Quadrum


Classification: Mesozoic -> Nannoliths inc sedis -> Polycyclolithaceae -> Quadrum
Sister taxa: Eprolithus, Radiolithus, Farhania, Lithastrinus, Uniplanarius, Quadrum, Micula, Palaeomicula,

Distinguishing features: 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.


Daughter taxa (blue => in age window 0-300Ma)
Cubiform Quadrum with four wall-cycle elements.
Quadrum with a central depression and elements that appear to be thickened at the edges.
Quadrum with one cycle larger than the other.
Stellate to cubiform Quadrum with four large wall-cycle elements alternating with one to three smaller wall-cycle elements.
Quadrum with 7 elements per cycle
Quadrum with 8 elements per cycle
Quadrum with 9 elements per cycle
Large (>11ยต) Quadrum with 9 elements per cycle
Specimens not identified to species level

Taxonomy:

Citation: Quadrum Prins & Perch-Nielsen in Manivit et al., 1977
Rank: Genus
Type species: Quadrum gartneri Prins & Perch-Nielsen in Manivit et al., 1977
Notes & discussion: The Quadrum/em> species with more than 4 elements are very similar to the species of Lithastrinus with the same number of elements and have similar ranges so the distinction between them arguably requires more research.

Farinacci & Howe catalog pages: Quadrum + *

Distinguishing features: 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.

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 Albian Stage (100.50-112.95Ma, base in Albian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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.

Manivit, H.; Perch-Nielsen, K.; Prins, B. & Verbeek, J.W., (1977). Mid Cretaceous calcareous nannofossil biostratigraphy. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, B80(3): 169-181.


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Quadrum compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-4-2018

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