Explore the vast range of titles available.

Sauropods, the giant long-necked dinosaurs, became the dominant group of large herbivores in terrestrial ecosystems after multiple related lineages became extinct towards the end of the Early Jurassic (190–174 Ma). The causes and precise timing of this key faunal change, as well as the origin of eusauropods (true sauropods), have remained ambiguous mainly due to the scarce dinosaurian fossil record of this time. The terrestrial sedimentary successions of the Cañadón Asfalto Basin in central Patagonia (Argentina) document this critical interval of dinosaur evolution. Here, we report a new dinosaur with a nearly complete skull that is the oldest eusauropod known to date and provide high-precision U–Pb geochronology that constrains in time the rise of eusauropods in Patagonia. We show that eusauropod dominance was established after a massive magmatic event impacting southern Gondwana (180–184 Ma) and coincided with severe perturbations to the climate and a drastic decrease in the floral diversity characterized by the rise of conifers with small scaly leaves. Floral and faunal records from other regions suggest these were global changes that impacted the terrestrial ecosystems during the Toarcian warming event and formed part of a second-order mass extinction event.

The rock record from the late Early Jurassic in southern Africa encompasses the history of voluminous continental flood basalt outpourings associated with the magmatic events in the Karoo–Ferrar Large Igneous Province (LIP) in southern and eastern Gondwana. This multiphase magmatism produced one of Earth’s largest continental flood basalt successions volumetrically and is assumed to have been a main driving mechanism in late Early Jurassic global environmental perturbations, including mass extinctions and changes in climate. In southern Africa, these Lower Jurassic flood basalts are interbedded with fossiliferous sedimentary rocks, which in turn host the last signs of ‘Karoo life’ in the form of fossil plants, invertebrates and vertebrates, including the trackways of hopping mammals and the ultimate Karoo dinosaurs. The sedimentology and palaeontology of the interbeds archived depositional and biotic processes in running water as well as in and around shallow, up to ∼10 m deep freshwater lakes and ponds in the late Early Jurassic. This study explains how a complex freshwater palaeo-habitat prevailed – albeit temporarily – in this extremely stressful environment, which was unlike any modern volcanic system. The evidence collectively points to seasonally wet, warm temperate climatic conditions during the early phases of Karoo volcanism. Moreover, the evidence in the rocks also suggests that the dynamic volcanic conditions resulted in shifting habitats that likely facilitated the migration of the ultimate Karoo biota towards the north and west, away from the main Karoo land of fire, just before Gondwana started to disassemble. This refinement of the environmental dynamics in southern Gondwana presented herein lays the groundwork for future high-resolution volcanological, geochronological and chemostratigraphical studies aimed at the nuanced understanding of the global environmental effect of the Karoo–Ferrar LIP.

This work represents the most complete approximation to date of the taphonomy, biostratigraphy and bioevents recorded in the foraminifera of the Upper Pliensbachian-Middle Toarcian in the western sector of the Basque-Cantabrian Basin (Spain). The foraminifera are preserved as skeletal remains or internal moulds, consistent with resedimented elements with minimal transport, autochthonous or para-autochthonous. The assemblages are typical of the Atlantic Boreal Domain and inhabited a marine platform of normal salinity. The Lagenina Suborder is the most abundant and diverse, and the Miliolina, Robertinina, Spirillinina and Textulariina suborders are accessory in most of the samples. A foraminiferal biozonation calibrated against the standard ammonite biozonation is proposed. The Upper Pliensbachian to Middle Toarcian interval is divided into two biozones (Prima and Chicheryi) and five subzones (Sublaevis, Obonensis, Aragonensis, Clathrata and Iberica). The biotic crisis recorded globally in the Tenuicostatum Chronozone has also been detected in this basin. This crisis produced the stepwise extinction of typical Lower Jurassic species but without affecting generic and supra-generic taxonomic categories. Several Pliensbachian-Toarcian transition and Lower Toarcian characteristic species, such as Eoguttulina palomerensis , Planularia obonensis and Saracenella aragonensis , previously identified in different Spanish and European basins, have also been recorded in the Basque-Cantabrian Basin. After the extinction, a bioevent of diversification takes place in the Serpentinum Chronozone with the appearance of the genus Citharina and other characteristic taxa of the Toarcian and Middle Jurassic. The composition of the assemblages and the recorded bioevents are comparable to those of other areas in the Iberian Peninsula and northwestern Europe. Se presenta la aproximación más completa hasta la fecha sobre la tafonomía, bioestratigrafía y bioeventos registrados en los foraminíferos del Pliensbachiense superior al Toarciense medio en el sector occidental de la Cuenca Vasco-Cantábrica (España). Los foraminíferos están preservados como restos esqueléticos o moldes internos, siendo elementos resedimentados con transporte mínimo, autóctonos o para-autóctonos. Las asociaciones son típicas del Dominio Boreal Atlántico, y habitaban una plataforma marina de salinidad normal. El Suborden Lagenina es el más abundante y diverso, y los subórdenes Miliolina, Robertinina, Spirillinina y Textulariina son accesorios. Se propone una biozonación de foraminíferos calibrada con la biozonación estándar de ammonoideos. El intervalo Pliensbachiense superior-Toarciense medio se ha dividido en dos biozonas (Prima y Chicheryi) y cinco subzonas (Sublaevis, Obonensis, Aragonensis, Clathrata e Ibérica). La crisis biótica, registrada a nivel global en la Cronozona Tenuicostatum, se ha detectado también en esta cuenca. Ésta produjo la extinción escalonada de especies típicas del Jurásico Inferior, pero sin afectar a las categorías taxonómicas genéricas y supragenéricas. Especies características de la transición Pliensbachiense-Toarciense y del Toarciense inferior como Eoguttulina palomerensis , Planularia obonensis y Saracenella aragonensis , identificadas previamente en otras cuencas, también se han registrado en la Cuenca Vasco-Cantábrica. Después de la extinción, tiene lugar un bioevento de diversificación en la Cronozona Serpentinum con la aparición del género Citharina y de otras formas características del Toarciense y del Jurásico Medio. La composición de las asociaciones y los bioeventos registrados son comparables a los de otras áreas en la Península Ibérica y el noroeste de Europa.

