INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Post- Permian tetrapod record in the Ischigualasto-Villa Unión Basin (Talampaya and Tarjados formations, NW Argentina)
MANCUSO, ADRIANA CECILIA; SCHULTZ, CESAR; KRAPOVICKAS, VERÓNICA; DOMNANOVICH, NADIA; LEARDI, JUAN MARTÍN; GAETANO, LEANDRO
Congreso; X Congreso Argentino de Paleontología y Bioestratigrafía; 2010
Talampaya and Tarjados formations correspond to the initial stages of Ischigualasto-Villa Unión Basin filling, and record the oldest post-Permian events in the region. The sequence consists of red beds deposited essentially by ephemeral alluvial and fluvial systems, and overlay in discordance a Permian unit (Patquía =La Colina Formation). Until present contribution, only a manus-pes pair track of a probable basal synapsid was reported from the Talampaya Formation. From Tarjados Formation, fragmentary skeletal remains of therapsid dicynodont were the only mention of tetraopods. Here, we disclose new material found, in recent field work, at the upper member of the Tarjados Formation, from the equivalent levels where dicynodont remains were previously found. New material includes likely tetrapod footprints in transversal section associated in the same levels with large burrows. Their morphology and dimensions are comparable with burrows related to the activity of small synapsids, probably therapsids. In addition, a vertebra from a medium-sized archosaur (approx. 3cm long and 4 cm high) was collected. The new record allows us to identify a more diverse tetrapod fauna present inside post-Permian interval from this study area. Thus, during the initial stage of basin filling, as part of the beginning of the post-Permian recovery, two completely different groups of tetrapods were already present, archosaurs and different groups of synapsids. In general, the Talampaya-Tarjados association (basal archosaurs and therapsids) is very similar to that recorded in the sequences form the Early Triassic of South Africa and the Middle Triassic of Brazil.