Valsequillo Basin and Hueyatlaco

Record summary

Hueyatlaco is a locality in Mexico’s Valsequillo Basin associated with stone artifacts, fossil fauna, and controversial dates that were once interpreted as indicating a very early human presence. The findings produced a long dispute involving stratigraphy, dating methods, artifact authenticity, and the geological history of the basin. The case is important for comparison because different specialists reached sharply different conclusions from the same broad body of evidence. It should be studied through the original reports and later geological critiques, with no assumption that the oldest proposed age is accepted.