Taphonomic study of Pleistocene mammals from Playa del Barco site (Pehuen Co) Buenos Aires Province, Argentina. Results are presented of a comparative taphonomic study conducted on mammal remains from Playa del Barco, Buenos Aires Province, Argentina. Two bearing levels, belonging to a fluvial environment were recognized: one constituted mainly by conglomerates and the other by silty sandstones. The mammal remains collected belong to the orders Xenarthra, Notoungulata, Litopterna, Rodentia, Carnivora, Perissodactyla, Artiodactyla, and Proboscidea, all of them components of the typical Pleistocene megafauna. When taking into account the source level, variations in the taphonomic attributes of the analysed materials were observed. Remains from the conglomerate show evidence of having been rapidly buried and then reelaborated before their final deposition. Fossils from silty sandstones show signs of longer exposure to weather, more intensely subject to processes that took place before burial. Due to their characteristics they are interpreted as re-deposited remains. In both cases, processes related to mass transport are inferred. Nevertheless, the diversity in conservation status and taphonomic attributes would result from processes originated at each of the source levels. The lithostratigraphic, taxonomic, and taphonomic evidences do not allow relating these two levels to a unique event. Therefore, the fossils that they contain are interpreted as members of two different associations.

Evidence of the coexistence of hadrosaurine and lambeosaurine dinosaurs in the upper Maastrichtian of the Iberian Peninsula (Arén, Huesca, Spain). Many cranial and postcranial remains of hadrosaurid ornithopods from the upper Maastrichtian have been recovered in Arén (Huesca, Spain) in the sites Blasi 1–5. Three of these cranial remains, found at Blasi 1 (Arén Formation), and Blasi 4 and 5 (Conques Formation) are jugals and are the only jugals described from Western Europe. The jugals from Arén differ from those of Telmatosaurus transsylvanicus (Nopcsa, 1900) by being these more slender and presenting an anterior process isosceles-triangle-like. The jugals found at Arén are assigned provisionally to the subfamilies Hadrosaurinae (Blasi 5) and Lambeosaurinae (Blasi 1 and 4). The hadrosaurine jugal presents an asymmetrical anterior process along the maxilla-lacrimal contact and a wide jugal neck, while the jugals of lambeosaurines have an anterior process very wide dorsoventrally and symmetric, narrow jugal neck and maxillary process perpendicular to the antero-posterior axis of the jugal. The hadrosaurine from Arén represents the first mention of the subfamily in Europe and, together with the remains of lambeosaurines found in Europe, shows an active interaction with the migratory route existing then between Asia and North America. Remains found in Arén are essential in the knowledge of the phylogenetic relationships and the biogeography of this clade in Europe.

The surveyed microflora was recovered from six cores from the Tonono x-1 well in northwestern Argentina. Most of the studied interval corresponds to the Tonono Formation, i.e., the upper part to the Jollín Member and the basal part of the interval may be related to the Michicola Formation. The microflora totals 73 species represented by trilete spores (35 species), microplankton (30 species) including prasinophycean, acritarch and chlorophycean algae and chitinozoans (8 species). The stratigraphic distribution of these species allowed the definition of three associations. The palynoassemblage To1 (3946,5 – 3638,5 m) is characterized by species such as Grandispora douglastownense Mc Gregor, Dibolisporites eifeliensis (Lanninger) McGregor, Verrucosisporites sp. cf. V. loboziakii Marshall and Fletcher, Alpenachitina matogrossensis Burjack and Paris, Alpenachitina sp. cf. A. eisenacki Dunn and Miller and Ancyrochitina simplex Grahn, Bergamaschi and Pereira suggesting a late Eifelian to earliest Givetian age. Based on the presence of Geminospora lemurata Balme, Aneurospora greggsii (McGregor) Streel, Biharisporites parviornatus Richardson, Raistrickia aratra Allen and Leiotriletes balapucencis di Pasquo a Givetian age is proposed for palynoassemblage To2 (3367,35 – 3285 m). Palynoassemblage To3 (3073,2 – 3137,5 m) is predominantly composed of marine elements together with AOM. Few key species are recognized; however the presence of Acinosporites sp. cf. A. eumammillatus Loboziak, Streel and Burjack together with the chitinozoans Angochitina katzeri Grahn and Melo and Angochitina mourai Lange support an early Frasnian age. The distinctive increase of marine elements and AOM between To2 and To3 suggests that a maximum flooding event would have occurred there during this period.

