Biscutum constans


Classification: Mesozoic -> Podorhabdales -> Biscutaceae -> Biscutum -> Biscutum constans
Sister taxa: B. arrogans, B. asymmetricum, B. boletum, B. constans, B. coronum, B. davyi, B. dekaenelii, B. depravatus, B. dissimilis, B. dorsetensis, B. dubium, B. ellipticum, B. erismatum, B. gaultensis, B. grande, B. hattneri, B. intermedium, B. magnum, B. melaniae, B. notaculum, B. planum, B. profundum, B. thurowii, B. virginica, B. zulloii, B. sp.,

Distinguishing features: Minute to medium biscutaceans without any discernible (LM) structure inside their birefringent central tube cycle. These forms show considerable variation in size and in the relative width of the central tube. The smallest forms (c.1.5µm) are barely discernible in the LM.


Daughter taxa: (blue => in age window 0-800Ma)
A large, elliptical Biscutum with a large central opening

Taxonomy:

Citation: Biscutum constans (Górka, 1957) Black in Black and Barnes, 1959
Rank: Species
Basionym: Discolithus constans Górka, 1957
Synonyms: Biscutum ellipticum (Górka, 1957) Grün in Grün and Allemann, 1975 (basionym: Tremalithus ellipticus Górka, 1957)
List of Cretaceous synonyms, from Verbeek (1977)
Notes & discussion: In the Jurassic B. constans type specimens occur but they are typically somewhat smaller than in the Cretaceous and are often named B. dubium

Farinacci & Howe catalog pages: Discolithus constans * , Biscutum testudinarium * , Biscutum castrorum * , Cribrosphaerella tectiforma * , Coccolithites polycingulatus * , Biscutum blacki * , Maslovella blackii * , Maslovella pulchra * , Biscutum multiforme * , Biscutum concavum * , Biscutum gartneri * , Biscutum martellum * , Biscutum sulcata *

Distinguishing features: Minute to medium biscutaceans without any discernible (LM) structure inside their birefringent central tube cycle. These forms show considerable variation in size and in the relative width of the central tube. The smallest forms (c.1.5µm) are barely discernible in the LM.

Geological Range:
Last occurrence (top): within Late Maastrichtian Substage (66.04-69.91Ma, top in Maastrichtian stage). Data source: Bown et al. 1998
First occurrence (base): within Bathonian Stage (166.07-168.28Ma, base in Bathonian stage). Data source: Bown et al. 1998

Plot of occurrence data:

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Biscutum constans, synonyms included - Biscutum castrorum; Biscutum constans; Biscutum testudinarium; space-time plot :: Samples map :: Parent: Biscutum

    References:

    Black, M. & Barnes, B. (1959). The structure of Coccoliths from the English Chalk. Geological Magazine. 96: 321-328. gs

    Black, M. (1971a). Coccoliths of the Speeton Clay and Sutterby Marl. Proceedings of the Yorkshire Geological Society. 38: 381-424. gs

    Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs

    Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. The University of Kansas Paleontological Contributions. Article 51 (Protista 2): 1-79. gs

    Burns, D. A. (1976). Nannofossils from the Lower and Upper Cretaceous deposits, Nettleton,Lincolnshire, England. Revista Española de Micropaleontología. 8(2): 279-300. gs

    Górka, H. (1957). Les Coccolithophoridés du Maestrichtien supérieur de Pologne. Acta Palaeontologica Polonica. 2: 239-284. gs

    Grün, W. & Allemann, F. (1975). The Lower Cretaceous of Caravaca (Spain): Berriasian Calcareous Nannoplankton of the Miravetes Section (Subbetic Zone, Prov. of Murcia). Eclogae Geologicae Helvetiae. 68: 147-211. gs

    Huh, J. M. & Smith, C. I. (1972). Coccoliths and related calcareous nannofossils from the Upper Cretaceous Fencepost Limstone of Northwestern Kansas. Contributions from the Museum of Paleontology, University of Michigan. 24(3): 17-22. gs

    Perch-Nielsen, K. (1968c). Der Feinbau und die Klassifikation der Coccolithen aus dem Maastrichtien von Danemark. Biologiske Skrifter. Kongelige Danske Videnskabernes Selskab. 16: 1-96. gs

    Perch-Nielsen, K. (1973). Neue Coccolithen aus dem Maastrichtien von Danemark, Madagaskar und Agypten. Geological Society of Denmark, Bulletin. 22: 306-333. gs

    Pienaar, R. N. (1968). Upper Cretacous coccolithophorids from Zululand, South Africa. Palaeontology. 11(3): 361-367. gs

    Reinhardt, P. (1965). Neue Familien für fossile Kalkflagellaten (Coccolithophoriden, Coccolithineen). Monatsberichte der Deutschen Akademie der Wissenschaften zu Berlin. 7: 30-40. gs


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    Biscutum constans compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-8-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10070 Go to Archive.is to create a permanent copy of this page - citation notes



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