Catalog - Truncorotaloides

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Truncorotaloides

Citation: Truncorotaloides Brönnimann and Bermúdez, 1953.

Type species: Truncorotaloides rohri Brönnimann and Bermúdez, 1953

Diagnosis.-Test a low trochoidal planoconvex spiral of two volutions. Final volution contains five to six chambers, not overlapping, or overlapping at spiral side only. Chambers subglobular throughout or subglobular in early and subangular in late ontogenetic stage or angular throughout. Spiral side slightly convex to almost flat, umbilical side slightly to strongly convex. Sutures straight to curved in direction of coiling. Umbilicus deep and small. Apertures large, arcuate, with lip-like borders, directed into umbilicus. Small, arcuate to slit-like additional sutural openings at spiral side. Surface with heavy spines. Walls finely perforate. Direction of coiling predominantly sinistral.

Discussion.-The new genus differs from Truncorotalia by the supplementary opennings at the spiral side; from Globigerinoides which possesses "numerous, large, supplementary apertures around the margin of the chamber," by the low trochoidal, planoconvex test and the characteristic heavy spinose ornamentation. The heavy spines of Truncorotaloides are permanent protuberances of the test. Further, Truncorotaloides is restricted to the Eocene, whereas Globigerinoides is known from the Eocene?, possibly Oligocene to Recent.

Occurrence. The material (sample K.R. 23842, T.L.L. Cat. No. 172694) originates from a marl pebble bed situated in the Duff road area, near Kelly junction, about seven miles east of Pointe-a-Pierre, central Trinidad. The larger components of this bed, consisting of subangular to rounded marl pebbles of Eocene and Oligocene age, are embedded in a finely pebbly heterogeneous matrix of predominantly Oligocene origin. The new pelagic Foraminifera were encountered only in the heterogeneous matrix, thus their exact stratigraphic significance is not known. However, it can be assumed from the vertical distribution of the spinose Globigerinas and Truncorotalias, that Truncorotaloides can only be of Paleocene to upper Eocene age. No such forms are known from the Oligocene. The absence in the Trinidad Paleocene of species related to Truncorotaloides, and the lower Eocene age of the oldest components of the marl pebble bed, suggest that a Paleocene age can be excluded.

Outside Trinidad, Truncorotaloides has been encountered in Cuba, where typical representatives of Truncorotaloides rohri and its varieties occur abundantly in a lower to middle Eocene marl at Jaruco, Province of Habana (P. Bronnimann, private collection) and, according to Dr. Bermudez, in samples from the type locality of the Guayabal formation, State of Vera Cruz, Mexico.

Neither the type species (T. rohri) nor the other species and sub-species in the original publication, indicate gender, so the genus should, by default, by treated as masculine

References:

Brönnimann, P. & Bermudez, P. J. (1953). Truncorotaloides, a new foraminiferal genus from the Eocene of Trinidad, B.W.I. Journal of Paleontology. 27: 817-820. gs

			Truncorotaloides haynesi Samanta 1970 = Acarinina rohri
			Truncorotaloides libyaensis El Khoudary 1977 = Acarinina topilensis
			Truncorotaloides rohri Bronnimann & Bermudez 1953 = Acarinina rohri
			Truncorotaloides rohri var. guaracaraensis Bronnimann & Bermudez 1953 = Acarinina rohri
			Truncorotaloides rohri var. mayoensis Bronnimann & Bermudez 1953 = Acarinina rohri
			Truncorotaloides rohri var. piparoensis Bronnimann & Bermudez 1953 = Acarinina rohri

CATALOG OF ORIGINAL DESCRIPTIONS: Truncorotaloides Brönnimann and Bermúdez, 1953.

Truncorotaloides

References:

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