Stephanorhinus hemitoechus (Mammalia, Rhinocerotidae) from the Late Pleistocene of Valle Radice (Sora, Central Italy) and re-evaluation of the morphometric variability of the species in Europe

During the 1960s, a remarkable collection of rhinoceros postcranial remains was recovered in a Late Pleistocene karst cavity at Valle Radice near Sora (Frosinone, Central Italy). Based on the morphological characters, the specimens are ascribed to Stephanorhinus hemitoechus. This record is the only one with abundant postcranial elements in Italy and Southern Europe; it enables a careful analysis of the most important morphometric features in the postcranial skeleton of the species. The palaeobiogeographic boundaries and the relative biochronological importance of the evolutionary stages of the species in Europe are investigated. The new data suggest the morphometric variability of the species is strictly related to the geographic area; the evolutionary trends described during the past for the postcrania of the species are not confirmed. In Italy, the species is characterised by the presence of large-sized specimens during the Middle and Late Pleistocene, as well as in Great Britain. In Central Europe, the species is characterised by a fluctuation in size with the occurrence of relatively small-sized specimens during MIS 11-8. In the Iberian Peninsula, during the late Middle and Late Pleistocene S. hemitoechus is characterised by the presence of relatively small-sized specimens with respect to those from other European localities; this feature could be related to a geographic isolation.