Catalog - Globigerina azerbaidjanica

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Globigerina azerbaidjanica

Citation: Globigerina azerbaidjanica Khalilov 1956

Type age (chronostrat): Lower upper Eocene

Type locality: The northeastern foothills of the Maly Caucasus, Azerbaidzhan S.S.R.

Type repository: Baku; Geological Institute, Academy of Sciences, Baku, Azerbaijan

[Translation from the Russian] - Test quadrangular, inflated, the final largest chamber on the ventral side with a large, nearly round aperture, and almost perpendicular to the two spherical preceding chambers. Test quadrangular, inflated, low conical, peripheral margin broadly lobate. Dorsally, the initial chamber is small, round, surrounded by five barely discernible chambers. The second whorl has four small semispherical chambers, which moderately project on the surface. In the third whorl there are only three subspherical chambers, which rapidly increase in size. Ventrally, there are three spherical chambers, of which the last, the largest one, is perpendicular to the two preceding chambers. Sutures between the chambers narrow, straight, sometimes weakly curved, depressed, barely discernible in the first whorl. The most characteristic feature of this species is the very large, almost round aperture, opening on the last chamber, at the side of the umbilicus. Wall calcareous, densely porous. Diameter 0.36 mm.; thickness 0.24 mm. Comparison - This species is very close in its structure to Globigerina posttriloculinoides Khalilov, from the middle Eocene of Azerbaidzhan, and differs mainly in the large, almost round, aperture on the last chamber. Moreover, the present species appears somewhat later than globigerina posttriloculinoides, probably being genetically related to it.

Problematica - Possibly a juvenile globigerinathekid. [Huber et al. 2006, p. 502]

References:

Huber, B. T., Olsson, R. K. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene microperforate planktonic foraminifera (Jenkinsina, Cassigerinelloita, Chiloguembelina, Streptochilus, Zeauvigerina, Tenuitella, and Cassigerinella) and Problematica (Dipsidripella). In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 16): 461-508. gs V O

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

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina azerbaidjanica Khalilov 1956

Globigerina azerbaidjanica

References:

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