Catalog - Marginotruncana pileoliformis Catalog - Marginotruncana pileoliformis

CATALOG OF ORIGINAL DESCRIPTIONS: Marginotruncana pileoliformis Lamolda 1977

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> M -> Marginotruncana -> Marginotruncana pileoliformis
Other pages this level: M. arcaformis, M. bouldinensis, M. caronae, M. paraconcavata, M. paraconcavata veronikae, M. paraventricosa, M. pauperata, M. pileoliformis, M. pseudolinneiana, M. pseudomarginata, M. scorpionis, M. sinuosa

Marginotruncana pileoliformis

Citation: Marginotruncana pileoliformis Lamolda 1977
Taxonomic rank: species
Type specimens: 1048
Type age (chronostrat): Late Turonian
Type locality: Valle de Mena (Burgos Province, Spain), outcrops in the cuts of the La Robla railroad close to the Alto de El Cabrio.
Type repository: Bilbao, Spain; Bilbao University - BIPA (Paleontological Collection)

Current identification/main database link: Marginotruncana pileoliformis Lamolda 1977


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.

Size:
D = 0.52 mm .. H = 0.18 mm .. H' = 0.05mm., O = 0.20 mm.

Etymology:
Medieval Latin pileolus = Italian zucchetto (a skull cap worn by Roman Catholic ecclesiastics).

Extra details from original publication
Remarks: Since Marginotruncana sigali (Reichel) is considered a homeomorph of Globotruncana stuarti (de Lapparent) . M. pileoliformis Lamolda may be considered a homeomorph of G. conica White. It differs from the last species by having a primary aperture extraumbilical-umbilical in position rather than umbilical. from M. sigali (Reichel) by being spiroconvex rather than biconvex. and from Dicarinella hilalensis (Barr) by having raised umbilical sutures. not depressed ones. M. pileoliformis Lamolda. evolved from D. aft. hilalensis (Barr). by proterogenetical acquisition of raised sutures on the ventral side. in the same way that M. siga/i (Reichel) evolved from D. aff. schneegansi (Sigal). In the upper Turonian, M. pileoliformis Lamolda underwent doubling of the keel. which became general in the lower Coniacian. and gave rise to M. sp. aff. M. angusticarinata (Gandolfi). This phenomenon occurred also to M. sigali (Reichel). from which M. renzi (Gandolfi) has arisen.

Occurrence: M. pileoliformis is present in all sections studied. It is associated with Dicarinella schneegansi (Sigal). M. siga/i (Reichel). D. imbricata (Mornod). Helvetoglobotruncana helvetica ( Bolli). D. aff. hilalensis (Barr). M. pseudolinneiana Pessagno and M. fungicamerata (Martirosjan); appearing a little later than H. helvetica (Bolli).

Range: Middle and late Turonian. although it is possible that it may already be present in the uppermost early Turonian, like M. sigali (Reichel) and M. marianosi (Douglas) .

References:

Lamolda, M. (1977). Lamolda, M. (1977). Three new species of planktonic foraminifera from the Turonian of northern Spain. Micropaleontology. 23: 470-477. Micropaleontology. 23: 470-477. gs


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Marginotruncana pileoliformis compiled by the pforams@mikrotax project team viewed: 17-6-2025

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