Comparative Taphonomy of Mollusk Assemblages in Quaternary Freshwater Sequences from the Salado River Basin, Buenos Aires

Abstract. From the analysis of the taphonomic attributes of the specimens of Heleobia parchappii found in fluvial and paleolacustrine sequences of the lower basin of the Salado River, the surface alteration of their shells was comparatively studied in order to assess the differences between both environments. The main results that were obtained by means of Non-Metric Multidimensional Scaling (NMDS) and analysis of similarity (ANOSIM) tests (R=0.31, p<0.01) enabled the recognition and statistical differentiation of both groups of samples. The taphonomic characteristics presented by those that were recovered from the paleolacustrine environment are more similar to each other, whereas those from the fluvial environment showed greater dispersion. Through the similarity percentage (SIMPER) analysis we could determine that the variables of discoloration and dissolution were the most important features to differentiate both groups, and that the values of the indexes (Total Taphonomic Grades) were always higher i...