A new archaeological find by the University of Pennsylvania Museum of Archaeology and Anthropology, otherwise known as the Penn Museum, proves it's never too late to come out of the closet.

Scientists at the Philadelphia-based museum say they recently re-discovered in one of their storage closets a complete human skeleton, estimated at about 6,500 years old.

The intact remains of what is believed to have been a well-muscled male, who died around 50 years old and stood about 5 feet and 10 inches, had been kept in a coffin-like box for 85 years, all identifying documentation nowhere to be found, a news release said.

A project kicked off this summer to digitize old records from a world-famous excavation from the area that is now modern-day Iraq provided long-lost background about the remains, prompting researchers to pull brought the skeleton and its story back out of the closet -- apparently for good.

Museum scientists have since realized how extraordinarily important the long-time closet inhabitant is because skeletons from the region the prehistoric man inhabited and time he died -- in the ancient Near East, during what is known as the Ubaid period, which is roughly roughly 5500-4000 BCE -- are extremely rare, and complete skeletons from the period are rarer still.

Unearthed in 1929-30 by Sir Leonard Woolley's joint Penn Museum/British Museum excavation team at the site of Ur, in what is now southern Iraq, the skeleton is about 2,000 years older than the materials and remains found in the famous Mesopotamian "royal tombs," which were actually the focus of a Penn Museum signature exhibition.

Woolley's team excavated 48 graves in an early, Ubaid-era flood plain, found nearly 50 feet below the surface of the site; only one skeleton, however, was determined in good enough condition to recover -- the remains now identified in the Penn Museum's collection.

Janet Monge, the curator-in-charge for the museum's physical anthropology section, says that, in fact, she had known for some time about the particular skeleton in the storage area -- one of about 2,000 complete human skeletons in the museum collection, which altogether houses more than 150,000 bone specimens from throughout human history.

For as long as she remembered, the curious skeleton in the closet had always been there with no catalog card, no identifying number, nothing to explain its origins.

In 2012, as researchers dove into old files in an effort to digitize records from the 1922-1934 excavations at Ur, a set of division lists telling which objects went to which museums caught the eyes of team leader William Hafford, who recalls half of all the artifacts retrieved at the site stayed in the new nation of Iraq, but the other half was split between collections in London and Philadelphia.

Records for the eighth season of the excavation, 1929-30, indicated one of the items the Penn Museum would receive was one tray of "mud of the flood" and two "skeletons." Further research into the Museum's object record database indicated that one of those skeletons -- 31-17-404, deemed "pre-flood" and found in a stretched position -- was recorded as "Not Accounted For," as of 1990.

Exploring the extensive records Woolley kept, Hafford was able to find additional information and images of the missing skeleton.

When Hafford asked Monge about the remains missing remains, she said she had no record of such a skeleton in her basement storage, but noted the closeted skeleton in a box.

And when the box was opened later that day, it was evident the "mystery" was indeed the same skeleton indicated in Woolley's field records.

When applied to the newly-discovered skeleton, scientific techniques unavailable in Woolley's time are expected to offer new information about the diet, ancestral beginnings, trauma, stress and diseases of the poorly understood population or Ur, which Woolley concluded had originally been sited on a small island in a surrounding marsh -- until a great flood washed over the land.

The burial plot that produced the Penn Museum skeleton had been cut into a layer of deep silt, an indication the original owner of the skeleton lived after the flood -- when inhabitants of Ur still seems to have flourished -- and then buried after death in the silt left from the flood event.