N. abundans group


Classification: Mesozoic -> Braarudosphaerales -> Nannoconaceae -> Nannoconus -> N. abundans group
Sister taxa: N. steinmannii group, N. kamptneri group, N. abundans group, N. truitti group, N. circularis group, N. compressus group, Nannoconus - atypical, N. sp.,

Distinguishing features: Cylindrical nannoconids with thin, low-angled wall cycles and relatively narrow canal (ct < wt); also may have apical and/or antapical flanges and/or bulbous base


Daughter taxa: (blue => in age window 0-800Ma)
Cylindrical nannoconids with apical flange. A smaller flange may also be present at the basal end. Wall cycles are thin and low angled, and the canal is relatively narrow.

cylindrical ‘apical’ part and an expanded, bulbous base (height typically >x2 width)

squat, cylindrical; without flanges
Squat cyclindrical Nannoconus with incomplete central-canal, shows central extinction cross in plan view.

Taxonomy:

Citation: N. abundans group
Rank: species group
Notes & discussion: informal grouping first used here

Farinacci & Howe catalog pages: N. abundans group [no catalog entry yet]

Distinguishing features: Cylindrical nannoconids with thin, low-angled wall cycles and relatively narrow canal (ct < wt); also may have apical and/or antapical flanges and/or bulbous base

Geological Range:
Last occurrence (top): at top of Aptian Stage (100% up, 113Ma, in Aptian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Berriasian Stage (55% up, 141.9Ma, in Berriasian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs

Caratini, C. (1963). Contribution à l'étude des coccolithes du Cénomanien supérieur et du Turonien de la région de Rouen. PhD thesis, Université d'Alger, Faculté des Sciences, Publication du Laboratoire de Géologique Appliquée. -. gs


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N. abundans group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-10-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10710 Go to Archive.is to create a permanent copy of this page - citation notes



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