Neandertal baby rises from French archive. (Lost-and-Found Fossil Tot).

For nearly 90 years, a prehistoric baby's bones lay unidentified in the recesses of a French museum. This was no minor case of misplaced fossils: It was a rare instance of a nearly complete skeleton of a Neandertal.

A survey of the museum's fossil collection has now salvaged the approximately 40,O00-year-old Stone Age specimen, according to a report in the Sept. 5 Nature.

University of Bordeaux anthropologist Bruno Maureille, who rediscovered the skeleton, calls it "a rich source of data" for studying the evolution of individual development as well as the relationship between Neandertals and Homo sapiens.

French schoolteacher and fossil hunter Denis Peyrony unearthed the ancient infant's skeleton in southwestern France in 1914. Neandertals had apparently buried the child in a rock shelter called Le Moustier 2. In the late 1800s, the first stone tools attributed to Neandertals were unearthed at the nearby Le Moustier cave.

Researchers lost track of the Neandertal child's remains shortly after their excavation. French investigators have long suspected that the fossils were lost in Paris after being shipped there by Peyrony, Maureille says. However, he found no mention in Peyrony's archived notes about the Neandertal specimen ever having been sent to Paris.

Instead, it turned up in 1996 when Maureille was assigned to survey fossils stored at France's National Museum of Prehistory in Les Eyzies-de-Tayac-Sireuil. No anthropological assessment of the collection there had ever been conducted.

Maureille's reconstruction of the fossil child's travels into and out of obscurity will appear later this year in a French journal.

One reason for the infant's misplacement was the widespread belief in the early 1900s that little of importance could be gleaned from juvenile fossils, comments anthropologist Erik Trinkaus of Washington University in St. Louis. "Fossils such as these got stuck on a shelf and forgotten," he says.

Maureille's analysis of the specimen provided strong clues to its identity. First, some of the infant's bones were still embedded in sediment that displayed a chemical composition long associated with fossil-bearing soil at Le Moustier. Also, flint flakes and nonhuman animal bones stored with the child's skeleton were identical to stones and bones found among other Le Moustier Neandertals.

The Le Moustier 2 infant lacks only its shoulder blades and pelvis. The fight upper-arm and right upper-leg bones had been mistakenly stored in the museum with a child's skeleton from another French Neandertal site, La Ferrassie, Maureille says. Although it's not possible to determine the sex of the Le Moustier 2 baby, the arm and leg lengths indicate that he or she died at no more than 4 months of age.