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

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

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 1971. Edizioni Tecnoscienza, Rome 2: 1301-1321. gs


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Palaeomicula compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-7-2019

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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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