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The Pliensbachian–Toarcian succession of North Yorkshire provides a global reference for the interval incorporating the Toarcian Oceanic Anoxic Event (T-OAE, ∼183 Ma). Major and trace element, carbon stable-isotope (δ13Corg) and total organic carbon (TOC) data for the Dove’s Nest core, drilled close to the classic outcrop sections of the Yorkshire coast, demonstrate geochemical, mineralogical and grain-size trends linked to sea level and climate change in the Cleveland Basin. High-resolution correlation between the core and outcrop enables the integration of data to generate a comprehensive chemostratigraphic record. Palaeoredox proxies (Mo, U, V, TOC/P, DOP and Fe speciation) show a progressive shift from oxic bottom waters in the late Pliensbachian through dysoxic–anoxic conditions in the earliest Toarcian to euxinia during the T-OAE. Anoxia–dysoxia persisted into the middle Toarcian. Elemental and isotope data (Re, Re/Mo, δ34SCAS, δ98Mo and ε205Tl) from the coastal sections evidence global expansion of anoxic and euxinic seafloor area driving drawdown of redox-sensitive metals and sulfate from seawater leading to severe depletion in early Toarcian ocean water. The record of anoxia–euxinia in the Cleveland Basin largely reflects global-scale changes in ocean oxygenation, although metal depletion was temporarily enhanced by periods of local basin restriction. Osmium and Sr isotopes demonstrate a pulse of accelerated weathering accompanying the early Toarcian hyperthermal, coincident with the T-OAE. The combined core and outcrop records evidence local and global environmental change accompanying one of the largest perturbations in the global carbon cycle during the last 200 Ma and a period of major biotic turnover.

We have reinvestigated the marine mass extinction interval that occurred during the early Toarcian, which was a time of widespread marine anoxia. The ranges of marine benthic invertebrates are significantly altered using new observations from the Cleveland Basin, UK. Goniomya rhombifera is reported for the first time from the Whitby Mudstone Formation and together with an increased epifaunal bivalve diversity indicates a brief, relatively oxygenated period towards the end of the event. The new data, together with published results, suggest three apparent extinction horizons on a global scale; the first is just above the Pliensbachian-Toarcian boundary, and the following two are in the semicelatum ammonite Subzone. As a result of the Signor-Lipps effect there may be only one, or possibly two, true extinctions. The youngest extinction horizon coincides with the first of the abrupt carbon isotope shifts that characterize this interval, and with increases in sea surface temperature, continental weathering rates, and seawater anoxia. Pseudomytiloides dubius is the only abundant benthic macroinvertebrate during the most hostile environmental conditions but it and all other benthic species are almost entirely absent for many thousands of years immediately after each abrupt negative carbon isotope shift.

Dinosaur tracks and trackways yield invaluable information as to the identity, size, and gait of the trackmaker and the conditions of the media (=substrate) it traversed. Correctly interpreting tracks requires consideration of their three-dimensional morphology. Laboratory-controlled simulations were conducted to investigate the subsurface track morphology formed from differently shaped feet, as the shape of the footprint deteriorates with depth. A circular, triangular, and a tridactyl dinosaur foot-shaped template, or indenter, were indented vertically into two types of sand, with four moisture contents—dry, 10%, 20%, and saturated. The morphology of all three indenters was preserved most accurately in the moist sand. Tracks in dry and saturated sand were distorted by a greater degree of media deformation. Digit imprints of tridactyl tracks were only clearly discernible in near-surface layers and were deformed by shear zones or inward movement of sediment in dry and saturated sand. The long digits of the template produced the greatest degree of outward displacement, and tracks became wider with depth and deepest in the heel region. This was most distinct in dry sand, where extensive shear zones in cross section demonstrated the outward and upward movement of sediment. All tracks in saturated sand were characterized by considerable downward displacement of sediment and features related to the upward pull of sediment as the templates were withdrawn. These diagnostic features allow vertebrate tracks to be differentiated from nonbiogenic, soft-sediment deformation. Fossil tracks studied from the Middle Jurassic succession of the Cleveland Basin, Yorkshire, demonstrate affinities to the experimental tracks formed in saturated sand.

Diverse aspects of the fossil floras of the Early to Middle Jurassic (Cleveland Ironstone and Dogger Formations and Ravenscar Group; Pliensbachian-Bathonian stages) of North Yorkshire, England, have been investigated in order to better define the prevailing Early-Middle Jurassic paleoclimate. Growth rings in fossil woods have been characterized in terms of their \"mean sensitivity\"; overall woods are \"complacent\" and grew well within the bounds of their climatic tolerance, but woods from the oldest and, particularly, youngest parts of the succession analyzed (the Dogger and Scalby Formations, respectively) show greater interseasonal variation in growth. Intraseasonal variability in growth is indicated by the ubiquitous presence of false rings. Further evidence of seasonality from the fossil floras is the occurrence of leaf beds (ginkgophytes and Nilssoniopteris) interpreted as resulting from the deposition of leaves shed from deciduous plants during flood seasons. Charcoal is ubiquitous throughout the succession and wood samples often show \"checking\" of cell walls as a microscopic feature. These observations, combined with a consideration of the depositional and diagenetic history of the host sedimentary rocks, indicate the predominance of a winter-wet seasonal paleoclimate, which was characterized by greater aridity in the late Bajocian-Bathonian relative to the Pliensbachian-mid Bajocian. The increasing aridity towards the close of this interval may have been partly a function of regional withdrawal of the extensive seaway that characterized the area for most of the preceding Early Jurassic, but also may have been an early manifestation of the continent-wide arid phase that affected Eurasia during the Late Jurassic.

We surveyed the taxa, ecosystems, and localities of the Devonian fishes of Michigan to provide a framework for renewed study, to learn about the diversity and number of these fishes, and to investigate their connection to other North American faunas. Nineteen genera of fishes have been found in the Middle and Late Devonian deposits of Michigan, of which thirteen are ‘placoderms’ represented by material ranging from articulated head shields to ichthyoliths. As expected from the marine nature of these deposits, ‘placoderms’ are overwhelmingly arthrodire in nature, but two genera of ptyctodonts have been reported along with less common petalichthyid material. The remaining fish fauna consists of fin-spines attributed to ‘acanthodians’, two genera of potential crown chondrichthyans, an isolated dipnoan, and onychodont teeth/jaw material. There was an apparent drop in fish diversity and fossil abundance between Middle and Late Devonian sediments. This pattern may be attributed to a paucity of Late Devonian sites, along with a relative lack of recent collection efforts at existing outcrops. It may also be due to a shift towards open water pelagic environments at Late Devonian localities, as opposed to the nearshore reef fauna preserved in the more numerous Middle Devonian localities. The Middle Devonian vertebrate fauna in Michigan shows strong connections with same-age assemblages from Ohio and New York. Finally, we document the presence of partially articulated vertebrate remains associated with benthic invertebrates, an uncommon occurrence in Devonian strata outside of North America. We anticipate this new survey will guide future field work efforts in an undersampled yet highly accessible region that preserves an abundance of fishes from a critical interval in marine vertebrate evolution.