Martes wenzensis Stach, 1959 within the early history of the genus Martes Pinel, 1792

Martes wenzensis Stach, 1959 is the only European Pliocene marten and possible ancestor of an evolutionary lineage leading through Martes vetus Kretzoi, 1942 to Martes martes Linnæus, 1758. Its occurrence ranged between c. 3.6–2.2 Ma and its presence is recorded herein from four sites: three Polish and one Bulgarian (Varshets). The oldest record from Węże 1, dated to 3.6–3.2 Ma, is also the most abundant and the type locality for this species. Only isolated teeth came from two other Polish sites, Węże 2 and Rębielice Królewskie 1A, dated to 2.5–2.2 Ma. The visceocranium from Varshets (c. 2.5 Ma) shows intermediate features between the type specimen from Węże 1 and the Early Pleistocene M. vetus, its possible descendant. The palaeontological records corroborate well with molecular data. The comparison of marten crania from Węże 1 and Varshets shows decrease in size and massiveness of teeth during the evolution of the species. Martes wenzensisshows an admixture of features inherent to M. vetus, M. martes, and M. foina Erxleben, 1777. The species resembles more M. vetus and M. martes than M. foina. It is described as a large, robust marten, with a flat forehead, short and broad viscerocranium, wide snout, robust canines, elongated and narrow premolars and enlarged carnassials.