CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina quadritriloculinoides Khalilov 1956
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Citation: Globigerina quadritriloculinoides Khalilov 1956Rank: speciesType specimens: pl. 1, fig. 5a-c, holotype, X 6o. : no. 249 Type age (chronostrat): Not designated. Ranges from the lower Paleocene, Danian (first appearance) to the lower Eocene (abundant in upper Paleocene and lower Eocene).Type locality: Holotype from northeastern Azerbaidzhan S.S.R. Found also in the Maly Balkhan, Turkmen S.S.R. Type repository: Baku; Geological Institute, Academy of Sciences, Baku, Azerbaijan
Original Description [Translation from the Russian. - Test quadrangular, somewhat compressed, early chambers flattened. Dorsally, following the initial chamber, there are four chambers in the first whorl, and, in the second and third whorls, three and one-half chambers in each, Ventrally, there are three chambers, with deep sutures. [Test low conical, rather large, somewhat compressed from two opposite sides. Test quadrangular in outline, with a lobate periphery. Dorsally, the chambers of the final whorl project conspicuously around the preceding ones. Initial chamber round, followed by four small chambers of the first whorl. The second and third whorls have three and one-half chambers each. The final three chambers are large, semispherical, and slightly compressed. Ventrally, around the well-expressed umbilicus, there are three subspherical chambers, rapidly increasing in size, the last chamber being perpendicular to the two preceding. Septal sutures of the final whorl narrow, straight, strongly depressed. Aperture slitlike, on the ventral side of the final chamber; there is weakly expressed supplementary test material in the form of a calcareous lip overhanging the aperture. Wall calcareous, covered by dense alveolar sculpture. Extra details from original publication Comparison. - This species is subject to variation, mainly in the arrangement of the early whorls and the final chamber. In the early stage of growth, on the dorsal side, the chambers of the final whorl protrude only moderately compared to the preceding ones, and only in the later stage do they project strongly. Subsequently, the plane of the ioner whorls is at a considerable distance, forming a broadened depression within the final whorl. The position of the final chamber also varies, either toward the umbilicus or away from it. Judging by the illustrations, Subbotina (1953, VNIGRI, Trudy, n. s ., vypusk 76, p. 8o, pl. 11, figs. 8a-c-11a-c) apparently referred the present species to Globigerina eocaenica eocaenica Terquem, but, from our point of view, Terquem's form differs from the present species not only in the number and position of the chambers but also in the outline and the character of the surface of the ventral side. The new species has a certain similarity to Globigerina triloculinoides Plummer; it is not excluded that the present species arose from the latter.]
References:
Khalilov, D. M. (1956). 0 pelagicheskoy faune foraminifer Paleogenovykh otlozheniy Azerbaydzhana [Pelagic Foraminifera of the Paleogene Deposits of the Azerbaizhan SSR]. Trudy Instituta Geologii, Akademiya Nauk Azerbaidzhanskoi SSR. 17: 234-255. gs
Globigerina quadritriloculinoides compiled by the pforams@mikrotax project teamviewed: 22-3-2023
Khalilov 1956 1_5.jpg
Khalilov 1956 1_5.jpg
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