ams radiocarbon dates of the sediments at tepexpan show ages between 19,110±90 and 612±2214c years bp. new uranium-series date the skeleton to 4,700±200 years bp, which would indicate a holocene age. the evidence suggests that there were large changes around lake texcoco in terms of the balance between water and land plants, c3 and c4 plants, saline, alkaline and freshwater conditions, volcanic activity, reworking of lake sediments, and input from the drainage basin throughout the late pleistocene and late holocene. these changes also had large effects on the prehistoric human populations living around the lake at this time.