India, Oct. 25 -- A strange stone monument stretching across the desert has given archaeologists a rare glimpse into how prehistoric communities in the Western Sahara buried their dead. Built from limestone slabs and marked by two long, antenna-like extensions, the structure had remained difficult to date and even harder to interpret. Now, a new excavation has established that the monument was used for burial roughly 4,400 years ago.

The monument was found at Wadi Lawash el Telli, on the eastern edge of the Sluguilla Lawash rock-art site in northern Western Sahara. As reported in Archaeology Magazine, researchers dated the burial to between about 4,417 and 4,100 calibrated years before present, providing the first absolute chronology for...