TOMASSINI Rodrigo Leandro
congresos y reuniones científicas
Paleohistology, mineralogy and geochemistry of Pliocene mammals from the Monte Hermoso Formation (Argentina): Paedotherium Bonaerense (Notoungulata, Hegetotheriidae) as a case study
TOMASSINI, RODRIGO; MONTALVO, CLAUDIA; MANERA, TERESA; VISCONTI, GRACIELA
Congreso; 4th International Palaeontological Congress; 2014
IANIGLA-CONICET. International Palaeontological Association
The mammalian faunas from the South American Neogene are generally analyzed from a systematic and/or biochronostratigraphic perspective, however the taphonomic studies are still scarce. In this contribution we describe and analyze mineralogical, geochemical and paleohistological characteristics present in hemimandibles of the micromammal Paedotherium bonaerense (Mammalia, Notoungulata, Hegetotheriidae). Remains were recovered from the floodplain deposits of Monte Hermoso Formation (early Pliocene), at Farola Monte Hermoso locality (Buenos Aires Province, Argentina). 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 where they were buried. Original bone microstructure shows good preservation, only affected by permineralization and microfissures. Osteons, vascular canals, osteocyte lacunae and canaliculi were recognized. 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 detailed taphonomic analysis increases the knowledge of the South American Neogene faunal communities from a novel perspective, different from the one traditionally considered and, on the other hand, also establishes a framework for the analysis of other micromammal assemblages with similar characteristics.