Published online by Cambridge University Press: 20 January 2017
A unique grinding tool, termed a "gyratory crusher," was developed very early in Phase I of the Amargosan-Pinacateño occupation of the Sierra Pinacate, an isolated ecological and archaeological enclave in extreme north-western Sonora, Mexico. The gyratory crusher resembles a perforated mortar, either in slab or block form, in which a wooden pestle with a projection extending through the perforation in the mortar base was gyrated, the projection providing leverage against the under rim of the hole, to grind mesquite pods. The crusher underwent modification, and its use seems to have been discontinued with the disappearance of mesquite forests at the end of the Yuman I period, about A.D. 1100-1200. A few similar tools are reported late in time in the western Sierra Madre, Mexico, and also from early horizons in Iran and Israel. Recognition of the tool type may extend its known distribution in both the New World and the Old World.