Evaluating Sexual Dimorphism in Postcranial Elements of Eurasian Extinct Stephanorhinus etruscus (Falconer, 1868) (Mammalia, Rhinocerotidae)

Sexual dimorphism has been poorly evaluated or investigated in Pleistocene Eurasian Stephanorhinus species, leaving a gap in our knowledge about their morphometric variability. Among the representatives of this genus, S. etruscus is the most abundant species, with several remains collected from Western European localities, allowing us to investigate the presence of sexual dimorphism in the limb bones of this taxon. We considered measurements taken on 45 postcranial variables and three different statistical metrics to identify patterns of bimodality in the dataset. This work represents the first application of sex-combined statistical analysis to a dataset composed of individuals from various European localities. The morphometrical analyses revealed that a relatively weak sexual dimorphism is present in all the considered bones. Larger forelimbs and hindlimbs are interpreted as belonging to adult males of S. etruscus, similarly to what was observed in the modern Sumatran rhino, where males are a little bit larger than females. The recognition of a weak sexual dimorphism in the postcranial bones of S. etruscus increases our understanding of the paleoecology of this extinct taxon. However, only a better study of the morphological and morphometrical variability of the crania of fossil rhinoceroses could deeply contribute to the investigation of the social habits and behavior of these taxa.