Is Hippopotamus antiquus (Mammalia, Hippopotamidae) affected by body size variations? The contribution of the Mosbach (Germany, Middle Pleistocene) specimen

Abstract Hippopotamus antiquus is a well-documented species within the Hippopotamidae family, with evidence of its presence in almost all Europe during the Pleistocene. Despite its abundance in the fossiliferous record, there is still much debate surrounding the first and last appearance data of this taxon, as well as its evolutionary trend. In this work we present a well-preserved mandible recovered from Mosbach (Germany) referred to the Middle Pleistocene. The latter period is represented by less H. antiquus remains in comparison to the Early Pleistocene, making the description of this specimen helpful for morphometric and morphological considerations. Early Pleistocene H. antiquus specimens from Upper Valdarno, Collecurti and Durfort display larger dimensions in comparison to those from Middle Pleistocene localities, including Maglianella, Ortona, Ponte Molle and the specimen from Mosbach. A decrease in body size in H. antiquus , most likely correlated to climate fluctuations, is therefore discussed providing news insights into the biogeography, morphology and morphometry of late H. antiquus.