Distinguishing features:
Parent taxon (Arkhangelskiales): Tiered placoliths with 3-5 closely-appressed shields.
This taxon: Arkhangelskielids with shields predominantly formed of R-units, thus bright in cross-polarised light; V-units often form dark outer rim.
Daughter taxa (time control age-window is: 0-800Ma) | Granddaughter taxa | ||||
Arkhangelskiella 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. | Arkhangelskiella maastrichtiensis Arkhangelskiella cymbiformis Arkhangelskiella confusa Arkhangelskiella specillata Arkhangelskiella sp. | ||||
Broinsonia Outer rim of V-units, with slight clockwise obliquity, visible on distal surface and form dark rim in LM; central-area spanned by an axial cross, grill or perforate plate. 3 tiers visible in side view. | Broinsonia parca Broinsonia enormis Broinsonia furtiva Broinsonia gammation Broinsonia verecundia Broinsonia dentata Broinsonia cenomanica Broinsonia ethmoquadrata Broinsonia signata Broinsonia galloisii Broinsonia matalosa Broinsonia viriosa Broinsonia sp. | ||||
Thiersteinia Similar to Broinsonia but with well-developed central spine |
Taxonomy:
Farinacci & Howe catalog pages: Arkhangelskiellaceae + *
Distinguishing features:
Parent taxon (Arkhangelskiales): Tiered placoliths with 3-5 closely-appressed shields.
This taxon: Arkhangelskielids with shields predominantly formed of R-units, thus bright in cross-polarised light; V-units often form dark outer rim.
Morphology:
Moshkovitz & Osmond (1989) analyse the birefringence pattern in detail.
: placolith, |
Lith size: 0->0µm; |
Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Valanginian Stage (132.60-137.70Ma, base in Valanginian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Lower Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 86-131. gs O Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles. 51 (Protista 2): 1-79. gs O 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: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series . 76-97. gs O Vekshina, V. N. (1959). Coccolithophoridae of the Maastrichtian deposits of the West Siberian lowlands. Trudyi Instituta Geologii i Geogiziki, Sibiriskoe Otlodelenie, Akademiya Nauk SSSR (Nauka) Moscow. 2: 56-81. gsReferences:
Arkhangelskiellaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-11-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10042 Go to Archive.is to create a permanent copy of this page - citation notes |
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