Abstract

Quantitative analysis of footprint shape is central to ichnology, yet the application of geometric morphometrics is often limited by the difficulty of defining homologous landmarks on irregular or variably preserved impressions. Here we present a polygon-based approach to footprint morphometrics in which the footprint margin is digitised as a continuous outline and resampled into a standardised set of boundary points for analysis. Using a combination of simulated perturbation experiments and empirical datasets, we assess the sensitivity of this method to annotation uncertainty and compare it to natural variation within and between trackways. The results demonstrate a clear hierarchy of variance, in which annotation noise is lower than inter-observer variability, intra-trackway variation, and between-trackway differences. These findings suggest that polygon-based representations of footprint shape are robust to realistic levels of digitisation uncertainty. Application of the method to modern and fossil trackways, including the Laetoli footprints, shows that resampled polygon outlines retain meaningful morphological structure and can be used effectively in comparative analyses.

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