Controls on authigenic mineralization in experimental Ediacara-style preservation.

The earliest evidence of complex macroscopic life on Earth is preserved in Ediacaran-aged siliciclastic deposits as three-dimensional casts and molds, known as Ediacara-style preservation. The mechanisms that led to this extraordinary preservation of soft-bodied organisms in fine- to medium-grained sandstones have been extensively debated. Ediacara-style fossilization is recorded in a variety of sedimentary facies characterized by clean quartzose sandstones (as in the eponymous Ediacara Member) as well as less compositionally mature, clay-rich sandstones and heterolithic siliciclastic deposits.

Lithium isotopic evidence for enhanced reverse weathering during the Early Triassic warm period.

Elevated temperatures persisted for an anomalously protracted interval following pulsed volcanic carbon release associated with the end-Permian mass extinction, deviating from the expected timescale of climate recovery following a carbon injection event. Here, we present evidence for enhanced reverse weathering-a CO source-following the end-Permian mass extinction based on the lithium isotopic composition of marine shales and cherts. We find that the average lithium isotopic composition of Lower Triassic marine shales is significantly elevated relative to that of all other previously measured Phanerozoic marine shales.

Environmental and temporal patterns in bioturbation in the Cambrian-Ordovician of Western Newfoundland.

The early Paleozoic emergence of bioturbating (sediment-dwelling and -mixing) animals has long been assumed to have led to substantial changes in marine biogeochemistry, seafloor ecology, and the preservation potential of both sedimentary and fossil archives. However, the timing of the rise of bioturbation and environmental patterns in its expansion have long been subjects of debate-resolution of which has been hampered, in part, by a paucity of high-resolution bioturbation data or of systematic investigations of facies trends in lower Paleozoic bioturbation. To address these issues, we conducted an integrated sedimentological and ichnological characterization of the Cambrian-Ordovician Port au Port succession and Cow Head Group of western Newfoundland, encompassing over 350 meters of stratigraphy logged at the centimeter to decimeter scale.

The evolution of the marine carbonate factory.

Calcium carbonate formation is the primary pathway by which carbon is returned from the ocean-atmosphere system to the solid Earth. The removal of dissolved inorganic carbon from seawater by precipitation of carbonate minerals-the marine carbonate factory-plays a critical role in shaping marine biogeochemical cycling. A paucity of empirical constraints has led to widely divergent views on how the marine carbonate factory has changed over time.

Biofilms as agents of Ediacara-style fossilization.

Earth's earliest fossils of complex macroscopic life are recorded in Ediacaran-aged siliciclastic deposits as exceptionally well-preserved three-dimensional casts and molds, known as "Ediacara-style" preservation. Ediacara-style fossil assemblages commonly include both macrofossils of the enigmatic Ediacara Biota and associated textural impressions attributed to microbial matgrounds that were integral to the ecology of Ediacara communities. Here, we use an experimental approach to interrogate to what extent the presence of mat-forming microorganisms was likewise critical to the Ediacara-style fossilization of these soft-bodied organisms.

A largely invariant marine dissolved organic carbon reservoir across Earth's history.

Marine dissolved organic carbon (DOC), the largest pool of reduced carbon in the oceans, plays an important role in the global carbon cycle and contributes to the regulation of atmospheric oxygen and carbon dioxide abundances. Despite its importance in global biogeochemical cycles, the long-term history of the marine DOC reservoir is poorly constrained. Nonetheless, significant changes to the size of the oceanic DOC reservoir through Earth's history have been commonly invoked to explain changes to ocean chemistry, carbon cycling, and marine ecology.

Biostratinomy of the Ediacara Member (Rawnsley Quartzite, South Australia): implications for depositional environments, ecology and biology of Ediacara organisms.

The Precambrian Ediacara Biota-Earth's earliest fossil record of communities of macroscopic, multicellular organisms-provides critical insights into the emergence of complex life on our planet. Excavation and reconstruction of nearly 300 m of fossiliferous bedding planes in the Ediacara Member of the Rawnsley Quartzite, at the National Heritage Ediacara fossil site Nilpena in South Australia, have permitted detailed study of the sedimentology, taphonomy and palaeoecology of Ediacara fossil assemblages. Characterization of Ediacara macrofossils and textured organic surfaces at the scale of facies, bedding planes and individual specimens has yielded unprecedented insight into the manner in which the palaeoenvironmental settings inhabited by Ediacara communities-particularly hydrodynamic conditions-influenced the aut- and synecology of Ediacara organisms, as well as the morphology and assemblage composition of Ediacara fossils.

Publisher Correction: The role of calcium in regulating marine phosphorus burial and atmospheric oxygenation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The role of calcium in regulating marine phosphorus burial and atmospheric oxygenation.

The marine phosphorus cycle plays a critical role in controlling the extent of global primary productivity and thus atmospheric pO on geologic time scales. However, previous attempts to model carbon-phosphorus-oxygen feedbacks have neglected key parameters that could shape the global P cycle. Here we present new diagenetic models to fully parameterize marine P burial.

Infaunal augurs of the Cambrian explosion: An Ediacaran trace fossil assemblage from Nevada, USA.

Morphologically complex trace fossils, recording the infaunal activities of bilaterian animals, are common in Phanerozoic successions but rare in the Ediacaran fossil record. Here, we describe a trace fossil assemblage from the lower Dunfee Member of the Deep Spring Formation at Mount Dunfee (Nevada, USA), over 500 m below the Ediacaran-Cambrian boundary. Although millimetric in scale and largely not fabric-disruptive, the Dunfee assemblage includes complex and sediment-penetrative trace fossil morphologies that are characteristic of Cambrian deposits.

Ecological Expansion and Extinction in the Late Ediacaran: Weighing the Evidence for Environmental and Biotic Drivers.

The Ediacara Biota, Earth's earliest communities of complex, macroscopic, multicellular organisms, appeared during the late Ediacaran Period, just prior to the Cambrian Explosion. Ediacara fossil assemblages consist of exceptionally preserved soft-bodied forms of enigmatic morphology and affinity which nonetheless represent a critical stepping-stone in the evolution of complex animal ecosystems. The Ediacara Biota has historically been divided into three successive Assemblages-the Avalon, the White Sea, and the Nama.

The 'Tully monster' is a vertebrate.

Problematic fossils, extinct taxa of enigmatic morphology that cannot be assigned to a known major group, were once a major issue in palaeontology. A long-favoured solution to the 'problem of the problematica', particularly the 'weird wonders' of the Cambrian Burgess Shale, was to consider them representatives of extinct phyla. A combination of new evidence and modern approaches to phylogenetic analysis has now resolved the affinities of most of these forms.

Ediacaran Marine Redox Heterogeneity and Early Animal Ecosystems.

Oxygenation has widely been viewed as a major factor driving the emergence and diversification of animals. However, links between early animal evolution and shifts in surface oxygen levels have largely been limited to extrapolation of paleoredox conditions reconstructed from unfossiliferous strata to settings in which contemporaneous fossils were preserved. Herein, we present a multi-proxy paleoredox study of late Ediacaran (ca.