When Corps leaders learned that the Natural History Museum was interested in borrowing the Wankel Rex, he said, they were happy to oblige.
The Wankel Rex is currently crated and stored in a warehouse in Montana. (Secrecy abounds, given the sky-high prices the bones would fetch in the shadowy commercial fossil market.) At the Museum of the Rockies, the staff has been planning to say farewell to a very old friend.
"Some people are sad about it leaving - it's kind of like seeing your beloved kid go off to college and into the real world," said Shelley McKamey, the museum's executive director who helped excavate the Wankel Rex, which is also known as MOR 555. "You're going to miss him, but you're also really proud of him. . . . We're happy to share the best we've got with the world."
The Smithsonian already has a T. rex, sort of. One recent morning, a young boy entered the old dinosaur hall and walked straight to the replica.
Its pose suggested it was walking and just beginning to crouch - "and presumably about to inflict mayhem on somebody," said Hans-Dieter Sues, the Natural History Museum's curator of vertebrae paleontology.
"Look at the size of it!" the boy said. "Woah."
His father nodded, then read at the sign at the base of the dinosaur. "They found this in South Dakota," the father said.
He did not mention it was a cast made from "Stan," a T. rex found on private land in Montana's Hell Creek Formation in the 1980s.
Many of the museum's more than 7 million annual visitors don't realize it's a replica (even though it says so on the sign), or they don't care, officials said.
So, why the years-long obsession over securing a real specimen?
"Think about what the museum is," said Johnson, the museum's director. "It's a place where real treasures of the natural world are on display. If I said I have a glass replica of the Hope Diamond, you'd be less impressed,"
Johnson, who took part in Stan's excavation in 1992, said the Wankel Rex won't look much different than the cast of Stan. "But at the end of the day, it's a plastic reproduction. It's really important for us to have a real object for people to see and experience and be amazed by."
Fewer than 50 T. rexes have ever been found - and only about a quarter of them are considered "nearly complete," meaning more than 50 percent of the bones have been collected, Johnson said. About 80 to 85 percent of the Wankel Rex bones were collected - it's hard to accurately measure, Johnson said - making it the fifth- or sixth-most complete T. rex skeleton in existence.
It was found just before Labor Day in 1988. The Western states were dried out by one of the worst droughts in U.S. history, and Yellowstone National Park had been burning for most of the summer.
Kathy and Tom Wankel were camping with their family near the reservoir. Their three kids were with an uncle, and Kathy and Tom were hiking. They walked across what was once a bay and to what was once an island. Kathy was looking down, because she was a rock hound and because she knew there could be dinosaurs around; she wasn't from the area, but she'd seen bones before at a local bar.
She saw something - "like just a corner of an envelope sticking out," she recalled recently - and crouched down to investigate. "Tom said, 'Hey, I think I'm finding some bone stuff down here.' And I said, 'No, you'd better come up here.' We started chiseling away around the bone and didn't get it all dug, so we covered it up and came home."
The kids had to get back to school, and then the governor told people to suspend outdoor activity because of the drought and fires. So the Wankels didn't return for a couple of weeks. When they did, they uncovered the bones of . . . something.
They brought the fossilized bones to their camper. That night, a violent thunderstorm pounded the Wankels, who were camping near the dam. "It was almost like the gods were saying, 'Don't take them out,' " she said.
But they did, and that Thanksgiving, the family drove the bones to the Museum of the Rockies.
The museum's chief preparator of paleontology, Patrick Leiggi, was smoking a Marlboro, Kathy Wankel said. When he saw what they had in the back of their station wagon, "he really got puffing. He said, 'You guys better follow me.' We went downstairs to their lab, and pretty soon people were coming out of their offices and they were all puffing on Marlboros and talking."
The paleontologists asked the Wankels whether they'd take them to the site the following year, and when they did, they located the golden prize - the skull - along with some of the vertebrae. Because the bones were going into the hillside, they had to go back again in 1990 to finish the dig with a larger crew and some heavy machinery to move the over-dirt.
The Wankels knew that they'd found the bones on federal land and that the dinosaur belonged to the Corps.
"We laugh because our ranch is about 50, 60 miles away," she said, "and if he would have just taken some giant T. rex steps as he was dying and staggered down here, we could have paid off our ranch mortgage."
She laughed and then remembered something about the aftermath of her discovery.
"We got a hand-slap letter from the Army Corps of Engineers," she said. "They said, 'You did the right thing by bringing it to the museum and not taking it in the middle of the night and selling it to the Japanese or something. But you weren't supposed to be digging it out.' We didn't know."
She has casts made from the dinosaur's arm and shoulder blade - gifts from the Museum of the Rockies.
She'll be in Washington when her eponymous skeleton arrives in October.
It has been a long time since she has set eyes on it, she said.
"I can't wait to see my little baby," she said.