Résumé
Caviomorpha or South American hystricognaths are taxonomical and ecological diverserodents with broad dietary habits, ranging from frugivorous to grass eaters. The oldestfossil record of the group dates back to the late middle Eocene of Peru. Continuouspaleontological field efforts increase the knowledge and diversity of most ancientspecies, testifying a rich and complex early evolutionary history. However, little isknown regarding the ecology of these Paleogene caviomorphs and its impact on theearly evolution of the group.In this work we analyze the teeth enamel surface of extantcaviomorphs in order to assess if their different dietary habits are reflected by distinctmicrowear textures. This approach aims to obtain a model to be applied topaleoecological studies.The method, named dental microwear texture analysis(DMTA), describes and analyzes automatically surface textures, with a high degree ofprecision. In the last decade, various studies from several authors explore itsapplication yet this work is the first to look at caviomorph rodents. We studied 90specimens representing 15 species and 4 families of extant caviomorphs with differentfeeding habits all coming from the state of Rio de Janeiro, Brazil. For each specimen,we performed a scan on a high resolution silicon mold of the occlusal surface of thefirst upper molar with aLeica DCM8 optical surface profilometerat the IPHEP lab (CNRSand University of Poitiers, France). Then we applied a scale-sensitive fractal analysiswith Toothfrax and Sfrax softwares to describe the microwear textures through fivevariables: Asfc (complexity), epLsar (anisotropy), HAsfc (heterogeneity of thecomplexity), Smc (scale of maximum complexity) and TFV (textural fill volume). Ourresults indicate that there is significant microwear texture differences betweenprimarily frugivorous and grass-eater species.These preliminary results on livingspecies demonstrate that the DMTA method represents a potentially powerful analytictool for reconstructing the diet of extinct species of caviomorphs.