Wyniki wyszukiwania - BazTech

1

Systematic palaeontology of the Perisphinctoidea in the Jurassic/Cretaceous boundary interval at Le Chouet (Drôme, France), and its implications for biostratigraphy

Frau C., Bulot L. G., Wimbledon W. A. P., Ifrim C.

Acta Geologica Polonica

|

2016

|

Vol. 66, no. 2

175--204

EN

This study describes ammonite taxa of the Perisphinctoidea in the Jurassic/Cretaceous boundary interval at Le Chouet (Drôme, France). Emphasis is placed on new and poorly known Himalayitidae, Neocomitidae and Olcostephanidae from the lower part of the Jacobi Zone auctorum. Significant results relate the introduction of Lopeziceras gen. nov., grouping himalayitid-like forms with two rows of tubercles, and Praedalmasiceras gen. nov., grouping the early Berriasian Dalmasiceras taxa. Study of the ontogenetic sequences of both genera show that they were derived from late Tithonian Himalayitidae. This supports the distinction between the subfamilies Himalayitinae and Dalmasiceratidae subfam. nov. Content, variation, dimorphism and vertical range of the Neocomitidae Berriasella, Pseudoneocomites, Elenaella and Delphinella are discussed. A conservative use of the Olcostephanidae Proniceras is followed herein.

2

New Heteroceratidae (Ammonoidea) from the late Barremian deepening succession of Marseille (Bouches-du-Rhône, France)

Frau C., Delanoy G., Masse J.-P., Lanteaume C., Tendil A. J. B.

Acta Geologica Polonica

|

2016

|

Vol. 66, no. 2

205--225

EN

Investigation of the late Barremian deepening succession of the Provence platform, cropping out south of Marseille (Bouches-du-Rhône, France), has yielded a new ammonite fauna belonging to the Martelites sarasini Subzone (Martelites sarasini Zone). The fauna is dominated by representatives of the Heteroceratidae Spath, characterized by different patterns of coiling, high intraspecific variabilities and dwarfism. These heteroceratids are distinctive and utterly different from all previously known taxa, and this justifies the introduction of the new taxa Heteroceras denizoti sp. nov., Heteroceras veratiae sp. nov., Calanquites gen. nov., based on Imerites katsharavai Rouchadzé; Giovaraites gen. nov., based on Giovaraites massiliae gen. et sp. nov., Barguesiella gen. nov., based on Barguesiella goudesense gen. et sp. nov. and the closely allied Barguesiella mantei gen. et sp. nov. The occurrence of the latter species at the top of the Maiolica Formation in Italy questions its early Aptian age assumed in the literature. The newly described fauna could be considered as the first case of micromorphy in the Heteroceratidae. Its biostratigraphy, palaeoenvironmental and palaeobiogeographical significance are discussed.

3

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

EN

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.