Effects of the early Toarcian Oceanic Anoxic Event on ichthyosaur body size and faunal composition in the Southwest German Basin

Paleobiology ◽  
2015 ◽  
Vol 42 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Erin E. Maxwell ◽  
Peggy Vincent
Keyword(s):  
Body Size ◽  
Environmental Changes ◽  
Marine Invertebrates ◽  
Abundant Species ◽  
Extinction Rate ◽  
Oceanic Anoxic Event ◽  
Environmental Perturbations ◽  
Anoxic Event ◽  
Posidonia Shale ◽  
German Basin

AbstractThe Early Jurassic Toarcian Oceanic Anoxic Event is considered one of the most dramatic environmental perturbations of the Mesozoic. An elevated extinction rate among marine invertebrates accompanied rapid environmental changes, but effects on large vertebrates are less understood. We examined changes in ichthyosaur body size in the Posidonia Shale of the Southwest German Basin spanning the extinction interval to assess how environmental changes and biotic crisis among prey species affected large reptiles. We report no species-level extinction among the ichthyosaurs coinciding with peak invertebrate extinction. Large ichthyosaurs were absent from the fauna during the extinction interval, but became more abundant in the immediate aftermath.Stenopterygius quadriscissus, the most abundant species during the extinction interval, increased in body size after the biotic event. Rapid invasion by large taxa occurred immediately following the extinction event at the end of the first ammonite zone of the early Toarcian. Greater mobility permitting exploitation of ephemeral resources and opportunistic feeding behavior may minimize the impacts of environmental change on large vertebrates.

Record of the Toarcian oceanic anoxic event in the Grands Causses Basin (southern France) and its implications for vertebrate preservation

2021 ◽  
Author(s):  
Brahimsamba Bomou ◽  
Guillaume Suan ◽  
Jan Schlögl ◽  
Anne-Sabine Grosjean ◽  
Baptiste Suchéras-Marx ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Clay Mineralogy ◽  
Lower Jurassic ◽  
Large Igneous Province ◽  
Volcanic Emissions ◽  
Oceanic Anoxic Event ◽  
Environmental Perturbations ◽  
Anoxic Event ◽  
Posidonia Shale ◽  
Rock Eval

<p>Paleontological excavations realized by our group in Toarcian shales (Lower Jurassic) of the Grands Causses Basin in Roqueredonde (Hérault, France), yielded several specimens of marine vertebrates. The newly discovered specimens are partly or entirely preserved in anatomical connection and include a partial ichthyosaur skeleton with soft tissues, and a 4 m-long thalattosuchian longirostrine marine crocodile. A multi-proxy approach has been developed (XRD-bulk and clay mineralogy, Rock-Eval pyrolysis, phosphorus and mercury contents) in order to replace these findings in a well-defined temporal and paleoenvironmental context, and hence constrain the factors that led to their remarkable preservation. The fossiliferous succession exposes a 3 m-thick upper Pliensbachian interval of marl and nodular carbonate beds, overlain by a 3 m-thick interval of lower Toarcian laminated shales and limestone beds. Our high-resolution ammonite biostratigraphy, combined with inorganic and organic carbon isotope chemostratigraphy, shows that the fossiliferous Toarcian strata were deposited at a time of global warming and major carbon cycle perturbation known as the Toarcian Oceanic Anoxic Event (T-OAE). The studied succession shows several similarities with the classical coeval fossiliferous levels of the Posidonia Shale in SW Germany, including high organic matter and hydrocarbon contents as well as extremely reduced sedimentation rates. These results indicate that the unusual richness in well-preserved vertebrates of the studied site can be explained by a combination of warming-induced, low salinity and stratified waters, prolonged seafloor anoxia and reduced dilution by low carbonate and terrigenous input due to rapid sea-level rise. Our results also reveal a significant peak in mercury at the base of the T-OAE interval, consistent with that recorded in several coeval sections (e.g. Portugal, Morocco, Argentina, Chile). This mercury anomaly, most likely resulting from intense volcanic activity Karoo-Ferrar large igneous province, suggests that widespread exceptional vertebrate preservation during the T-OAE was initiated by a suite of severe environmental perturbations ultimately triggered by intense volcanic emissions.</p>

scholarly journals Organic facies variability and paleoenvironmental interpretation of the Early Toarcian of the Pyrenean Basin: the Bizanet and the Pont de Suert sections

