Distinguishing features:
Parent taxon (Calyculus): High, broad, flaring distal-shield composed of radial, non-imbricating elements, and a proximal-shield which is often reduced to a simple, narrow cycle of elements; central-area structures are highly variable, including numerous bars, concentric structures, nets and grills.
This taxon: Elliptical Calyculus ;rim moderately elevated; central area with axial cross finely perforate net and large spine-base
Taxonomy:
Farinacci & Howe catalog pages: I. derivatum *
Distinguishing features:
Parent taxon (Calyculus): High, broad, flaring distal-shield composed of radial, non-imbricating elements, and a proximal-shield which is often reduced to a simple, narrow cycle of elements; central-area structures are highly variable, including numerous bars, concentric structures, nets and grills.
This taxon: Elliptical Calyculus ;rim moderately elevated; central area with axial cross finely perforate net and large spine-base
Search data:
LITHS: placolith, elliptical, hollow, CA: grill, process, ca_disjunct, CROSS-POLARS: V-prominent, rim-unicyclic, |
Lith size: 3->4µm; Data source notes: holotype +/- 0.5 µm |
Geological Range:
Last occurrence (top): within Early Toarcian Substage (177.50-184.20Ma, top in Toarcian stage). Data source: Bown 1987 (original description)
First occurrence (base): within Early Toarcian Substage (177.50-184.20Ma, base in Toarcian stage). Data source: Bown 1987 (original description)
Plot of occurrence data:
Crux, J. A. (1987a). Concerning dimorphism in Early Jurassic coccoliths and the origin of the genus Discorhabdus Noël 1965. Abhandlungen der Geologischen Bundesanstalt. 39: 51-55. gs Goy, G. (1981). Nannofossiles calcaires des schistes carbon (Toarcien Inferieur) du Bassin de Paris. Doc. de la RCP 459, Nature et genese des facies confines, (Editions du BRGM). 1: 1-86. gs OReferences:
Calyculus derivatus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 13-1-2025
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10187 Go to Archive.is to create a permanent copy of this page - citation notes |
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