Conusphaera mexicana


Classification: Mesozoic -> Nannoliths inc sedis -> Eoconusphaeraceae -> Conusphaera -> Conusphaera mexicana
Sister taxa: C. mexicana, C. rothii, C. maledicto, C. sinespina, C. sp.,

Distinguishing features: Tapering nannoliths with steeply sloping rim and central area filled with a core of radially arranged elements, which in LM shows relatively uniform birefringence with an axial extinction line. Most commonly seen in side view.


Daughter taxa: (blue => in age window 0-800Ma)
Tall (height >4 microns) tapering nannoliths with steeply sloping rim and central area filled with a core of radially arranged elements, which in LM shows relatively uniform birefringence with an axial extinction line. Most commonly seen in side view.
Short (height <4 microns) tapering nannoliths with steeply sloping rim and central area filled with a core of radially arranged elements, which in LM shows relatively uniform birefringence with an axial extinction line. Seen in plan and side view.

Taxonomy:

Citation: Conusphaera mexicana Trejo, 1969
Rank: Species
Notes & discussion: Short (height <4 microns: Conusphaera mexicana minor) and tall (height >4 microns: Conusphaera mexicana mexicana) subspecies are distinguished. Tethyan distribution.

Farinacci & Howe catalog pages: Conusphaera mexicana * , ,

Distinguishing features: Tapering nannoliths with steeply sloping rim and central area filled with a core of radially arranged elements, which in LM shows relatively uniform birefringence with an axial extinction line. Most commonly seen in side view.


Ecology & Biogeography: Tethyan distribution.

Geological Range:
Notes: Most commonly recorded in the Tithonian. Last occurrence Aptian according to Bergen (1994).
Last occurrence (top): within NJ18 zone (145.01-148.35Ma, top in Tithonian stage). Data source: [PRB rough estimate]
First occurrence (base): within NJ17a subzone (149.09-151.50Ma, base in Tithonian stage). Data source: Bown & Cooper 1998

Plot of occurrence data:

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Conusphaera

    References:

    Bergen, J. A. (1994). Berriasian to early Aptian calcareous nannofossils from the Vocontian Trough (SE France) and Deep Sea Drilling Site 534: new nannofossil taxa and a summary of low-latitude biostratigraphic events. Journal of Nannoplankton Research. 16: 59-69. gs

    Bown, P. R. & Cooper, M. K. E. (1989a). Conical nannofossils in the Mesozoic. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications. British Micropalaeontological Society Publication Series. 98-106. gs

    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

    Bralower, T. J., Monechi, S. & Thierstein, H. R. (1989). Calcareous nannofossil zonation of the Jurassic-Cretaceous boundary interval and correlation with the geomagnetic polarity timescale. Marine Micropaleontology. 14: 153-235. gs

    Trejo, M. (1969). Conusphaera mexicana, un nuevo coccolitoforido del Jurassico Superior de Mexico. Revista del Instituto Mexicano del Petroleo. 1: 5-15. gs


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    Conusphaera mexicana compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-7-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10270 Go to Archive.is to create a permanent copy of this page - citation notes



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