pforams@mikrotax - Globotruncanella semsalensis pforams@mikrotax - Globotruncanella semsalensis

Globotruncanella semsalensis


Classification: pf_mesozoic -> Globotruncanidae -> Globotruncanella -> Globotruncanella semsalensis
Sister taxa: G. compressiformis, G. havanensis, G. minuta, G. petaloidea, G. pschadae, G. semsalensis, G. sp.

Taxonomy

Citation: Globotruncanella semsalensis (Corminboeuf, 1961)
taxonomic rank: Species
Basionym: Globotruncana ? semsalensis
Taxonomic discussion: SEM photos will be taken in Fribourg, before deposit in collections of the NHM Basel. [copied from Chronos database]

Type images:

Original description: Translated from French:
Test trochoidal, lobate, dextral in all the examined specimens (47). 2½ - 3 whorls. 4½ - 7, generally six, chambers per whorl, compressed, generally increasing slowly in size. One or several chambers of the last whorl may be smaller in size than the previous chambers or they all are the same size. The last-formed chamber is usually larger, sometimes the same size or even smaller than the penultimate chamber. Rounded or slightly elongate, or spine-like pustules densely present on the two sides of the test. On the first chambers of the last whorl they are thick, gradually becoming thinner and thinner on the following chambers so that the last chamber(s) may be more or less smooth.

Spiral side convex. The chambers of the first whorl look like buttons tightly fit one against the other. In the second whorl, they become more distinct.They have a flat or slightly convex surface with thick rounded, spiky or slightly elongate pustules concentrating along the periphery and roughly shaping spiral and septal ridges, the two ridges forming a curve or an "u" between them . This ornamentation often remains present in the two or three first chambers of the last whorl; then it disappears, resulting in a depressed, radial, or curved in a frontward direction septal suture. The spiral side of the chambers of this last whorl is weakly to moderately convex.

Umbilical side: due to this side being strongly inflated, its shape is convex from the periphery toward the center of the chambers and concave from there toward the umbilicus. Sutures radial, depressed. Strong and thick pustules on the first chambers of the last whorl, either randomly distributed or aligned in the coiling direction or else perpendicular to that direction and, in this case, appearing like short costae spreading out from the umbilical edge toward the margin. In some specimens ,(presence of) one or two rows of pustules set in the coiling direction , becoming stronger on the two or three first chambers of the last coil and doubling or tripling the already existing peripheral row.

The primary aperture of the chambers is umbilical but often extends slightly toward the edge. It is covered by a tegillum directed toward the umbilicus, each tegillum is provided with a main aperture in the front and with one or two secondary apertures in the back. The infralaminal apertures (main and secondary) are provided - or not - with a thin lip. Each tegillum partly or totally extending over the tegillum of the preceding chamber, the tegillum of the last chamber sometimes sealing the whole umbilicus. I did not notice the presence of secondary intralaminal apertures.

Entries in the Catalog of original descriptions: Globotruncana semsalensis

Character matrix
test outline:Subcircularchamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Petaloidcoiling axis:Low-moderateperiphery:Single keelaperture border:Thin flange
umb chbr shape:Trapezoidalumbilicus:Wideperiph margin shape:Subangularaccessory apertures:Infralaminal
spiral sutures:Moderately depressedumb depth:Deepwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:5.5-6.5 N.B. These characters are used for advanced search. N/A - not applicable

Geological Range:
Last occurrence (top): within R. calcarata zone (75.06-75.91Ma, top in Campanian stage). Data source: [copied from Chronos database]
First occurrence (base): within R. calcarata zone (75.06-75.91Ma, base in Campanian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

References:

Corminboeuf, P. (1961). Association de Belemnitella et de Globotruncanidae dans le Campanien superieur des Alpettes (Prealpes externs fribourgeoises). Eclogae Geologicae Helvetiae. 54(2): 491-498. gs


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Globotruncanella semsalensis compiled by the pforams@mikrotax project team viewed: 30-5-2024

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