411 GEODIVERSITAS • 2001 • 23 (3) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.mnhn.fr/publication/ Contribution to the study of Microstonyx: evidence from Bulgaria and the SE European populations Dimitris S. KOSTOPOULOS University of Thessaloniki, School of Geology, Dept. of Geology, 54006 Thessaloniki (Greece) dkostop@geo.auth.gr Nikolai SPASSOV National Museum of Natural History (NMNH), Bulgarian Academy of Sciences, 1 Tzar Osvoboditel Blvd., 1000 Sofia (Bulgaria) wild_fund@mbox.cit.bg Dimitar KOVACHEV Paleontological Museum of Assenovgrad, Branch of the NMNH Sofia (Bulgaria) Kostopoulos D. S., Spassov N. & Kovachev D. 2001. — Contribution to the study of Microstonyx: evidence from Bulgaria and the SE European populations. Geodiversitas 23 (3): 411-437. ABSTRACT The suid material from four Turolian localities (MN11-13) in Bulgaria has been studied and compared. All specimens belong to Microstonyx major (Gervais, 1848), a common faunal element of the late Miocene South-East European faunas. The Greek and Bulgarian fossil record allows several sugges- tions to be made, concerning metrical and morphological features of Microstonyx major, as well as the species-level taxonomic diversity. The elabo- ration and evaluation of several characters allow us to distinguish three groups of M. major, in the Balkan territory. The first group (MN11-12) represents a small sized form, probably related with the Maragha suid (MN11). The second group (MN12-13) includes the typical M. major erymanthius and the third one M. major major (MN13). The last two groups indicate relation bet- ween them, as well as with the latest Vallesian Microstonyx major from Nikiti (end of MN10). The first group of Microstonyx major from Perivolaki, Kerassia and Vathylakkos probably consists in new subspecies, characterized by small to medium sized toothrow, small third molar and relatively elonga- ted premolar row. The molar row reduces from the early to the middle Turolian representatives of the group. KEY WORDS Mammalia, Suidae, Microstonyx, late Miocene, Bulgaria, Greece, fossil species.