One of the World’s Largest Stegosaurus Skeletons Was Moved. Twice.

This article is part of the Fine Arts & Exhibits special section on how creativity can inspire in challenging times.

Arranging suitable accommodations for an unexpected visitor can be a challenge, especially when the guest is 11 feet tall and 27 feet long. The American Museum of Natural History has done it twice in less than a year for one of the world’s largest and most complete stegosaurus skeletons.

The skeleton, aptly named Apex, is on loan to the museum. It includes about 80 percent of the dinosaur’s estimated 320 fossilized bones.

The time from discovery to display was so swift that the museum was challenged to find space suitable for showing it — though there was never a doubt it would do so. “To get something this complete, in such good shape, is very rare,” said Melissa Posen, the vice president of exhibitions at the New York museum.

The museum first installed Apex last December in an atrium of the Richard Gilder Center for Science, Education, and Innovation, five months after the hedge fund billionaire Kenneth Griffin bought the 150 million-year-old fossil at auction for $44.6 million, about 10 times the presale estimate. The display gave the public an opportunity to see the elephant-size skeleton, with its distinctive rows of bony plates along both sides of its spine, but there was not enough time for museum staff to prepare informational and educational exhibits, or for paleontologists to fully examine individual fossils.

So the institution took Apex out of public view in early September, a museum spokeswoman said, to move the dinosaur, which dates from the late Jurassic period, to a more suitable location. Its new home is adjacent to the museum’s established dinosaur and fossil halls, which also house well-known reptiles like T. rex and titanosaur. Moving Apex to the fourth floor also allowed the museum to include more displays and other information about the dinosaur.

The relocation required the fossil’s finder, Jason Cooper, a commercial paleontologist, to remove each fossilized bone from the armature, or metal framework, that gave the assemblage the familiar stegosaurus shape. One of his colleagues, Zoltan Faltay, made the armature to display the fossils at the Sotheby’s auction in July 2024. When Apex was moved, the armature was taken apart and moved as well.

The disassembly of Apex gave the museum’s scientists an opportunity to meticulously document the size, shape and structure of each fossil. That data will be made available to paleontologists around the world and could help them provide answers to fundamental questions about stegosauri, such as how quickly they grew and how long they lived.

Apex was scheduled to reopen to the public in its new home in mid- to late- October. It is expected to remain there until late 2028, when Griffin could extend the loan.

While Cooper said the move could have been accomplished in less than a week, the museum took Apex off display for more than a month to give scientists time to digitally document each of the roughly 250 fossils comprising it.

“This period of a month when the specimen is unmounted, that was our opportunity to study various aspects of the bones,” said Roger Benson, the museum’s curator-in-charge of fossil amphibians, reptiles, birds and plants, early in the move process. “We already had great 3-D surface models on the skeleton, but those models generally don’t tell us what’s restored and what’s original.”

Disassembling the dinosaur by extracting each fossil from the armature and nestling them in custom-fitted polyurethane foam pads inside handmade wooden crates took less than two days, as did reversing the process on the fourth floor. Cooper managed the work on both ends with the help of two employees.

In the interim, Benson and Robert Smyth, a postdoctoral researcher on a three-year fellowship funded by Griffin, used a variety of processes to gather the fossils’ images. Structured light technology let them make exceptionally detailed external 3-D images and print 3-D copies; infrared scans enabled them to distinguish original fossil bone and keratin from restorative materials; and CT scans revealed the interior structure of each fossil.

“It precisely and very fully and clearly shows the difference between real material and restored material in three dimensions,” Benson said. “That’s particularly important for the skull. The skull, you see, has a lot of original material, but it can be quite difficult to tell original from restored material just by looking from the outside.”

Collecting as much data as practicable in the limited time available was important because Apex is owned by an individual, not an institution. That has raised concern about how much access scientists will have to such an important fossil find.

“The fossil is privately owned, but one of our jobs here is to really precisely record scientific data — accurate, high-resolution scientific data — that can be available in perpetuity,” Benson said at the peak of his data-gathering endeavor. “That’s why this is a really crucial period for us.”

Benson also had Griffin’s permission to take a small sample of Apex’s biggest bone, its 45-inch-long femur. The scientist said he was interested in the internal structure of the bone, which grew layer by layer, leaving a record of the animal’s life. “That includes things like annual growth marks, which are a bit like tree rings,” he added.

Combining information from Apex, which he described as “a big old individual,” with information from other stegosauri of different sizes and ages could help paleontologists learn more about the life history of the slow-moving herbivores. Apex is unlikely to settle the debate over the purpose of a stegosaurus’s signature physical trait, the ostentatious bony plates running down its spine (likely “ornamental structures similar to plumage on birds or the frill of some lizards,” Benson said). However, Apex may help paleontologists deduce how fast stegosauri grew and how long they tended to live.

Judging by its large size and fused vertebrae, Apex had a long life and peaceful death. The skeleton shows no sign of battle wounds or post-mortem scavenging by other animals. “If you combine size, completeness and bone preservation, it is the best stegosaurus I’ve seen,” Rod Scheetz, curator at the Brigham Young University Museum of Paleontology, told The New York Times after inspecting the fossils before they were sold.

Cooper said he discovered Apex while he and a friend were looking for fossils on property Cooper owns in Moffat County, Colo., near a town appropriately named Dinosaur. “We actually found two stegosaurs that day,” he said in an interview at the museum at the start of the disassembly process “They were a few hundred meters apart. I initially thought this was the less-complete of the two because he was curled up backwards. His back was sticking out so I thought the whole business end was gone.”

So Apex “sat in the ground while we excavated the other one,” Cooper recalled. “He was in the ground for over a year.

“Once we got into it we realized he was curled back on himself. It was a super happy time,” he said. “I got everyone — the whole crew — in there and we were able to do all the mapping and excavation in 10 days, because it was October and we didn’t want to leave it over the winter.”

Discovering Apex certainly has raised Cooper’s public profile. Displaying Apex is set to do the same for the American Museum of Natural History.

Stegosaurus is one of the best-known dinosaurs among the general public, but there’s still a lot to learn. Having a nearly complete skeleton of one can help answer those scientific questions. It is also a spectacle that can make a lifelong impression.

“We want people to say ‘wow!’ when they see it,” Posen said.

Megan McCrea contributed reporting.