Catalog - Globotruncana bollii

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Globotruncana bollii

Citation: Globotruncana bollii Gandolfi 1955

Type specimens: PL 5, fig. la-c ; 20853: type description p.62

Type sample (& lithostrat): Molino section, S. 12161.

Type age (chronostrat): Campanian-Maastrichtian

Type locality: Cesar Valley, Rio Molino, 200 km. NE of Villanueva; Northern Colombia

Type repository: Ithaca, New York; Paleontological Research Institution

Slightly convex on the dorsal side, more strongly so on the umbilical one with a narrow double keel fringing the early chambers, the second one often reduced to an indistinct rugose line, becoming single-keeled in the adult stages. The test coils in a more pronounced way in the early stages with long, arched chambers (cf. Glt. thalmanni thalmanmi, n.ssp.) which becomes larger and petaloid in later stages. The sutural elevations are thick and rugose in the early stages, later becoming; thin, well defined and smooth, with a somewhat straight, oblique development (stuarti type). On the umbilical side the sutural elevations are present, well defined and curved as in all area and rosetta tests. The umbilical cavity is large with thin, nearly straight or slightly arched lips. The test is dextrally coiling.

Dimensions of holotype. Width 0.51 x 0.48 mm.; thickness, 0.22 mm.

named after H. Bolli, paleontologist of Trinidad Leaseholds, Ltd., for his contribution to the knowledge of Globotruncana.

Remarks.—This species was interpreted from Cushman's figures as a Glt. rosetta by Cita, 1948, and as Glt. stuarti by Bolli, 1951. Actually, this species shows intermediate (undifferentiated) characteristics between Glt. rosetta, Glt. stuarti, and Glt. area. The present material is poor. However, a sample of the Pecan Gap, which was available to the writer through the courtesy of Mr. F. B. Ellis, shows a complete set of transitional passages from Glt. bollii, Glt. area area, and stiuirti-rosetta forms. A point of phylogenetic interest is that, in the early stages, the test becomes more trochoidal with elongated chambers, similar to a complete test of Glt. thalmanni thalmanni. Bolli, 1945, described and named Glt. leupoldi only from thin sections, a species which apparently shows an internal double keel later becoming a single one. The thin sections were found later by Reichel, 1949, (p. 614) to be identical with thin sections of Glt. area. It is probable, therefore, that Glt. leupoldi may include both forms, Glt. bollii and Glt. area area, inasmuch as it ranges through the Campanian and Maestrichtian. Glt. leupoldi is, at any rate, more convex on the dorsal side (Glt. area area) than the present one. This species was named after H. Bolli, paleontologist of Trinidad Leaseholds, Ltd., for his contribution to the knowledge of Globotruncana.

References:

Gandolfi, R. (1955). The genus Globotruncana in northeastern Colombia. Bulletins of American Paleontology. 36: 1-118. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globotruncana bollii Gandolfi 1955

Globotruncana bollii

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