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Marginotruncana schneegansi


Classification: pf_mesozoic -> Globotruncanidae -> Marginotruncana -> Marginotruncana schneegansi
Sister taxa: M. angusticarenata, M. caronae, M. coronata, M. desioi, M. manaurensis, M. marginata, M. paraconcavata, M. pileoliformis, M. pseudolinneiana, M. renzi, M. schneegansi, M. sigali, M. sigmoconcavata, M. sinuosa, M. tarfayaensis, M. undulata, M. sp.,

Taxonomy

Citation: Marginotruncana schneegansi (Sigal, 1952)
Rank: Species
Basionym: Globotruncana schneegansi
Synonyms: Globotruncana lakrai Haque 1962
Taxonomic discussion: The holotype was lost (according to Sigal; see Caron, 1974, p.330), but was replaced by a neotype selected by Sigal from a topotype sample and described and illustrated in Caron (1974, p.330-333, fig.1a-c). SEM photos of the neotype were published in the "Atlas du Cretace Moyen" 1979, vol.2, pl.70/1a-c.
Robaszynski et al., 1979: Early representatives of M. schneegansi resemble somewhat Dicarinella hagni in having globose chambers and depressed radial sutures on the umbilical side. [copied from Chronos database]

Type images:

Original description: A côte d'elle [G. sigali] se développe une autre espece très caractéristique, à une carène aussi, Globotruncana schneegansi n. sp. faiblement dissymetrique et dont les loges conservent une certaine globulosité; toutes les formes existent depuis celles à une carene jusqu'à celles à deux carenes franches, étroitement accolées.

Translated from French: (G.) schneegansi n. sp. occurs with (G.) sigali, another species characterized by its single keel. (G.) schneegansi has a slightly asymmetrical test profile and the surface of chambers are inflated on both sides. All intermediate forms exist between single-keeled to closely spaced double-keeled specimens.

Entries in the Catalog of original descriptions: Globotruncana schneegansi, Globotruncana lakrai


Emended description: Translated from French and summarized from Caron, 1974: Coiling mode is trochospiral, with a biconvex, slightly asymmetrical profile; chambers subglobular; 2.5 to 3.0 whorls of chambers increasing regularly and rapidly in size as added. Shell surface densely perforate except imperforate keels. Equatorial outline lobate. Axial periphery appears to be single-keeled but detailed SEM photos show the presence of two very closely spaced keels (see Caron, 1974, pl. I, fig. 4 and 5). The primary aperture is interio-marginal, extraumbilical-umbilical, with well developed portici (see Caron 1974, neotype Fig.1b and topotypes pl.I, figs. 3, 4 and 7). On spiral side, chambers are trapezoidal and slightly inflated; sutures curved and moderate-raised. On umbilical side, chambers are elongated in direction of coiling and inflated; sutures sigmoidal and depressed. [copied from Chronos database]

Geological Range:
Last occurrence (top): within D. asymetrica zone (84.19-86.71Ma, top in Santonian stage). Data source: [copied from Chronos database]
First occurrence (base): within H. helvetica zone (92.56-93.52Ma, base in Turonian stage). Data source: [copied from Chronos database]

Plot of occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Marginotruncana schneegansi, synonyms included - Globotruncana schneegansi; Marginotruncana schneegansi;
  • space-time plot :: Samples map :: Parent: Marginotruncana

    Character matrix

    test outline:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:-
    sp chamber shape:Crescenticcoiling axis:Low-moderateperiphery:Single keelaperture border:Thin porticus
    umb chbr shape:-umbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
    spiral sutures:Raisedumb depth:Deepwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
    umbilical or test sutures:Weakly depressedfinal-whorl chambers:5.5-6.5 N.B. These characters are used for advanced search. N/A - not applicable

    References:

    Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs

    Sigal, J. (1952). Apercu stratigraphique sur la micropaleontologie du Cretace. XIX Congr. géol. internat., Algers, Monographies Regionales. 1(26): 3-43. gs


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    Marginotruncana schneegansi compiled by the pforams@mikrotax project team viewed: 22-10-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110339 Go to Archive.is to create a permanent copy of this page - citation notes



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