Starch granules (1 and 7) recovered from two ground stone tools (FS153, Sample SS275 and FS153, Sample SS275-2). The date was taken from associated charcoal (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.