FLORENCE, ITALY—A research team that has been excavating beneath the Sant’ Orsola convent in Florence for several years claims to have found bone fragments that may have belonged to Lisa Gherardini, the silk merchant’s wife thought by some scholars to have been Leonardo da Vinci’s model for the Mona Lisa. Gherardini lived in seclusion at the convent during the last years of her life. Carbon-14 dating shows that the bones in question date to about the time that Gherardini died, in July 1542, at the age of 63, but they are too degraded for DNA testing. “Our biggest problem has been the fact that the fragments were very fragmented, very deteriorated,” Giorgio Gruppioni of the University of Bologna told The Guardian. If a skull had been found, there had been plans to reconstruct its face and compare it with the famous painting. To read about the excavation of an Etruscan necropolis, go to "Tomb of the Silver Hands."