THE SCHMELZMUSTER OF THE INCISORS IN GLIROIDEA (GLIRIDAE AND SELEVINIIDAE, RODENTIA, MAMMALIA) AND THEIR SYSTEMATIC SIGNIFICANCE

Investigated is the enamel ultrastructure in incisors of about 20 foss il and extant gliroid genera and subgenera. According to the schmelzmu ster of the lower incisor three groups can clearly be differentiated. Group 1 contains Myoxus and Glirulus having mainly transversly orienta ted Hunter-Schreger bands (HSB) and a thick prismless external enamel (PLEX). The schmelzmuster of group 2 is more derived in having diagona lly orientated HSB. This group contains Dryomys, Eliomys with its seve ral fossil subgenera from the Mediterranean islands, and Leithia, Micr odyromys, and ''Peridyromys'' brailloni. Group 3 with the most derived schmelzmuster characterized by longitudinally arranged HSB covers Gra phiurus, Myomimus, Miodyromys, Muscardinus, Selevinia, and Plioselevin ia. This schmelzmuster is represented at least since the early Middle Miocene (MN 4) and indicates the early separation of these groups. Thi s allows plenty of time for further differentiation in other character s. The probability of parallelism has to be rejected according to a su rvey of other rodents with rearranged HSB. Group 3 is tying together t he Seleviniidae with some but not all Gliridae. Therefore, the Selevin iidae are not a sister group of the Gliridae in general and should be incorporated into the Gliridae. The grouping according to the schmelzm uster contradicts to some degree the systematic arrangement according to molar morphology (DAAMS 1981) but corresponds widely with the analy sis of soft parts as done by KRATOCHVIL (1973). This indicates the imp ortance of the enamel analysis.