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Conoglobigerina


Classification: pf_mesozoic -> Conoglobigerinidae -> Conoglobigerina
Sister taxa: Conoglobigerina, Globuligerina
Daughter taxa: (blue => in age window 0-800Ma)
Conoglobigerina caucasica

Conoglobigerina grigelisi

Low to medium high conical test with a compact spire and 3.5 to 4 chambers in the last whorl. H/D ratio 0.5 to 1, and rarely over 1. No preferred coiling direction observed. The chambers of the last whorl are large and have deeply incised sutures. Last whorl strongly embraces previous (? 2) whorls such that the earlier part of the test may hardly be visible. Apex generally blunt, rarely pointed. Umbilical area depressed. Aperture generally a more or less symmetrical arch with lip, rarely comma-shaped. Specimens may have a small bulla over the umbilicus with one or two, low-arch apertures; it may resemble the bulla structure of Cenozoic Catapsydrax taxa. Wall microperforate, strongly pustulose; pustules form low and broken ridges that create an imperfectly reticulate pattern over the surface of the chambers.


Conoglobigerina gulekhensis

Conoglobigerina helvetojurassica
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
Conoglobigerina sp.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Conoglobigerina Morozova 1961
Rank: Genus
Basionym: Globigerina (Conoglobigerina) dagestanica
Type species: Globigerina (Conoglobigerina) dagestanica Morozova, in Morozova and Moskalenko, 1961;
Taxonomic discussion: The taxonomic concpets of this genus has varied. Morozova and Moskalenko (1961) used it for species with test diameter < test height. Simmons et al. (1997) used it for forms with an intraumbilical, interiomarginal and low arch aperture. Gradstein et al. (2017) used it for froms with an irregularly reticulate wall surface pattern. This has resulted in the species assigned to the genus changing. See Gradstein et al. (2017) for full discussion.

Original description: Translation from the Russian - Test with a high spiral, height usually equal to or greater than the diameter (H:D > 1:1). The spiral is formed by three or four whorls less frequently by 2 or 2½ whorls. Chambers subspherical, more or less losely aranged. The number of chambers is inconstant, and varies from three to six per whorl. Fre:quently, there there are specimens with a multichambered initial whorl consisting of 5 or 6 chambers, the subsequent wholrs comprising 3 or 4 chambers each; however some forms have an equal numbers of chambers in all whorls. in some representatives of the subgenus the chambers are arranged so as to form more or less regular rows; in others, no regular pattern in the arrangement of chambers is noticeable. Aperture small, single. Wall thin, finely porous, surface smooth or slightly rugose. Family Globigerinidae. Middle Jurassic-Recent(?).

Entries in the Catalog of original descriptions: Conoglobigerina

Distinguishing features: Chambers of the last whorl strongly embrace previous whorls; irregularly reticulate wall surface pattern

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

Geological Range:
Last occurrence (top): within Valanginian Stage (133.88-139.39Ma, top in Valanginian stage). Data source: Total of range of species in this database
First occurrence (base): within Oxfordian Stage (157.25-163.47Ma, base in Oxfordian stage). Data source: Total of range of species in this database

Plot of range and occurrence data:

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Spiroconvexaperture:Umbilical
sp chamber shape:Globularcoiling axis:Low-moderateperiphery:N/Aaperture border:
umb chbr shape:Globularumbilicus:periph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:wall texture:Finely pustuloseshell porosity:Microperforate: <1µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:0.0-0.0 N.B. These characters are used for advanced search. N/A - not applicable

References:

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 V O

Loeblich, A. R. & Tappan, H. (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York. 1-1059. gs

Morozova, V. G. & Moskalenko, T. A. (1961). Планктонные фораминиферы пограничных отложений байосского и батского ярусов Центрального Дагестана (Северо-Восточный Кавказ) [Foraminiferes planctoniques des depots limitrophes du Bajocien et du Bathonien du Daghestan central (Nord-Est du Caucase)]. Voprosyi Mikropaleontologii. 5: 3-30. gs

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 V O


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Conoglobigerina compiled by the pforams@mikrotax project team viewed: 25-10-2020

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