Nannotax3 - ntax_mesozoic - Nannoconus borealis

Nannoconus borealis


Classification: ntax_mesozoic -> Braarudosphaerales -> Nannoconaceae -> Nannoconus -> N. abundans group -> Nannoconus borealis
Sister taxa: N. abundans, N. alvus, N. borealis, N. concavus, N. inornatus, N. troelsenii

Distinguishing features:
Parent taxon (N. abundans group): 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
This taxon: cylindrical ‘apical’ part and an expanded, bulbous base (height typically >x2 width)


Taxonomy:

Citation: Nannoconus borealis Perch-Nielsen, 1979
Rank: Species

Farinacci & Howe catalog pages: N. borealis *

Distinguishing features:
Parent taxon (N. abundans group): 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
This taxon: cylindrical ‘apical’ part and an expanded, bulbous base (height typically >x2 width)


Morphology:

Nannoconid with cylindrical apical part formed from thin, shallowly-spiralling cycles, and an expanded, bulbous basal end composed of coarse plates; the canal is relatively narrow. Can be very large (10-25µm).
Shows considerable variation in form but the similar morphotypes seem to have concurrent ranges. Can break into different parts that look distinctly different.

Size:


Ecology & Biogeography: Mainly Boreal (North Sea) distribution.

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, hollow, CA: vacant, CROSS-POLARS: T-prominent,
MetricsLith size: 10->25µm;
Data source notes: Bown via nannotax
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of BC16 zone (100% up, 126.4Ma, in Barremian stage). Data source: Bown et al. 1998 - zonal marker
First occurrence (base): at base of BC14 zone (0% up, 129.8Ma, in Barremian stage). Data source: Bown et al. 1998 - zonal marker

Plot of occurrence data:

References:

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

Perch-Nielsen, K. (1979d). Calcareous nannofossils from the Cretaceous between the North Sea and the Mediterranean. In, Weidmann, J. (ed.) Aspekte der Kreide Europas. International Union of Geological Sciences Series A. 6: 223-272. gs V O

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Nannoconus borealis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 7-7-2022

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10726 Go to Archive.is to create a permanent copy of this page - citation notes
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