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)
Small to medium sized with a <1.5µm thick rim
Large sized (>8µm) 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

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. 

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. & Heck, S. E. v. (eds) Nannofossils and their applications. Ellis Horwood, Chichester 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: 18-11-2019

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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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