Pseudo-Sarmatian mollusc assemblages from the Early Messinian of Sicily (Italy)

The coastal cliff at Faro Santa Croce at Augusta (SE Sicily) is formed by Late Miocene limestones of the Monte Carrubba Formation. A striking feature of this outcrop is the occurrence of dense venerid-cardiid coquinas in association with cross-bedded oolite deposits. Fuchs (1874) was the first to visit the locality and compared the assemblages with those of the Volhynian and Bessarabian (Upper Serravallian and Lower Tortonian) of Russia (now Ukraine and Moldova), which are also characterised by oolites and venerid-mactrid-cardiid coquinas. Due to very similar morphologies represented in the Sicilian assemblages, he concluded that the molluscs are conspecific with those from the Paratethyan assemblages. Consequently, the list given by Fuchs (1874) comprised 55% of Sarmatian Paratethyan species. Later workers reproduced the influential identifications, including even endemic Paratethyan/Euxinian cardiid genera such as Obsoletiforma, Didacna and Euxinicardium, although the Messinian age of these deposits was already known. Consequently, the oolite-associated assemblages in the Monte Carrubba Formation were interpreted as evidence for reduced (mesohaline) salinity. Thus, the existing literature suggested a close (on the species level) Mediterranean-Paratethyan faunistic relation between 6.4 to 5.96 Ma comparable to the alleged Paratethyan influence during the Late Messinian Lago Mare phase. This, however, is in striking contrast to the age of the endemic Sarmatian assemblages, which developed roughly between 12 and 10 Ma. After revising the fauna, not a single Paratethyan Sarmatian species was detected in the assemblage. Instead, all species represent typical Mediterranean species of which 20% are restricted to the Late Miocene. No indications for lowered salinities during the Messinian interval at Faro Santa Croce can be documented. Alleged brackish water taxa, such as Didacna and Euxinicardium, turned out to represent normal marine species of Acanthocardia. This revision is a perfect example to document the importance of a proper taxonomy to avoid severe misinterpretations concerning paleogeography and biogeography, which tend to become “common knowledge” by uncritical repetition.