Nannotetrina


Classification: ntax_cenozoic -> Zygodiscales -> Zygodiscaceae -> Nannotetrina
Sister taxa: Lophodolithus, Neochiastozygus, Zygodiscus ⟩⟨ Chiphragmalithus, Isthmolithus, Neococcolithes, Nannotetrina

Daughter taxa (time control age-window is: 0-800Ma)
cross-shaped species
Nannotetrina spinosa
Broadly square with elongations from the corners and shorter spines from the sides resulting in an stellate (eight-pointed) symmetrical outline.
Nannotetrina pappii
Broadly square to cruciform with spinose projections resulting in a stellate (eight-pointed) asymmetrical outline.
Nannotetrina fulgens
Large to very large Nannotetrina with arms that taper to a point.
Nannotetrina alata
Large to very large Nannotetrina with long parallel sided free rays with blunt ray tips.
compact species, without free rays
Nannotetrina cristata
Large three-dimensional Nannotetrina, broadly cross-shaped with curving arms that widen towards their ends and with inter-arm fill.
Nannotetrina plana
Subcircular to broadly elliptical with a low basal disc crossed by broad, raised cross-bars.
Nannotetrina ruda
Compact, blocky, form with poorly developed arms
Nannotetrina sp.
Specimens which cannot be assigned to any established species - and some rarely cited species

Taxonomy:

Citation: Nannotetrina Achuthan and Stradner, 1969
Rank: Genus
Type species: Nannotetrina fulgens (Stradner, 1960) Achuthan and Stradner, 1969 [Nannotetraster]
Taxonomic discussion: The genus was originally called Nannotetraster but the type of that genus Discoaster staurophora is now considered to belong to Micula so the name Nannotetrina was substituted.

Distinguishing features: Typically large (>8 µm) cruciform nannoliths with high curving ridges running from the centre to ray tips.

Farinacci & Howe catalog pages: Nannotetrina *


Morphology: Relatively low birefringence in XPL, but the four rays are separate crystal units and go into extinction separately. Restricted to middle Eocene zones NP14b to NP16. Other nannofossils with similar appearance include four-rayed discoasters, e.g. Discoaster cruciformis and disarticulated cross-bars of Neococcolithes protenus.

Size: Typically large (8-15 µm) and can be very large - up to 30 µm

See also: Neococcolithes - possible heterococcolith ancestor;

Search data:
TagsLITHS: nannolith-radiate, star-shaped, CA: ca_conjunct, cross-axial, CROSS-POLARS: V-prominent,
MetricsLith size: 8->30µm; Segments: 4->4;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Largely restricted to middle Eocene zones NP15 to NP16.
Last occurrence (top): in lower part of Bartonian Stage (22% up, 40.4Ma, in Bartonian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Lutetian Stage (0% up, 47.8Ma, in Lutetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Achuthan, M. V. & Stradner, H. (1969). Calcareous nannoplankton from the Wemmelian stratotype. In, Brönnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva 1967. Brill, Leiden, Geneva 1: 1-13. gs

Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs


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Nannotetrina compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 11-4-2021

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=885 Go to Archive.is to create a permanent copy of this page - citation notes



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