2D geometric morphometrics of murine mandibular toothrows from Liang Bua (Flores, Indonesia): implications for taxonomic identification

Abstract

This study uses—and evaluates the efficacy of—two-dimensional geometric morphometrics (2DGM) to quantitatively characterize the size and shape of murine rodent (i.e., rat) mandibular molar rows from the archaeological site of Liang Bua, a limestone cave located on the Indonesian island of Flores and the type site of Homo floresiensis. Murine remains make up a significant portion of Liang Bua’s sizable faunal assemblage and contribute significantly to understanding the paleoecology of western Flores. As such, it is essential to develop robust methodologies to accurately assess the taxonomy of these remains. Using images of complete mandibular toothrows, this study aims to test the functionality of 2DGM for taxonomic assessments based on the size and shape variation present in the Liang Bua murine assemblage. The results show that 2DGM offers important information about mandibular toothrow size and shape that can be used in conjunction with qualitative and other quantitative data for murine species identification at Liang Bua and other archaeological sites on Flores. Additionally, this study explores the effects of image angle and tooth wear on 2DGM analyses and provides several recommendations for how to mitigate these potential issues in future work. Since the Liang Bua murine remains represent multiple species of varying body sizes and habitat preferences, quantitative variation and descriptions of previously uncharacterized inter- and intra-species variation described in this study will help to facilitate ongoing paleoecological reconstructions of the cave’s history.