Nannotax3 - ntax_main - Diazomatolithus

Nannotax3 - ntax_main - Diazomatolithus Nannotax3 - ntax_main - Diazomatolithus

Diazomatolithus

Classification: ntax_main -> Mesozoic nannofossils -> Watznaueriales -> Watznaueriaceae -> Diazomatolithus
Sister taxa: Tergestiella ⟩⟨ Bussonius, Cyclagelosphaera, Diazomatolithus, Lotharingius, Watznaueria ⟩⟨ Ansulasphaera, Bibreviconus, Perchnielsenella

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

Taxonomic rank: genus

Type species: Diazomatolithus lehmanii Noël, 1965.

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.

Farinacci & Howe catalog pages: Diazomatolithus *

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:

LITHS: placolith, circular, CA: ca_disjunct, vacant, CROSS-POLARS: rim-unicyclic, R-prominent,

Lith 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): at top of Early Aptian Substage (100% up, 118.7Ma, in Aptian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Tithonian Stage (143.10-149.24Ma, base in Tithonian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Watznaueriaceae

References:

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

Noël, D. (1965). 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

Diazomatolithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 12-6-2025

Taxon Search:

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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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