Nannotax3 - ntax_cenozoic - B. clavus group Nannotax3 - ntax_cenozoic - B. clavus group

B. clavus group


Classification: ntax_cenozoic -> Syracosphaerales -> Rhabdosphaeraceae -> Blackites -> B. clavus group
Sister taxa: B. morionum group, B. clavus group, B. inflatus group, B. spinosus group, B. amplus group, B. sp.

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Blackites bipartitus
Spine vase-shaped constructed from two distinct structural units when viewed in XPL. Typically the height is about 2x the width, and the maximum spine width is similar to base width.

Blackites clavus
Spine short and tapers rapidly to a point. Typically the spine height is similar to base width.
The rim is relatively broad and the outer cycle is small and does not lie distally over the inner cycle. In overall shape the coccolith and spine resemble a short nail or pin.

Blackites dupuisii
Spine tall, tapering, hollow; broad at its base but tapering and narrow in its upper half. Two or three spine-cycles are seen low on the spine, along with striated ornamentation. Spine height is usually 2-3x basal width.
Blackites cf. B. dupuisii

Blackites gamai
Spine broad, hollow, bullet-shaped; initially broadens slightly before tapering gently to a point.
Typically the height of the spine is greater than the basal width.

Blackites spiculiformis
Rhabdolith coccolith with a Blackites gladius-like rim and a relatively short, narrow, tapering, hollow spine that may incorporate a basal collar.

Blackites thiedei


Taxonomy:

Citation: Blackites clavus group
Taxonomic rank: species group
Taxonomic discussion: informal grouping used here to sort species within this large genus

Distinguishing features:
Parent taxon (Blackites): Coccoliths process-bearing with complex base including outer rim, radial lath and lamellar cycles
This taxon: Spine conical, tapering with maximum width near base

Farinacci & Howe catalog pages:


Size:
Mostly medium sized - spines typically 5-8 µm high, can get up to about 12 µm. Bases 3-5 µm across

Search data:
Lith size: 5->12µm;
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 NP16 zone (100% up, 40.4Ma, in Bartonian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP10 zone (54.17-55.86Ma, base in Ypresian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:


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B. clavus group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-2-2025

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=58 Go to Archive.is to create a permanent copy of this page - citation notes
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