First fossil remains of the extant colubrid Zamenis situla (Linnaeus, 1758) (Serpentes) from the island of Crete, Greece

We here provide the first description of fossil remains of the colubrid snake cf. Zamenis situla from Crete, Greece, originating from the Late Pleistocene of the Rethymnon fissure. Although Zamenis situla (Linnaeus, 1758) is a widespread snake species in Greece, including Crete, its fossil record in the area has thus far been restricted to Middle Pleistocene material from Tourkobounia 2, near Athens, which also represents the sole confirmed fossil occurrence of the species. We provide a comparison of the fossil specimens to other extant Cretan snakes, and highlight key morphological features that distinguish it from other colubrids. This fossil material provides further support to recent molecular studies suggesting long-term presence of Z. situla on the island. However, due to the scarcity of the fossil record, it remains unclear whether Z. situla inhabited Crete continuously since the Late Pleistocene or was instead reintroduced to it later on. Finally, we investigate skeletal material of Z. situla, providing anatomical descriptions of key cranial and vertebral structures, which could facilitate in future fossil identifications and comparisons among colubrid snakes.