Bivalve mollusks from the Triassic-Jurassic transition collected in eight localities in Asturias and the western Basque-Cantabrian Basin (Palencia province) are systematically revised. Preservation is poor at all localities. The dominant Rhaetian bivalves are Isocyprina concentrica (Moore) and Bakevellia (Bakevelloides) praecursor (Quenstedt). These species, together with Isocyprina cf. ewaldi (Bornemann), Pteromya cf. crowcombeia (Moore), Pseudoplacunopsis alpina (Winkler), and Modiolus? sp. (cf. minimus J. Sowerby), with a specimen of Arcestidae (?), belong to an assemblage similar to that found in the Westbury and Lilstock formations (Penarth Group) in the late Rhaetian of southern England. The most abundant Hettangian species is Isocyprina (Eotrapezium) germari (Dunker). Others are referred to Cuneigervillia rhombica (Cossmann), Sphaeriola? sp., Eomiodon? sp. and Pteromya cf. tatei (Richardson and Tutcher). All Hettangian shell beds examined are monotypic or have very low diversity, a biological indication that they may belong to a restricted marine environment, with high environmental stress levels. Even the more diverse assemblage (Pteromya-Cuneigervillia-Eomiodon) was probably also salinity controlled. The fauna analyzed here clearly belongs to the same facies and environment as those described from Aquitaine (France) and the Pyrenees and is different from coeval bivalve assemblages from other European Hettangian localities. The Triassic-Jurassic boundary cannot be precisely located at the studied sections on the basis of the bivalve faunas alone, but these indicate that the transition beds in Asturias were deposited in a marginal marine environment and the benthic fauna was dominated by shallow burrowing, suspensivorous bivalves.

The Pampa de Jones fossil site, a stratigraphically isolated roadcut near the northeastern shore of Nahuel Huapi Lake in Neuquén Province, Argentina, holds a rich fossil biota including a macroflora, a microflora, insects, and most famously, an ontogenetic series of pipid frogs. The site exposes tuffaceous mudstone and sandstone beds of probable lacustrine origin, considered to belong to the volcanic Huitrera Formation. However, there have been no reliable age constraints for the fossil assemblage. We undertook laser fusion analyses of sanidine and biotite crystals occurring in a tuff layer found 4.4 m above the main fossil horizon. Twenty-eight sanidine crystals yielded an ⁴⁰Ar/³⁹Ar age of 54.24 ± 0.45 Ma that is preferred over our biotite age of 53.64 ± 0.35 Ma. Pampa de Jones is thus the oldest well-dated Eocene fossil site in Patagonia, predating two other recently ⁴⁰Ar/³⁹Ar-dated sites: Laguna del Hunco (51.91 ± 0.22 Ma) and Río Pichileufú (47.46 ± 0.05 Ma). The improved age control makes possible a finer scale of evolutionary hypothesis testing and turnover analysis in the region. The age is concordant with the site's placement in the Huitrera Formation and a depositional origin related to Early Paleogene arc volcanism, and it correlates to an interval of significant climate fluctuations following the Paleocene-Eocene boundary.

Floian chitinozoans (Lower Ordovician) from Santa Victoria area, Cordillera Oriental, northwestern Argentina. Systematics. Floian chitinozoans from the Acoite Formation outcropping in the La Huerta and Grande creeks in the Santa Victoria area, northestern end of the Argentinian Cordillera Oriental, in Salta Province are studied. The chitinozoans are calibrated according to the previously established graptolite zonation in the La Huerta stratigraphic section which includes the Tetragraptus akzharensis (latest early Floian), “Baltograptus deflexus” (latest middle Floian) and Didymograptellus bifidus (late Floian) zones, and the associated acritarch assemblages. Despite the fact that species identifications of chitinozoans are usually difficult to carry out because of the scarce and poorly preserved specimens, a fairly diverse assemblage is observed in the studied levels. Seven genera and 15 species are recognized. Of these genera, Rhabdochitina, Velatachitina and Siphonochitina are described for the first time in Agentina. Ten species are described for the first time in Argentina. Lagenochitina sp. A and Eremochitina sp. A are local species exlusively recorded in northwestern Argentina.

Cranial Morphology in Sabertooth cats: allometry, function and phylogeny. Cranial morphology of felids and other sabre-toothed mammals has been studied using different approaches and methodologies. Recent studies used geometric morphometry analyses of the lateral view of the mandible and skull, and showed that “derived” sabretooth cats differ from recent felids by having a set of characters (e.g., small coronoid process, large chin and mastoid processes) associated with the presence of hypertrophied upper canines. In this study, we used geometric morphometrics to analyze the shape of the skull (dorsal and ventral views) and mandible (lateral view) in a large sample of extant felids (Felinae), extinct sabretooth felids (machairodontines), nimravids, creodonts, and the marsupial sabretooth Thylacosmilus Riggs. Results were congruent with those obtained using a lateral view of the skull: “primitive” sabretooth fell next to recent Felinae, but “derived” ones fell outside the range of Felinae, because they possessed larger mastoid process, larger and more procumbent upper incisors, and smaller temporal fossa, among other characters. However, sabretooth shared some features (e.g., large palate and canines) with larger Felinae (e.g., Panthera spp.), suggesting that they were able to hunt large mammals. The pattern of cranial variability of these groups is explained by ecological factors but also by phylogenetic constraints. The shape of the skull was correlated with the size and the length of the upper canines, two features that presented a clear correlation along the phylogeny of the group.