Catalog - Globigerina (Conoglobigerina) avarica

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina (Conoglobigerina) avarica Morozova, in Morozova & Moskalenko 1961

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> G -> Globigerina (Conoglobigerina) -> Globigerina (Conoglobigerina) avarica
Other pages this level: G. (Conoglobigerina) avarica, G. (Conoglobigerina) dagestanica, G. (Conoglobigerina) gaurdakensis

Globigerina (Conoglobigerina) avarica

Citation: Globigerina (Conoglobigerina) avarica Morozova, in Morozova & Moskalenko 1961
Rank: Species
Type locality: Holotype (pl. 2, figs. 1-4) from the village of Chokh; and found also in the village of Gunib, both in central Dagestan, Soviet Russia.
Type age (chronostrat): Middle Jurassic, lower Bathonian,
Type sample (& lithostrat): Mogokh beds, in the upper band of an argillite, Globigerina (Conoglobigerina) dagestanica Globigerina (Conoglobigerina) auarica Zone. Ten fairly well-preserved and thee slightly distorted specimens.
Type specimens: Pl2 f 1-13, 20; 3513/3
Type repository: Moscow, Russia; Museum of the Geological Institute of the Academy of Sciences
Described on page(s) : 27-28

Current identification:


Original Description

Diagnosis: Conoglobigerina with a high, heteromorphic test consisting of three or four whorls. There are three to four chambers in each whorl

Description: Test narrow, high (its diameter equal to or greater than its height), formed by three or four spiral whorls. Each whorl consists of three or four spherical chambers rapidly increasing in size. Initial end acuminate or slightly blunt. Chambers of adjoining whorls sometimes form more or less regular rows which are usually oblique, as if twisted. Sutures deep, their depth markedly increasing toward the apertural end. Aperture small, slit-like, marginal, often barely discernible. Wall thin, finely porous. Surface smooth or slightly rugose.


Size: Greatest diameter 0.16-0.10mm; Smallest diameter 0.14-0.9mm; Height 0.18-0.15mm

Extra details from original publication

Variability - The described species is very variable. Among its representatives are two groups. which most likely belong to the micro and megalospheric generations. Tests with a higher spiral. blunt initial end, a small initial chamber, and a four-chambered initial whorl (see tf. 8, figs. 1 - 12) should probably be referred to the microspheric generation, whereas tests with a relatively lower spire, an acuminate initial end, a large initial chamber and a three-cambered initial whorl (see tf. 8, figs. 13- 21) should be referred to the megalospheric form. The number of chambers varies strongly in the present species. In some individuals (mainly the microspheric ones) there is an equal number of chambers (three or four) in each whorl; in some others (megalospheric) the number of chambers varies; the initial chamber is surrounded by the initial half whorl consisting of four, less frequently five, chambers, the second and the third whorls each comprise four chambers and the final whorl has four or three chambers. The shape of the test is inconstant, and varies from narrowly cuneate to broadly conical. Chambers of adioining whorls form rows. which are frequently oblique as if "twisted"" (see: tf. 8, fig. 1). Sometimes, however, there is an altenate arrangement of chambers (see tf. 8. fig. 17).

Comparison. - The present species is close to Globigerina (Conoglobigerina) dagestanica Morozova and Globigerina (Conolobigerina) jurassica Gofman, from which it differs in the narrower and broader test; the smaller number of chambers. up to three in the early whorls; and in the arrangements of chambers in rows in some specimens. The last feature makes the described species similar to the representatives of Guembelitria Cushman; however, this characteristic is considerably less pronounced in our species, and is absent in some specimens.] 


Editors' Notes
content migrated from chronos

References:

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


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Globigerina (Conoglobigerina) avarica compiled by the pforams@mikrotax project team viewed: 20-9-2021

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