A new Late Miocene ovibovine-like bovid (Bovidae,Mammalia) from the Kassandra Peninsula (Chalkidiki,Northern Greece) and implications to the phylogeography of the group

A new Late Miocene bovid, Urmiatherium kassandriensis sp. nov., from Northern Greece is described. The material comes from the Fourka locality in the Kassandra Peninsula (Chalkidiki), and the included fauna is estimated to be of Vallesian age. The two preserved crania represent a medium-sized taxon with short, conical horn cores, a flat cranial roof (consisting of the posterior part of the frontals, parietal and occipital), thick and porous frontals and pneumatized short parietals, an extremely thick basioccipital with voluminous posterior tuberosities and accessory articular facets for the atlas. The specialized atlanto-occipital joint recalls Pleistocene and extant ovibovines, but the braincase structure as a whole and the horn core features closely match Late Miocene ovibovine-like taxa, especially Plesiaddax and even more Urmiatherium. Nevertheless, the Kassandra bovid differs from representatives of both genera in the simpler horn core morphology and external brain anatomy. Urmiatherium is known to appear first in China and Iran at about 7.8 Ma, whereas its westernmost appearance on Samos Island (Greece) is dated much later. The presence of Urmiatherium kassandriensis sp. nov. in N. Greece suggests a farther west and earlier (Vallesian at least) first appearance of the genus. This would justify a basic geographic and phylogenetic split of Urmiatherium into two main Turolian lineages: a central-eastern Asian one leading to the sister species U. polaki and U. intermedium and a western one leading to U. rugosifrons.