Marginotruncana pileoliformis

Taxonomy

Original description: Test trochospiral; spiral side convex; ventral side flat to nearly flat. Eighteen to twenty chambers arranged in 2.5 to 3 whorls; 6 to 7 chambers in outer whorl. Equatorial periphery rounded or slightly lobulate; axial periphery sharp to sharplly rounded. Single keel on outer whorl; double keel on preceding one. Sutures on umbilical side radial to curved, raised, showing subtrapexoidal chambers;sutures on spiral side curved, raised and beaded. In younger specimens, umbilical sutures of last chambers are depressed, like those of its ancestor, Dicarinella aff. hilalensis (Barr), while those of older specimens become sigmoidal. Primary aperture interiomarginal, extraumbilical-umbilical in position. Umbilicus large, diameter approximately 1/3 of diameter of test or more. Test surface generally smooth. Wall perforate except for keel and ornamentation, which are imperforate.

Entries in the Catalog of original descriptions: Marginotruncana pileoliformis

Geological Range:
Last occurrence (top): within D. concavata zone (85.60-89.75Ma, top in Santonian stage). Data source: [copied from Chronos database]
First occurrence (base): within H. helvetica zone (92.51-93.52Ma, base in Turonian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

• Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
• Triangles indicate an event for which a precise placement has been suggested
• (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Marginotruncana

Marginotruncana pileoliformis compiled by the pforams@mikrotax project team viewed: 12-5-2025 Taxon Search: Advanced Search Short stable page link: https://mikrotax.org/pforams/index.php?id=110336 Go to Archive.is to create a permanent copy of this page - citation notes

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