Palaeomicula


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

Distinguishing features: Nannolith formed of four blocks, nannolith shape is approx square with diagonal sutures, elements show tangential crystallographic orientations


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

Taxonomy:

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

Farinacci & Howe catalog pages: Palaeomicula *

Distinguishing features: Nannolith formed of four blocks, nannolith shape is approx square with diagonal sutures, elements show tangential crystallographic orientations


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

Evolution & Phylogeny: 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:
TagsLITHS: nannolith-radiate, circular, quadrate, CA: closed, T-UNITS: T-prominent,
MetricsLith size: 3->7µm; Segments: 4->4;
Sources: 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, 130.8Ma, in Hauterivian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Kimmeridgian Stage (0% up, 157.3Ma, in Kimmeridgian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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

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 :: ::


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Palaeomicula compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 1-6-2020

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Short stable page link: http://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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