Nannotax3 - ntax_mesozoic - Palaeomicula Nannotax3 - ntax_mesozoic - Palaeomicula

Palaeomicula


Classification: ntax_mesozoic -> Braarudosphaerales -> Polycyclolithaceae -> Palaeomicula
Sister taxa: Eprolithus, Radiolithus, Farhania, Lithastrinus, Uniplanarius, Quadrum, Micula, Palaeomicula

Distinguishing features:
Parent taxon (Polycyclolithaceae): Nannoliths composed of two superposed wall cycles and a central-area which may be closed, open and vacant, or spanned by a diaphragm-like structure. Elements have tangential c-axis orientation.
This taxon: Nannolith formed of four blocks, nannolith shape is approx square with diagonal sutures, elements show tangential crystallographic orientations


Daughter taxa (time control age-window is: 0-800Ma)
Palaeomicula jacovidesii
Medium-sized (4.0–7.0 μm) circular species with four imbricated, triangular, segments positioned along the sinusoidal sutures.
Palaeomicula maltica
Almost square, sutures run to corners of nannolith, elements wedge-shaped and outline notched
Palaeomicula quadrisphena

Taxonomy:

Citation: Palaeomicula Varol & Jakubowski 1989
taxonomic rank: Genus
Type species: Tetralithus quadrisphenus Worsley 1971

Farinacci & Howe catalog pages: Palaeomicula *

Distinguishing features:
Parent taxon (Polycyclolithaceae): Nannoliths composed of two superposed wall cycles and a central-area which may be closed, open and vacant, or spanned by a diaphragm-like structure. Elements have tangential c-axis orientation.
This taxon: Nannolith formed of four blocks, nannolith shape is approx square with diagonal sutures, elements show tangential crystallographic orientations


Morphology:

Looks superficially like Micula but show opposite crystallographic orientation and is formed of single layer of four crystals.


Phylogenetic relations

Very unlikely to be directly related to Micula but may be a primitive polycyclolith, alternatively it may be an unrelated nannolith, or even a spine calyx

Search data:
LITHS: nannolith-radiate, circular, quadrate, CA: closed, CROSS-POLARS: T-prominent,
Lith size: 3->7µm; Segments: 4->4;
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 Hauterivian Stage (100% up, 126.5Ma, in Barremian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Kimmeridgian Stage (149.24-154.78Ma, base in Kimmeridgian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:

Varol, O. & Jakubowski, M. (1989). Some new nannofossil taxa. INA Newsletter. 11(1): 24-29. gs

Worsley, T. R. (1971). Calcareous nannofossil zonation of Upper Jurassic and Lower Cretaceous sediments from the Western Atlantic. In, Farinacci, A. (ed.) Proceedings of the Second Planktonic Conference Roma 1970. Edizioni Tecnoscienza, Rome 2: 1301-1321. gs O


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Palaeomicula compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-5-2024

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10848 Go to Archive.is to create a permanent copy of this page - citation notes
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