2019 ◽  
Author(s):  
Carolina Fonseca ◽  
João Graciano Mendonça Filho ◽  
Carine Lézin ◽  
Luís Vítor Duarte ◽  
Philippe Fauré
Keyword(s):  
Organic Carbon ◽  
Environmental Changes ◽  
Insoluble Residue ◽  
Free Swimming ◽  
Shallow Marine ◽  
Oceanic Anoxic Event ◽  
Average Value ◽  
Organic Facies ◽  
Anoxic Event ◽  
Paleoenvironmental Interpretation

The Early Toarcian is characterized by major worldwide environmental changes recorded in an organic-rich black shale sedimentation and carbon cycle disturbances, the so-called Toarcian Oceanic Anoxic Event (T-OAE) (e.g. Jenkyns, 2010). This organic-rich sedimentation is particularly recorded in shallow marine epicontinental basins that developed as part of the Toarcian European epicontinental shelf, paleogeographical framework in which the Pyrenean Basin is incorporated (e.g. Fonseca et al., 2018; McArthur et al., 2008). With these premises, the main objective of this study is to assess the organic facies variability and to define the depositional paleoenvironments of two sections from the Pyrenean Basin (Bizanet and Pont de Suert) during the T-OAE, using palynofacies and geochemical (Total Organic Carbon - TOC and insoluble residue - IR) data. The Pyrenean tectonics that occurred between the latest Cretaceous and the Oligocene, deformed, detached and fragmented the substrate resulting in diverse tectonic units (Faure, 2002). The late Pliensbachian-early Toarcian of the Pont de Suert section, located in the South Pyrenean zone, is characterized by the limestone dominated Barre a Pecten Formation (Fm.), and the carbonate and/or argillaceous-carbonate alternation of its three members (alternations of marl and argillaceous limestone of the Calcaires argileux à Spirifèrines Member (Mb.), the argillaceous limestones and marls of the Calcaires argileux et marnes à Soaresirhynchia Mb., and the marl and argillaceous limestone dominated Calcaires argileux à Telothyris Mb.; Faure, 2002). The Bizanet section is located in the eastern Corbières, and is characterized by a 3m thick succession of late Pliensbachian-early Toarcian sediments comprising, at the base, the limestone dominated Barre a Pecten Fm., followed by a sedimentary gap dated to the Tenuicostatum Chronozone, topped by the marly dominated succession of the Bizanet Fm. (black ferruginous marls intercalated with limestones and topped by dolomitic limestones of the Schistes carton Mb., and the black marls of the Argilites noires litées Mb.; Faure, 2002). The geochemical results evidenced that the Bizanet section presents higher TOC contents than the Pont de Suert section, with values reaching 2.03 wt.%. In the Bizanet section IR ranges between 12 wt.% and 82 wt.% and in the Pont de Suert section varies from 13wt.% to 67 wt.%, displaying a similar average value for the two sections (45 wt.%). The palynofacies assemblage is dominated in both sections by the same components, belonging to the Phylum Cnidaria, Class Hydrozoa and Order Hydroida, and are represented by fragments of colonial and non-colonial sessile polypoid forms and free-swimming medusoid forms, with different degrees of amorphization. (This abstract has been truncated, please see the complete PDF version)

scholarly journals Biostratigraphic constraints of the Early Toarcian Oceanic Anoxic Event: new data from calcareous nannofossil investigations of Boreal and Tethyan sections