For much of the Mesozoic record there has been an inconclusive debate on the possible global significance of isotopic proxies for environmental change and of sequence stratigraphic depositional sequences. We present a carbon and oxygen isotope and elemental record for part of the Early Jurassic based on marine benthic and nektobenthic molluscs and brachiopods from the shallow marine succession of the Cleveland Basin, UK. The invertebrate isotope record is supplemented with carbon isotope data from fossil wood, which samples atmospheric carbon. New data elucidate two major global carbon isotope events, a negative excursion of 2 at the SinemurianPliensbachian boundary, and a positive excursion of 2 in the Late Pliensbachian. The SinemurianPliensbachian boundary event is similar to the slightly younger Toarcian Oceanic Anoxic Event and is characterized by deposition of relatively deepwater organic-rich shale. The Late Pliensbachian strata by contrast are characterized by shallow marine deposition. Oxygen isotope data imply cooling locally for both events. However, because deeper water conditions characterize the SinemurianPliensbachian boundary in the Cleveland Basin the temperature drop is likely of local significance; in contrast a cool Late Pliensbachian shallow seafloor agrees with previous inference of partial icehouse conditions. Both the large-scale, long-term and small-scale, short-duration isotopic cycles occurred in concert with relative sea level changes documented previously from sequence stratigraphy. Isotope events and the sea level cycles are concluded to reflect processes of global significance, supporting the idea of an Early Jurassic in which cyclic swings from icehouse to greenhouse and super greenhouse conditions occurred at timescales from 1 to 10 Ma.

The Pliensbachian–Toarcian transition was characterised by a drastic turnover from a cool climate to a period of rapid global warming. While the warming associated with the Early Toarcian Oceanic Anoxic Event is rather well-studied, the cause, intensity and extent of the preceding cooling in the late Pliensbachian are still discussed. Occurrences of glendonite play an important role in this debate, since glendonite is a pseudomorph after the cryophilic carbonate mineral ikaite. This study describes the first glendonite-bearing carbonate concretions from South Germany (Buttenheim clay pit, northern Franconian Alb), which represent the southernmost glendonite occurrence in the late Pliensbachian documented so far. Based on petrographical and sedimentological investigations as well as stable isotope analyses it is concluded that a low temperature was the main factor for ikaite formation in the studied section, suggesting that the late Pliensbachian cooling had a more far-reaching impact on the temperature of the European epicontinental sea than previously assumed. To explain the low temperatures required for ikaite precipitation, a model for the sea-ice driven formation of cold bottom-water masses on the continental shelf is proposed. The occurrence of several layers containing reworked hiatus concretions in the studied outcrop is interpreted as the result of recurrent sea-level falls caused by multiple glacial pulses characterising the overall cool climate in the late Pliensbachian.

The Lower Jurassic sedimentary sequence deposited on the outer shelf (Hallstat shelf) of the Neo-Tethys passive margin occurs mainly as blocks in different melanges, or in rare cases, far-travelled nappes formed in the frame of the Middle-Late Jurassic mountain building process related to ophiolite obduction. Datable Lower Jurassic blocks are very rare in the Western Tethyan Realm, and are studied in detail for their age and sedimentological characteristics in order to reconstruct the Jurassic distal parts of the Neo-Tethyan passive continental margin. One of these exotic blocks, belonging to the marly siliceous limestones of the Durrnberg Formation, was discovered in the Haselgebirge Melange of the Weitenau Area (Northern Calcareous Alps, Austria). The block yielded a well-preserved radiolarian fauna, which is assigned here to the uppermost Lower Pliensbachian Gigi fustis-Lantus sixi Radiolarian Zone. The occurrence of this Lower Jurassic block beside other exotic blocks in the Upper Jurassic Haselgebirge Melange proves the allochthony of the Haselgebirge Melange in the Weitenau area.

The Lower Pliensbachian series (Ibex Chronozone) of Southern Vendée (France) contains a unique mix of ammonites, with several Polymorphitidae, Uptonia atlantica [Fauré and Bohain, 2017], and Dayiceras dayiceroides [Mouterde, 1951], whose distribution till date seemed restricted to the Lusitanian Basin. As in Portugal, these taxa extend the linear evolutionary sequence of this family during the Masseanum and Valdani Subchronozones. Their discovery in Vendée enables qualifying the importance of the Lusitanian endemism. It allows integrating the Lusitanian Basin and Vendée, which paleogeographic reconstructions place closer, into the same Atlantic paleobiogeographic area. It can be extended to the western borders of the North-West European Bioprovince. During the Late Pliensbachian, it is probably through a diffusion within this paleogeographic area that the Tethyan taxa, which are very numerous in Portugal, would have reached Vendée and Western Europe in successive waves. It seems that this atlantic communication route was privileged, at least until the Early Toarcian.

A new dinosaurian track-bearing site, with tridactyl footprints from the Lower Jurassic (pre-middle Pliensbachian) volcanogenic and epiclastic rocks of the Marifil Volcanic Complex, Patagonia, Argentina, is presented and described. The best-preserved footprint, classified as cf. Anomoepus, confirms the utility of the Anomoepus-like tracks for the Early Jurassic biochronology. Palaeobiogeographically, this record supports the idea that the South American Early Jurassic dinosaur fauna presents elements of Pangaean distribution, and others with Gondwanan relationships with prevalent southern African affinities. Dinosaur records from South America between the Rhaetian and the Pliensbachian are very scarce, and this find contributes to the knowledge of early radiation and evolution of Dinosauria.

A stratigraphic study of the carbonate deposits from the interval between the uppermost Sinemurian and the base of the Upper Pliensbachian is presented herein. For this purpose, four expanded sections of the Asturian Basin, in Northern Spain, were sampled. The sections are located between Rodiles E section (Villaviciosa municipality) and Playa de Vega section (Ribadesella municipality). The ammonites recorded in over 100 successive levels of this sector enabled the substantial improvement of the biochronostratigraphic scale of reference; making it comparable with those defined for other basins of the Iberian Peninsula and other areas of the western Tethys. The lower boundary of the Pliensbachian is indicated by the first appearance of Gemmellaroceras aff. aenigmaticum (Gemmellaro) below the first appearance of the genus Apoderoceras . The upper boundary is defined by the first record of the Protogrammoceras. ( Matteiceras ) subgenus which in some levels is associated with Amaltheus stokesi (Sowerby). The boundaries between the zones and subzones were able to be established accurately in most cases. The ammonite assemblages are similar to those established for the NW European Province. Some intervals, however, include species typical of the Mediterranean Province. Among these, the Taylori Subchronozone ( Gemmellaroceras ) and the transition between the Jamesoni Subchronozone and the Valdani Subchronozone ( Tropidoceras ) can be highlighted. Additionally, taking into consideration the succession between of ammonite genera and species, 27 horizons were identified, 24 of which correspond to the Lower Pliensbachian, and the other 3 to the uppermost Sinemurian and the lowermost part of the Upper Pliensbachian. Moreover, the identification of 3 of the Lower Pliensbachian horizons were based upon the evolution of the Mediterranean Tropidoceras .

The knowledge of Pliensbachian (Early Jurassic, ∼192.9–184.2 Ma) plesiosaurs is notoriously insufficient. Although there have been specimens described from different parts of the world, only three of them have been established as diagnosable taxa. Here, we describe two previously unreported lower Pliensbachian plesiosaur occurrences that originate from two sites located in North Rhine-Westphalia, Germany. One of the new occurrences is represented by three cervical and three indeterminable vertebrae from Werther, the other includes two associated pectoral or anterior dorsal vertebrae from Bielefeld. Although highly incomplete, the Werther individual, which derived from the Uptonia jamesoni Zone, is found to represent the only reliably identified early Pliensbachian pliosaurid known to date. Its material is geographically and stratigraphically proximate to the late Pliensbachian pliosaurid Arminisaurus schuberti , found in a clay-pit located in the Bielefeld district of Jöllenbeck. However, even though the Werther plesiosaur and A. schuberti show a broadly similar morphology of the preserved cervical section, a precise identification of the Werther taxon is currently impossible.