Catalog - Globigerina gaultina

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Globigerina gaultina

Citation: Globigerina gaultina Morozova 1948

Type specimens: holotype (figs. 16-18) 6, specimen 16. [Subbotina's figured specimens (fig. 1-4) deposited in the collections of the All-Union Petroleum Scientific-Research Geological-Prospecting Institute (VNIGRI) Leningrad, USSR, 5069-5072.]

Type sample (& lithostrat): basal Clansayesian; in a green marl. Also occurs in the Cenomanian. [Subbotina's figured specimens (figs. 1-4) from the Cenomanian.]

Type age (chronostrat): Lower Cretaceous, lower Albian

Type locality: Ravine along the right bank of the upper Bol'shaya Khosta River, near the town of Khosta, south of Sochi, in the southwestern Caucasus, southern USSR. (Subbotina's figured specimens (figs. 1-4) from the Barakayevskaya region, Northern Caucasus, southern USSR.)

Type repository: Moscow, Inst. of Geol. Sci. of the Academy of Sciences

[Translation from the Russian] - Test very small, coiled in a flat spiral, the initial whorls of which do not surmount the surface of the last whorl. Consists of 2-2.5 whorls, slowly increasing in height. In the last whorl there are seven inflated chambers. The last and next-to-last chambers are often slightly smaller than the preceding ones. Sutures depressed, straight. Outer margin of the test lobate. Umbilicus deep and quite broad, in width somewhat less than the height of the first chamber of the last whorl. Aperture a narrow, barely discernible slit on the ventral side of the last chamber and opening into the umbilical opening. Wall matte, finely perforate.

Synonym - Globigerina cretacea d'Orbigny. - Chapman, 1896, Roy. Micr. Soc. London, Jour., p. 588, pl. 3, figs. 5, 6.

Variation - Among the tests belonging to this species, specimens are found with a spire the early chambers of which, unlike the typical case described, are somewhat higher than the surface of the last whorl. The number of whorls in some specimens reaches three. In two or three specimens a rudimentary double keel was observed (possibly the trace of a broken-off final chamber?).

Comparison. - The tests of this species differ from Globigerina cretacea d 'Orbigny, which is broadly distributed in the Upper Cretaceous deposits and is encountered locally in the Lower Cretaceous, and also from the Lower Cretaceous Globigerina infracretacea Glaessner, 1937, by its flat spire, greater number of chambers (6-7 instead of 5), broader umbilicus, and a typical aperture similar to the Globotruncana aperture type. This similarity, and also the outer appearance of the tests, which resemble representatives of the genus Globotruncana and differ from the latter only by the absence of keels and their small dimensions, not usual for the globotruncanids, leads to one hypothesizing that these forms are close genetically. The continuous accumulation of sediments in the Sochi region of the Caucasus in Albian-Cenomanian time and identical physicogeographical conditions make this hypothesis probable. Some specimens of G. cretacea d'Orbigny that have six chambers in the last whorl from the Albian of southern England, judging from Chapman's description and figure (Chapman, 1896), correspond to this species. [The tests with 6-7 chambers in the last whorl the presence of which was ascertained by Berthelin (1880, Soc. Geol. France, Mem., ser. 3, vol. I, p. 65) in the Albian of France also apparently belong to this species.]

References:

Morozova, V. G. (1948). Foraminifera of the Lower Cretaceous deposits of the Sochi region (southwestern Caucasus).] [Russian.]. Byulleten Moskovskogo Obshchestva Ispytateley Prirody Otdel Geologicheskiy. 23(3): 41-. gs

Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina gaultina Morozova 1948

Globigerina gaultina

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