2019 ◽  
Author(s):  
Stefano Visentin ◽  
Elisabetta Erba ◽  
Joerg Mutterlose
Keyword(s):  
Calcareous Nannofossil ◽  
Northern Germany ◽  
Lower Saxony ◽  
Oceanic Anoxic Event ◽  
Anoxic Event ◽  
First Occurrence ◽  
Calcareous Nannofossil Biostratigraphy ◽  
Posidonia Shale ◽  
Boreal Realm ◽  
Interval Expression

Calcareous nannofossil biostratigraphy was carried out in Upper Pliensbachian – Lower Toarcian sediments, which cover the Toarcian Oceanic Anoxic Event (T-OAE) interval. In particular, semiquantitative analyses were performed on a total of 156 samples in the composite Sogno Core (Lombardy Basin, Southern Alps) representing a pelagic Tethyan section. Quantitative investigations were applied to additional 168 samples across the Amaltheenton Fm. and Posidonienschiefer Fm., from two cores of the Boreal Realm (Lower Saxony Basin, northern Germany). Primary and secondary events of the Tethyan and Boreal zonations were recognized, allowing the identifications of the NJT5, NJT6 nannofossil Zones for the Sogno Core and the NJ5, NJ6, NJ7 Zones for the German sections, respectively. The sequence of nannofossil biohorizons is generally consistent with data available for various areas at lower and higher latitudes, confirming their reproducibility and reliability for intra and inter-regional correlations. Geochemistry evidences the presence of the negative C isotopic excursion across the “Fish Level” black shale interval expression of the T-OAE in the Sogno Core. The same anomaly is recorded in the German successions at the base of the Posidonia Shale witnessing the passage from well oxygenated to predominantly anoxic conditions. Our results show that the T-OAE C isotopic excursion recorded in the Sogno Core is excellently constrained by the first occurrence (FO) of Carinolithus superbus at the onset and the last occurrence (LO) of Mitrolithus jansae at the end. A significant decrease in abundance and size of Schizosphaerella punctulata (the “S. punctulata crisis”) and an abundance drop of M. jansae further characterise the T-OAE perturbation. Only S. punctulata shows a recovery at the end of the T-OAE, while M. jansae barely survived the palaeoenviromental stress and disappeared soon after its termination. The extreme rareness of S. punctulata and the absence of M. jansae in the Boreal Realm prevent the recognition of the “S. punctulata crisis” and the M. jansae decline. Our study reveals the LO of Biscutum finchii together with the FO of C. superbus as an additional event approximating the onset of the C isotopic excursion exclusively in the German successions. Further events, such as the LOs of Biscutum grandis, Crepidolithus granulatus and Parhabdolithus liasicus are detected within the C isotopic anomaly exclusively in the German sections. Nannofossil biostratigraphy permits the effective dating and correlating of Early Jurassic major palaeoceanographic events and particularly of the T-OAE which are of a great importance to derive a definitive model for the Posidonia Shale deposition.

scholarly journals The impact of the Pliensbachian–Toarcian crisis on belemnite assemblages and size distribution

2021 ◽  
Vol 140 (1) ◽  
Author(s):  
Kenneth De Baets ◽  
Paulina S. Nätscher ◽  
Patricia Rita ◽  
Emmanuel Fara ◽  
Pascal Neige ◽  
...  
Keyword(s):  
Body Size ◽  
Size Distribution ◽  
Marine Organisms ◽  
Second Order ◽  
Regional Diversity ◽  
Oceanic Anoxic Event ◽  
Quantitative Studies ◽  
Anoxic Event ◽  
The Impact

