The distribution of the Tumdae in the Pliocene of Catalonia (NE Spain) is heterogeneous. It appears to be determined to a greater extent by the particular autoecological traits of each species than by more general environmental factors.
The area formed by the Pla de Barcelona and the Baix Llobregat may be regarded as a bio-geographical unit due to tunid species, which do not occur in other basins. The tunid distribution in the Alt Emporda basin manifests a high degree of environmental diversity among the different outcrops of the area, thus confirming the earlier provided taphonomic and biogeographic data. Species of the Turridae from Poble de Siurana (Alt Emporda) are also present in different parts of the Pla de Barcelona and Baix Llobregat areas. This indicates the existence of similar ecological enclaves in both basins, within a quite different general context.

Key words: paleoecology, paleobiogeography, Mollusca, Turridae, Pliocene, N.E. Spain (Catalonia).