The early evolution of Ornithodira —the clade including pterosaurs and dinosaurs— is poorly known. Until a decade ago, the basal radiation of Dinosauromorpha, the clade including dinosaurs and birds, was poorly understood because of the poor fossil record restricted to specimens known from the Ladinian Chañares Formation in Argentina. Over the last years the discovery of several non-dinosaurian dinosauromorphs dramatically expanded this record and also demonstrated that this group —previously restricted to de Middle Triassic— survived at least well into the Norian. Although Norian non-dinosaurian dinosauromorphs have been reported from several regions around the world, the only known Norian non-dinosauriform dinosauromorphs —Dromomeron romeri Irmis, Nesbitt, Padian, Smith, Turner, Woody, and Downs and Dromomeron gregorii Nesbitt, Irmis, Parker, Smith, Turner, and Rowe— come from North America. We report here the first record from the Southern Hemisphere of a non-dinosauriform dinosauromorph, Dromomeron gigas sp. nov., from the Norian Quebrada del Barro Formation, northwestern Argentina. A phylogenetic analysis recovers Dromomeron gigas nested into the monophyletic group Lagerpetidae, and as the sister taxon to Dromomeron romeri. The inclusion of D. gigas within Lagerpetidae suggests that body size increased in this lineage over time, as was previously demonstrated for Dinosauriformes as a whole, and that lagerpetids reached a larger size than previously thought. Finally, the new finding provides new information on the basal radiation of Dinosauromorpha constituting the first record of a Norian association of dinosaurs with non-dinosauriform dinosauromorphs outside North America.

Peirosaurids are a group of Cretaceous continental crocodyliforms from Gondwana. Two species are known from the Neuquén Group in Argentina: Lomasuchus palpebrosus (Portezuelo Formation, late Turonian—early Coniacian) and Gasparinisuchus peirosauroides (Bajo de la Carpa and Anacleto formations, Santonian and early Campanian, respectively). Here, we describe the first peirosaurid from the Cerro Lisandro Formation, Bayomesasuchus hernandezi gen. et sp. nov. The material corresponds to a fragmentary skull and mandible. Although fragmentary, this is the most complete crocodyliform specimen recorded for the Cerro Lisandro Formation. In a phylogenetic analysis Bayomesasuchus is depicted in a polytomy together with South American peirosaurids and the African form Hamadasuchus rebouli.

The fossil remains from La Barda locality are part of the Paso del Sapo fauna (Chubut, Argentina), the main early Eocene mammal assemblage from west-central Patagonia. Until now, mammals from La Barda had only been recognized by isolated teeth and osteoderms. In this study, postcranial Litopterna remains were identified and segregated into morphological groups, or morphotypes, and their sizes were correlated with litoptern teeth. Morphotype 1 is represented by one astragalus similar to those of post-Deseadan litopterns. Morphotype 2 groups more generalized tibiae, astragali and calcanei which are similar to basal Protolipternidae (e.g., Miguelsoria). The regression model was derived from a known sample of 62 extant and fossil mammals. A 99.7% confidence interval was used to accept or reject a possible relationship between postcranial and dental remains. Dental remains from La Barda have been referred to two species of Asmithwoodwardia (Protolipternidae?). The dental size of both species correlates well with morphotype 2. However, the largest, more derived morphotype 1 astragalus does not appear to be represented in the fauna by any dental remains. This brings to the table the importance of postcranial remains to the comprehension of the diversity of ancient faunas.

Diet and habitat were estimated, based on stable isotopes, for six species of proboscideans inhabiting the Americas during the Pleistocene. In North America, Mammuthus columbi (Elephantidae) was a mixed C₃/C₄ herbivore inhabiting open areas, while Mammut americanum (Mammutidae) fed exclusively on C₃ plants and preferred closed areas. In contrast, members of the family Gomphotheriidae showed a wide range of food preference and habitats. This is the case of Cuvieronius tropicus, a mixed-diet herbivore living in open areas. In South America, another gomphothere — Cuvieronius hyodon — inhabited open areas and had a C₃-plant diet similar to others from some Southern plains such as Stegomastodon platensis. On the other hand, S. waringi from tropical South America lived in open areas and had a C₃/C₄ mixed diet. The fact that gomphotheres had more flexible diet habits could explain why those animals were able to cross the Panamanian Isthmus, while mammoths and mastodons did not.

Actinocythereis imbeensis n. sp. is described from the early Miocene strata of the Pelotas Basin, the southernmost Brazilian marginal basin. The specimens were recovered from the base to the top of an offshore core composed of greenish-gray shale interpreted as part of a transgressive sequence. Morphological features and faunal composition indicate that the ostracods were autochthonous and lived in the photic zone.

Lakes are ideal sites to study environmental changes since they preserve climatic, anthropogenic, and volcanic signals in their sediments. Brazo Blest is one of the most important ramifications of Lake Nahuel Huapi and it is an interesting site to study climatic variations as it receives direct discharge of heavy suspended sediments loads from Tronador Glacier through the Frías River, as a result of the abrasion of the bedrock and runoff from the surrounding Valdivian Forest. A short sediment core from Brazo Blest was analyzed for chironomid and diatom assemblages and pigments in order to reconstruct environmental changes during the last 100 years in the basin under study. This multiproxy study also included geochemical and physical analyses and reveals changes in the productivity of the lake over time, showing a shift in the 1950s from autochthonous to allochthonous organic matter. This modification is related to the increase of precipitation and the consequent fluvial runoff from two catchments, Frías River and the Blest-Cántaros basin together with the effects ofrising temperatures, which affected Tronador Glacier. Further, it allows us to link volcanic eruptions to a decrease in species richness and number of chironomids and diatoms, as a consequence of reduced light intensities and food availability induced by the high content of suspended sediments in the water column. This study highlights the effectiveness of multiproxy analyses to reconstruct environmental changes.