Eoconusphaeraceae


Classification: Mesozoic -> Nannoliths inc sedis -> Eoconusphaeraceae
Sister taxa: Goniolithaceae, Eoconusphaeraceae, Lapideacassaceae, Microrhabdulaceae, Polycyclolithaceae, Nannoliths inc sed - radiate multielement, Nannoliths inc sed - other,

Short diagnosis: Nannoliths with a truncated-cone-like morphology constructed from an outer rim of thin, elements joined along vertical sutures, and an inner core of numerous radial lamellae that may protrude distally.


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Tapering nannoliths with steeply sloping rim and central area filled with a core of radially arranged elements. Most commonly seen in side view. The rim elements are joined along vertical sutures (protolith-rim-like).

Tall tapering nannoliths with steeply sloping rim and central area filled with a mass of radially arranged elements. LM image shows relatively uniformily birefringent core with axial extinction line.

Taxonomy:

Citation: Eoconusphaeraceae Kristan-Tollmann, 1988
Rank: Family

Farinacci & Howe catalog pages: Eoconusphaeraceae [no catalog entry yet]

Short diagnosis: Nannoliths with a truncated-cone-like morphology constructed from an outer rim of thin, elements joined along vertical sutures, and an inner core of numerous radial lamellae that may protrude distally.


Morphology remarks: The two included Jurassic genera (Eoconusphaera, Conusphaera, plus arguably Calcivascularis) have non-concurrent stratigraphic ranges but very closely comparable morphologies and biogeographies (Bown and Cooper, 1989). The taxonomic validity of this grouping is thus uncertain. These forms may prove to be modified heterococcoliths.

See also: Calcivascularis - possibly related genus currently classified in the Parhabdolithaceae;

Geological Range:
Last occurrence (top): within Aptian Stage (112.95-126.30Ma, top in Aptian stage). Data source: Total of range of species in this database
First occurrence (base): within Norian Stage (209.46-228.35Ma, base in Norian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P.R. & Cooper, M.K.E., (1989). Conical nannofossils in the Mesozoic. In: Crux, J.A. and Heck, S.E.v. (Editors), Nannofossils and their applications. British Micropalaeontological Society Series. Ellis Horwood, Chichester, pp. 98-106.

Bown, P.R., (1998). Triassic. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 29-33.

Bown, P.R.; Rutledge, D.C.; Crux, J.A. & Gallagher, L.T., (1998). Early Cretaceous. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 86-131.

Kristan-Tollmann, E., (1988). Coccolithen aus den Älteren Allgäuschichten (Alpiner Lias, Sinemur) von Timor, Indonesien. Geologische und Paläontogische Mitteilungen Innsbruck, 15: 71-83.


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Eoconusphaeraceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 16-12-2017

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