One starch granule was recovered from a ground stone tool (FS380, Sample SS278-2). The date was taken from associated charcoal in the same layer and context as the stone tool (Zarrillo et al. 2008).
Zarrillo, S., D. M. Pearsall, J. S. Raymond, M. A. Tisdale and D. J. Quon 2008 Directly dated starch residues document early formative maize (Zea mays L.) in tropical Ecuador. Proceedings of the National Academy of Sciences, USA 105(13):5006–5011.