PLEISTOCENE LANDSNAILS FROM THE COASTAL PLAIN OF ISRAEL

ABSTRACT

The landsnail fauna of five fossil layers from two sites in Israel's Coastal Plain, Shefayyim and Netanya, was analyzed. The layers date from about 45,000 years ago to Subrecent. Four species were found: The Jaminia ovularis-sulcidens complex, Trochoidea (Xerocrassa) davidiana, Xeropicta vestalis and Monacha syriaca—all present in the Coastal Plain today. Remarkable is the absence from all fossil layers of Theba pisana, the landsnail most abundant today in the Coastal Plain. As T. pisana has also not been found in any other Pleistocene sites in Israel, it is suggested that this species was introduced into Israel during historic times. Thereafter, competition with Xeropicta vestalis was inevitable, as both occupy a similar habitat. Rich morph diversity occurs in recent Xeropicta as compared with the fossil samples; it is tempting to suggest that this outburst of diversity is related to some ecological displacement into which Xeropicta was perhaps forced, due to competition with Theba. Within Jaminia, the alternating frequencies of ovularis and of sulcidens suggest that about 40,000–50,000 years ago, presumably due to regression of the sea, Shefayyim was an inland plain. About 35,000–40,000 years ago, presumably due to marine transgression, it became a coastal sand dune as it is nowadays.