New material and revision of hipparions from the upper Miocene locality Ravin des Zouaves-5, RZO of Axios Valley (Macedonia, Greece)

The reconsideration of the hipparions from the locality Ravin des Zouaves-5 (RZO) of the lower Axios Valley provides a better taxonomy, based on the revision of the old known collection (up to 1987), the inclusion of new discoveries and the bibliographic data of the last 30 years related to the study of the hipparions in Greece and the neighboring countries. Based on the cranial material and metapodials, five different taxa have been distinguished. New cranial material confirms the presence of the large-sized Hipparion proboscideum and the small-sized Hipparion macedonicum in the RZO fauna. In the new middle-sized hipparion sample from RZO two species have been identified, Hipparion philippus, and another form similar to Hipparion mediterraneum, which is attributed to Hipparion cf. mediterraneum. Cranial remains of a second small-sized hipparion are also recognized in the RZO fauna, which is attributed to Hipparion sithonis. The relationships of H. mediterraneum and H. proboscideum are discussed; a cladistic analysis suggests that they are sister taxa, sharing a common ancestor with the Hipparion moldavicum group, and a form similar to H. mediterraneum is a possible ancestor of H. proboscideum.