Praeglobotruncana stephani

Taxonomy

Original description: Translation from Italian: Test small with a round outline. It is convex on the dorsal side, flat or concave on the umbilical side. The peripheral margin is rounded and slightly depressed. The chambers are depressed or angular in the middle whorl, more rounded and convex in the last whorl, rosetta-like overlapping in the inner part where they are distinctly separated and elongated in the external part like typical chambers of Globigerina. The sutures are oblique and curved in the inner whorls, tending to become radial and straight in the last whorl. In the middle whorl, following the initial globigerinid appearance, the sutures are ornamented by an alignment of pustule-like structures. Such alignment is either not-distinct or distinct when the pustules-like structures are coalescing to form a real keel. These pearl-like keels are not distinct in the external part and the last chambers are simple. In the umbilical area the chambers are well convex, the umbilicus is middle-sized, the sutures are simple, radial and deep. In thin section it is possible to see that the chambers are opened regularly in the umbilicus. The test is coarsely porous than in G. appenninica Renz and the general aspect is therefore more rugose. The chambers of the last whorl are 4 to 6.

Conchiglia piccola, rotonda al contorno, superiormente convessa, inferiormente piana o un poco concava, margine arrotondato o un po' depresso. Camere depresse o angolose nel giro mediano, più arrotondate e convesse nel giro esterno; ricoprentisi in parte a rosetta internamente, nettamente staccate e affusolate in ultimo quali tipiche camere di Globigerina. Suture un po'oblique e curve nei giri interni, con tendenza radiale e diritta nel giro esterno. Nel giro mediano dopo lo stadio globigerinoide dette suture sono orlate da una fila di tubercoli, talvolta indistinta; talvolta più netta per la fusione dei detti tubercoli tra loro, sì da formare una vera e propria carena. Queste carene perlate si fanno esternamente di nuovo indistinte sin che le ultime camere sono come si è detto semplici.

Nella parte ombelicale le camere sono ben convesse, l'ombelico è di media grandezza, le suture sòno semplici, radiali' profonde. Dalle sezioni è visibile che le camere si aprono sull'ombelico regolarmente. La conchiglia è più grossolanamente porosa che nella G. apenninica e pertanto l'aspetto è più ruvido.

Numero camere all'ultimo giro : 4-6. 

Entries in the Catalog of original descriptions: Globotruncana stephani, Globorotalia californica

Geological Range:
Last occurrence (top): within H. helvetica zone (92.51-93.52Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within P. appenninica zone (100.50-101.92Ma, base in Albian 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
• Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
• Taxon plotted: Praeglobotruncana stephani, synonyms included - Globotruncana californica; Praeglobotruncana californica; Praeglobotruncana stephani;
• See also space-time plot :: Samples map :: Parent: Praeglobotruncana

Praeglobotruncana stephani compiled by the pforams@mikrotax project team viewed: 20-9-2024 Taxon Search: Advanced Search Short stable page link: https://mikrotax.org/pforams/index.php?id=110438 Go to Archive.is to create a permanent copy of this page - citation notes

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