking at human civilization and the challenges presented by 7.5 billion people and the changing climate. You’re challenged you to think: Now that you’re part of the story, how do you become an agent in the next chapter? That’s the great promise of prehistoric exhibits, rarely delivered. Museums around the world are very concerned about how our knowledge of the past can inform our future. That’s what the theme of the hall is.”

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