TOMASSINI Rodrigo Leandro
Mineralogy, geochemistry and paleohistology of Pliocene mammals from the Monte Hermoso Formation (Argentina). Paedotherium bonaerense (Notoungulata, Hegetotheriidae) as case study
TOMASSINI, RODRIGO; MONTALVO, CLAUDIA; MANERA, TERESA; VISCONTI, GRACIELA
ASOCIACION PALEONTOLOGICA ARGENTINA
Lugar: Buenos Aires; Año: 2014 vol. 51 p. 385 - 395
Mineralogical, geochemical and paleohistological characteristics present in hemimandibles of Paedotherium bonaerense (Mammalia, Notoungulata, Hegetotheriidae) are described and analyzed. Remains were recovered from the floodplain deposits of the Monte Hermoso Formation (early Pliocene). Francolite is the main mineral component in all hemimandibles, evidencing compositional changes in the internal crystalline structure during fossil-diagenesis. Similarities in the chemical composition between fossils and host rock would indicate that the enrichment of the remains with new elements was due to a direct exchange with the sediments in which they were buried. Original bone microstructure shows good preservation, only affected by permineralization and microfissures. Manganese and iron oxides are the most abundant minerals infilling microstructural features and microfissures. The dark color identified on the outer surface of some remains is related to manganese oxides precipitation. The obtained results allowed us to establish the processes that affected the remains both before and after the burial, and interpret the different taphonomic histories. This work provides new information on a problematic scarcely considered in the study of the vertebrates communities from the South American Neogene and, on the other hand, also establishes a framework for the analysis of assemblages with similar characteristics.