Serpulid opercula (Annelida: Polychaeta) from the Upper Eocene of Possagno, NE Italy: taxonomy, taphonomy and palaeobiological significance

A relatively rich assemblage of serpulid opercula (Polychaeta) is recognized, for the first time in Italy, in the Upper Eocene strata of the Possagno Marl exposed in the southern Alps (Province of Treviso, NE Italy). The studied material comprises for species referable to the genus Pyrgopolon De MONTFORT, 1808. Of these, the new species Pyrgopolon (Pyrgopolon) tubula sp. n. is also present in the lower and middle Eocene deposits of north-western Europe, whereas P. (P.) trochoides (NYST, 1845) ranges from the middle Eocene to early Oligocene. The second new species, Pyrgopolon cunialense sp.n., is tentatively ascribed to the subgenus Turbinia MICHELIN, 1845. A common or even a mass, occurrence of Pyrgopolon opercula in some Eocene/Oligocene sequences of western Europe is discussed. It is suggested that such an "opercular bloom" may have resulted from ether taphonomic (selective transport and fossilization) or biologic (mass-shedding of opercula) factors, or a combination of both