We hereby describe fish material collected from the lowermost Upper Triassic continental levels of the Chañares Formation (Campo de Córdoba and El Torcido localities). The specimens consist of a fragmentary dermal skull roof bone assigned to Mawsoniidae based on its ornamentation marked by coarse ridges and wide shallow grooves, plus patches of ganoid scales referred to cf. Pseudobeaconiidae based on the presence of an elevated central region in most of the scales. However, unlike that which is observed in pseudobeaconiids, these scales are characterized by an ornamentation pattern consisting of concentric and/or parallel ganoine ridges covering their surface. These scale patches, for which a brief taphonomic approach is hereby provided, are the first vertebrate fossil remains to be collected from the upper member of the Chañares Formation. The Mawsoniidae described herein represents the southernmost record of the family, being the first coelacanth from Argentina and the first Triassic mawsoniid from South America. Freshwater mawsoniid coelacanths established in Laurasia during the Late Triassic and the new Gondwanan record suggests that similar weather conditions (hot and arid but with seasonal precipitations) may have affected north and south Pangea during this period.

Sauropod dinosaurs achieved the largest body sizes and the most elongate necks and tails of any terrestrial vertebrate. The elongate, cantilevered necks of sauropods comprised opisthocoelous vertebrae joined at concavo-convex joints. Opisthocoelous centra also occurred in the dorsal region of sauropods and procoelous centra in the tails of certain lineages. Concavo-convex intercentral joints have been hypothesized to increase the flexibility of the vertebral column or to stabilize intervertebral joints against shear stresses. Using Alligator as an extant analog, condyle convexity and range of motion were measured at every intervertebral joint in an individual, with the latter measured in situ. Results reveal that convexity is greatest in the alligator presacral column where flexibility is low; amphiplatyan vertebrae occur in the distal caudal region where flexibility is highest. The negative relationship between convexity and flexibility is not significant, indicating that flexibility is independent of centrum articular morphology. Convexity is greatest in regions in which high shear stresses are predicted to result from terrestrial locomotion and tail flexion. The evolution of opisthocoelous cervical vertebrae in early sauropods likely strengthened the long and massive neck against catastrophic dislocations without compromising joint mobility. The stabilization provided by dorsal opisthocoely and caudal procoely may relate to clade-specific specializations such as the “whiplash” tails of flagellicaudatans and the “wide-gauge” limb stance in titanosaurs. The study of opisthocoely and procoely provides a means to understand the loading regimes of the vertebral column in sauropods and other vertebrates, with implications for the behavior and ecology of fossil taxa.

The debate regarding a possible marine influence during the middle—late Miocene in the Loja, Malacatos-Vilcabamba and Catamayo-Gonzanamá Basins (southern Ecuador) continues. To shed light on this controversy, we present a detailed stratigraphic and micropaleontological (benthic foraminifers and ostracods) study of selected sections from these basins. The facies associations, together with the presence of several benthic foraminifer species from marginal marine and open-water environments and ostracod genera resistant to high salinity changes, verify a marine water influence and sporadic marginal marine conditions in this area during certain periods of the middle—late Miocene. Additionally, six new ostracod species are hereby described: Heterocypris ballentae, Cyprideis lojaensis, Cyprideis petersonae, Cyprideis pachamama, Cyprideis tumi and Cyprideis amaru.

Three shallow lakes from the southeastern pampas, which are different in their physicochemical characteristics, were studied with the aim of comparing live/dead fidelity and preservation of mollusk shells. The studied lakes were Las Mostazas, Los Carpinchos and Nahuel Rucá, which proved different in terms of their specific richness, abundance, compositional fidelity and taphonomic alteration. The lake that presented the higher values of conductivity (3.34±0.72), hardness (286±83 mgl^-1) and carbonates saturation index (SI_calcite;= 1.95±0.21) was the one for which lower specific richness in living assemblages was recorded and differences in richness and diversity between the living and the dead assemblages became apparent. It was also the lake where the number of species was higher in death assemblages (R= 5) than in living communities (R= 2). Such characteristics suggest a higher residence time in the taphonomically active zone. On the other hand, the lakes featuring lower values of the same characteristics (conductivity= 2.2±1.2; 0.8±0.5; hardness= 157±55; 250±127 mgl^-1; saturation index of calcite= 0.35±0.15; 0.43 0.36, for LC and NR respectively) presented a higher species richness, lower numbers of species in death assemblages (R= 8) than in living communities (R= 10) and taphonomic attributes that suggested recently dead and deposited individuals. All these results indicate that water conditions in these lakes result in the decrease of the preservation of carbonate remains in comparison with the previously mentioned lake. Even though the lakes are located close to each other and are of similar shape and depth, such differences in water characteristics may be affecting shell preservation.

New plant remains from the upper section of the Paso Flores Formation, at the Cañadón de Pancho locality, western area of the Collón Curá River, Neuquén Province, Argentina, are herein described and illustrated. These are: Lutanthus ornatus, Rissikistrobus plenus, Rissikistrobus reductus, Rissikia media, Umkomasia sp., Sphenobaiera argentinae, Pseudoctenis spatulata, Taeniopteris crassinervis and Yabeiella brackebuschiana. Additionally, Baiera triassica, in replacement of the homonymous species previously identified in Argentina as Baiera taeniata, Ginkgo taeniata and Sphenobaiera taeniata, is herein described. Furthermore, species previously described for other localities in the Paso Flores Formation are recorded for the first time for the Quemquemtreu area of the Cañadón Pancho locality. These species are: Asterotheca rigbyana, Marattiopsis muensteri, Cladophlebis kurtzii, C. indica, Dictyophyllum (Dictyophyllum) tenuifolium, Goeppertella stipanicicii, Dicroidium incisum, D. odontopteroides, D. lancifolium, Pachydermophyllum praecordillerae, Heidiphyllum elongatum, Baiera furcata, Sphenobaiera robusta, Pseudoctenis carteriana and P. falconeriana. The Voltziales male cone Lutanthus herein described from the Paso Flores Formation represents its second record for the Gondwana realm while the Podocarpaceae female cone Rissikistrobus is hereby reported for the first time from Triassic strata of Argentina and constitutes its third record for Gondwana. Comparisons with the plant diversity recorded from other localities of the Paso Flores Formation throughout the Neuquén Province are analyzed. The Cañadón de Pancho microflora assemblages suggest a Late Triassic (Latest Norian= Rhaetian) age and therefore the fossil flora is the youngest recorded from Argentinian Triassic basins to date.