Systematics and Paleobiology of Hippotherium malpassii n. sp. (Equidae, Mammalia) from the latest Miocene of Baccinello V3 (Tuscany, Italy).

A new species of hipparionine horse, Hippotherium malpassii, is described from the MN13 interval from localities of the Baccinello V3 area (Italy). This species exhibits some advanced features of the facial region and cheek tooth dentition while other skull features and the postcranial skeleton are plesiomorphic. Research related to paleodiet suggests that Hippotherium malpassii was a mixed feeder, not as committed to grass feeding as many Central European species of Hippotherium. However, it may be considered as being similar to others such as Hippotherium primigenium from Eppelsheim (Germany) and Hippotherium microdon from Baltavar (Hungary). Studies of carbon and oxygen isotopes suggest that Hippotherium malpassii from the Baccinello V3 area lived in a forested context and it is inferred herein that it likely ate grass of relatively low abrasive character. Regarding the paleogeography of the species, Hippotherium originated in Central Europe early on in the MN9 interval (ca. 11 Ma) and underwent a modest evolutionary radiation there during the Vallesian and early Turolian (MN9-11). It is documented as having then dispersed throughout the Balkans into Greece during MN11/12 where it is represented by Hippotherium brachypus from the locality of Pikermi (Greece). During the interval MN12, the range of Hippotherium brachypus was extended and populations of very large size with massive metapodials evolved throughout this period. Hippotherium is not documented from the Baccinello area in Tuscany until the base of the MN13 interval (Baccinello V3 faunas) and may have immigrated from the Pannonian Basin, Hungary. The genus Hippotherium would appear to have become extinct at the end of MN12, the latter considered as being a result of increased continental drying and reduction of forest and woodland habitat. Its occurrence at Baccinello V3 in the MN 13 interval represents the latest occurrence of the genus in Europe.