Catalog - Globigerina krosniensis

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Globigerina krosniensis

Citation: Globigerina krosniensis Blaicher 1970

Type specimens: holotype (fig. I a, b), no. 22 4 76: and para type. no. 22 4 76a.

Type sample (& lithostrat): Sub-Menilite Globigerina Marls

Type age (chronostrat): Lower Oligocene and also occurs in the upper Eocene.

Type repository: Krakow; Stratigraphic Section of the Carpathian Branch of the Institute of Geology, Krakow, Poland;

"Test trochoidal, composed of 10-11 chambers anangccl in 2-3 whorls. Chambers in the lst whorl strongly dliffer in size. Last whorl consists of three chambers. Sometimes, the fourth overhanging chamber or the preceding whorl can be partly seen. The two older ones globular, somewhat compressed on the dorsal side, are fused and strongly variable in size. They may differ but slightly in size. Sometimes the earliest chamber in the last whorl may be distinctly small. The youngest one, pushed apart from the preceding chambers is the size of the two older ones put together, or even much larger. Its exceptional height, slightly compressed on either side of the test is another characteristic feature of this chamber. The height of the last chamber is generally one half or twice the height of the two older chambers. The width is, however, smaller. hence, in the equatorial section the test is trapezoid-like, with height greater than the width. The older chambers, beginning with the last one in the second whorl, are elongated. overlapping, closely coiled into a minute compressed spiral, excentrically arranged. Three or four very minute chambers in the oldest whorl, sometimes hardly visible; hence, the dorsal side is generlly flat or slightly convex. The convexity on the ventral side consists of two older globular chambers and a part of the youngest chamber at the margin of the test, hence, the test in axial section is flatly ovate. Sutures between chambers on the ventral side straight. radial and more depressed between the two older chambers in the last whorl. On the dorsal side, sutures arched and poorly depresed. particularly in the older part of test. Umbilical depression small and compressed. The last chamber. increasingly compressed towards the umbilical depression, passing into the apertural shelter, placed somewhat excentrically anteriorly. Aperture rather small, higher than broad, protruding, formed, so to say, in the neck from the somewhat elongated wall of the last chamber protruding beyond the peripheral margin of this wall. Aperture provided with a narrow unporous margin. Besides the main aperture, minute, variously shaped apertures, also provided with an extremely narrow unporous margin, are densely distributed along the umbilical depression and all the sutures. These apertures are so small that their diameter equals approximately thar of two or three pores in the test wall of this species. An additional small umbonal chamber may be present, obscuring the main aperture and occasionally prese nt in other apertures (fig. 1 c). Wall of test finely porous.

"Remarks. - In its general morphological pattern the species here described somewhat resembles a specimen of the species Globigerina abscissa [lapsus pro G. incisa Hillebrandt] , described from the Middle Paleocene of the Reichenhall and Salzburg Basin (A. Hillebranclt, 1962, Bayer. Akad. Wiss., Math.-Naturw. KI.. Abh., n. s.. no. I 08, pl. II , figs. 6, 8). Numerous apertures, distributed along the sutures. occur also in the species 'Globigerina' kozlowskii Brotzen and Poiaryska, though the latter species has no other morphological features in common with the species here described .

References:

Blaicher, J. (1970). "Globigeryny" podmenilitowych margli globigeryn owych. Biuletyn Panstwowego Instytutu Geologicznego. 221(5): 137-204. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina krosniensis Blaicher 1970

Globigerina krosniensis

References:

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