Catalog - Ventilabrella browni

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Ventilabrella browni

Citation: Ventilabrella browni Martin 1972

Type locality: from the south bank of Tradinghouse Creek 3.5 feet above the creek level, 1.5 miles west of the juncture between Tradinghouse Creek and Tehuacana Creek, 1 airline mile S68E of Harrison Switch, or .2 milesdue south of the county road bridge over Tradinghou

Type repository: Washington; USNM

Test flabelliform, laterally compressed, with 6-8 subglobular chambers in biserial portion; up to 10 subglobular to pyriform chambers in multiserial portion. Longitudinal costae very heavy on biserial portion; costae finer and discontinuous on multiserial portion. Sutures indistinct, depressed. Arched, basal apertures on front and back of all but outermost chambers in final row; outermost chambers with apertures on front only, facing inward.

The holotype measure 385µm in length, 425µm in width, and 125µm in maximum thickness. Other specimens vary from 325 to 450 µm in length; 250 to 475µm in width; and 125 to 130µm in maximum thickness.

V. browni Martin, n. sp., is named for the late Noel K. Brown, Jr., in honor of his work on the Heterohelicidae

Remarks: V . browni Martin, n. sp., differs from V. glabrata Cushman by having: (1) stronger costae on the biserial portion; (2) fewer chambers in the multiserial portion of the test; and (3) less distinct sutures. V. browni, n. sp. should not be confused with Sinalia alpina (de Klasz) (= Ventilabrella alpina de Klasz), which occurs abundantly with V. browni in the “Lower Taylor Marl” Member of the Taylor Formation, and in the Wolfe City Sand. S. alpina has raised, beaded sutures (PI. 1, fig. 5 ) ; otherwise, both forms are similar in their test shape and strongly costate early chambers. There is some possibility that V. browni may represent a transitional form between Sigalia and Ventilabrella. .

Range: G. bulloides Assemblage Zone, G. fornicata Subzone to G. fornicata-stuartiformis Assemblage Zone, G. elevata Subzone, (G. calcarata Zonule).

Occurrence: In Texas V. browni has been observed in the late Santonian portion of the “Hutchins Chalk” Member of the Austin Chalk (011-1 of Martin, see appendix). It also occurs abundantly with V. glabrata Cushman and V. eggeri Cushman in the Campanian “Lower Taylor Marl Member" of the Taylor Formation, and in the Wolfe City Sand (TX 255A of Pessagno, see appendix). In Arkansas V. browni is found in the lower part of the Brownstown Marl ( AR74 of Pessagno, see appendix). V. browni occurs in the late Santonian and early campanian portions of the Cariblanco Formation of Puerto Rico ( OP 2196 and OP 200 of Pessagno, see appendix).

References:

Martin, S. E. (1972). Reexamination of the Upper Cretaceous planktonic foraminifera genera Planoglobulina and Ventilabrella Cushman. Journal of Foraminiferal Research. 2(2): 73-92. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Ventilabrella browni Martin 1972

Ventilabrella browni

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