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Upper upper Albian (Mortoniceras rostratum Zone) cephalopods from Clansayes (Drôme, south-eastern France)

Jattiot Romain, Lehmann Jens, Latutrie Benjamin, Tajika Amane, Vennin Emmanuelle, Vuarin Pauline, Brayard Arnaud, Fara Emmanuel, Trincal Vincent

Acta Geologica Polonica

2022

Vol. 72, no. 2

187--233

We document an upper upper Albian (Mortoniceras rostratum Zone) cephalopod assemblage from Clansayes (Drôme, south-eastern France). Although fossils are rare in local exposures and in the single sampled level, a decade of intensive fossil collecting yielded 290 ammonite and 5 nautilid specimens. In total, we describe 1 species of nautilid and 24 species (within 17 genera) of ammonites, including 13 heteromorphs. Only two of these ammonite taxa were previously recorded from the upper upper Albian at Clansayes, which demonstrates the value of this fauna with regard to taxonomy, palaeobiology and palaeobiogeography. Based on morphological and biometric analyses performed on an extensive material (104 specimens), we discriminate two species for the heteromorphic ammonite genus Mariella Nowak, 1916 within the Mortoniceras rostratum Zone. In addition, we investigate shell chirality patterns in Mariella from the late Albian of southern France. Upon comparison of the Clansayes material with older material from the immediately underlying upper Albian Mortoniceras fallax Zone at the neighbouring Salazac locality, we identify an increase in the proportion of sinistral specimens. This observed increase in the frequency of sinistral Mariella specimens may hypothetically be part of a global evolutionary pattern, considering that nearly all documented younger Cenomanian Mariella (and more generally Cenomanian turrilitids) are sinistral.

New and poorly known Perisphinctoidea (Ammonitina) from the Upper Tithonian of Le Chouet (Drôme, SE France)

Bulot L., Frau C., Wimbledon W.

Volumina Jurassica

2014

Vol. 12, no. 1

113--128

The aim of this paper is to document the ammonite fauna of the upper part of the Late Tithonian collected at the key section of Le Chouet (Drôme, SE France). Emphasis is laid on new and poorly known Ataxioceratidae, Himalayitidae and Neocomitidae from the upper part of the Tithonian. Among the Ataxioceratidae, a new account on the taxonomy and relationship between Paraulacosphinctes Schindewolf and Moravisphinctes Tavera is presented. Regarding the Himalayitidae, the range and content of Micracanthoceras Spath is discussed and two new genera are introduced: Ardesciella gen. nov., for a group of Mediterranean ammonites that is homoeomorphic with the Andean genus Corongoceras Spath, and Pratumidiscus gen. nov. for a specimen that shows morphological similarities with the Boreal genera Riasanites Spath and Riasanella Mitta. Finally, the occurrence of Neocomitidae in the uppermost Tithonian is documented by the presence of the reputedly Berriasian genera Busnardoiceras Tavera and Pseudargentiniceras Spath.

Contribution of Eocene sharks and rays from southern France to the history of deep-sea selachians

Adnet S., Cappetta H., Reynders J.

Acta Geologica Polonica

2008

Vol. 58, no. 2

257-260

Fossil deep-sea selachians are rare and their diversity underestimated as a consequence of the scarcity of available outcrops of sediments containing them. Here we report a new fossil locality from the Middle Eocene of southwestern France and give a first synthesis of the deep-sea deposits of this area which have yielded one of the richest fossil selachian faunas ever to have inhabited the continental slope. The fossil records of deep-sea sharks and rays are discussed in the context of these new fossil occurrences, a literature review and the recent phylogenetic hypothesis.