PALEOECOLOGÍA DE LA FORMACIÓN SANTA CRUZ (MIOCENO INFERIOR) EN EL EXTREMO SUDESTE DE LA PATAGONIA

Abstract

"The Santa Cruz Formation cointains one of the most di verse and rich vertebrate fossil assemblages in South America. Palaeoecological interpretation of this unit is based on the analysis of 22 fossiliferous horizons (20 of which include specimens identifiable at specific level, collectively including representatives 60 species of 44 genera, 25 families and 13 orders). Mammals are the most commonly recorded vertebrates, although amphibians and birds are also present. Main trends from base to top of sequence are: 1) decrease of taxonomic diversity; 2) increase of number of species with euhypsodont teeth, and decrease of those with brachyodont dentition; 3) decrease of number of species at the largest and smallest body sizes; 4) glyptodontids and toxodontids become more diverse; 5) reduction of megatheroideid average body size; 6) protheroteid diversity decreases. This suggests that during the deposition of the Estancia La Costa Member, the climate deteriorated and became less humid; thus, the paleoenvironmental conditions, and consequently the fauna, changed."