Crucirhabdus


Classification: Mesozoic -> Stephanolithiales -> Parhabdolithaceae -> Crucirhabdus
Sister taxa: Bucanthus, Calcivascularis, Crucirhabdus, Diductius, Mitrolithus, Parhabdolithus, Timorella, Umbria,

Distinguishing features: Protolith coccoliths with low, sloping rim; central area wide with axial cross supporting a tall spine


Daughter taxa: (blue => in age window 0-800Ma)
Minute Crucirhabdus with relatively narrow central area and broad axial cross. In XPL the transverse bars appears as two birefringent dots filling the central area and the longitudinal bars are inconpicuous.
Crucirhabdus with relatively low, narrow rim and wide central area spanned by axial cross bars. Additional lateral bars may be present, probably dependent on preservation state. A tall, hollow spine rises from the centre of the cross bars.

Specimens not identified to species level

Taxonomy:

Citation: Crucirhabdus Rood et al., 1973
Rank: Genus
Type species: Crucirhabdus primulus Rood et al., 1973
Synonyms: Apertius Goy, in Goy et al. 1979 [type species A. dorei is synonym of C. primulus cf. Bown 1987]

Farinacci & Howe catalog pages: Crucirhabdus + * , Apertius *

Distinguishing features: Protolith coccoliths with low, sloping rim; central area wide with axial cross supporting a tall spine


Morphology remarks: Protolith coccoliths with low, sloping rim and relatively wide central area spanned by a tall-spine-bearing axial cross, with or without additional lateral bars. Bicyclic rim image in XPL.

Geological Range:
Last occurrence (top): at top of Pliensbachian Stage (98% up, 182.9Ma, in Pliensbachian stage). Data source: Total of range of species in this database
First occurrence (base): in mid part of Norian Stage (50% up, 218.9Ma, in Norian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. gs

Goy, G., Noël, D. & Busson, G. (1979). Les conditions de sédimentation des schistes-carton (Toarcien inf.) du bassin de Paris déduites de l'étude des nannofossiles calcaires et des diagraphies. Documents de Géologie de la Faculté des Sciences de Lyon. 75: 33-57. gs

Rood, A. P., Hay, W. W. & Barnard, T. (1973). Electron microscope studies of Lower and Middle Jurassic coccoliths. Eclogae Geologicae Helvetiae. 66: 365-382. gs


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Crucirhabdus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 17-10-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10332 Go to Archive.is to create a permanent copy of this page - citation notes



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