Distinguishing features: Parent taxon (Stephanolithiaceae): Murolith (protolith type) coccoliths with rims of non-imbricate V-units and weakly-developed, or vestigial, proximal/inner-cycles (R-units), with central-areas spanned by one to numerous bars. This taxon: Circular or sub-circular with high, sculpted, wall; central-area vacant or with cross bars.
Daughter taxa (time control age-window is: 0-800Ma)
Cylindralithus biarcus Cylindralithus with diagonal central-area cross-bars defining two large and two small pores
Cylindralithus coronatus Circular or broadly elliptical; central area with broad symmetric crossbars, serrated outline
Distinguishing features: Parent taxon (Stephanolithiaceae): Murolith (protolith type) coccoliths with rims of non-imbricate V-units and weakly-developed, or vestigial, proximal/inner-cycles (R-units), with central-areas spanned by one to numerous bars. This taxon: Circular or sub-circular with high, sculpted, wall; central-area vacant or with cross bars.
Morphology: The earliest species, C. nudus, has watznaueriacean-like construction, with high shields (cf. Ansulasphaera). Unfortunately, the precise nature of the construction of the type species is difficult to discern from the LM holotype images. In the electron microscope they are very reminiscent of Stephanolithids such as Rotelapillus but they show higher birefringence, suggesting that more of the coccolith is formed of R-units.
Geological Range: Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of range of species in this database First occurrence (base): at base of Albian Stage (0% up, 113Ma, in Aptian stage). Data source: Total of range 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
Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gsVO
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
Bramlette, M. N. & Martini, E. (1964). The great change in calcareous nannoplankton fossils between the Maestrichtian and Danian. Micropaleontology. 10(2): 291-322. gs
Cylindralithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 29-3-2023
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