Autochthonous and allochthonous species in some mixed fossil assemblages, paleoenvironments

Relationships between autochthonous and allochthonous species in different death assemblages of shelf environment, both recent and fossil, are discussed on the grounds of their relative abundances. The percentages, plotted against the sedimentary features (grain size distribution primarily) of the biotopes, exhibit significant variations which seem to be useful in the reconstruction of some physical characters of the paleoenvironments, like depth, wave motion and bottom currents. -English summary