When Pete Makovicky first sets eyes on a new dinosaur fossil, it’s typically after it emerges from the dust and other debris of a rock formation.

Until 2019, he’d never seen one come out of a briefcase in a Swiss hotel.

But that’s where the Field Museum’s then-chief dinosaur scientist found himself in the spring of that year — accompanied by a small group that had flown in from Chicago, there to meet a businessman from the Middle East.

In the privacy of a Zurich conference room, the businessman opened the briefcase, and the Chicago visitors stared bug-eyed at what was inside.

“Really, no other living paleontologist had seen one in the raw state,” said Makovicky, now a professor at the University of Minnesota. “So it was a very sort of exciting moment for me.”

Embedded in a creamy limestone slab, measuring about 6 by 12 inches, lay the contorted fossil of Archaeopteryx (ar-key-AHP-ter-icks) — a birdlike, holy grail creature of sorts, that when first discovered in 1861, helped prove Charles Darwin’s then-controversial theory of evolution.

Even though gritty limestone concealed much of the Zurich specimen, Makovicky saw enough of its immaculately preserved ribs, vertebrae and feather impressions to get excited; he ultimately recommended the Field buy it.

On Monday, the Field unveiled its Archaeopteryx, one of only about a dozen such specimens ever found and the only one housed in a “major natural history museum in the Western Hemisphere,” according to the Field. The fossil specimen arrived in Chicago in 2022.

The fossil will remain at its current location near the entrance to Griffin Halls through June 9. It will return some time in the fall in a permanent installation.

It’s a relatively tiny fossil. Even so, Julian Siggers, the Field’s president and CEO, has called the Archaeopteryx the museum’s “most significant fossil acquisition since Sue, the T. rex.”

Archaeopteryx lived about 150 million years ago, a dinosaur with feathers, hollow bones, tiny teeth and clawed wings. Much about its lifestyle remains unknown. Could it fly? Perhaps, but not very well, Field scientists said. And it was small too — the Field’s specimen is about the size of a pigeon.

In the 19th century, some saw Archaeopteryx remains and couldn’t figure out what it was, with some thinking it might be an angel, according to London’s Natural History Museum.

The first specimen was discovered just two years after the publication of Darwin’s “On the Origin of Species.” A lot of people at the time didn’t believe that animals could evolve. The Archaeopteryx appeared to prove otherwise — that dinosaurs had evolved into birds.

All of the specimens to date have been found embedded in a limestone quarry in southern Germany. Millions of years ago, the land was quite different — a large, tropical lagoon surrounded by subtropical islands.

A private fossil collector found the Field’s specimen some time before 1990, according to the museum. It then remained in private hands before coming to Chicago.

Makovicky, who continues to work as a Field research associate, said he’s never in his near-30 years of paleontology experienced anything quite like the meeting in Zurich.

“This was the first and only experience for me,” he said. “I usually go out and dig this stuff up.”

The meeting wasn’t quite cloak and dagger, but odd nonetheless, he said.

“At the time, [the seller] didn’t tell us he was the seller,” Makovicky said. “He pretended to be a representative of the seller.”

The seller told the Chicago group that it could take photographs, but the camera’s data card would have to remain with him, Makovicky said.

Museum staff have taken pains to detail how their specimen was obtained. They note that while a 2015 German law prohibits the removal of newly discovered Archaeopteryx fossils from the country, the Field’s specimen was sold and removed 25 years before the law went into effect.

“We are confident that the removal of the fossil from Germany was compliant with laws that were in effect at the time,” Field spokeswoman Bridgette Russell told the Chicago Sun-Times last week.

Of course, the fossil that Makovicky first saw back in 2019 doesn’t look like that today. The Field’s fossil preparators, Akiko Shinya and Connie Van Beek, have spent hundreds of hours in a lab hunched over the specimen, delicately picking and grinding away at the excess sedimentary rock to expose the fossil.

Makovicky, who has been able to sneak a look at the work on the Archaeopteryx since its arrival at the Field, said his former employer is right to be excited about what it has in its collection.

“It turned out to be better than expected,” he said. “The skull is phenomenal, both in its preservation and the fortuitous way it was preserved. It’s providing a lot of new and interesting scientific insights.”