Nannotax3 - Mesozoic

Calyculus

Classification: Mesozoic -> Podorhabdales -> Calyculaceae -> Calyculus
Sister taxa: Calyculus, Carinolithus,

Distinguishing features: 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.

Daughter taxa: (blue => in age window 0-800Ma)
				Central area with lozenge & cross-bars (Calyculus)
				Calyculus cribrum Elliptical Calyculus ; rim moderately elevated; central area with axial cross,concentric lozenge.
				Calyculus depressus Small elliptical Calyculus; rim low & narrow; central area with axial cross and concentric lozenge.
				Central area with radial bars (Vikosphaera)
				Calyculus noeliae Calyculus with central area with around 14-20 lateral bars. Rim elevation very variable, even on a single coccosphere
				Central area with lozenge, cross-bars & radial bars (Catillus)
				Calyculus hommerili Elliptical Calyculus ; rim low; central area with axial cross; concentric lozenge and short radial bars
				Calyculus serrai Elliptical Calyculus; rim moderately elevated; central area with axial cross, small lozenge and long radial bars.
				Central area with grill (Incerniculum)
				Calyculus absolutus Elliptical Calyculus; rim moderately elevated, narrow; central area with finely perforate net and spine-base
				Calyculus derivatus Elliptical Calyculus ;rim moderately elevated; central area with axial cross finely perforate net and large spine-base
				Calyculus magnus Large (ca 6-8 µm across), broadly elliptical Calyculus; rim elevated, broad; central area with grill
				Calyculus sp. Specimens not identified to species level

Taxonomy:

Citation: Calyculus Noël, 1973

Rank: Genus

Type species: Calyculus cribrum Noël, 1973.

Synonyms: Proculithus Medd, 1979; Incerniculum Goy, 1979; Vikosphaera Goy, 1979; Catillus Goy, 1979.
NB The genera Incerniculum, Vikosphaera and Catillus were proposed based on variations in central area structure, Bown (1987) and Crux (1987) both argued that this was impractical and such characters were better used at specific level. Nonetheless, it is useful to sort the species out into the categories proposed by Goy in order to understand the taxonomy - this is what I have done in the table [JRY]

Farinacci & Howe catalog pages: Calyculus + * , Proculithus * , Incerniculum * , Vikosphaera * , Catillus *

Morphology remarks: Species are often difficult to differentiate in LM because the distinctive central area structures may be imperceptible or missing.

Search data:

Tags	LITHS: placolith, elliptical, hollow, CA: concentric-ring(s), cross-axial, grill, V-UNITS: V-prominent, DETAILS: ca_disjunct, rim-unicyclic,
Metrics	Lith size: 3->8µm; Sources: 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): in lower part of Bajocian Stage (30% up, 169.7Ma, in Bajocian stage). Data source: Total of range of species in this database
First occurrence (base): in lower part of Pliensbachian Stage (40% up, 187.6Ma, in Pliensbachian 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
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Calyculaceae

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 :: ::

Bown, P. R. (1987a). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs :: ::

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 :: view :: open

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 :: ::

Medd, A. W. (1979). The Upper Jurassic coccoliths from the Haddenham and Gamlingay boreholes (Cambridgeshire, England). Eclogae Geologicae Helvetiae. 72: 19-109. gs :: view :: open

Noël, D. (1973). Nannofossiles calcaires de sédiments jurassiques finement laminés. Bulletin du Muséum National d'Histoire Naturelle. 3e serie, 75: 95-156. gs :: ::