Diazomatolithus


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

Distinguishing features: 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: (blue => in age window 0-800Ma)
A small- to medium-sized species of Diazomatolithus possessing a narrow rim and bicyclic distal shield.
Circular coccoliths with one conical/flaring shield (proximal) with elements joined along oblique sutures, and a smaller, flatter shield (distal) with the principle elements joined along near radial sutures. Moderately wide, open central area. In the LM they exhibit relatively low birefringence due to the expanded V-unit cycle, which forms the distal shield. The image flares when focussing and this species is often encountered in side view.
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: 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 remarks: 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, typically 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.

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 Tithonian 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. (1965). Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Éditions du Centre National de la Recherche Scientifique, Paris. -. gs


nannotaxlogo400px

Diazomatolithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 24-7-2019

Taxon Search:
Advanced Search

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



Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics