Miocene? paleoenviroments of Ituzaingó Formation (Argentina northeast) from fossil wood proxies

BREA, M.; PRADO, D.; FRANCO, M J.; PROTTI, L-.; MARTÍNEZ MARTÍNEZ, C.

Simposio; I Virtual Meeting of Systematics, Biogeography and Evolution (SBE); 2020

The term Ituzaingó Formation (De Alba 1953) refers to the continental sediments of fluvial origin developed after the regressive phases of the ?Paranense Sea?,. Its outcrops are widely distributed along the cliffs on the left margin of the Paraná River, from the north of Corrientes Province (c. 27°S, 56°W) to the south near Paraná City in Entre Ríos Province (c. 31°S, 60°W), Argentina, as well as along various tributary rivers and streams. We analyzed more than 40 different fossil wood taxa from the Ituzaingó Formation and recognized gymnosperm, palms and 10 angiosperm families.The materials came from ten fossiliferous localities in Entre Ríos Province, Argentina. Palaeoclimatic data was determined based on physiognomic anatomical features using multivariate anatomical analyses. These results were compared with other proxies, including Carlquist´s index and Nearest Living Relatives (NLRs). The comparison with the living relative suggests that the Ituzaingó Formation flora has elements linked with Chaco, riparian, and components of Seasonally Dry Tropical Forest (SDTF). Quantitative estimation of temperature and precipitation indicates Tropical-Subtropical Climate, with annual precipitation probably around 1300 mm and a marked and long dry season. The anatomical features of the fossil wood analyzed show a tendency to xerophytic and seasonal vegetation because of the character indicators. Quantitative estimation of temperature and precipitation could indicate a Tropical Seasonal Forest. Ituzaingó paleoflora is characterized by the presence of an SDTF component and supporting the idea that SDTFs were more widespread in the past. The Vulnerability Index (V) and Mesomorphy (M) indicate a dry climate with some species adapted to wet environments.