A systematic revision of the Mactracea, Tellinacea and Myacea (Mactra isabelleana, Raeta plicatella, Macoma uruguayensis, Abra aequalis, Tagelus plebeius, Corbula patagonicaandErodona mactroides) recorded from marine taphocoenoses (Las Escobas Formation; + 4.5–2.5 m above m.s.l., mid-Holocene transgression, c.7,000–2,50014C ybp) distributed along 400 km in the coastal area of Buenos Aires Province (Argentina) has been undertaken. This has yielded important palaeoecological and palaeobiogeographical data with respect to the palaeonvironmental reconstruction of the area in relation to sea-level changes, especially since c.7,000 ybp. These data provide new evidence of the strong influence that sea-level fluctuations and climatic change have exerted on the molluscan fauna. This fauna varied in composition and distribution primarily due to progressively decreasing salinity (due to falling sea-level trend after c.7,000–6,500 ybp) and declining temperature (caused by post-hypsithermal cooling after c.4,000 ybp) affecting the bonaerensian coastal area (Río de La Plata and Argentine Sea in the western South Atlantic) during the Holocene.