Distinguishing features:
Parent taxon (Podorhabdales): Placolith (or modified placolith) coccoliths showing little or no imbrication. Typically, V-units form distal shield, R-units form proximal shield.
This taxon: 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 (time control age-window is: 0-800Ma) | Granddaughter taxa | ||||
Manivitella Tubodiscids with low proximal collar cycle and wide central-area. | |||||
Tubodiscus Tubodiscids with high and birefringent proximal collar cycle and wide central-area. Rim image is clearly bicyclic in XPL. | Tubodiscus bellii Tubodiscus burnettiae Tubodiscus frankiae Tubodiscus jurapelagicus Tubodiscus verenae Tubodiscus sp. |
Taxonomy:
Farinacci & Howe catalog pages: Tubodiscaceae *
Distinguishing features:
Parent taxon (Podorhabdales): Placolith (or modified placolith) coccoliths showing little or no imbrication. Typically, V-units form distal shield, R-units form proximal shield.
This taxon: 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:
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.
: placolith, |
Lith size: 0->0µm; |
Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Late Tithonian Substage (143.10-145.00Ma, base in Tithonian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Lower Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 86-131. gs O Thierstein, H. R. (1973). Lower cretaceous calcareous nannoplankton biostratigraphy. Abhandlungen der Geologischen Bundesanstalt. 29: 3-52. gs References:
Tubodiscaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 5-12-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11271 Go to Archive.is to create a permanent copy of this page - citation notes |
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