The Middle Pleistocene Hippopotamus from Malagrotta (Latium, Italy): New Data and Future Perspectives

The Middle Pleistocene was characterized by the presence in continental Europe of at least two different species of hippopotamus: Hippopotamus antiquus and H. amphibius. Although suspected, the presence of both hippopotamuses in the same geographical area has not yet been proven. The following manuscript describes findings from Malagrotta (Rome, central Italy), dating back to the time span between 0.45 and 0.38 Ma. These findings offer new insights into the Middle Pleistocene period. The fragmented mandible has a slender and low corpus, the humerus is robust with a deltoid tuberosity placed medially on the diaphysis, the unciform shows a facet for the MCIV wider than the one for the MCV and the calcaneum is clepsydra-shaped. The morphological characteristics of the sample are closer to those of H. antiquus, despite the fact that the morphometric measurements are smaller than those of the samples coming from Valdarno (Italy), Untermaßfeld (Germany) or Colle Curti (Italy). Considering all the information, the material from Malagrotta is here attributed to H. cf. antiquus, indicating the survival of the European hippopotamus until at least 0.38 Ma in central Italy. The coexistence of H. amphibius and H. antiquus in the same geographical area is also discussed.