Hábitos alimentares de Subulo (Cervidae, Mammalia) durante evento de expansão populacional no Quaternário tardio brasileiro

Abstract

The fossil record from Gruta Cuvieri (Minas Gerais) documents an event of population expansion of Subulo gouazoubira Fisher 1814, Cervidae, which occurred close to the Pleistocene-Holocene transition. Due to this, it is important to explore the causes of this population expansion. One hypothesis that could explain the observed patterm is a change in the species' eating habits over time. In this study, we investigated this issue through the analysis of dental microwear produced during chewing. We examined the occlusal surface of replicas of second molars (M2) from 20 left hemimandibles, with four samples from the Pleistocene and 16 from the Holocene. The dental microwear features (coarse scratch, fine scratch, large pit, and small pit) were observed using Scanning Electron Microscopy (SEM) technique, from which four replicas were discarded and 16 replicas were evaluated. These features were subsequently qualified and quantified semi-automatically using the MicroWeaR package for the R programming language. The difference in medians between the two time epochs was tested using the Kruskal-Wallis test (based on the results of the Shapiro-Wilk normality test), and the data were also analyzed through Principal Component Analysis (PCA). The Kruskal-Wallis test did not support a difference in diet over time, while PCA supported this result. Although no temporal differences were observed in the diet, the PCA revealed two main diet trends based on the variance and covariance of dental microwear features: a mixed diet with fruits, dominated by leaves (browsers), and a mixed diet with fruits, dominated by grasses (grazers). The quantity of scratches separated the two main diet groups: browsers and grazers, while the pits indicated a mixed diet with fruits, suggesting harder foods due to the existence of thick skin and/or hard seeds. This study demonstrates the importance of analyzing dental microwear in paleoecological investigations, providing a robust methodology for identifying dietary patterns and aiding in paleoenvironmental interpretation. It also highlights challenges in inferring diet from dental microwear data, such as potential interference from differences in eating habits due to climatic seasonality, changes in habitat for the group, or taphonomic effects in the cave context. This study also highlights some of the challenges faced when inferring diet from data on dental microwear, since the interpretation may suffer interference due to the way in which this wear is imprinted on the tooth and the possibility of its obliteration due to, among other factors, taphonomic effects on the tooth on cave context.