Morphometrics of Second Iron Age ceramics - strengths, weaknesses, and comparison with traditional typology

Although the potential of geometric morphometrics for the study of archaeological artefacts is recognised, quantitative evaluations of the concordance between such methods and traditional typology are rare. The present work seeks to fill this gap, using as a case study a corpus of 154 complete ceramic vessels from the Bibracte oppidum (France), the capital of the Celtic tribe Aedui from the Second Iron Age. Two outline-based approaches were selected: the Elliptic Fourier Analysis and the Discrete Cosine Transform. They were combined with numerous methods of standardisation/normalisation. Although standardisations may use either perimeter or surface, the resulting morphospaces remain comparable, and, interestingly, are also comparable with the morphospace built from traditional typology. Geometric morphometrics also present the advantage of being easily implemented and automated for large sets of artefacts. The method is reproducible and provides quantitative estimates, such as mean shape, and shape diversity of ceramic assemblages, allowing objective inferences to be statistically tested. The approach can easily be generalised and adopted for other kinds of artefacts, to study the level of production standardisation and the evolution of shape over space and time, and to provide information about material and cultural exchanges.