Study of the shape and size in lower molars of Toxodon platensis (Mammalia: Toxodontidae) of the Late Pleistocene of South America - 06/09/24

Doi : 10.1016/j.geobios.2024.05.005

Donato Costamagna ^a,^b,^⁎ , Brenda S. Ferrero ^a,^b , Federico Giri ^c,^d, Ana María Ribeiro ^e
^a Laboratorio de Paleontología de Vertebrados, Centro de Investigación Científica y de Transferencia Tecnológica a la Producción (CICyTTP, CONICET- Prov. ER-UADER), Materi y España. Code 3105, Diamante, Entre Ríos, Argentina
^b Laboratorio de Paleo-Vertebrados. Facultad de Ciencia y Tecnología. Universidad Autónoma de Entre Ríos (UADER). Tratado del Pilar 314, Sede Diamante. Code 3105, Diamante, Entre Ríos, Argentina
^c Laboratorio de Macrocrustaceos. Instituto Nacional de Limnología (INALI, CONICET-UNL). University City, Pje el Pozo s/n, Santa Fe, Argentina
^d Facultad de Humanidades y Ciencias (FHUC-UNL), Ciudad Universitaria, Pje el Pozo s/n, Santa Fe, Argentina
^e Museu de Ciências Naturais, Secretaria Estadual do Meio Ambiente e Infraestrutura, Av. Salvador França, 1427, Jardim Botânico, Porto Alegre, RS, Brazil

^⁎Corresponding author.

En prensa. Pruebas corregidas por el autor. Disponible en línea desde el Friday 06 September 2024

Abstract

This study aims to assess shape and size variations in lower molars (m1-m3) of Toxodon platensis Owen across diverse South-American regions: northern Pampa, Mesopotamia, northwestern Argentina (NWA), southwestern Uruguay, and southern Brazil. We examined 102 specimens, capturing 20 landmarks for each molar. Principal component analyses were used for shape analysis, and geographic origin relationships were explored through cluster analysis. Centroid size (CS) was analyzed with ANOVA. The shape of T. platensis molars differed among different populations in each geographic region. Molars from NWA exhibited a slenderer shape, whereas Mesopotamia specimens displayed more robust trigonids. Northern Pampa and southwestern Uruguay molars were the most similar in shape, and the molars of the populations in southern Brazil showed more curved morphologies. CS was similar among the different populations of T. platensis, which suggests a probability of similar food particle fracture and processing. On the other hand, when observing shape variations as a result of diet, it can be concluded that the shape changes observed in different geographic areas could be related to the type of vegetation consumed by various T. platensis populations.

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Keywords : Toxodontia, Notoungulata, Geometric Morphometry, Paleobiology, Quaternary, South America