Identifying maize in neotropical sediments and soils using cob phytoliths

Phytoliths-plant opal silica bodies-identified as maize (Zea mays, Poaceae) cob bodies have been recognized in residues from prehistoric pottery vessels and in human dental calculus. Maize cob phytoliths had not been formally tested against similar phytoliths produced in wild grass inflorescences, which are likely to be encountered in soils and sediments. We report the results of such tests, and formalize maize cob diagnostic types to permit separation of maize cob phytoliths from wild Zea (teosinte) and wild panicoid grasses in soils and sediments from the lowland Neotropics. Blind tests of the formalized types demonstrate the reliability of the identification protocol, and reveal a tendency for under-identification. Comparison of phytoliths extracted from charred maize cupules and sediments containing those cupules from the Pechichal site in the Jama River valley, coastal Ecuador, demonstrates that cob phytoliths are readily recognizable in sediments, but that cob phytolith assemblages may be altered in the burial environment, or during chemical processing. (C) 2003 Elsevier Science Ltd. All rights reserved.