Study of the shape and size in lower molars of Toxodon platensis (Mammalia: Toxodontidae) of the Late Pleistocene of South America

Abstract

This study aims to assess shape and size variations in lower molars (m1-m3) of Toxodonplatensis Owen across diverse regions: northern Pampa, Mesopotamia, northwesternArgentina (NWA), southwestern Uruguay and southern Brazil. We examined 102specimens, capturing 20 landmarks for each molar. Principal component analyses wereused for shape analysis, and geographic provenance relationships were explored throughsimilarity/dissimilarity analysis. Centroid size (CS) was analysed with ANOVA. The shapeof T. platensis molars differed among different populations in each geographic region.Molars from NWA exhibited a more slender shape, whereas Mesopotamia specimensdisplayed more robust trigonids. Northern Pampa and southwestern Uruguay molars werethe most similar in shape and the molars of the populations in southern Brazil showed morecurved morphologies. CS was similar among the different populations of T. platensis,which suggests a probability of similar food particle fracture and processing. On the otherhand, when observing shape variations as a result of diet, it can be concluded that the shapechanges observed in different geographic areas could be related to the type of vegetationconsumed by various T. platensis populations.