About inter- and intra-specific variability of dental microwear texture in rodents: Study of two sympatric Proechimys (Echimyidae) species from the Cacao locality, French Guiana

Abstract

Material properties of the diet of extant species is reflected by the microwear texture recorded on the enamel tooth surface, a signal that can be useful for estimating the diets of extinct species. Intra-specific dietary variations can occur between sexes or depend on seasonal vegetation cover changes in their habitat. However, these factors cannot, or very rarely, be incorporated within a paleontological context, especially if the fossil record of an extinct species is mainly composed of isolated teeth. In order to assess the effects of these factors on microwear texture features, we studied 42 wild-caught specimens of two sympatric extant species of caviomorph rodents, Proechimys cuvieri and Proechimys guyannensis (Echimyidae, Octodontoidea) from the Cacao area located in French Guiana. Animals were captured between 2007 and 2012, in July and October, along a 1.5 km transect ranging from an old secondary forest to a disturbed forest. We applied a Scale Sensitive Fractal Analysis (SSFA) to the first upper molars of these specimens. Differences of dental microwear textures were found between sexes, between months, and between habitat, leading to one species overlapping in microwear texture parameter space with the other in some cases. The results obtained help identifying which factors might drive intra-population variations in dental microwear texture. Its understanding is indeed a key-step to better interpret the dispersion observed within a given fossil sample set to obtain refined dietary reconstructions.