Take a virtual walk around a T. rex and other dinosaurs destined for the Smithsonian's National Museum of Natural History. (Lee Powell/The Washington Post)

TRENTON, Ontario – Inside a warehouse-sized workshop on the shore of the Bay of Quinte, the Tyrannosaurus rex has visitors.

Humans are here – from the Smithsonian – to give the specimen a close look. Its fossilized bones are arrayed on a towering metal mount, its teeth starting in on the neck frill of a Triceratops.

The 66-million-year-old creature, dubbed the "Nation's T. rex," is still the centerpiece of a revamped fossil hall, coming to the National Museum of Natural History in 2019.

But the shape of the exhibit is starting to fill out, with the addition of two herbivores – Edmontosaurus and Thescelosaurus – alongside the famous T. rex.

These Smithsonian dinosaurs are busting out of walls, getting a new life as full-bodied floor models. (Lee Powell/The Washington Post)

“These are two of the most important – scientifically important – dinosaur specimens we have,” says Matthew Carrano, the museum’s curator of dinosauria. “They’re the type specimens, the original fossils on which the species were named.”

The skeletons are posed in the mounting room of Research Casting International, or RCI. This set-up is how millions of visitors will find them in Washington, D.C., at one of the most visited museums on Earth.

Take a lingering look: This is the last time you will see these dinosaurs in one piece until their Washington debut. Sometime soon, these mounts will be disassembled to make room for another batch of dinosaurs needing the touch of RCI craftsmen.

The Smithsonian’s bones have all converged in this small Canadian town, shipped from Washington, D.C. The T. rex is one of the most complete found. Its journey started in Montana when rancher Kathy Wankel saw a bone sticking out of the dirt.

For now, some imagination is needed. The mounting room is a sort of temporary exhibit hall: Tape on the floor marks the spot of a future railing, separating dinosaurs from people. Rolls of paper stretched between stands display text visitors will read.

In the background, the larger duck-billed Edmontosaurus looks over the dainty Thescelosaurus. Reviving these two fossils started with chiseling, followed by grinding and scraping not unlike what you'd expect to find in a dental office.

Prodding by paleontologists is part of any long-dead dinosaur's life. Bones are studied, the most minute fractures scrutinized. On this day, part of the Nation’s T. rex is going to Belleville General Hospital in Belleville, Ontario.

It needs its head examined.

A close-up look at the so-called brain case of the T. rex will help in building a 3-D model of the beast. Eventually, people may download it and 3-D print their own dinosaur from home.

The Smithsonian uses surface scanners to get a look at objects. But this T. rex skull is complicated, with all its nooks and crannies, says Vincent Rossi, whose specialty is 3-D imaging at the Smithsonian. Seeing all those hidden spaces means taking a CT scan.

Unfortunately, the brain case of the T. rex is big and the circular opening of the CT scanner small. It's sized for humans, not prehistoric animals.

Did it fit? Yes, with about half an inch of clearance:

Part of an almost-complete T. rex rolls into a hospital in Canada. What happened next makes for good pictures. (Lee Powell/The Washington Post)

At least the dino skull doesn't have to be reminded to hold its breath.

Lee Powell is a video reporter at The Washington Post.

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