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Globuligerina dagestanica


Classification: pf_mesozoic -> Conoglobigerinidae -> Globuligerina -> Globuligerina dagestanica
Sister taxa: G. avariformis, G. balakhmatovae, G. bathoniana, G. dagestanica, G. jurassica, G. oxfordiana, G. oxfordiana calloviensis, G. tojeiraensis, G. sp.,

Taxonomy

Citation: Globuligerina dagestanica (Morozova in Morozova & Moskalenko, 1961)
Rank: Species
Basionym: Globigerina (Conoglobigerina) dagestanica Morozova in Morozova & Moskalenko, 1961
Synonyms:
Taxonomic discussion: Recombination in Globuligerina follows Gradstein et al. 2017

Type images:

Original description: Test small, high, its diameter equal to or greater than the height. Chambers arranged in a high, very steep spiral consisting of three whorls. The final whorl consists of three or four spherical chambers differing but little in size. The penultimate and final whorls usually have the same number of chambers, the first whorl often having up to five chambers. Sutures between the chambers of late whorls depressed, straight; those between the chambers of the first whorl weakly depressed, straight or slightly oblique. Aperture umbilical, an elongate slit, or low, crescentic. Wall radiate, thin, moderately porous. Surface matte.

Entries in the Catalog of original descriptions: Globigerina (Conoglobigerina) dagestanica

Distinguishing features:

The original description by Morozova and Moskalenko (1961) mentions a highly variable morphology regarding the number of chambers in the last whorl, height of test and shape of the trochospire. Typically the diameter of the test is about the same as the height, or the test is higher than wide. As seen from the apex (first chambers) upwards to the third and last whorl, the test may be slightly triangular in outline. Up to 5 chambers in the initial (often very small) whorls and 3 to 4 in the final (third whorl) which increases rapidly in width and height; chambers subglobular in shape with straight sutures; the intra-umbilical aperture is a low to medium high symmetrical arch.


Wall type: Simmons et al. (1977) mentions that the surface of the test wall is covered with pseudomuricae, which often fuse laterally into very short ridges. This agrees with the wall texture of topotypes from Khouroukra, Dagestan (Gradstein et al., 2017) and the LM photographs displayed here.

Test morphology:

In the topotype assemblage from the Khouroukra section, Dagestan, collected by Larisa Glinskikh, Novosibirsk (Gradstein et al., 2017, and LM photographs displayed here), a majority of specimens is also about as high as wide, but higher or wider specimens also occur.  The test shape may be quite variable, with many specimens having a rather irregular, deformed test. There are specimens with 3, 3-4 and 4 chambers in the last whorl; aperture is generally a low arch, and rarely a bit higher, and sometimes looped. Apertures have a thickened rim around it, above the umbilicus. A small bulla may be present.

 

The 20 or so specimens described by Wernli and Görög (2007) under Globuligerina aff. dagestanica (Morozova) from the Upper Bajocian through Lower Bathonian of the Southern Jura Mountains in France are more triangular in outline and have less globose chambers. More comparative study is warranted to ascertain that G. dagestanica also occurs in France.

 

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

Geological Range:
Notes: Late Bajocian through Bathonian, possibly already occurring in Early Bajocian (Wernli and Görög, 1999 and 2000). Given the overlap in test morphology of G. bathoniana and G. dagestanica, it is possible to find dagestanica-type specimens over a wider stratigraphic and geographic range than provided in the literature.
Last occurrence (top): within Bathonian Stage (166.07-168.28Ma, top in Bathonian stage). Data source: Gradstein et al. 2017
First occurrence (base): within Bajocian Stage (168.28-170.30Ma, base in Bajocian stage). Data source: Gradstein et al. 2017

Plot of occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Globuligerina

    Character matrix

    test outline:Lobatechamber arrangement:Trochospiraledge view:Spiroconvexaperture:Umbilical
    sp chamber shape:Inflatedcoiling axis:Highperiphery:N/Aaperture border:Thin lip
    umb chbr shape:Inflatedumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
    spiral sutures:Moderately depressedumb depth:Shallowwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
    umbilical or test sutures:Moderately depressedfinal-whorl chambers:3.5-5.5 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. (2017a). The planktonic foraminifera of the Jurassic. Part I: material and taxonomy. Swiss Journal of Palaeontology. 136(2): 187-257. 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)]. Voprosy 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 Micropaleontological Society Series. 17-30. gs


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    Globuligerina dagestanica compiled by the pforams@mikrotax project team viewed: 19-10-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110060 Go to Archive.is to create a permanent copy of this page - citation notes



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