Gastropods from the Early/Middle Jurassic transition of Franconia (Southern Germany).

Beitrag in einer Fachzeitschrift


Details zur Publikation

Autorinnen und Autoren: Schulbert C, Nützel A
Zeitschrift: Bulletin of Geosciences
Verlag: Czech Geological Survey
Jahr der Veröffentlichung: 2013
Band: 88
Heftnummer: 4
Seitenbereich: 723-778
ISSN: 1214-1119
eISSN: 1802-8225


Abstract


A rich gastropod fauna is decribed from the Early/Middle Jurassic boundary (late Toarcian/early Aalenian) of Franconia (N Bavaria, South Germany). It comprises 35 nominate species and additional 9 species are treated in open nomenclature. With a few exceptions, the studied material comes from the Jurensismergel and the Opalinuston formations of the Mistelgau clay pit near Bayreuth. These sediments represent marine soft bottom environments. Gastropods are the most diverse and the most abundant group of the benthic communities in the Mistelgau clay pit. Bivalves, ophiurid and crinoid ossicles as well as foraminifera are also abundant. Among the bivalves, the paper pecten Bositra buchi and the inoceramid Pseudomytiloides dubium are especially abundant. Most of the members of the benthic fauna are small (< 15 mm) or even minute. Only the bivalve Pseudomytiloides dubium, some of the vetigastropods (e.g., Pleurotomarioidea) and the family Gordenellidae (Turritelloidea and Proacirsa) attain a size larger than 2 cm. However, these large species are rare. The most abundant gastropods are the caenogastropod species Coelodiscus minutus and Toarctocera subpunctata. Both species are especially abundant in the lowermost portions of the sampled section. Towards the Aalenian, an increase in diversity can be observed. This reflects recovery from the late Pliensbachian/early Toarcian extinction event. This event was connected with early Toarcian anoxia in Central and Northern Europe including black shale deposition (Posidonienschiefer). The studied gastropod fauna lived during still impoverished but improving environmental conditions. The relatively high diversity and abundance of the benthos suggest aerobic or dysaerobic conditions, however with possible fluctuations of oxygen concentrations. The fauna was also constrained by soft bottom conditions. 12 species are described as new: Mistelgauia monarii, Hummelgauia microstriata, Jurilda zapfi Schulbert, Nützel & Gründel sp. nov., Franconicilda juliae, Carinathilda? dieneri, Conusella convexa, Cossmannina eggmaieri, Sinuarbullina? mistelgauensis, Striactaeonina waltschewi Schulbert, Nützel & Gründel sp. nov., Striactaeonina richterorum Schulbert, Nützel & Gründel sp. nov., Parvulactaeon imprimum Schulbert, Nützel & Gründel sp. nov. and Parvulactaeon inclinatum Schulbert, Nützel & Gründel sp. nov. Three genera are described as new: Hummelgauia, Mistelgauia and Franconicilda. The family Coelodiscidae Gründel&Nützel fam. nov. is described as new based on the probably holoplanktonic gastropod genus Coelodiscus.



FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Schulbert, Christian
Lehrstuhl für Paläoumwelt


Zitierweisen

APA:
Schulbert, C., & Nützel, A. (2013). Gastropods from the Early/Middle Jurassic transition of Franconia (Southern Germany). Bulletin of Geosciences, 88(4), 723-778. https://dx.doi.org/10.3140/bull.gesci1418

MLA:
Schulbert, Christian, and Alexander Nützel. "Gastropods from the Early/Middle Jurassic transition of Franconia (Southern Germany)." Bulletin of Geosciences 88.4 (2013): 723-778.

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Zuletzt aktualisiert 2018-25-07 um 18:23