INVESTIGADORES
TOMASSINI Rodrigo Leandro
congresos y reuniones científicas
Título:
The outstanding Río Chalía (= Sehuén) outcrops of the Santa Cruz formation (early Miocene, Burdigalian) and its fossil vertebrate content
Autor/es:
VIZCAÍNO, SERGIO; BARGO, SUSANA; CUITIÑO, JOSÉ IGNACIO; PÉREZ, MARÍA; MUÑÓZ, NAHUEL; ARAMENDÍA, INÉS; TOMASSINI, RODRIGO; KAY, RICHARD
Lugar:
Puerto Madryn (Chubut)
Reunión:
Encuentro; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2018
Institución organizadora:
CENPAT-CONICET
Resumen:
The continental Early Miocene Santa Cruz Formation (SCF) is widely distributed in southern Patagonia. It fossil mammals comprise the basis of the Santacrucian Land Mammal Age. Fossil prospecting of exposures along the southern escarpment of Río Chalía have been neglected until now. They represent the greatest known aerial exposure and sedimentary thickness of all the SCF. The maximum thickness measured in a single locality is 295 m. The SFC in Río Chalía is mostly composed of fine-grained sediments (clay, silt, fine sand) with abundant intermingled pyroclastic material, accumulated in a low-gradient fluvial system. New preliminary U-Pb tuff dates permit us to correlate the Río Chalía SCF levels with those of the Río Santa Cruz and coastal localities. We collected some 480 lots and 10 individual specimens, including fish, frog, squamate, bird and mammal remains. 64% of the fossils come from horizons near the base of the section (between 170?240 masl), 27% from middle levels (250?300 masl), and 9% from near the top (350?400 masl). Fossils from Río Chalía are consistent with a Santacrucian Age (e.g., Cochlops muricatus, Nesodon imbricatus, Diadiaphorus majusculus, Neoremys australis, Perimys spp., etc.) and no taxa typical of other ages (e.g., Notohippidian, Colloncuran) have been recorded so far. They will help to address gaps in our understanding of the local response of vertebrate faunas to regional Andean uplift and its climatic effects and the worldwide climate warming during the mid-Miocene climate optimum and just prior to the global plunge in temperatures after about 14.75 Ma.