The Hippopotamus remains from the latest Early Pleistocene site of Cava Redicicoli (Rome, central Italy)

The Quaternary record of hippopotamuses is extremely abundant, yet there are still conflicting opinions about their systematics and evolution. The main diagnostic characters of fossils and extant hippopotamuses are recorded in the skulls, while the distinct morphological features between species are less evident in dental and postcranial remains. When hippopotamus skulls are not available, taxonomic identification is often chronologically-based. Herein are described for the first time the hippopotamus remains of the historical museum collections from the latest Early Pleistocene site of Cava Redicicoli, housed in the Museo Universitario di Scienze della Terra, Dipartimento di Scienze della Terra, Sapienza Università di Roma and Istituto Italiano di Paleontologia Umana, Anagni. This material, although formally never morphologically studied, has been referred in the literature either to Hippopotamus antiquus (considering Hippopotamus major as a synonym of H. antiquus) or to Hippopotamus ex gr. antiquus. Morphological and biometric comparisons with other Pleistocene hippopotamuses permit to attribute the studied material to Hippopotamus cf. antiquus. Biometric analysis of teeth and complete postcranial bones shows that the size of fossil hippopotamuses is quite variable, with the largest dimension for the European fossils recorded from the Villafranchian and the Epivillafranchian. The rich sample from the Cava Redicicoli provides new data regarding the morphological and biometric variability of this group during the large faunal renewal that occurred during the Early-Middle Pleistocene transition.