Janet Monge knew for years that the Penn Museum had quite the skeleton in its closet, a box of bones supinely displayed, carefully encased in wax, wrapped in burlap, and positioned on a board.

"Somebody took great pains to take a very fragmentary skeleton and bring it here," said Monge, the curator who oversees the physical anthropology section of the museum in University City. "Therefore, it must be important."

There was no catalog card or identifying information. So the skeleton sat obscurely for years in a ground-floor storage room at the University of Pennsylvania Museum of Archaeology and Anthropology.

"I've been obsessed with him," Monge said.

So when Penn researcher William "Brad" Hafford asked whether she knew anything about a missing skeleton in a stretched position, she knew just the one.

Turns out, her mystery skeleton dates back 6,500 years and comes from ancient Ur, now known as southern Iraq. The skeleton, of a man about 50, was excavated in 1929-30 by Sir Leonard Woolley, who worked on behalf of Penn and the British Museum.

Somewhere along the way, all identifying information was lost, and records showed only that the skeleton, apparently in Penn's possession for the last 85 years, was "not accounted for" as of 1990. Hafford came across the record while conducting a project to make into a digital site all the old records and artifacts from the famous Ur excavation.

Upon closer inspection, Monge and Hafford confirmed the match.

They were thrilled.

"Me and my students," Monge said, "we are going to hang out for a while with this dude."

It's not uncommon, she said, for some items that came to the museum many decades ago to lack full identification.

"The structure of museums is not like it is today, so they didn't do the same kind of cataloging," she said.

"Certainly, incomplete documentation is common," Hafford said. "Completely unknown is less common."

Now that Penn researchers know the identity of the skeleton and general time period in which the man lived, they can study the remains to learn more about diet, ancestral origins, trauma, stress, and diseases of people from that period.

They will try to extract DNA, but they'll start by getting a CT scan at the Hospital of the University of Pennsylvania to better view the bones.

The skeleton, lying in a coffinlike plywood box with its arms at its sides and its hands over its abdomen, is believed to be that of a man who stood 5-foot-8 to 5-foot-10 and was muscular.

Monge and Hafford said they were especially interested that the skeleton is of a man who appeared to be taller and older than the average man from that period, which may indicate adequate nutrition and lack of disease.

Skeletons from the period - 5500 to 4000 B.C.E. - are extremely rare, especially complete skeletons, Penn officials said. Most of the other skeletons have come from what's known as the Royal Cemetery, a couple of thousand years later.

But Woolley, Hafford said, specifically dug well under that cemetery to uncover earlier specimens. Researchers can tell the time period of the skeleton in part because of the type of pottery buried near it.

The Ur skeleton was found in an area that experienced a great flood, leading Penn researchers to nickname it "Noah."

It is one of about 2,000 complete human skeletons in the museum's collections, which includes more than 150,000 bone specimens from human history.

While working on the digital project, Hafford, the project manager, noticed records that indicated which artifacts went to Penn and which went to the British Museum following Woolley's expedition. While half of the artifacts remained in Iraq, the other half were split between the museums, Hafford said.

Penn does not plan to return the skeleton to Iraq, he said. The digital project will give researchers all over the world access to the Ur excavation records and remains, he said. Researchers are hoping that Iraq will participate and make its Ur collection available as part of the project, likely to take a decade or longer.

The record from the 1929-30 excavation said that Penn would receive one tray of "mud from the flood" and two skeletons.

The second skeleton remains unaccounted for.

But Monge and Hafford think they have a pretty good idea where it is. There's another box in the storage room marked "No number" that they have yet to open. The box is smaller, which would fit the description of the missing skeleton, said to be in a "flexed" position, Hafford said.

Monge and Hafford declined to open the box for a reporter and photographer, but said they would do so soon.

"What if it's chocolate chip cookies? That wouldn't be good," Monge said. "We have a lot of strange things."

215-854-4693 @ssnyderinq