AbstractThe second-order Pliensbachian–Toarcian crisis affected major groups of marine organisms. While its impact has been intensively studied for ammonites, the response of belemnites is only currently emerging through quantitative studies. Novel overall and regional diversity analyses suggest that belemnite richness in the NW-Tethys drops at the Pliensbachian–Toarcian boundary, while overall diversity slightly increases in NW-Tethys assemblages during the Toarcian Oceanic Anoxic event (T-OAE), mostly driven by NW European assemblages (e.g., Yorkshire). The T-OAE coincides with marked taxonomic turnover within individual basins, which is associated with an increase in median rostrum size of specimens in taxa at most localities. The changes in median body size across the Pliensbachian–Toarcian boundary are less consistent and driven by changes in body size within individual lineages crossing the boundary. However, our analyses also illustrate differences in sampling across the Pliensbachian–Toarcian crisis, which needs to be considered in further studies.

scholarly journals Global controls on phosphatization of fossils during the toarcian oceanic anoxic event

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sinjini Sinha ◽  
A. D. Muscente ◽  
James D. Schiffbauer ◽  
Matt Williams ◽  
Günter Schweigert ◽  
...  
Keyword(s):  
Lower Jurassic ◽  
X Ray ◽  
Oceanic Anoxic Event ◽  
Exceptional Preservation ◽  
Level Change ◽  
Environmental Controls ◽  
Anoxic Basins ◽  
Anoxic Event ◽  
Anoxic Events ◽  
Posidonia Shale

AbstractKonservat-Lagerstätten—deposits with exceptionally preserved fossils—vary in abundance across geographic and stratigraphic space due to paleoenvironmental heterogeneity. While oceanic anoxic events (OAEs) may have promoted preservation of marine lagerstätten, the environmental controls on their taphonomy remain unclear. Here, we provide new data on the mineralization of fossils in three Lower Jurassic Lagerstätten—Strawberry Bank (UK), Ya Ha Tinda (Canada), and Posidonia Shale (Germany) —and test the hypothesis that they were preserved under similar conditions. Biostratigraphy indicates that all three Lagerstätten were deposited during the Toarcian OAE (TOAE), and scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) show that each deposit contains a variety of taxa preserved as phosphatized skeletons and tissues. Thus, despite their geographic and paleoenvironmental differences, all of these Lagerstätten were deposited in settings conducive to phosphatization, indicating that the TOAE fostered exceptional preservation in marine settings around the world. Phosphatization may have been fueled by phosphate delivery from climatically-driven sea level change and continental weathering, with anoxic basins acting as phosphorus traps.

About this title - Carbon Cycle and Ecosystem Response to the Jenkyns Event in the Early Toarcian (Jurassic)

10.1144/sp514 ◽  
2021 ◽  
Vol 514 (1) ◽  
pp. NP-NP
Author(s):  
M. Reolid ◽  
L. V. Duarte ◽  
E. Mattioli ◽  
W. Ruebsam
Keyword(s):  
Environmental Changes ◽  
Sea Level Change ◽  
Global Changes ◽  
Ecosystem Response ◽  
Oceanic Anoxic Event ◽  
Level Change ◽  
Isotopic Geochemistry ◽  
Anoxic Event ◽  
Collateral Effects ◽  
Integrated Stratigraphy

The Toarcian Oceanic Anoxic Event, also known as the Jenkyns Event, was a hyperthermal episode which occurred during the early Toarcian (c. 183 Ma; Early Jurassic) and resulted in numerous collateral effects including global warming, enhanced weathering, sea-level change, carbonate crisis, marine anoxia–dysoxia, and a second-order mass extinction. This volume presents the last advances for understanding early Toarcian environmental changes through different disciplines: biostratigraphy, micropalaeontology, palaeontology, ichnology, palaeoecology, sedimentology, integrated stratigraphy, inorganic, organic and isotopic geochemistry, and cyclostratigraphy. The study of this abrupt climate change is critical for predicting future global changes, and for understanding the complex biogeochemical interactions through time between geosphere, atmosphere, hydrosphere and biosphere.

scholarly journals Ocean warming affected faunal dynamics of benthic invertebrate assemblages across the Toarcian Oceanic Anoxic Event in the Iberian Basin (Spain)

