Xihuatoxtla

Xihuatoxtla is a rock shelter in the Rio Balsas valley, Guerrero, Mexico, formed beneath a massive boulder. Archaeological excavations have uncovered grinding tools and knapped blades, with occupation evidence dating to approximately 8900–8600 years ago (roughly 6900–6600 BC) [1]. The site is particularly significant for yielding starch grain and phytolith evidence of domesticated maize and squash among the earliest known in Mesoamerica, pushing back timelines for New World agriculture [1].