Yale Peabody’s dinosaurs head to Canada for some TLC

When the Peabody’s iconic dino bones are back on display in 2023, they’ll be cleaned, mended, and adjusted with a better understanding of modern science.

The Stegosaurus that inhabited the Yale Peabody Museum of Natural History’s Great Hall since 1925 has migrated to Canada. And it won’t be long before several of the spikey-tailed herbivore’s New Haven neighbors, including Brontosaurus, join it north of the border.

It’s a temporary migration, an extended vacation, really, and it coincides with the start of a major renovation of the Peabody, the dinosaurs’ longtime (in human years) home.

In preparation for the renovation, the museum’s Great Hall — where the biggest dinosaurs have been on display for generations — closed to the public on Dec. 31. Soon afterward, Peabody staff began dismantling the hall’s smaller exhibits, including the raptor-clawed Deinonychus skeletons and horned Triceratops skulls. On Jan. 21, a “skeleton crew” from Research Casting International (RCI) — an Ontario-based company that specializes in preparing and preserving fossil mounts — arrived to tackle the large fossil skeletons, beginning with Stegosaurus.

The skeletons — nine in all — will be shipped by truck to RCI’s headquarters in Trenton, Ontario be cleaned, mended, and adjusted into poses that reflect science’s latest understanding of them.   

The dinosaurs return to New Haven in 2023, when the Peabody’s public galleries reopen.

The RCI crew first detached the Stegosaurus’ tiny skull, which is a cast of a specimen at the Smithsonian’s National Museum of Natural History (NMNH). Next they removed the tail’s eight weapon-like spikes. (The revamped Stegosaurus will have fewer spikes. Current research indicates the dinosaur had only four tail spikes for defending against hungry foes like Allosaurus.)

Removing the head from the stegosaurus
(Photo courtesy of the Yale Peabody Museum of Natural History)

Wielding hammers, pliers, chisels, and a reciprocating power saw, the crew set to work dismantling the skeleton’s forelegs. They soon discovered that the bones were cemented together with large amounts of plaster.

Every mount comes apart slightly differently,” said Matt Fair, RCI general manager. “We always find something new. Given the amount of plaster here, we’ll need to be very careful not to damage the bones while separating them from the armature.”

After noticing small cracks in the ulna and radius bones of the specimen’s right foreleg, the crewmembers stabilized the fossilized bones with shrink-wrap before prying them away from the mount’s metal frame. The skeleton’s left humerus bone was similarly braced.

By day’s end, the crew had reduced Stegosaurus to about 200 pieces — a mix of fossilized bones and plaster-cast replicas that had filled in gaps. The pieces were labeled and packed into crates for shipment to RCI’s 48,000-square-foot facility in Trenton, Ontario. The company, one of the few firms in the world that specializes in fossil mounts, recently remounted the fossil skeletons in the NMNH’s newly renovated dinosaur hall.

Famed Yale paleontologist Othniel Charles “O.C.” Marsh described and named the species Stegosaurus ungulatus in 1877 from bones collected in the Morrison Formation in Como Bluff, Wyoming. Marsh originally believed Stegosaurus was an aquatic reptile whose body was protected by bony plates like a sea turtle. This theory had been substantially revised by 1910, when the Peabody’s Stegosaurus skeleton was initially erected from the bones of at least five specimens. The skeleton was exhibited in the museum’s original building on the corner of Elm and High streets, demolished in 1917 to create space for dorms.

In the early 1920s, Richard Swann Lull, Sterling Professor of Paleontology, rearranged the skeleton’s large dorsal plates from a double-paired row to a double-alternating row — a modification based on new fossil evidence. When the Peabody’s current Whitney Avenue building opened in 1925, the Stegosaurus was an original resident of the Great Hall.

These mounts are both scientifically valuable and historically important,” said David Skelly, the Frank R. Oastler Professor of Ecology and director of the Yale Peabody Museum. “Taking them apart has to be done really carefully by people who absolutely know what to expect. RCI are total pros. Beyond just the mechanics, they understand the artistry that’s involved. They have to make something that's been dead for 150 million years look like it’s alive.”

Removing the tail from the stegosaurus
(Photo credit: Mike Cummings)

While the specifics of the mount’s new pose are still to be determined, one change is certain: The skeleton’s tail, which rested on the floor, will rise into the air. The change will reflect the new scientific consensus that dinosaurs were quick and lively animals, not the plodding, tail-dragging brutes depicted in old textbooks and popular culture for the past century. Also, epoxy, not plaster, will bind the bones.

While in New Haven to work on Stegosaurus, the RCI team also dismantled the Camptosaurus and Camarasaurus skeletons that shared the Great Hall’s central island with Stegosaurus and Brontosaurus. They’ll be replaced with different exhibits when the hall reopens.

The skeleton crew returned at the end of January to dismantle the giant sea turtle Archelon, the aquatic predator Platecarpus, and several large mounts in the museum’s Hall of Mammals. 

In February, RCI will tackle the project’s most imposing challenge: taking apart the 65-foot-long Brontosaurus, another Marsh discovery and the original specimen and namesake of the colossal species. It will be the largest mount the company has handled since it refurbished a Brachiosaurus at Berlin’s museum of natural history in 2007, Fair said.

For Skelly, who first visited the museum as a child, seeing the skeletons taken apart is a bittersweet experience.

I remember walking through the hall and seeing the Brontosaurus and being astonished that an animal that size had walked the earth,” he said. “It changed how I thought about the world. When the hall reopens, visitors will be able to walk underneath the Brontosaurus’s head and tail and get a new perspective. It’ll be a special experience.”

The museum building, located at 170 Whitney Ave. in New Haven, will close to the public in July. Construction is scheduled to begin in November. The Peabody will continue to offer an array of public programming and events throughout the building closure, including its EVOLUTIONS Afterschool Program and its annual “Fiesta Latina” Latin American culture festival, at venues on Yale’s campus.


Share this with Facebook Share this with X Share this with LinkedIn Share this with Email Print this

Media Contact

Bess Connolly :,