Search results for "TRIASSIC"

Coping between crises: Early Triassic–early Jurassic bivalve diversity dynamics

2011

The Triassic is bounded by two of the most severe biotic crises, but nevertheless this time was, for bivalves, both a recovery and a diversification period, and a moment to fully exploit some of their evolutionary novelties. Just how and when this was achieved is analyzed in this paper, which covers Induan to Sinemurian bivalve diversity, based on a newly compiled database. Taxonomic diversity and ecospace dynamics are examined separately. Diversity and evolutionary rates were assessed, extinction selectivity was tested using a resampling algorithm, and cohort analysis was used to study extinction patterns. During the Early Triassic most bivalve genera were survivors from the Permian and th…

An enormous sulfur isotope excursion indicates marine anoxia during the end-Triassic mass extinction

2020

The role of ocean anoxia as a cause of the end-Triassic marine mass extinction is widely debated. Here, we present carbonate-associated sulfate δ34S data from sections spanning the Late Triassic–Early Jurassic transition, which document synchronous large positive excursions on a global scale occurring in ~50 thousand years. Biogeochemical modeling demonstrates that this S isotope perturbation is best explained by a fivefold increase in global pyrite burial, consistent with large-scale development of marine anoxia on the Panthalassa margin and northwest European shelf. This pyrite burial event coincides with the loss of Triassic taxa seen in the studied sections. Modeling results also indica…

Mercury contents and isotope ratios from diverse depositional environments across the Triassic–Jurassic Boundary: Towards a more robust mercury proxy…

2021

Abstract Mercury is gaining prominence as a proxy for large igneous province (LIP) volcanism in the sedimentary record. Despite temporal overlap between some mass extinctions and LIPs, the precise timing of magmatism relative to major ecological and environmental change is difficult to untangle, especially in marine settings. Changes in the relative contents of Hg in sedimentary rocks through time, or ‘Hg anomalies’, can help resolve the timing of LIP activity and marine extinctions. However, major questions remain unanswered about the fidelity of Hg as a proxy for LIP magmatism. In particular, depositional (e.g., redox) and post-depositional (e.g., oxidative weathering) processes can affec…

Conodonts versus Triassic Climatic and Eustatic Changes

2015

Kılıç, Ali Murat (Balikesir Author)

Positive Sulfate Sulfur Isotope Excursion Indicates Large-Scale Pyrite Burial and Marine Anoxia during the End–Triassic Mass Extinction

2020

The late Rhaetian–early Hettangian transition is characterised by the emplacement of Central Atlantic magmatic province and associated climatic effects, coincident with a severe biotic crisis (~201.5 Ma). The oxygen deficiency in the ocean realm is possibly linked to this significant loss in marine biodiversity. However, direct evidence of contemporaneous development of marine anoxia on a global scale has been lacking and the relationship between oxygen and extinction is unclear. Here we report carbonate-associated sulfate δ34S data from three sections across the Late Triassic–Early Jurassic transition. We find synchronous large positive δ34S shifts with a magnitude of >10‰ in the latest…

Bivalves and evolutionary resilience: Old skills and new strategies to recover from the P/T and T/J extinction events

2011

Diversity dynamics among bivalves during the Triassic and Early Jurassic provides the opportunity to analyse the recovery patterns after two mass extinctions: Permian/Triassic and Triassic/Jurassic (T/J). The results presented here are based on a newly compiled worldwide genus-level database and are contrasted to the main morphological characters of the different taxonomical (orders and their constituent families and genera) and ecological groups. Many of such morphological characters are innovations appearing during the time span considered. Diversity and evolutionary rates were assessed and compared between these groups. During the Early Triassic there was a slow recovery, dominated by ep…

Challenging Darwin: Evolution of Triassic Conodonts and Their Struggle for Life in a Changing World

2017

Abstract The phylogeny and distribution of Triassic conodonts reveal many aspects of their natural history. Conodonts incorporate the morphologic response to temperature as well as to eustatic cycles. Speciation, radiation, and extinction are not fortuitous and evolution uses heterochrony (progenesis and neoteny) in response to stress-generating events. Proteromorphosis (reappearance of ancestral morphs) and paedomorphosis (retention of juvenile traits) is a reaction to sublethal environmental stress. This often follows radiation of fully developed forms in the recovery stage after extinction that timely matches transgressions. Evolutionary retrogradation (neoteny) during eustatic high stan…

The genus Palaeolituonella (Foraminifer) and description of Palaeolituonella angulata nov. sp. from Upper Triassic reef limestones of the Tethys

2009

The Potential Geosite of the “Libeccio Antico” Quarries: a Sedimentological and Stratigraphic Characterisation of Ornamental Stone from Mt Cocuccio, …

2018

The Custonaci marble district of western Sicily is known for the production of a valuable ornamental stone that has been, and nowadays is exploited due to its suitable properties and aesthetic qualities. The “Libeccio Antico” was, among the “marbles”, the most appreciated ornamental stone during the Baroque Age (the XVII–XVIII centuries), due to its strong polychrome contrasts from ivory to yellow, green or dark red. This polychrome pattern is the result of dissolution processes that involved an Upper Triassic peritidal limestone. The varicoloured sediments in paleocavities, collapse breccias, paleosols and neptunian dykes that occur in the “Libeccio Antico” represent the peculiar character…

A diagenetic control on the Early Triassic Smithian-Spathian carbon isotopic excursions recorded in the marine settings of the Thaynes Group (Utah, U…

2016

17 pages; International audience; n the aftermath of the end-Permian mass extinction, Early Triassic sediments record some of the largest Phanerozoic carbon isotopic excursions. Among them, a global Smithian-negative carbonate carbon isotope excursion has been identified, followed by an abrupt increase across the Smithian–Spathian boundary (SSB; ~250.8 Myr ago). This chemostratigraphic evolution is associated with palaeontological evidence that indicate a major collapse of terrestrial and marine ecosystems during the Late Smithian. It is commonly assumed that Smithian and Spathian isotopic variations are intimately linked to major perturbations in the exogenic carbon reservoir. We present p…