scholarly journals Ups and downs of belemnite diversity in the Early Jurassic of Western Tethys

Palaeontology ◽  
2021 ◽  
Author(s):  
Pascal Neige ◽  
Robert Weis ◽  
Emmanuel Fara
Keyword(s):  
Early Jurassic ◽  
Western Tethys

Early Pliensbachian (Early Jurassic) C-isotope perturbation and the diffusion of the Lithiotis Fauna: Insights from the western Tethys

2014 ◽  
Vol 410 ◽  
pp. 255-263 ◽  
Author(s):  
Marco Franceschi ◽  
Jacopo Dal Corso ◽  
Renato Posenato ◽  
Guido Roghi ◽  
Daniele Masetti ◽  
...  
Keyword(s):  
Early Jurassic ◽  
Western Tethys

scholarly journals TESTATE AMOEBAE FROM THE EARLY JURASSIC OF THE WESTERN TETHYS, NORTH-EAST ITALY

Palaeontology ◽  
2008 ◽  
Vol 51 (6) ◽  
pp. 1335-1339 ◽  
Author(s):  
DAVIDE BASSI ◽  
ANNA FUGAGNOLI ◽  
RENATO POSENATO ◽  
DAVID B. SCOTT
Keyword(s):  
Testate Amoebae ◽  
Early Jurassic ◽  
Western Tethys ◽  
North East

The Pliensbachian ammonite Dayiceras dayiceroides and Early Jurassic paleogeography

1983 ◽  
Vol 20 (1) ◽  
pp. 86-91 ◽  
Author(s):  
Paul L. Smith
Keyword(s):  
British Columbia ◽  
Early Jurassic ◽  
Eastern Pacific ◽  
Western Tethys ◽  
Disjunct Population ◽  
Northeastern Pacific ◽  
Pacific Margin ◽  
Genetic Continuity ◽  
Central Atlantic ◽  
New Occurrences

Uptonia? dayiceroides Mouterde is placed in the genus Dayiceras and its age established as latest Jamesoni Zone to possibly earliest Domerian. The species is abundant and associated with faunas of Tethyan aspect along the northeastern Pacific margin. First occurrences in Oregon and Nevada and new occurrences in British Columbia are reported. Localities at apparently high paleolatitudes are attributed to post-early Pliensbachian transcurrent fault displacements. Genetic continuity with a disjunct population in Portugal is postulated via a central Atlantic seaway, here named the Hispanic Corridor, connecting the eastern Pacific and western Tethys Oceans. The existence of this corridor during the Pliensbachian is supported by several lines of independent paleobiogeographic evidence.

Clumped isotope evidence for polar warmth and reduced salinity during the Early Jurassic

2021 ◽  
Author(s):  
Thomas Letulle ◽  
Guillaume Suan ◽  
Mikhail Rogov ◽  
Mathieu Daëron ◽  
Arnauld Vinçon-Laugier ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Climate Models ◽  
Early Jurassic ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Arctic Seas ◽  
Proxy Data ◽  
Western Tethys ◽  
Surface Temperatures ◽  
Clumped Isotope

<p><span>Greenhouse climates are periods characterized by high atmospheric CO<sub>2</sub> levels and the absence of large continental icecaps, conditions that define most of the Phanerozoic eon. Fossil record and proxy data from the Cretaceous-Early Paleogene (145-33 My) greenhouse interval suggest increased polar warmth and reduced latitudinal gradient. Such features are challenging for most climate models. They imply either misinterpretation of paleoenvironmental data or an underestimation of climate sensitivity under greenhouse climate. Here we present a new record from polar (>80°) paleolatitudes of the Early Jurassic (~180My) global warming episode known as the Toarcian Oceanic Anoxic Event. Carbonate clumped isotope (Δ47) thermometry and stable isotope analyses (</span><span>δ<sup>18</sup>O<sub>c, </sub>δ<sup>13</sup>C</span><span>) were performed on pristine aragonite bivalve shells from the Polovinnaya River succession (N Siberia) recording exceptionally low burial. Reconstructed growing season temperatures of 9.7</span><span>±5.2 to 19.0±3.4 °C and water δ<sup>18</sup>O<sub>w</sub> values of −4.6±1.2 to −2.2±0.8‰VSMOW imply increased warmth and significant freshwater contribution in the Toarcian Arctic seas, in line with coeval Siberian paleobotanical data. The unusually low δ<sup>18</sup>O<sub>w </sub>values confirm the incorrectness of assuming a spatially uniform δ<sup>18</sup>O<sub>sw</sub> value for calculation of δ<sup>18</sup>O-derived paleotemperatures. The inferred Early Jurassic polar sea surface temperatures are in good agreement with independent high latitude proxy data from Cretaceous and Eocene warming events. Together with coeval sea surface temperatures data from the western Tethys Ocean, our new data suggest a strong reduction of latitudinal temperature gradients during the Toarcian relative to modern gradients. The reconstructed polar warmth and reduction in latitudinal temperature gradient are substantially higher than those simulated by most climate models of the Jurassic to Eocene greenhouse periods, and support the increasing amount of data and models indicating an increase of climate sensitivity with CO<sub>2</sub> levels. Our results bring critical new constraints for model simulations of Jurassic temperatures and δ<sup>18</sup>O<sub>sw</sub> values and suggest that high climate sensitivity is the hallmark of greenhouse climates since at least 180 My.</span></p>

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