Nannotax3 - ntax_mesozoic - Rhagodiscus indistinctus Nannotax3 - ntax_mesozoic - Rhagodiscus indistinctus

Rhagodiscus indistinctus


Classification: ntax_mesozoic -> Eiffellithales -> Rhagodiscaceae -> Rhagodiscus -> Rhagodiscus indistinctus
Sister taxa: R. achlyostaurion, R. amplus, R. angustus, R. asper, R. cepekii, R. dekaenelii, R. infinitus, R. pseudoangustus, R. splendens ⟩⟨ R. adinfinitus, R. gallagheri, R. indistinctus, R. pancostii, R. plebeius, R. robustus, R. sageri, R. sicutclipeus ⟩⟨ R. eboracensis, R. hamptonii, R. reniformis, R. sp.

Distinguishing features:
Parent taxon (Rhagodiscus): Loxolith coccoliths with low rim and central-area filled by a granular plate which may be perforate and/or spine-bearing. In xpl the rim is unicyclic moderately bright, the central area is granular, lacking a clear extinction cross.
This taxon: Medium to large elliptical rhagodiscid-like coccolith with moderately broad rim and narrow central area spanned by a spine (base). Rim is unicyclic in XPL and overall the coccolith exhibits low birefringence.


Taxonomy:

Citation: Rhagodiscus indistinctus Burnett, 1997
taxonomic rank: Species

Farinacci & Howe catalog pages: R. indistinctus *

Distinguishing features:
Parent taxon (Rhagodiscus): Loxolith coccoliths with low rim and central-area filled by a granular plate which may be perforate and/or spine-bearing. In xpl the rim is unicyclic moderately bright, the central area is granular, lacking a clear extinction cross.
This taxon: Medium to large elliptical rhagodiscid-like coccolith with moderately broad rim and narrow central area spanned by a spine (base). Rim is unicyclic in XPL and overall the coccolith exhibits low birefringence.


Morphology:

A medium-sized, elliptical coccolith with a moderately broad rim, and a narrow central area which contains a spine(-base). It is unclear whether the central area contains a floor or not. The coccolith is of low birefringence, and the spine-base often difficult to discern, which gives it an overall appearance of indistinction. The indistinct appearance of this form differ- entiates it from other species of Rhagodiscus. Although this form may appear to be simply a poorly-preserved specimen, it has a well-defined distribution in a number of locations, in material with a range of preservational states, and is thus believed to represent a definite species. [Burnett 1997]

Search data:
LITHS: murolith, elliptical, CA: plate, process, CROSS-POLARS: rim-unicyclic, R-prominent,
Lith size: 8->10µm;
Data source notes: original description & illustrated specimens
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 Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Lees & Bown 2005 - consistently present to end Cret
First occurrence (base): within Early Campanian Substage (80.60-83.65Ma, base in Campanian stage). Data source: Burnett 1998

Plot of occurrence data:

References:

Burnett, J. A. (1997c). New species and new combinations of Cretaceous nannofossils and a note on the origin of Petrarhabdus (Deflandre) Wise & Wind. Journal of Nannoplankton Research. 19(2): 133-146. gs

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Lees, J. A. & Bown, P. R. (2005). Upper Cretaceous calcareous nannofossil biostratigraphy, ODP Leg 198 (Shatsky Rise, Northwest Pacific Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-60. gs

Rahman, A. & Roth, P. H. (1991). Upper Jurassic calcareous nannofossils from the DSDP Site 534 in the Blake Bahama Basin, western North Atlantic. Eclogae Geologicae Helvetiae. 84: 765-789. gs O


nannotaxlogo400px

Rhagodiscus indistinctus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 13-4-2024

Taxon Search:
Advanced Search

Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11023 Go to Archive.is to create a permanent copy of this page - citation notes
nannotaxlogo400px

Nannotax is being sponsored through 2024 by Woodside Energy and Shell USA


Add Comment

* Required information
Captcha Image
Powered by Commentics

Comments

No comments yet. Be the first!