Two fallen blocks of the Marlstone and stratigraphically overlying Junction Bed sampled on the beach below Doghouse Cliff in Dorset, UK (Wessex Basin) have been examined for carbon and oxygen isotopes of bulk carbonate as well as for strontium, carbon and oxygen isotopes and Mg:Ca ratios in the contained belemnites. The sequence, which contains most of the Toarcian zones and subzones within a metre or less of grey to yellow to pink, red and brown fossil-rich nodular limestone, is extremely condensed and lithologically similar to pelagic red limestones of the Tethyan Jurassic that are locally mineralized with Fe-Mn oxyhydroxides (e.g., Rosso Ammonitico). Strontium-isotope ratios of the contained belemnites are compatible with existing reference curves and both blocks show a rise to more radiogenic values post-dating the Pliensbachian–Toarcian boundary. The high degree of correlation between the relatively negative carbon and oxygen isotopes of the bulk carbonate is compatible with significant diagenetic overprint, and contrasts with higher carbon-isotope values in coeval condensed coccolith-rich limestones elsewhere. Evidence for the characteristic signature of the Toarcian Oceanic Anoxic Event, as represented by organic-rich sediment, is absent, possibly owing to a stratigraphic gap. Both blocks exhibit abrupt carbon-isotope shifts to lower values, one of which could represent the limbs of an incompletely recorded negative excursion associated with the Toarcian Oceanic Anoxic Event. That the Toarcian Oceanic Anoxic Event was also a significant hyperthermal is illustrated in both blocks by a drop in oxygen-isotope values and rise in Mg:Ca ratios of belemnites close to the base of the Junction Bed in the lowest part of the serpentinum zone.

Marine reptile occurrences are rare in the Lower Jurassic Series outside of Europe. Here we describe diverse marine reptile faunas from the Lower Jurassic Series (Pliensbachian and Toarcian stages, including the Toarcian–Aalenian boundary interval) of Eastern Siberia. The taxonomic composition of Toarcian marine reptile assemblages of Siberia highlight their cosmopolitan nature, with the presence of taxa previously known nearly exclusively from coeval strata of Europe, such as ichthyosaurians Temnodontosaurus and Stenopterygius, microcleidid plesiosaurians (including the genus Microcleidus), rhomaleosaurids and basal pliosaurids. The palaeogeographic reconstruction places these faunas to the palaeopolar region, north of the 80th northern parallel and up to the palaeo north pole (upper value within the 95% confidence interval for some of the localities). The materials include remains of both mature and juvenile (or even infant, judging by their very small size and poor ossification) animals, indicating a possibility that these polar seas may serve as a breeding area. The diversity and abundance of plesiosaurians and ichthyosaurians, along with a lack of thalattosuchian remains (considering their wide distribution elsewhere at low latitudes), is an additional argument that plesiosaurians and neoichthyosaurians were able to live and reproduce in a polar environment. There is no certainty whether these animals lived in polar seas permanently, or whether they were taking seasonal migrations. However, given the polar night conditions at high latitudes, the latter seems more plausible, and both these scenarios are further indirect evidence that these groups likely had a high metabolism.

This study focuses on the Tianshifu Basin, eastern Liaoning, China, which is filled with Lower–Middle Jurassic fluviolacustrine sediments rich in macroplants. Our aim is to explore the continental climate features of the late Early Jurassic period. The composition of the Early–Middle Jurassic flora and the carbon isotopic ratios of organic matter, total organic carbon, total organic nitrogen and sulphur of the rock samples from the Changliangzi section (the upper part of the Lower Jurassic deposits) have been investigated. Based on the flora, eastern Liaoning was generally characterized by temperate and humid conditions during the Early–Middle Jurassic period, but with rising temperatures during late Early Jurassic time. The sediments of the Changliangzi section show a transformation from shallow-lake facies to deep-lake facies. A positive organic carbon isotope excursion correlates with the deepening of this palaeolake, considered to be caused by climate warming. The late Early Jurassic climate warming indicated by floral and isotopic evidence corresponds to the climatic events recorded elsewhere in marine and continental sequences during the Toarcian Age, the so-called Toarcian Anoxic event, and may be associated with enhanced global greenhouse warming. This study provides new continental data supporting global warming during the late Early Jurassic period.

Most of the known and most-complete Early Jurassic specimens of plesiosaurians were recovered from the United Kingdom and Germany, and few specimens from that age originate from other areas in Europe. This study describes a new plesiosaurian taxon from Toarcian deposits of Luxembourg, Microcleidus melusinae, represented by the most complete skeleton ever discovered from this country. A preliminary phylogenetic analysis places Microcleidus melusinae within Microcleididae, as a sister taxon of the species previously included in the genus Microcleidus. The new specimen studied here contributes to our understanding of the palaeodiversity of Early Jurassic plesiosaurians and confirms their high degree of ‘endemism’ and low morphological disparity.

A perturbation in the carbon-isotope record at the time of the Pliensbachian–Toarcian boundary (~ 184 Ma) in the Early Jurassic is reported, based on new data from Yorkshire, England. Two sharp δ13Corg negative excursions, each with a magnitude of ~ −2.5 ‰ and reaching minimum values of −28.5 ‰, are recorded in the bulk organic-matter record in sediments of latest Pliensbachian to earliest Toarcian age. A similar pattern of negative carbon-isotope excursions has been observed at the stage boundary in the SW European section at Peniche, Portugal in δ13Ccarbonate, δ13Cwood and δ13Cbrachiopod records. The isotopic excursion is of interest when considering the genesis and development of the later Toarcian Oceanic Anoxic Event (OAE), as well as the second-order global extinction event that spans the stage boundary. Furthermore, the isotope excursion potentially provides a chemostratigraphic marker for recognition of the stage boundary, which is currently achieved on the basis of different ammonite faunas in the NW European and Tethyan realms.