pforams@mikrotax - Conoglobigerina helvetojurassica pforams@mikrotax - Conoglobigerina helvetojurassica

Conoglobigerina helvetojurassica


Classification: pf_mesozoic -> Conoglobigerinidae -> Conoglobigerina -> Conoglobigerina helvetojurassica
Sister taxa: C. caucasica, C. grigelisi, C. gulekhensis, C. helvetojurassica, C. sp.

Taxonomy

Citation: Conoglobigerina helvetojurassica (Haeusler, 1881 emend. Oesterle, 1968) Gradstein et al. (2017)
Taxonomic rank: species
Basionym: Globigerina helvetojurassica
Synonyms:

Type images:

Original description: Test milky white, smooth, more rarely more or less rough, 5 to 6 chambers with the last 5 nearly of same size. Test appears finely punctuate under high magnification. Fragments are abundant and completely preserved specimens are numerous mainly at B_zen and B_ren. The half-moon shaped and often narrow openings can be readily observed on these specimens, in particular on the less corroded specimens.

Entries in the Catalog of original descriptions: Globigerina helvetojurassica


Emended description:
Low to medium high trochospiral, with an H/D ratio of 0.5 to 1. The trochospire axis may be slightly curved, such that the chambers of the final whorl sit oblique of the chambers of the previous whorl. No preferred coiling direction observed. Last whorl flaring out and much larger than previous (2) whorls. Spherical-circular chambers (nicely ball shaped), four in the last whorl; chambers in the last whorl not much increasing in size. Umbilicus generally open and wide, rarely narrow. Sutures depressed, mostly straight. Aperture variable in shape, low to medium high arch, umbilical to slightly extraumbilical; a looped aperture was rarely observed also. The aperture often has a thickened rim around it. A bulla is observed in some specimens. Wall pustulose and reticulate to strongly reticulate

Morphology:
Low to medium high trochospiral, with an H/D ratio of 0.5 to 1. The trochospire axis may be slightly curved, such that the chambers of the final whorl sit oblique of the chambers of the previous whorl. No preferred coiling direction observed. Last whorl flaring out and much larger than previous (2) whorls. Spherical-circular chambers (nicely ball shaped), four in the last whorl; chambers in the last whorl not much increasing in size. Umbilicus generally open and wide, rarely narrow. Sutures depressed, mostly straight. Aperture variable in shape, low to medium high arch, umbilical to slightly extraumbilical; a looped aperture was rarely observed also. The aperture often has a thickened rim around it. A bulla is observed in some specimens. Wall pustulose and reticulate to strongly reticulate. [F. Gradstein, Feb 2019]  

Wall type:
Microperforate and reticulate

Size:
100 to 200 micron

Character matrix
test outline:Lobatechamber arrangement:Trochospiraledge view:Spiroconvexaperture:Umbilical
sp chamber shape:Globularcoiling axis:Moderate-highperiphery:N/Aaperture border:Thin lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:Deepwall texture:Reticulateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:4-4 N.B. These characters are used for advanced search. N/A - not applicable

Most likely ancestor:
Globuligerina oxfordiana - at confidence level 2 (out of 5). Data source: Gradstein et al. 2017 p.263.

Geological Range:
Notes: Type locality: Birmenstorfer Schichten, Eisengraben Section, Canton Aargau, Switzerland
Last occurrence (top): within Early Kimmeridgian Substage (152.20-154.78Ma, top in Kimmeridgian stage). Data source: Gradstein et al. 2017
First occurrence (base): within Middle Oxfordian Substage (156.60-159.40Ma, base in Oxfordian stage). Data source: Gradstein et al. 2017

Plot of range and occurrence data:

References:

Gradstein, F. & Waskowska, A. (2021). New insights into the taxonomy and evolution of Jurassic planktonic foraminifera. Swiss Journal of Palaeontology. 140(1): 1-12. gs O

Gradstein, F. M. (2017a). New and emended species of Jurassic planktonic foraminifera. Swiss Journal of Palaeontology. 136(2): 161-185. gs

Gradstein, F. M., Gale, A. S., Kopaevich, L., Waskowska, A., Grigelis, A. & Glinskikh, L. (2017b). The planktonic foraminifera of the Jurassic. Part I: material and taxonomy. Swiss Journal of Palaeontology. 136(2): 187-257. gs O

Gradstein, F. M., et al. (2017c). The planktonic foraminifera of the Jurassic. Part II: Stratigraphy, palaeoecology and palaeobiogeography. Swiss Journal of Palaeontology. 136(2): 259-271. gs O

Haeusler, R. (1881). Untersuchungen uber die microscopischen Structurverhaltnisse de Aargauer Jurakalke mit besonderer Berucksichtigung ihrer Foraminiferenfauna. Dissertation, Univ Zurich. 1-47. gs

Oesterle, H. (1968). Foraminiferen der Typlokalitat der Birmenstor- fer-Schichten, unterer Malm. Eclogae Geologicae Helvetiae. 61(2): 695-792. gs O

Simmons, M. D., Boudagher-Fadel, M. K., Banner, F. T. & Whittaker, J. E. (1997). The Jurassic Favusellacea, the earliest Globigerina. In, Boudagher-Fadel, M. K., Banner, F. T. & Whittaker, J. E. (eds) The Early Evolutionary History of Planktonic Foraminifera. British Micropalaeontological Society Publication Series . 17-30. gs

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Conoglobigerina helvetojurassica compiled by the pforams@mikrotax project team viewed: 10-6-2026

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