Distinguishing features: Parent taxon (Tubodiscaceae): 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. This taxon: Tubodiscids with high and birefringent proximal collar cycle and wide central-area. Rim image is clearly bicyclic in XPL.
Daughter taxa (time control age-window is: 0-800Ma)
Tubodiscus bellii Medium sized (5-7 µm) with narrow shields / wide central area. In xpl the inner rim cycle is usually slightly narrower than the outer rim cycle
Tubodiscus burnettiae Medium to large (5-10 µm), typically broadly elliptical; the central area is broad (usually greater than the width of the rim). Inner and outer rim cycles of similar width.
Tubodiscus frankiae Medium sized (5-7 µm) with relatively broad shields/relatively narrow central area; in xpl inner rim cycle significantly narrower than the outer rim cycle.
Tubodiscus jurapelagicus Large (8-16 µm) with wide central area. Inner and outer rim cycles of similar width.
Tubodiscus verenae Large (8-16 µm) Tubodiscus with broad, high collar cycle that is highly birefringent (yellow-orange) in XPL; often seen in side view.
Tubodiscus sp. Specimens not identified to species level
Distinguishing features: Parent taxon (Tubodiscaceae): 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. This taxon: Tubodiscids with high and birefringent proximal collar cycle and wide central-area. Rim image is clearly bicyclic in XPL.
Lith size: 5->16µm; Data source notes: size range of included species
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Last occurrence (top): at top of Albian Stage (100% up, 100.5Ma, in Albian stage). Data source: Total of ranges of the species in this database First occurrence (base): within Berriasian Stage (137.70-143.10Ma, base in Berriasian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Tubodiscaceae
References:
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. gsO
Thierstein, H. R. (1973). Lower cretaceous calcareous nannoplankton biostratigraphy. Abhandlungen der Geologischen Bundesanstalt. 29: 3-52. gs
Tubodiscus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-10-2024
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