In the 1930s archaeologists working at the site of Zhoukoudian near Beijing recovered an incredible trove of partial skulls and other bones representing some 40 individuals that would eventually be assigned to the early human species Homo erectus. The bones, which recent estimates put at around 770,000 years old, constitute the largest collection of H. erectus fossils ever found. They were China’s paleoanthropological pride and joy. And then they vanished.

According to historical accounts, in 1941 the most important fossils in the collection were packed in large wooden footlockers or crates to be turned over to the U.S. military for transport to the American Museum of Natural History in New York for safekeeping during World War II. But the fossils never made it to the U.S. Today, all scientists have are copies of the bones. The disappearance of the originals stands as one of the biggest mysteries in paleoanthropology.

Researchers have found a new lead, however. In a paper published today in the South African Journal of Science, Lee Berger of the University of the Witwatersrand in Johannesburg and Wu Liu and Xiujie Wu of the Institute for Vertebrate Paleontology and Paleoanthropology in Beijing detail their investigation into a recent report concerning the location of the missing bones. Former U.S. Marine Richard M. Bowen, now in his 80s, claimed that in 1947, when he was stationed at Camp Holcomb in the port city of Qinhaungdao during China’s Nationalist-Communist Civil War, he came across a box full of bones while digging foxholes one night. Spooked, he reburied the box. Soon thereafter his company evacuated Qinhaungdao.

Because the most credible accounts of what happened to the fossils have them reaching Camp Holcomb, the researchers thought Bowen’s report worthy of further investigation. Perhaps the officer in charge of the fossils in 1941, seeing that the fossils were not going to make it on board the ship amid the wartime chaos, had chosen to bury them for later retrieval—only to never make it back.

Working with information from Bowen and a local expert on the harbor, the team formulated three best guesses as to the location of the stone barracks where Bowen said he dug up the box of bones. All three sit within an area of about 200 meters by 200 meters. “One possible location sits underneath a large warehouse, but the remaining locations all fall under a large parking area and roadway” the researchers note.

According to the authors, the odds are high that the box Bowen claims to have found would have been destroyed during development of the area. But if it wasn’t, science may yet recover the missing Peking Man fossils. The team concludes:

“We established that the area in question is due to undergo development in the near future and that ‘large buildings’ are to be erected on the site. This development of course offers the opportunity that the roads and warehouses will be excavated and that if the footlocker noted by Richard Bowen has somehow miraculously survived, it or its contents might be uncovered during the course of excavation. Local authorities of the Cultural Heritage Office have committed to monitor any excavations in the area for remnants of the footlockers or fossils, and it is on this slim chance that the recovery of the bones Richard Bowen observed in 1947 rests.”

03/30/12 update: Reader @_timskinner commented via Twitter: "Sometimes a box of bones is just an old coffin. I gather they have reason to believe that's not the case here?" I put the question to Lee Berger, one of the authors of the new paper, who replied: "Yes that is a possibility of course--but firstly they were in a 'footlocker' of sorts, and in a plausible location, and perhaps most importantly Mr. Bowen feels that the bones resembled the Peking Man fossils. It is of course possible that this was a 'box of bones' or some sort of temporary coffin, but one begins to question why the bones would be in such a wooden footlocker, in this position, and why they would look like the Peking Man fossils (or at least why they would draw this association in the mind of Mr. Bowen). It is enough evidence--given the unique historical circumstances’ of their loss and their importance--to investigate, and to report, this account. Sometimes exploration is a bit like that old golf/statistics joke: 'It’s a proven fact that 100% of putts that don’t reach the hole don’t go in'--well '100% of explorers who don’t investigate a claim by going don’t find anything.'"