Catalog - Trinitella scotti

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Other pages this level: T. scotti, T. suturis

Trinitella scotti

Citation: Trinitella scotti Bronnimann 1952

Type specimens: 4856 Holotype:T.L.L.Cat.Nos.155591-155594-Text fig.30a,b,c.All appr,X80.Plate 4,figs.4-6.

Type sample (& lithostrat): Globotruncana mayaroensis zone. Frequent.Possibly also Globotruncana gansseri zone.

Type age (chronostrat): Maastrichtian

Type locality: Trinidad Leaseholds Ltd. Catalogue nos. 155591-155594, subsurface samples from the Guayaguayare area, southeastern Trinidad, B. W. I.

Type repository: Washington; USNM

The trochoidal test is small to medium-sized and elongate in direction of the end chamber. The five to six chambers of the adult volution are subglobular at first. They then become flattened at the spiral side, forming a keel. These new features pertain to the end chamber, occasionally also to the two last ones. The end chamber is about twice as large as the penultimate one and elongate in radial direction. About two whorls can be recognized on the spiral side. The slightly depressed initial portion is not clearly exposed, and no information regarding the arrangement of the early chambers can be obtained due to the coarse rugosities or adhering matrix.
The umbilicus is large, deep, subcircular and probably provided with a delicate covering plate. Only fragments of this plate are preserved along the border of the umbilicus. The chambers are truncate toward the apertural side and increase in size as added. Seen from the spiral side, each adult chamber overlaps the next one. The sutures on the spiral side, therefore, are strongly curved in the direction of coiling. Those on the umbilical side are deep and relatively straight to slightly curved backward.
The arcuate apertures open into the umbilicus. The walls seem to be thick, and the surface, especially of the inner chambers, is strongly rugose. The ornamentation appears to be of the meridional pattern, although no central point was noted on the surface of the end chamber.
The counted individuals are invariably dextrally coiling.

Holotype. - Maximum diameter 0.4 mm. Diameter of umbilicus 0.075 mm. End chamber: radial diameter 0.2 mm.; tangential diameter 0.225 mm. Diameter of aperture 0.075 mm.
The longer diameter of the paratypes measures from 0.27mm.to 0.425mm.

It is named after E. Cooper Scott,former Chief Geologist of Trinidad Leaseholds Limited

Remarks. The initial portion of this form seems to be identical with that of typical representatives of the rugosa-reicheli
groups of Rugoglobigerina.

Occurrence: Globotruncana mayaroensis zone. Frequent. Possibly also Globotruncana gansseri zone.

References:

Bolli, H. M., Loeblich, A. R. & Tappan, H. (1957). Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae and Globotruncanidae. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 3-50. gs V O

Brönnimann, P. (1952c). Globigerinidae from the Upper Cretaceous (Cenomanian-Maestrichtian) of Trinidad, B. W. I. Bulletins of American Paleontology. 34(140): 1-70. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Trinitella scotti Bronnimann 1952

Trinitella scotti

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