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242331
Author(s):  
Veronica Piazza ◽  
Clemens V. Ullmann ◽  
Martin Aberhan
Keyword(s):  
Carbon Cycle ◽  
Marine Invertebrates ◽  
Benthic Invertebrate ◽  
Ecological Change ◽  
Western Tethys ◽  
Oceanic Anoxic Event ◽  
Faunal Assemblages ◽  
Iberian Basin ◽  
Anoxic Event ◽  
Modes Of Life

The Toarcian Oceanic Anoxic Event (TOAE; Early Jurassic, ca. 182 Ma ago) represents one of the major environmental disturbances of the Mesozoic and is associated with global warming, widespread anoxia, and a severe perturbation of the global carbon cycle. Warming-related dysoxia-anoxia has long been considered the main cause of elevated marine extinction rates, although extinctions have been recorded also in environments without evidence for deoxygenation. We addressed the role of warming and disturbance of the carbon cycle in an oxygenated habitat in the Iberian Basin, Spain, by correlating high resolution quantitative faunal occurrences of early Toarcian benthic marine invertebrates with geochemical proxy data (δ18O and δ13C). We find that temperature, as derived from the δ18O record of shells, is significantly correlated with taxonomic and functional diversity and ecological composition, whereas we find no evidence to link carbon cycle variations to the faunal patterns. The local faunal assemblages before and after the TOAE are taxonomically and ecologically distinct. Most ecological change occurred at the onset of the TOAE, synchronous with an increase in water temperatures, and involved declines in multiple diversity metrics, abundance, and biomass. The TOAE interval experienced a complete turnover of brachiopods and a predominance of opportunistic species, which underscores the generality of this pattern recorded elsewhere in the western Tethys Ocean. Ecological instability during the TOAE is indicated by distinct fluctuations in diversity and in the relative abundance of individual modes of life. Local recovery to ecologically stable and diverse post-TOAE faunal assemblages occurred rapidly at the end of the TOAE, synchronous with decreasing water temperatures. Because oxygen-depleted conditions prevailed in many other regions during the TOAE, this study demonstrates that multiple mechanisms can be operating simultaneously with different relative contributions in different parts of the ocean.

scholarly journals The Toarcian Oceanic Anoxic Event: where do we stand?

2021 ◽  
pp. SP514-2021-74
Author(s):  
Matías Reolid ◽  
Emanuela Mattioli ◽  
Luís V. Duarte ◽  
Wolfgang Ruebsam
Keyword(s):  
Global Warming ◽  
Carbon Cycle ◽  
Sea Level ◽  
Climate Changes ◽  
Environmental Changes ◽  
Global Changes ◽  
Ecosystem Responses ◽  
Oceanic Anoxic Event ◽  
Anoxic Event ◽  
Collateral Effects

AbstractThe study of past climate changes is pivotal for understanding the complex biogeochemical interactions through time between the geosphere, atmosphere, hydrosphere and biosphere, which are critical for predicting future global changes. The Toarcian Oceanic Anoxic Event, also known as the Jenkyns Event, was a hyperthermal episode which occurred during the early Toarcian (∼183 Ma; Early Jurassic) and resulted in numerous collateral effects including global warming, enhanced weathering, sea-level change, carbonate crisis, marine anoxia-dysoxia, and biotic crisis. The IGCP-655 project of the IUGS-UNESCO has constituted an international network of researchers with different disciplinary skills who collaborated and shared conceptual advances on uncovering drivers of the environmental changes and ecosystem responses. This volume, Carbon Cycle and Ecosystem Response to the Jenkyns Event in the Early Toarcian (Jurassic), presents 16 works that investigate the early Toarcian environmental changes related to the global warming, sea-level rise, carbon cycle perturbation and second-order mass extinction through biostratigraphy, micropalaeontology, palaeontology, ichnology, palaeoecology, sedimentology, integrated stratigraphy, inorganic, organic and isotopic geochemistry, and cyclostratigraphy.

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