Biscutum dubium


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

Distinguishing features: Small, normally elliptical Biscutum with narrow central area. Bicyclic image in XPL.


Taxonomy:

Citation: Biscutum dubium (Noël, 1965) Grün in Grün et al., 1974
Rank: Species
Basionym: Palaeopontosphaera dubia Noël, 1965
Synonyms: Discorhabdus longicornis Medd 1979 [cf. Neptune database synonymy]

Farinacci & Howe catalog pages: P. dubia + + + * , D. longicornis *

Distinguishing features: Small, normally elliptical Biscutum with narrow central area. Bicyclic image in XPL.


Morphology: This name is primarily used in the Jurassic, but small Biscutum coccoliths are also a common feature of Cretaceous assemblages, where they tend to be called B. constans or B. ellipticum.

Search data:
TagsLITHS: placolith, elliptical, CA: ca_disjunct, process, closed, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 2.5->4µm;
Data source notes: illustrated specimens, Mattioli et al. 2004
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Berriasian Stage (139.39-145.01Ma, top in Berriasian stage). Data source: Bown & Cooper 1998
First occurrence (base): within Early Toarcian Substage (178.24-182.70Ma, base in Toarcian stage). Data source: Bown & Cooper 1998

Plot of occurrence data:

References:

Barnard, T. & Hay, W. W. (1974). On Jurassic coccoliths: A tentative zonation of the Jurassic of Southern England and North France. Eclogae Geologicae Helvetiae. 67(3): 563-585. gs V O

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. gs

Bown, P. R. (1987a). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs

Crux, J. A. (1987b). Early Jurassic calcareous nannofossil biostratigraphic events. Newsletters on Stratigraphy. 17: 79-100. gs

Crux, J. A. (1987a). Concerning dimorphism in Early Jurassic coccoliths and the origin of the genus Discorhabdus Noël 1965. Abhandlungen der Geologischen Bundesanstalt. 39: 51-55. gs V O

de Kaenel, E. & Bergen, J. A. (1993). New Early and Middle Jurassic coccolith taxa and biostratigraphy from the eastern proto-Atlantic (Morocco, Portugal and DSDP Site 547B). Eclogae Geologicae Helvetiae. 86(861-907): -. gs V O

de Kaenel, E. & Bergen, J. A. (1996). Mesozoic calcareous nannofossil biostratigraphy from sites 897, 899, and 901, Iberia Abyssal Plain: New biostratigraphic evidence. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 27-59. gs V O

Grün, W. & Zweili, F. (1980). Das kalkige Nannoplankton der Dogger-Malm-Grenze im Berner Jura bei Liesberg (Schweiz). Jahrbuch der Geologischen Bundesanstalt. 123: 231-341. gs V O

Grün, W., Prins, P. & Zweili, F. (1974). Coccolithophoriden aus dem Lias epsilon von Holzmaden (Deutschland). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 147: 294-328. gs

Mattioli, E., Pittet, B., Young, J. R. & Bown, P. R. (2004a). Biometric analysis of Pliensbachian-Toarcian (Lower Jurassic) coccoliths of the family Biscutaceae: intra- and interspecific variability versus palaeoenvironmental influence. In, Villa, G., Lees, J. A. & Bown, P. R. (eds) Calcareous Nannofossil Palaeoecology and Palaeocenographic Reconstructions, Proceedings of the INA9 conference, Parma 2002. Marine Micropaleontology. 52(1-4): 5-27. gs

Medd, A. W. (1979). The Upper Jurassic coccoliths from the Haddenham and Gamlingay boreholes (Cambridgeshire, England). Eclogae Geologicae Helvetiae. 72: 19-109. gs V O

Noël, D. (1965b). Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Éditions du Centre National de la Recherche Scientifique, Paris. 1-209. gs

Noël, D. (1973). Nannofossiles calcaires de sédiments jurassiques finement laminés. Bulletin du Muséum National d'Histoire Naturelle. 75: 95-156. gs

Rood, A. P., Hay, W. W. & Barnard, T. (1971). Electron Microscope Studies of Oxford Clay Coccoliths. Eclogae Geologicae Helvetiae. 64: 245-272. gs V O

Rood, A. P., Hay, W. W. & Barnard, T. (1973). Electron microscope studies of Lower and Middle Jurassic coccoliths. Eclogae Geologicae Helvetiae. 66: 365-382. gs V O

Varol, O. & Girgis, M. (1994). New taxa and taxonomy of some Jurassic to Cretaceous calcareous nannofossils. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 192: 221-253. gs

Wise, S. W. (1983). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 71 in the Falkland Plateau region, Southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 71: 481-550. gs V O


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Biscutum dubium compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-1-2021

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