Polycyclolithaceae


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

Short diagnosis: Nannoliths composed of two superposed wall cycles and a central-area which may be closed, open and vacant, or spanned by a diaphragm-like structure. Elements have tangential c-axis orientation.


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Moderately tall, circular to stellate, multiradiate nannoliths with 5-9 petaloid wall-cycle elements surrounding a wide central area spanned by a median diaphragm. Typically H-shaped in side view.

Near circular to stellate eprolithids with relatively narrow wall formed from 9-16 brick-like, wall-cycle elements surrounding a wide central area spanned by an amedian diaphragm. The wall is usually lower than those seen in Eprolithus.

Eprolithid with narrow wall (formed from 16-24 small, brick-like elements) surrounding a wide central spanned by an amedian diaphragm.

Eprolithids with two cycles of five to seven ray-like, curved, wall-cycle elements surrounding a narrow median diaphragm.

Stellate (triradiate or tetraradiate) nannoliths with three or four ray-like elements; there may be a small central diaphragm.

Stellate to cubiform nannoliths with walls formed from two cycles of 4-9 elements and no central opening or diaphragm. When cubiform, the elements are joined along sutures that go out to the mid-point of the 'cube' edges.

Typically cubiform nannoliths usually formed from two superimposed and complexly-intergrown cycles of four pyramidal/blocky elements each

Nannolith formed of four blocks, nannolith shape is approx square with diagonal sutures, elements show tangential crystallographic orientations

Taxonomy:

Citation: Polycyclolithaceae Forchheimer, 1972 emend Varol, 1992
Rank: Family

Farinacci & Howe catalog pages:

Short diagnosis: Nannoliths composed of two superposed wall cycles and a central-area which may be closed, open and vacant, or spanned by a diaphragm-like structure. Elements have tangential c-axis orientation.


Morphology remarks: This family has previously been used for a wide variety of nannoliths with circular to stellate, multiradiate morphologies (e.g. Perch-Nielsen, 1985). Varol (1992) redefined the family to include only those forms which appear to represent a phylogenetic grouping, and this is followed below. Those forms which do not fall into this category are placed in the nannoliths incertae sedis.

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): within Kimmeridgian Stage (152.06-157.25Ma, base in Kimmeridgian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P.R. & Cooper, M.K.E., (1998). Jurassic. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 34-85.

Burnett, J.A., (1998). Upper Cretaceous. In: Bown, P.R. (Editor), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series. Chapman & Hall, London, pp. 132-199.

Forchheimer, S., (1972). Scanning electron microscope studies of Cretaceous coccoliths from the Köpingsberg Borehole No. 1, SE Sweden. Sveriges Geologiska Undersökning; Series C, #668, 65: 1-141.

Perch-Nielsen, K., (1985). Mesozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K. (Editors), Plankton Stratigraphy. Cambridge University Press, Cambridge, pp. 329-426.

Varol, O., (1992). Taxonomic revision of the Polycyclolithaceae and its contribution to Cretaceous biostratigraphy. Newsletters on Stratigraphy, 27(93-127).


Nannotax3 - Mesozoic - Polycyclolithaceae by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-5-2017

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