Taxonomy and phylogeny of the smallest Miocene rhinocerotid Parvorhinus n. gen. (Mammalia, Rhinocerotidae)

Middle Miocene Rhinocerotini are particularly important to understand the origin and evolution of latest Miocene and then Plio-Pleistocene taxa. However, little is known about some early divergent Rhinocerotina such as ‘Dicerorhinus’ steinheimensis. A sample of a small-sized rhinocerotid from the Middle Miocene (Mammal Neogene Zone 6) locality of Devínska Nová Ves (Bratislava, Slovakia) is here described for the first time. The specimens consist of maxillae, fragment of mandibles and postcranial remains. The described specimens clearly differ from Middle Miocene representatives of elasmotheres, aceratheres and brachypotheres, but closely resemble the poorly known rhinocerotid ‘Dicerorhinus’ steinheimensis. A cladistic analysis shows that this taxon is related with the early divergent Rhinocerotina, such as Lartetotherium sansaniense and Gaindatherium browni, and it is distantly related with both Rhinoceros and Dicerorhinus. Considering the position and the peculiar morphological and morphometric features, such as smaller size with respect to other Rhinocerotini species, posterior border of the symphysis in front of p2, crochet always present on P2-P4, P1 always absent, protoloph interrupted on P2, lingual cingulum absent on M1-M2, posterior part of the ectoloph concave on M1-M2, ‘Dicerorhinus’ steinheimensis is here included in the new genus Parvorhinus.