Catalog - Marginotruncana pseudolinneiana

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Marginotruncana pseudolinneiana

Citation: Marginotruncana pseudolinneiana Pessagno 1967

Type specimens: Plate 65, figures 24-27; Plate 76, figures 1-3; 689259

Type age (chronostrat): Santonian

Type locality: Marl from the Lower Gosau beds; Gosautal, Edelbachgraben, Austria

Type repository: Washington; USNM

"Test lobate, trochospiral; extremely planiform, often concave spirally; planiform umbilically; peripherally truncated by a wide double keel; rims of double keel either not strongly beaded or beadless. Test comprised of 2.5 to 3 whorls of chambers which gradually expand in size; 7-8 chambers in final whorl. Chambers crescent-shaped spirally, separated by raised, curved, slightly beaded or beadless sutures; chambers subrectangular umbilically, separated by slightly curved, raised, beadless or slightly beaded sutures. Umbilicus broad, bordered by mildly elevated umbilical shoulder. Primary aperture interiomarginal, extraumbilical-umbilical in position, a lowly arched opening. Outer wall except for double keel radial hyaline, perforate; double keel radial hyaline, imperforate. Septal walls microgranular hyaline, sparsely perforate."

1960. Globotruncana lapparenti tricarinata (Quereau). Tollmann. Jahrb. Geol. Bund.. Bd. 103, pp. 193. 19-1. pl. 21, figs. 1a-c.

Remarks: Marginotruncana pseudolinneiana Pessagno, n. sp. is nearly homeomorphic extemally for Globotruncana linneiana (d'Orbigny). lt can be differentiated from G. linneiana by the following criteria: (1) its primary aperture is clearly extraumbilical-umbilical in position; (2) the spiral surface of its test is more planiform and is often concave; (3) its chambers are almost entirely crescent-shaped spirally whereas those of G. linneiana are more typically petaliform: and (4) it lacks the coarsely beaded sutures and keels of G. linneiana.
In thin-section, M. pseudolinneiana Pessagno. n. sp. shows typical marginotruncanid double keels which are entirely radial hyaline imperforate in character. G. linneiana and other double keeled species of Globotruncana show keels which are both radial hyaline imperforate and ultragranular hyaline imperforate in character (Text-figure 40). In addition, M. pseudolinneiana, n. sp. shows earlier whorls which are more compressed along a spiral-umbilical axis and which seem to represent a M. canaliculata stage of development.

M. pseudolinneiana, n. sp. seems to have arisen from M. canaliculata (Reuss) by obtaining wider double keels and by obtaining slightly curved, raised sutures umbilicallly. Transitional forms occur in Lower Gosau samples.

It should be noted that the sectioned specimen from the Austin chalk (Pe R59: Text-figure 51) listed under G. linneiana was found to be referrable to M. pseudolinneiana in the later part of this work.

References:

Pessagno, E. A. (1967). Pessagno, E. A. (1967). Upper Cretaceous planktonic foraminifera from the western Gulf Coastal Plain. Palaeontographica Americana. 5: 245-445. Palaeontographica Americana. 5: 245-445. gs O

Robaszynski, F., Caron, M. & le Groupe de Travail Européen des Foraminifères Planctoniques (1979). Robaszynski, F., Caron, M. & le Groupe de Travail Européen des Foraminifères Planctoniques (1979). Atlas des Foraminiféres Planctoniques du Crétace Moyen (Mer Boréale et Téthys). Cahiers de Micropaléontologie. 1 & 2: 1-185. Cahiers de Micropaléontologie. 1 & 2: 1-185. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Marginotruncana pseudolinneiana Pessagno 1967

Marginotruncana pseudolinneiana

References:

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