Orastrum colligatum


Classification: Mesozoic -> Holococcoliths -> Common genera -> Orastrum -> Orastrum colligatum
Sister taxa: O. asarotum, O. campanensis, O. porosuturalis, O. perspicuum, O. robinsonii, O. colligatum, O. sp.,

Distinguishing features: Holococcolith formed of four large, high birefringence, interlocking blocks forming both a rim and central cross. Medium sized (5-6 µm)


Taxonomy:

Citation: Orastrum colligatum Henderiks & Ziveri, 1997
Rank: Species
Notes & discussion: The taxonomic concept of Orastrum has evolved since the description of this species and it's placement here is now clearly anomalous, since it lacks the dark rim characteristic of Orastrum. It would be better placed in Calculites 

Farinacci & Howe catalog pages: O. colligatum *

Distinguishing features: Holococcolith formed of four large, high birefringence, interlocking blocks forming both a rim and central cross. Medium sized (5-6 µm)


Morphology remarks: "Medium-sized, elliptical, moderately-birefringent holococcolith constructed of four smooth. interlocking. crystallographically-coherent blocks, forming an offset X in the central area." [Henderiks & Ziveri 1997]

Search data:
TagsLITHS: holococcolith, elliptical, CA: ca_conjunct, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 5->6µm; Segments: 4->4;
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): within Cenomanian Stage (93.90-100.50Ma, top in Cenomanian stage). Data source: Burnett 1998
First occurrence (base): within Albian Stage (100.50-112.95Ma, base in Albian stage). Data source: Burnett 1998

Plot of occurrence data:

References:

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

Henderiks, J. & Ziveri, P. (1997). Orastrum colligatum, a new holococcolith species from the Upper Albian-Cenomanian of the Russian Craton (Ukraine). Journal of Nannoplankton Research. 19(2): 109-111. gs V O


nannotaxlogo400px

Orastrum colligatum compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-9-2020

Taxon Search:
Advanced Search

Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10824 Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet on this page. Please do add comments if you spot any problems, or have information to share

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics