THE FIRST PRE-QUATERNARY FOSSIL RECORD OF THE CLADE MABUYIDAE WITH A COMMENT ON THE ENCLOSURE OF THE MECKELIAN CANAL IN SKINKS

We here describe the first Neogene record of the squamate Glade Mabuyidae. Although this Glade has a cosmopolitan distribution today, no pre-Quaternary fossil record of these reptiles has so far been documented. The material comes from the locality Solnechnodolsk (Russia) and is dated to the late Miocene (MN 13). Although it comprises only jaw elements, it constitutes the first evidence of the occurrence of fossil skinks around the area of the Black Sea. The material is identical to Heremites vittatus, showing the existence of this lineage as early as the late Miocene. Thus, it may be used as a potential calibration point for further studies. The comparative anatomy of the structures of lower jaw in selected scincomorph taxa with a special reference to Mabuya group is presented. The closure of the Meckelian canal is the condition at the basal node of the Glade Sphenomorphidae + Eugongylidae + Egerniidae + Mabuyidea, whereas the closed canal in A co ntias (Acontidae) evolved independently. However, Sphenomorphidae (Asymblepharus and Scincella) Eugongylidae (Ablepharus) retain a large anterior opening of the Meckelian canal, whereas only a small opening characterizes the basal node of Egerniidae and Mabuyidae, except for H. vittatus and H. septemtaeniatus. The closure of the Meckelian canal in these two taxa is less well developed in comparison with other mabuyid skinks. Thus, a heterochronic pedomorphic process might have played a role in the evolution of these skinks. The Meckelian canal condition supports the monophyly of Heremites.