TAPHONOMIC DIFFERENCES IN MOLLUSCAN SHELL PRESERVATION IN FRESHWATER ENVIRONMENTS FROM THE SOUTHEASTERN PAMPAS, ARGENTINA

BERNAVA GUSTAVO VICENTE; TIETZE, ELEONOR; DE FRANCESCO, CLAUDIO G.

PALAIOS

SEPM-SOC SEDIMENTARY GEOLOGY

Lugar: Lawrence; Año: 2014

0883-1351

ABSTRACT: Actualistic studies in freshwater environments are scarce, limiting the interpretation of paleoenvironmentalinformation obtained from the fossil record. The objectives of this study are to assess the taphonomic factors that affect theformation of mollusk assemblages in freshwater environments of the pampean region. Twenty sites were analyzed at regional(La Brava and Nahuel Ruca´) and environmental (lentic and lotic) scales. Shells were primarily affected by loss of proteinaceousparts, fragmentation, and fine-scale surface alteration. Taphonomic differences were observed in dead shell condition related to EN ESTE ARTICULO SE ME AGRADECE LA COLABORACIONenvironmental conditions and faunistic composition (thin-/thick-shelled species proportion) in spite of the dominance of onespecies, Heleobia parchappii. The differences were related to extrinsic (environmental) factors probably due to differentialinfluence of organic decay, microbioerosion, and/or dissolution. However, intrinsic factors, especially those related todifferential preservation and input rates of thin-/thick-shelled species, may be also biasing the compositional fidelity of deathassemblages. Although the degree of taphonomic alteration across locales and environments was evident, all molluskassemblages still preserved their biological signature from the precursor communities.