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Contusotruncana fornicata


Classification: pf_mesozoic -> Globotruncanidae -> Contusotruncana -> Contusotruncana fornicata
Sister taxa: C. contusa, C. fornicata, C. morozovae, C. patelliformis, C. plicata, C. plummerae, C. walfischensis, C. sp.,

Taxonomy

Citation: Contusotruncana fornicata (Plummer, 1931)
Rank: Species
Basionym: Globotruncana fornicata
Synonyms: Globotruncana fornicata motai; Globotruncana contusa scutilla; Globotruncana sudrensis; Globotruncana thalmanni thalmanni
Taxonomic discussion: This species at its type locality in the Taylor formation (Station 226- T-8) is easily distinguished from its congeners by its narrow and strongly arched chambers that sweep in strong curves on the dorsal face. The chambers of the microspheric form are even more strongly curved than those of the megalospheric. Its dorsal sutures and margin are finely delineated by narrow and delicately beaded elevations which show a tendency to merge into sharp depressions from the periphery inward toward the earlier whorl. The center of each test is occupied by a globigerine spire of globular chambers, and this inflation persists in ma y tests in the strongly inflated inner extremities of the more mature chambers on the dorsal side. The dorsal convexity of the test varies from moderate to very high, especially in the microspheric form. The double carination is very characteristic of this species, but the secondary keel in some specimens weakens in late maturity. [copied from Chronos database]

Type images:

Original description: Globotruncana fornicata Plummer 1931: "Test biconvex, periphery truncate and lobate; chambers seven in final convolution, long narrow, strongly curved, smooth; dorsal sutures finely beaded, very strongly oblique and lightly curved; ventral sutures elevated and curved strongly forward in maturity, depressed and more nearly radial in youth; umbilicus broad and open; apertures from last 3 or 4 chambers of the final whorl into the umbilicus. Average diameter .4 mm; commonly up to .5 mm."

Entries in the Catalog of original descriptions: Globotruncana contusa scutilla;
Globotruncana fornicata;
Globotruncana fornicata motai;
Globotruncana sudrensis;
Globotruncana thalmanni thalmanni;

Geological Range:
Last occurrence (top): within A. mayaroensis zone (67.30-69.18Ma, top in Maastrichtian stage). Data source: [copied from Chronos database]
First occurrence (base): within D. concavata zone (86.71-89.91Ma, 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:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
umb chamber shape:Reniformcoiling axis:Lowperiphery:Double keelaperture border:Tegilla
sp chbr shape:Crescenticumbilicus:Wideperiph margin shape:Subangularaccessory apertures:Intralaminal
umbilical or test sutures:Raised beadedumb depth:Shallowwall texture:Mod. Pustuloseshell porosity:
spiral sutures:Raised beadeddiameter mm:0.40 mm to 0.50 mmwidth mm:breadth mm:
final-whorl chambers:4.5-5.0

References:

Plummer, H.J., (1931). Some Cretaceous foraminifera in Texas. University of Texas Bulletin, 3101: 109-203.

Plummer, H.J., (1931). Gaudryinella, a new foraminiferal genus. The American Midland Naturalist, 12(9): 341-342.


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Contusotruncana fornicata compiled by the pforams@mikrotax project team viewed: 20-9-2017

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