Decapod crustaceans from the Oligocene of the Ligure Piemontese Basin, northern Italy

Abstract

Lithologically, the decapod-bearing levels of Rupelian (Oligocene) age in the Ligure Piemontese Basin, are characterized by an alternation of greyish blue marls with nodular elements and silt-rich, occasionally sandy, marls. The fossil studied for the present note have been collected mainly from pebbles or nodules which were eroded out of the higher levels exposed of this sedimentary complex, referred to as the ‘Formazione di Molare’. These levels overli the ‘Formazioni continentali delle Brecce di Costa Cravara e Pianfolco’, studied by Charrier et al. (1964) and dated as Early Rupelian. The levels yielding brachyuran fossils were attributed by Allasinaz (1987) to the transition between the ‘Formazione di Molare’ and the overlying ‘Marne di Rigoroso’, and by Bianco (1985) and Balossino & Bianco (1986) to the biozone of the foraminifer Operculina complanata (Defrance).