The University of Pennsylvania has found quite the skeleton in its closet.

Scientists at the Penn Museum say they have uncovered a 6,500-year-old skeleton of a 50-ish man who has been in a coffin-like box in a basement storage room for the last 85 years - with no catalog card or identifying information.

They knew the "mystery skeleton" was there, but didn't know its origins until an ongoing project to digitize old records from the Ur excavation, in what is now southern Iraq, revealed its identity.

The skeleton 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.

The skeleton originally was discovered in 1929-30 by Sir Leonard Woolley's joint excavation team from the Penn Museum and the British Museum in London. The man was found in an area where a great flood occurred, but he apparently survived the flood and was buried in its silt deposits, records show.

Janet Monge, the curator who oversees the physical anthropology section of the museum, said the man appears to have been 5'8" to 5'10" and "well-muscled." He was buried with his arms at his sides and his hands over his abdomen.

Skeletons from this time period - 5500-4000 BCE — are extremely rare, especially complete skeletons, Penn officials said.

While working on the digitizing project, William Hafford, the project manager, noticed records that indicated which artifacts went to Penn and which went to the British museum. While half of the artifacts remained in Iraq, the other half were split between the two museums, Penn said. The record from 1929-30 said that Penn would receive one tray of "mud from the flood" and two skeletons. Delving into the museum's record database, Hafford saw that one of the skeletons found in a stretched position was "not accounted for" as of 1990.

Hafford asked Monge about it and she told him she knew nothing about that skeleton, but did have a "mystery skeleton" in the basement.

Further investigation showed it was a match.

Museum staff has nicknamed the skeleton "Noah" for his having survived the flood.