Weathering events recorded in uppermost Hauterivian–lower Barremian clay-dominated continental successions from the NW Iberian Range: climatic vs. tectonic controls

The facies and clay mineral study of clay/marl-rich levels from the Torrelapaja Formation (latest Hauterivian–early Barremian, NW Iberian Range, NE Spain) allowed to establish the palaeoclimatic and palaeoenvironmental conditions under they were generated. The muddy levels and pisoids contained therein of two logs were sampled and studied by X-ray diffraction and optical and electron microscopy. A similar mineralogical upwards trend is recorded in both logs, with a decrease in calcite coupled with an increase in quartz and orthoclase content and constant proportions in goethite, hematite, diaspore, anatase, rutile, ilmenite, and clay mineral content. The lower muddy levels have higher kaolinite content than the upper levels, where illitic phases are the dominant clay minerals. Smectite and intergrowths of illitic phases and kaolinite are also detected upwards. The kaolinite and smectite textures indicate an authigenic origin, whereas the illitic phases are former phases acting as a substrate for kaolinite crystallization. Pisoids mineralogy and texture show an in-situ origin, but some are fractured, indicating reworking processes. The mineral association found in the muddy levels is characteristic of oxisols formed under warm and humid conditions. The upward decrease in kaolinite content is coeval with an increase in the illitic phases and quartz content, related to siliciclastic input, but is also coeval with the presence of authigenic smectite. This indicates a decrease in chemical weathering, not fully registered due to the siliciclastic contribution, which was possibly associated with a change to colder, drier conditions during the latest Hauterivian–early Barremian in the studied area.

Chronology of recent sedimentary infill of the Inner Río de la Plata Estuary, Argentina

The Inner Río de la Plata Estuary is a sedimentary depositional system that resulted from fluvial-deltaic activity. Gentle Pliocene–Pleistocene slopes make-up the northern side of the estuary whereas small cliffs of the same age constitute the southern side. A long coastal estuarine barrier developed at about 6000 years BP when the maximum flooding surface occurred. Attached to this barrier, and at a lower elevation, is a large strandplain (covering an area of about 2400 km2) which displays more than 220 beach ridges. In different areas, the dating indicates a periodicity of 13.4–13.7 years for the development of each beach ridge. These data are like the periodicity of the ENSO effects, which could be associated with the variability of Sunspots. These ridges were formed shortly after the maximum flooding surface, which was followed by a gradual fall in sea-level that contributed significantly to the Inner Río de la Plata Estuary sedimentary infill. In addition, ENSO activities were probably instrumental in the distribution of the main geoforms in the Inner Rio de la Plata Estuary. Small deltas, which were generated by other rivers and creeks such as the Nogoyá Arroyo and the Gualeguay River, developed coevally with the coastal estuarine barrier. The Ibicuy Delta grew in the middle of the inner Río de la Plata Estuary when the former Paraná River flowed northwards during the sea-level fall. The upper part of the delta front was reworked, giving rise to a large dunefield. Thereafter, a chenier plain developed along with tidal flats. The current Paraná Delta continues to prograde at a rate of about 56–64 m/year (m year−1). The sedimentary infill of the Inner Río de la Plata Estuary occurred along the Holocene.

Digital 3D models of theropods for approaching body-mass distribution and volume

The aim of this work is to obtain diverse morphometric data from digitized 3D models of scientifically accurate palaeoreconstructions of theropods from eight representative families. The analysed polyvinyl chloride (PVC) models belong to the genera Coelophysis, Dilophosaurus, Ceratosaurus, Allosaurus, Baryonyx, Carnotaurus, Giganotosaurus, and Tyrannosaurus. The scanned 3D models were scaled considering different body-size estimations of the literature. The 3D analysis of these genera provides information on the skull length and body length that allows for recognition of major evolutionary trends. The skull length/body length in the studied genera increases according with the size of the body from the smallest Coelophysis with a ratio of 0.093 to ratios of 0.119–0.120 for Tyrannosaurus and Giganotosaurus, the largest study theropods. The study of photogrammetric 3D models also provides morphometric information that cannot be obtained from the study of bones alone, but knowing that all reconstructions begin from the fossil bones, such as the surface/volume ratio (S/V). For the studied theropod genera surface/volume ratio ranges from 35.21 for Coelophysis to 5.55 for Tyrannosaurus. This parameter, closely related to the heat dissipation, help in the characterization of the metabolism of extinct taxa. Accordingly, slender primitive forms of the Early Jurassic (i.e. Coelophysis and Dilophosaurus) had relatively smaller skulls and higher mass-specific metabolic rates than the robust large theropods of the Cretaceous (i.e. Giganotosaurus and Tyrannosaurus). This work presents a technique that, when applied to proper dinosaur models, provides extent and accurate data that may help in diverse study areas within the dinosaur palaeontology and palaeobiology.

‘Dinosaur-bird’ macroevolution, locomotor modules and the origins of flight

The dinosaurian origin of birds is one of the best documented events that palaeontology has contributed to the understanding of deep time evolution. This transition has been studied on multiple fossils using numerous multidisciplinary resources, including systematics, taxonomic, anatomical, morphological, biomechanical and molecular approaches. However, whereas deep time origins and phylogenetic relationships are robust, important nuances of this transition’s dynamics remain controversial. In particular, the fossil record of several maniraptoran groups clearly shows that aerial locomotion was developed before an ‘avialization’ (i.e., before the first divergence towards avialans), thus earlier than presumed. Although aspects as important as miniaturization and the acquisition of several anatomical and morphological modifications are key factors determining such evolutionary transition, understanding this macroevolutionary trend also involves to seize the evolution of developmental systems, which requires assessing the morphological expression of integration and modularity of the locomotor apparatus throughout time. This is so because, as it happened in other flying vertebrate taxa such as pterosaurs and bats, the transformation of the maniraptoran forelimbs into flying locomotor modules must not only have involved a gradual anatomical transformation, but also a complete developmental re-patterning of the integration scheme between them and the hindlimbs. Here, we review the most relevant aspects of limb morphological transformation during the so-called ‘dinosaur-bird’ transition to stress the importance of assessing the role of modularity and morphological integration in such macroevolutionary transition, which ultimately involves the origins of flight in dinosaurs.