Jimenezberrocosoia birchiae


Classification: ntax_mesozoic -> Podorhabdales -> Biscutaceae -> Jimenezberrocosoia -> Jimenezberrocosoia birchiae
Sister taxa: J. birchiae, J. bosunensis

Distinguishing features: Small to very small (<3µm), central area very narrow 


Taxonomy:

Citation: Jimenezberrocosoia birchiae Lees & Bown 2016
Rank: Species

Farinacci & Howe catalog pages: J. birchiae *

Distinguishing features: Small to very small (<3µm), central area very narrow 


Morphology: Very small to small Jimenezberrocosoia coccoliths with a broadly elliptical outline, usually relatively long slits between the elements of the distal shield and a very constricted central-area, with a diameter of less than half the width of the rim, spanned by an axial cross that is surrounded by a single set of concentric bars (Pl.1, figs 6, 9). The central structure is attached to the rim at the long- and short-axis points. A short spine sits at the centre of the cross. The elements of the proximal shield are thin and widely-spaced radiating from the central tube-cycle (Pl.1, fig.9). The ends of the arms of the cross structure can be seen to attach to this tube-cycle, proximally. [Lees & Bown 2016]

Remarks: The small size of these coccoliths (~3μm or less) has precluded us from unequivocally identifying this species in the LM so far. We have found specimens of this species in SEM samples from Blake Nose, in a similarly clay-rich lithology. [Lees & Bown 2016]

Size: Holotype L = 3.5μm, W = 3.0μm

Search data:
TagsLITHS: placolith, elliptical, CA: concentric-ring(s), cross-axial, ca_disjunct, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 2->4µm;
Data source notes: original description
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within UC7 zone (92.99-93.55Ma, top in Turonian stage). Data source: Lees & Bown 2016
First occurrence (base): within UC0a subzone (100.84-103.13Ma, base in Albian stage). Data source: Lees & Bown 2016

Plot of occurrence data:

References:

Lees, J. A. & Bown, P. R. (2016). New and intriguing calcareous nannofossils from the Turonian (Upper Cretaceous) of Tanzania. Journal of Nannoplankton Research. 36(1): 83-95. gs V O

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Jimenezberrocosoia birchiae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 13-4-2021

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