Arkhangelskiella


Classification: Mesozoic -> Arkhangelskiales -> Arkhangelskiellaceae -> Arkhangelskiella
Sister taxa: Arkhangelskiella, Broinsonia, Thiersteinia,

Distinguishing features: R-units cover the distal surface, so coccolith appears bright, unicyclic, in LM (although darker towards outer edge); central-area has perforate plate with axial sutures. 4 tiers visible in side view.


Daughter taxa: (blue => in age window 0-800Ma)
Varible sized, with a narrow rim (<1.5µm)
Large sized (>10µm) with a broad rim (>1.5µm)
Like A. cymbiformis but with >5 perforations per quadrant (Verbeek 1977)
Specimens not identified to species level

Taxonomy:

Citation: Arkhangelskiella Vekshina, 1959
Rank: Genus
Type species: Arkhangelskiella cymbiformis Vekshina, 1959
Notes & discussion: The typcial species is A. cymbiformis. Other species have been described based on numbers of pores (A. specillata, A. pauciperforata) or rim width (A. maastrichtiensis. A. confusa). None of these species, however, are well supported and they all appear to intergrade with A. cymbiformis. Linnert & Mutterlose (2009) investigated Arkhangelskiella size varation in the Campanian and Maastrichtian and concluded that only one psecies was present - bt there is a well docuemented trend toward larger size through time.  

Farinacci & Howe catalog pages: Arkhangelskiella + + + + *

Distinguishing features: R-units cover the distal surface, so coccolith appears bright, unicyclic, in LM (although darker towards outer edge); central-area has perforate plate with axial sutures. 4 tiers visible in side view.


Morphology remarks:

The most common genus and a characteristic component of Maastrichtian nannofossil assemblages. The central area structure is described in detail by Moshkovitz and Osmond (1989).
Ditinction from Broinsoinia:
- in LM the entire cocclith rim is brightly birefringent (vs there being a distinct dark outer cycle in Broinsoinia)
- in SEM in distal view, a single cycle of elements, typically with clear sutures, covers the distal surface (vs inner and outer cycles in Broinsonia).
- in SEM in side view, four tiers of elements are visible (vs 3 in Broinsonia).
- in SEM in proximal view, they are essentially identical. 

Search data:
TagsLITHS: placolith, elliptical, CA: plate, pores, closed, R-UNITS: R-prominent, DETAILS: rim-unicyclic,
MetricsLith size: 5->20µm;
Sources: size range of included species
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 Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Coniacian Stage (0% up, 89.8Ma, in Coniacian stage). Data source: Total of range of species in this database

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 :: ::

Moshkovitz, S. & Osmond, K. (1989). The optical properties and microcrystallography of Arkhangelskiellaceae and some other calcareous nannofossils of the Late Cretaceous. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications. British Micropalaeontological Society Publication Series. 76-97. gs :: ::

Vekshina, V. N. (1959). Coccolithophoridae of the Maastrichtian deposits of the West Siberian lowlands. Siberian Science Research Institute of Geology Geophysics Mineralogy and Raw Materials. 2: 56-81. gs :: ::


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Arkhangelskiella compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 4-6-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10035 Go to Archive.is to create a permanent copy of this page - citation notes



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