Nannotax3 - ntax_mesozoic - Diazomatolithus

Diazomatolithus


Classification: ntax_mesozoic -> Watznaueriales -> Watznaueriaceae -> Diazomatolithus
Sister taxa: Bussonius, Cyclagelosphaera, Diazomatolithus, Lotharingius, Watznaueria ⟩⟨ Ansulasphaera, Bibreviconus, Perchnielsenella

Distinguishing features:
Parent taxon (Watznaueriaceae): Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.
This taxon: Modified watznaueriacean coccoliths with one conical/flaring (proximal) shield with elements joined along oblique sutures, and a smaller, flatter (distal) shield with the principle elements joined along near radial sutures. Usually circular with a central opening.


Daughter taxa (time control age-window is: 0-800Ma)
Diazomatolithus galicianus
Narrow rim and wide central opening.
Diazomatolithus lehmanii
Wide rim and moderate sized central-opening
Diazomatolithus sp.
Specimens not identified to species level

Taxonomy:

Citation: Diazomatolithus Noël, 1965
Rank: Genus
Type species: Diazomatolithus lehmanii Noël, 1965.

Farinacci & Howe catalog pages: Diazomatolithus *

Distinguishing features:
Parent taxon (Watznaueriaceae): Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.
This taxon: Modified watznaueriacean coccoliths with one conical/flaring (proximal) shield with elements joined along oblique sutures, and a smaller, flatter (distal) shield with the principle elements joined along near radial sutures. Usually circular with a central opening.


Morphology: Interpreted here as modified watznaueriacean coccoliths, with flaring proximal shield and distal shield in which the R-unit elements are reduced and the V-unit elements expanded. The shield with non-imbricating radial sutures is interpreted as distal; this cycle is homologous with the median, usually reduced, V-unit cycle in typical watznaueriaceans. The main R-unit distal shield cycle of Watznaueria is absent or greatly reduced. The proximal shield of Diazomatolithus, although rather elevated and tapering, displays laevogyre element curvature with broadly sinistral obliquity (when viewed proximally), a feature typical of watznaueriaceans.

Search data:
TagsLITHS: placolith, circular, CA: ca_disjunct, vacant, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 4->6µm;
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:
Notes: Last occurrence is recorded as Barremian in the Boreal area (Bown et al., 1998).
Last occurrence (top): in lower part of Aptian Stage (25% up, 123Ma, in Aptian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Tithonian Stage (0% up, 152.1Ma, in Kimmeridgian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs

Noël, D. (1965b). Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Essai de classification des coccolithes fossiles. Éditions du Centre National de la Recherche Scientifique, Paris. 1-209. gs


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Diazomatolithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 9-12-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10371 Go to Archive.is to create a permanent copy of this page - citation notes



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