On New Records of Cephalopod Jaws from the Upper Bajocian (Middle Jurassic) of the Northern Caucasus (Russia, Karachay-Cherkessia)

2020 ◽  
Vol 54 (5) ◽  
pp. 477-486
Author(s):  
A. A. Mironenko ◽  
V. V. Mitta
2020 ◽  
Vol 296 (1) ◽  
pp. 147-156
Author(s):  
Ewa Krzemińska ◽  
Natalia Starzyk ◽  
Günter Schweigert ◽  
John Whicher ◽  
Robert Baron Chandler ◽  
...  

Of the anomuran Eogastrodorus granulatus (Förster, 1985), the sole representative of the genus, only the holotype from Bajocian strata in Switzerland was known until now. The five additional specimens described here have enabled us to supplement the morphological characterisation of both the genus and species. Of these five individuals, four originate from the shallow-marine Sherborne Limestone Member (Inferior Oolite Formation, lower upper Bajocian) in southern England. The fifth is from the shallow-marine biodetritic Audun-le-Tiche Limestone in Lorraine (France), of late early Bajocian ( Humphriesianum Zone) age; this is the stratigraphically oldest record of a gastrodorid known to date. Two juvenile carapaces from England are preserved within a piece of driftwood. We offer three possible interpretations for this occurrence; the hollowed out inside of the wood could have provided a place for moulting, retreating or mating. Alternatively, the two carapaces represent the remains of a meal of a predator that lived inside the wood or took shelter there, or, thirdly, it could constitute a random influx of carapaces into the empty space of the piece of wood. Each of these scenarios presupposes that these anomurans lived in an onshore habitat, where driftwood of all sizes is frequently encountered. These taphonomic circumstances could represent the earliest instance of the relationship between paguroids and plants.


2021 ◽  
Vol 50 (2) ◽  
pp. 69-74
Author(s):  
Lubomir Metodiev ◽  
Docho Dochev ◽  
Svetlozar Seferinov ◽  
Silviya Petrova

Fossil chela of an erymid lobster from a single locality of the upper Bajocian in the Western Fore-Balkan Mts (NW Bulgaria) was studied. Two segments of the thoracic appendages, probably belonging to one individual, were described: 1) P1 propodus with partially preserved pollex and dactylus; and 2) P1 carpus and P1 merus attached. These elements of the first pair of pereiopods of a lobster were identified as Eryma compressum (Eudes-Deslongchamps, 1842). Eryma compressum a is well-known taxon from numerous Jurassic localities in Europe but has not been recorded in Bulgaria to date. Therefore, albeit being an isolated finding with only a few elements, the Bulgarian example contributes to the overall record of European erymid faunas from the Middle Jurassic, and especially in Eastern Europe, from where only a few erymids have been reported.


1966 ◽  
Vol S7-VIII (3) ◽  
pp. 401-404
Author(s):  
Philippe Artru

Abstract The upper Bajocian (middle Jurassic) heterogeneous polygene breccias of the Riou d'Entraix (southeast France) are interpreted as olistostromes formed by gravity sliding along a paleoscarp. The scarp was to the east, in the area presently covered by overthrusts, and separated a euxinic deep basin from a well-oxygenated shallow shelf. Similar deposits in the Barcelonette window and the semi-window at Embrun are probably of the same origin.


Geologos ◽  
2016 ◽  
Vol 22 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Oksana S. Dzyuba ◽  
Anna A. Goryacheva ◽  
Dmitry A. Ruban ◽  
Victoria V. Gnezdilova ◽  
Pavel P. Zayats

Abstract Palaeontological data on the Caucasus are highly important for large-scale stratigraphical and palaeobiogeographical assessment of the northern Tethyan margin, but this information is often scarce and not available in English. Field studies in the Northern Caucasus have now permitted to amass some new data. Two belemnite species are described from the stratotype section of the Kamennomostskaja Formation (Callovian, Middle Jurassic) near the town of Kamennomostskij in Adygeja (Northern Caucasus). These are Belemnopsis subhastata (von Zieten, 1831) and Rhopaloteuthis ominosa Gustomesov, 1968. The latter is a rare species, and the present find allows new insights into its taxonomy. A palyno-logical analysis of the belemnite-bearing sample was carried out, and a diverse assemblage of dinocysts, acritarchs and prasinophytes, plus pollen and spores recognised. The most abundant palynomorphs are Micrhystridium and Classopollis. Data on belemnites coupled with those on palynomorphs indicate the early Callovian age of the sample level. This interpretation differs slightly from previous conclusions based on ammonites and dinocysts. If this age is correct, the degree of condensation of Callovian deposits in the section studied was lesser than previously assumed.


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