The impact of anoxia on pelagic macrofauna during the Toarcian Oceanic Anoxic Event (Early Jurassic)

Caswell, Bryony A.; Coe, Angela L.

doi:10.1016/j.pgeola.2014.06.001

Cited by 37 publications

(38 citation statements)

References 48 publications

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“…Brief oxygenation periods may have occurred in the EES during the T‐OAE (Caswell & Coe, , ; Montero‐Serrano et al, ; Röhl et al, ; Röhl & Schmid‐Röhl, ). In our records, this is especially visible from maxima in Fe/Al and Mn at the base of T‐OAE at Schandelah and in the middle of the T‐OAE at Dotternhausen (Figure ).…”

Section: Discussionmentioning

confidence: 99%

Ocean Circulation in the Toarcian (Early Jurassic): A Key Control on Deoxygenation and Carbon Burial on the European Shelf

Baroni

Pohl

Helmond

et al. 2018

Paleoceanog and Paleoclimatol

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The Toarcian Oceanic Anoxic Event (T‐OAE, ∼183 Myr) was a long‐lasting episode of ocean deoxygenation during the Early Jurassic. The event is related to a period of global warming and characterized by major perturbations to the hydrological and carbon cycles with high rates of organic matter burial in shelf seas. Ocean circulation during the Toarcian and its influence on marine biogeochemical cycles are still not fully understood. Here we assess the spatial extent of anoxia in the NW Tethys Ocean during the T‐OAE, the relationship with ocean circulation and the impact on organic carbon burial, using new and existing sedimentary records from the European Epicontinental Shelf in combination with general circulation model results. We demonstrate that bottom waters on the southwestern part of the shelf were mainly oxic during the T‐OAE, while those in the northeastern basins were mostly anoxic or even sulfidic. Results for two ocean‐atmosphere models (Fast Ocean‐Atmosphere Model and Massachusetts Institute of Technology general circulation model) suggest the presence of a strong clockwise gyre over the European Epicontinental Shelf, which brought oxygenated equatorial waters from the Tethys Ocean to the southern shelf. The northward limb of the gyre was significantly weakened due to the rough bathymetry of the northern shelf, making this relative small region highly sensitive to local ocean stratification. These sluggish ocean dynamics promoted bottom water anoxia and enhanced burial of organic carbon in the northeastern basins, which accounted for 3–5% of the total carbon extracted from the ocean‐atmosphere system as recorded by the positive carbon isotope shift.

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Section: Discussionmentioning

confidence: 99%

Ocean Circulation in the Toarcian (Early Jurassic): A Key Control on Deoxygenation and Carbon Burial on the European Shelf

Baroni

Pohl

Helmond

et al. 2018

Paleoceanog and Paleoclimatol

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“…Most of the previous studies on belemnite rostrum size have focused on particular taxa or lineages (Christensen, 2000;Morten and Twitchett, 2009), precluding a proper analysis of the potential differences observed when considering rostrum size changes at different levels of organization (i.e. populations, communities, individuals).…”

Section: Introductionmentioning

confidence: 99%

Rostrum size differences between Toarcian belemnite battlefields

Rita¹,

Baets²,

Schlott³

2018

Foss. Rec.

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Abstract. Body size changes have been reported across crisis intervals. Belemnites – now considered extinct stem-decabrachians – have rarely been investigated for this purpose, and the few studies have resulted in ambiguous outcomes. Here we investigate two Toarcian belemnite accumulations in southern Germany from a morphometric point of view with the support of computed tomography data. The aim of this study is to test whether a difference in size can be observed between the rostra of the two studied samples, from individual lineage to community, and which proxy is more reliable. A significant decrease in median size from the Early Toarcian (Dactylioceras tenuicostatum Zone) to the Middle Toarcian (Haugia variabilis Zone) is recognized. This is observed at the community level of organization, considering the whole assemblage, but also within Passaloteuthis–Acrocoelites lineage, at the genus level. It is also demonstrated that diameter-based measurements or maximum preserved length are not reliable proxies for size, and therefore apical length or three-dimensional approximations, such as the geometric mean or the post-phragmocone volume, are more advisable. This is especially important when comparing specimens with markedly different rostrum shapes. Further studies are, however, still necessary to disentangle the mechanisms behind the reduction in rostrum size within the Toarcian and their putative environmental causes.

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“…These changes also affected other primary consumers, e.g. marking a change from mainly passaloteuthid to acrocoelitid belemnites in NW Europe (Caswell & Coe ) and the possible evolution of filter feeding pachycormid fishes (Friedman ; see text).…”

Section: Discussionmentioning

confidence: 99%

Key innovations in Mesozoic ammonoids: the multicuspidate radula and the calcified aptychus

Keupp¹,

Hoffmann

Stevens

et al. 2016

Palaeontology

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A nearly complete radula with seven elements per row preserved inside of an isolated, bivalved, calcitic lower jaw (= aptychus) of the Late Jurassic ammonite Aspidoceras is described from the Fossillagerst€ atte Painten (Bavaria, southern Germany). It is the largest known ammonite radula and the first record for the Perisphinctoidea. The multicuspidate tooth elements (ctenodont type of radula) present short cusps. Owing to significant morphological differences between known aptychophoran ammonoid radulae, their possible function is discussed, partly in comparison with modern cephalopod and gastropod radulae. Analogies between the evolution of the pharyngeal jaws of cichlid fishes and the ammonoid buccal apparatus raise the possibility that the evolution of a multicuspidate radula allowed for a functional decoupling of the aptychophoran ammonoid jaw. The radula, therefore, represents a key innovation which allowed for the evolution of the calcified lower jaws in Jurassic and Cretaceous aptychophoran ammonites. Possible triggers for this morphological change during the early Toarcian are discussed. Finally, we hypothesize potential adaptations of ammonoids to different feeding niches based on radular tooth morphologies.

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The impact of anoxia on pelagic macrofauna during the Toarcian Oceanic Anoxic Event (Early Jurassic)

Cited by 37 publications

References 48 publications

Ocean Circulation in the Toarcian (Early Jurassic): A Key Control on Deoxygenation and Carbon Burial on the European Shelf

Ocean Circulation in the Toarcian (Early Jurassic): A Key Control on Deoxygenation and Carbon Burial on the European Shelf

Rostrum size differences between Toarcian belemnite battlefields

Key innovations in Mesozoic ammonoids: the multicuspidate radula and the calcified aptychus

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