The biological impact of the Messinian Salinity Crisis (MSC) and its bearing on the Pliocene Mediterranean marine molluscan fauna has been analyzed on the basis of the biogeographic and stratigraphic distribution of the taxa of 16 early Messinian outcrops. The extinction of the last paleoendemic Proto-Mediterranean taxa is historically significant but it appears numerically less important than the extinction of the Tortonian and Messinian neoendemic taxa. The available data suggest that the MSC caused a regional mass disappearance but only a limited number of extinctions. It is also emphasized that the Late Pliocene (Monegatti et al., 2002) extinctions were far heavier than those caused by the MSC. We suggest that the greatest Messinian extinctions were triggered, during the salinity crisis, in the Atlantic “sanctuary” by the Messinian glacial events TG22, TG20, TG14 and TG12, of Shackleton et al. (1994), dated between 5.79 and 5.55 Ma by Krijgsman et al. (2004). A comparison between the Mediterranean Messinian and the Redonian molluscan fauna was also carried out. Finally, the possible latitudinal stability of the climatic thresholds, despite the shifting of the climatic zones throughout the Neogene along the European coast, is pointed out.