Nannotax3 - ntax_mesozoic - N. steinmannii group

N. steinmannii group


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

Distinguishing features:
Parent taxon (Nannoconus): Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity (~>1µm in width) or canal (~<1µm in width). Plate c-axes are arranged tangentially to the longitudinal axis.
This taxon: Tapering nannoconids with narrow central canal (ct < wt).


Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Nannoconus bermudezii
Very large, tapering (20-28 microns) (height ~3x width or more).

Nannoconus dolomiticus
Tall, cylindrical (parallel sided) (height ~3x width or more).

Nannoconus farinacciae
Squat, pear-shaped.

Nannoconus regularis
Squat, barrel-shaped (similar height and width).

Nannoconus steinmannii
Pear-shaped to tapering
N. steinmannii subsp. minor
N. steinmannii subsp. steinmannii

Taxonomy:

Citation: N. steinmannii group
Rank: species group
Taxonomic discussion: informal grouping first used here

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

Distinguishing features:
Parent taxon (Nannoconus): Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity (~>1µm in width) or canal (~<1µm in width). Plate c-axes are arranged tangentially to the longitudinal axis.
This taxon: Tapering nannoconids with narrow central canal (ct < wt).

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, hollow, CA: vacant, CROSS-POLARS: T-prominent,
MetricsLith size: 8->30µm;
Data source notes: size range of included species
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 Campanian Stage (100% up, 72.1Ma, in Campanian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Tithonian Stage (0% up, 152.1Ma, in Kimmeridgian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Casellato, C. E. (2010). Calcareous nannofossil biostratigraphy of Upper Callovian - Lower Berriasian successions from the Souhern Alps, North Italy. Rivista Italiana di Paleontologia e Stratigrafia. 116(3): 357-404. gs V O


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N. steinmannii group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-1-2022

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10715 Go to Archive.is to create a permanent copy of this page - citation notes



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