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Archaeoglobigerina cretacea


Classification: pf_mesozoic -> Rugoglobigerinidae -> Archaeoglobigerina -> Archaeoglobigerina cretacea
Sister taxa: A. australis, A. blowi, A. bosquensis, A. cretacea, A. mateola,

Taxonomy

Citation: Archaeoglobigerina cretacea (d'Orbigny, 1840)
Rank: Species
Basionym: Globigerina cretacea
Synonyms: Globotruncana globigerinoides; Globigerina cretacea saratogaensis; Globotruncana (Rugoglobigerina) loetterlei subloetterlei

Type images:

Original description: Globigerina cretacea d'Orbigny 1840:

G. testa suborbiculari, compressa, rugoso-aculeata, spira obtusa, anfracribus tribus distinctis; loculis quinis, depresso-spheroidalibus, suturis excavatis; apertura magna in umbilico.

"Coquille suborbiculaire, comprimee, rugueuse, et meme couverte de petites pointes inegales. Spire a peine convexe, tres obtuse, composee de trois tours tres distincts, et formee, dans l'etat adulte, de quatorze a quinze loges. Loges spheriques, un peu deprimees, au nombre de cinq au dernier tour, fortement separees, et laissant a leur centre un ombilic large et profound. Ouverture tres grande en croissant, placee dans l'ombilic meme. On remarque une seconde ouverture, peut-etre accidentelle, a la troisieme loge. 

Type Description (translated from French): Dimensions: diameter, a quarter of a millimeter. Shell subcircular, compressed, rugose, even covered with small conical protuberances of unequal size. Spire barely convex, very obtuse, comprising three very distinct whorls and, in the adult stage, fourteen to fifteen chambers. Chambers spherical, slightly depressed, numbering five in the last whorl, strongly separated, providing room for a broad and deep umbilicus in their center. Aperture, large in size, crescent-shaped located in the umbilicus itself. In the third chamber, one notices a second aperture, perhaps accidental.

Description of lectotype: The test is a low trochospire consisting of about 2½ whorls of inflated chambers. The dorsal surface is flattened and only slightly convex. The axial periphery is rounded and only very slightly if at all truncated. The equatorial profile is subcircular and the equatorial periphery is lobulate. The last whorl consists of five slowly and regularly enlarging, little embracing but inflated chambers, which are slightly compressed dorso-ventrally. The dorsal sutures are depressed, distinct, not thickened or limbate and the intercameral sutures are slightly curved. The ventral sutures are distinct, depressed and nearly radial; they are not thickened or limbate. The periphery of each chamber bears two weak, widely spaced carinae bordering the imperforate peripheral band. The dorsal carina does not appear to extend along the dorsal intercameral suture. The ventral carina on the last chamber is reflected along the apertural face but becomes weak and indistinct above the aperture; it is difficult to see the umbilical extension of the ventral carina on any chamber except the last formed. The umbilicus is broad and deep; the primary aperture opens into the umbilicus and is bordered by an asymmetric lip-like flap (porticus, see Banner and Blow, 1959). Relict parts of the primary apertures of the earlier chambers of the last whorl remain open into the umbilicus. The imperforate fragile tegillum, observed in the d'Orbigny collections as well as in our own topotypic specimens, is missing on the lectotype. The wall is calcareous, apparently radial in structure, and is uniformly and finely perforate except for the imperforate area between the carinae. The surface of the test is hispid, the hispidity being greatest along the umbilical margins of the chambers. 

Entries in the Catalog of original descriptions: Globigerina cretacea;
Globigerina cretacea saratogaensis; Globotruncana (Rugoglobigerina) loetterlei subloetterlei;
Globotruncana globigerinoides;

Geological Range:
Last occurrence (top): within G. gansseri zone (71.75-72.97Ma, top in Maastrichtian stage). Data source: [copied from Chronos database]
First occurrence (base): within M. schneegansi zone (89.91-92.56Ma, base in Turonian stage). Data source: [copied from Chronos database]

Plot of occurrence data:

NB Plotting of Neptune data has been disabled on the Mesozoic pages because the dataset is both small and badly affected by a few sites with erroneous age models (our obs Huber, Petrizzo, Young, Nov 2016). The data can still be viewed via the range plottertool - tools menu.

Character matrix

test outline:Subcircularcoiling axis:Lowchamber arrangement:Trochospiralumbilicus:Wide
edge view:Spiroconvexumbilical or test sutures:Weakly depressedspiral sutures:Weakly depressedshell porosity:Macroperforate: >2.5
wall texture:Moderately muricateaperture:Umb.-extraumbilicalaperture border:Thin lipaccessory apertures:None
periphery:Double keelumb chamber shape:Crescenticsp chbr shape:Globularperiph margin shape:Moderately rounded
umb depth:Deepdiameter mm:0.25 mmwidth mm:breadth mm:
final-whorl chambers:5.0-6.0

References:

d'Orbigny, A., (1840). Mémoire sur les foraminiféres de la craie blanche du bassin de Paris. Mem. Soc. Géol. France, 4(1): +34+.


Archaeoglobigerina cretacea compiled by the pforams@mikrotax project team viewed: 26-6-2017

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