COLIMA, MEXICO—Many bones and at least eight skulls have been found in a shaft tomb in western Mexico. The tomb is estimated to be between 1,500 and 2,500 years old. “At first they identified the burials because of the odd rock groupings that were used to cover them, they also found evidence of ceramic material which drove us deeper into the investigation,” said Marco Zavaleta Lucido of the National Institute of Anthropology and History. Among the pottery offerings were pots, plates, censers, and two dog-shaped bowls.