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Globotruncanita angulata


Classification: pf_mesozoic -> Globotruncanidae -> Globotruncanita -> Globotruncanita angulata
Sister taxa: G. angulata, G. atlantica, G. conica, G. elevata, G. insignis, G. pettersi, G. stuarti, G. stuartiformis, G. sp.,

Taxonomy

Citation: Globotruncanita angulata (Tilev, 1951)
Rank: Species
Basionym: Globotruncana lugeoni var. angulata
Synonyms: Globotruncana torensis

Type images:

Original description: Translated from French. Test slightly convex or flat dorsally, very strongly convex ventrally. Chambers very rounded in the lower part of the test. On the dorsal side, the chambers of the internal whorls are semicircular in shape, but become roughly trapezoidal in the last whorl. The test displays a circular outline, the chamber sutures of the last whorl meeting the periphery at a well-marked angle. Profile- Slightly concave or flat dorsally, strongly convex ventrally.
Keel- On the dorsal side the test is bordered by a beaded keel at the beginning of the external whorl, becoming plain in the younger chambers. The beaded ornamentation is stronger along the spiral sutures. The first spiral suture is not clearly perceptible, the central part of the dorsal side being filled with pustules bigger in size than the beads. The keel appears to be broader on the dorsal side than in profile view, its axial projection being a continuous slightly undulated line.
Chambers: 1) The shape of the chambers of the internal whorls quite differs from the shape of the chambers of the external whorl. In the penultimate whorl, the shape is rather semicircular becoming trapezoidal, with a large convex base and an opposite concave base. This particular shape is not always conspicuous in each peripheral chamber; nevertheless, some display it quite well. The outline of the dorsal side is circular not lobate. 2) Shape of the chambers of the last whorl on the ventral side: roughly elliptical in shape, being separated by radial sutures or convex in a frontward direction, shaping grooves between the convex chambers. The inflated surface of these chambers is covered with small pustules lined up along the sutures or around the edge of the umbilicus. The last chamber and the one before are often devoid of this ornamentation. 3) Shape of the chambers in profile view: In profile view, the shape of the chambers is totally similar to that of the Globotruncana lugeoni type; their lower part having the shape of an acorn, their dorsal part being flat and bordered by a keel. The axial projection of the keel is a continuous, slightly undulated line.
Umbilicus: Broad, hexagonal in shape, the convex sides being directed toward the center. The edge of the umbilicus is produced by a periumbilical thickening of the test. This umbilical edge is bounded by pustules on one side and by this epigenetic filling on the other side. The umbilicus is deep, his depth being equal to the height of the shell. Its diameter is more or less half the size of the test diameter.
Axial section. The axial section displays the exact shape of the profile of the test (dorsal side flat, ventral side more convex than a half- circle), the thickness of the test- which is rather reduced- and its internal structure. The chambers become more and more elongate along an axial, inside- outside direction. The chambers of the internal whorls are single-keeled.

Dimensions: Number of whorls: three (the initial whorl being less noticeable). Number of chambers in the last whorls: six to seven.

Entries in the Catalog of original descriptions: Globotruncana lugeoni angulata, Globotruncana torensis

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: [copied from Chronos database]
First occurrence (base): within Maastrichtian Stage (66.04-72.05Ma, base in Maastrichtian 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: Globotruncanita angulata, synonyms included - Globotruncana torrensis; Globotruncanita angulata;
  • space-time plot :: Samples map :: Parent: Globotruncanita

    Character matrix

    test outline:Circularchamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical-extraumbilical
    sp chamber shape:Inflatedcoiling axis:Moderateperiphery:Single keelaperture border:N/A
    umb chbr shape:Inflatedumbilicus:Wideperiph margin shape:Moderately roundedaccessory apertures:None
    spiral sutures:Raised beadedumb depth:Deepwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
    umbilical or test sutures:Moderately depressedfinal-whorl chambers:6.0-7.0 N.B. These characters are used for advanced search. N/A - not applicable

    References:

    Almogi-Labin, A., Reiss, Z & Caron, M. (1986). Senonian globotruncanidae from Israel. Eclogae Geologicae Helvetiae. 79(3): 849-895. gs

    Tilev, N. (1951). Etude des Rosalines maestrichtiennes (genre Globotruncana) du Sud-Est de la Turquie (Sondage de Ramandaǧ). Maden Tetkik ve Arcana Enstitusu Yayinharindam (Mining Research and Exploration, Institute of Turkey Publ.). Ser. B. 16: 1-101. gs


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    Globotruncanita angulata compiled by the pforams@mikrotax project team viewed: 18-10-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110190 Go to Archive.is to create a permanent copy of this page - citation notes



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