Header

UZH-Logo

Maintenance Infos

Revised stratigraphic range of the Toarcian ammonite genus Porpoceras Buckman, 1911


Jattiot, Romain; Fara, Emmanuel; Brayard, Arnaud; Vennin, Emmanuelle (2016). Revised stratigraphic range of the Toarcian ammonite genus Porpoceras Buckman, 1911. Geodiversitas, 38(4):505-513.

Abstract

The Toarcian ammonite genus Porpoceras Buckman, 1911 is a cosmopolitan taxon with an uncertain stratigraphic range. The oldest known occurrence of the genus was reported from the Falciferum Subzone (Early Toarcian) in Morocco, although based on a unique specimen whose taxonomic assignment to the genus Porpoceras remains doubtful. The youngest occurrence was a simple mention of Porpoceras sp. from the Variabilis Subzone (Middle Toarcian) of the Thouars area (Western France), but it was later regarded as doubtful because no specimen was figured. We here provide the first robust evidence for the youngest known occurrence of the genus Porpoceras, from the Variabilis Subzone of the Thouars area. The known revised stratigraphic range of the genus therefore extends from the Falciferum Subzone to the Variabilis Subzone. In turn, the genus Porpoceras likely went extinct in the Illustris Subzone together with the genera Catacoeloceras Buckman, 1923 and Mucrodactylites Buckman, 1928, coinciding with the drastic loss of diversity observed between the Bifrons and Variabilis Zones in northwestern Europe (also known as the Bifrons-Variabilis extinction). Finally, in the light of our new data and of previous reports, the genus Porpoceras is not a foolproof biostratigraphic marker of the NW European Bifrons Horizon, although it remains an important taxon for identifying this biostratigraphic unit.

Abstract

The Toarcian ammonite genus Porpoceras Buckman, 1911 is a cosmopolitan taxon with an uncertain stratigraphic range. The oldest known occurrence of the genus was reported from the Falciferum Subzone (Early Toarcian) in Morocco, although based on a unique specimen whose taxonomic assignment to the genus Porpoceras remains doubtful. The youngest occurrence was a simple mention of Porpoceras sp. from the Variabilis Subzone (Middle Toarcian) of the Thouars area (Western France), but it was later regarded as doubtful because no specimen was figured. We here provide the first robust evidence for the youngest known occurrence of the genus Porpoceras, from the Variabilis Subzone of the Thouars area. The known revised stratigraphic range of the genus therefore extends from the Falciferum Subzone to the Variabilis Subzone. In turn, the genus Porpoceras likely went extinct in the Illustris Subzone together with the genera Catacoeloceras Buckman, 1923 and Mucrodactylites Buckman, 1928, coinciding with the drastic loss of diversity observed between the Bifrons and Variabilis Zones in northwestern Europe (also known as the Bifrons-Variabilis extinction). Finally, in the light of our new data and of previous reports, the genus Porpoceras is not a foolproof biostratigraphic marker of the NW European Bifrons Horizon, although it remains an important taxon for identifying this biostratigraphic unit.

Statistics

Altmetrics

Downloads

17 downloads since deposited on 20 Jan 2017
17 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Paleontological Institute and Museum
Dewey Decimal Classification:560 Fossils & prehistoric life
Language:German
Date:2016
Deposited On:20 Jan 2017 13:18
Last Modified:20 Jan 2017 13:22
Publisher:Museum National d'Histoire Naturelle Paris
ISSN:1280-9659
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.5252/g2016n4a3

Download

Download PDF  'Revised stratigraphic range of the Toarcian ammonite genus Porpoceras Buckman, 1911'.
Preview
Content: Published Version
Filetype: PDF
Size: 5MB
View at publisher