FOSSIL AVIFAUNA FROM THE SOPAS FORMATION (LATE PLEISTOCENE), URUGUAY: PALEOENVIRONMENTAL IMPLICATIONS

Carolina ACOSTA HOSPITALECHE ¹, Claudia TAMBUSSI ^1,3, Martín UBILLA ² y Daniel PEREA ²
1. Museo de La Plata, Paseo del Bosque s/no (1900) La Plata, Provincia de Buenos Aires, Argentina. 2. Paleontología, INGEPA, Facultad de Ciencias, Iguá 4225 (11400) Montevideo, Uruguay. 3. Departamento de Ciencias Biológicas, Universidad CAECE, Tte. Gral. Juan Domingo Perón 2933 (1198) Buenos Aires, Argentina.

Chloephaga picta and Cariama cristata were found at the Sopas Formation (Late Pleistocene) which constitute the first fossil records from Uruguay of both living species. Based on the analysis of climatic-environmentals variables (particularly annuals precipitations and hydric index), the possible paleoen-vironmental inferences derived from these species are restricted. The occurrence of Chloephaga picta indicates: 1) a seasonally climatic regime, and 2) that temperatures of January and July were probably lower than were previously reported for the same area in Late Pleistocene based on the fossil mammals. Its presence could have occurred as a response of rapid and short climatic changes in Late Pleistocene with drop of temperature, which is not revealed by the mammal record. As can be expected from fluvial environment time averaging could have affected the pattern. Cariama cristata is more eurioic than Chloephaga picta according to the climatic parameters analyzed and does not appear to be a climate indicative species. This species suggests open woodlands, savannas also hilly grasslands with nearby woods in a coincidentally way with the presence of mammals adapted to this habitats and recorded in the Sopas Formation in the same area. The topics of "disharmonious" Pleistocene faunas are addressed.