Tubodiscaceae


Ancestry: Mesozoic -> Podorhabdales -> Tubodiscaceae
Sister taxa: Axopodorhabdaceae, Biscutaceae, Calyculaceae, Cretarhabdaceae, Mazaganellaceae, Prediscosphaeraceae, Tubodiscaceae,

Short diagnosis: Elliptical placoliths composed of two narrow shields and a third, narrow, proximally-situated collar cycle that is variable in height. The central-area is broad and open; no central structures have yet been observed. The LM image is dark, although the collar cycle is brighter.


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Tubodiscids with low proximal collar cycle and wide central-area.

Tubodiscids with high and birefringent proximal collar cycle and wide central-area. Rim image is clearly bicyclic in XPL.

Taxonomy:

Citation: Tubodiscaceae Bown & Rutledge, 1997 in Bown & Young, 1997
Rank: Family
Type species: Tubodiscus Thierstein, 1973.

Farinacci & Howe catalog pages:

Short diagnosis: Elliptical placoliths composed of two narrow shields and a third, narrow, proximally-situated collar cycle that is variable in height. The central-area is broad and open; no central structures have yet been observed. The LM image is dark, although the collar cycle is brighter.


Morphology remarks: Elliptical placoliths composed of two narrow shields and a third, narrow, proximally-situated collar cycle that is variable in height. The central-area is broad and open; no central structures have yet been observed. The LM image is dark, although the collar cycle is brighter.
Manivitella and Tubodiscus have similar rim structures but differ in the elevation of the proximal collar cycle, which is low in Manivitella and higher in Tubodiscus. The 'high-collared' forms appear distinct in the LM, as the increased height of the cycle produces high birefringence colours.

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 Tithonian Stage (145.01-152.06Ma, base in Tithonian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P.R. & Young, J.R., (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research, 19(1): 21-36.

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.

Thierstein, H.R., (1973). Lower cretaceous calcareous nannoplankton biostratigraphy. Abhandlungen der Geologischen Bundesanstalt, 29: 3-52.


Nannotax3 - Mesozoic - Tubodiscaceae by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-6-2017

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