Globorotalia bullbrooki Bolli 1957 from: Bolli, H.M. (1957): Planktonic Foraminifera from the Eocene Navet and San Fernando formations of Trinidad, B.W.I. . Bull. U.S. natl. Mus. Vol. 215 p. 155-172 | . |
Notice: This catalogue page may contain unedited data.
|
Species Globorotalia bullbrooki Bolli 1957 |
|
|
|
| Alternative name: |
|
| Diagnosis / Definition: |
Bolli (1957):
Shape of test on spiral side almost flat or low trochospiral, umbilical side strongly convex, subangulax. Wall calcareous, perforate, surface covered with short, blunt spines. Chambers subangular, inflated; about 12-15, arranged in about 2 1/2 whorls; the 4 chambers of the last whorl increase fairly rapidly in size. Sutures on spiral side oblique or radial, depressed; on umbilical side radial, depressed. Umbilicus narrow, deep. Aperture a low arch, interiomarginal, umbilical extraumbilical. Coiling without distinct pattern in the preliminary study of eight isolated samples belonging to the Hantkenina aragonensis zone. In four of these samples, 70-90 percent of the specimens coiled dextrally, in two a preference for sinistral coiling was observed and in two the specimens coiled at random. It may be of interest to note that in the samples with a predominance of dextrally coiled specimens, Clavigerinella was found but Hantkenina was absent. To gain a clear picture of the coiling pattern in Globorotalia bullbrooki, it will be necessary to make further investigations in a more nearly complete stratigraphic section. Largest diameter of holotype 0.5 mm. |
| Discussion / Comments: |
Bolli (1957):
Globorotalia bullbrooki, now species, is distinguished from G. aspensis (Colom) by its more subangular test and by the presence of 4 chambers in the last whorl instead of the 5-7 of that species. Globorotalia crassata (Cushman), often referred to in publications, may be close to the new species. The single spiral view of the holotype given by Cushman (1925) is not sufficient for an accurate determination and comparison. G. crassata as figured by Cushman and Bermudez (1949) shows 5 1/2 chambers in the last whorl as against the 4 commonly found in G. bullbrooki. G. crassata var. densa (Cushman) is described as differing from G. crassata in its more rounded compact form, rounded periphery, and in having only 4 chambers in the last formed coil instead of 5 or 6 as in the typical form. No figure was given by Cushman for this variety. On the basis of the scanty description alone it is not possible to compare it with Globorotalia bullbrooki or any other possibly synonymous Navet species. Specimens found among the middle Eocene foraminiferal fauna of a Mid Pacific core (see p. 169), are indistinguishable from Globorotalia bullbrooki, with the exception that they possess small sutural supplementary apertures on the spiral side, which are typical of the genus Truncorotaloides. It is likely that G. bullbrooki also possesses such accessory apertures which, however, cannot be seen due to the poor preservation, and should therefore be placed in the genus Truncorotaloides. The species is named for Mr. J. A. Bullbrook, geologist and archeologist, Trinidad. |
| Systematics: |
24
Genus Globorotalia
Species Globorotalia aspensis
Species Globorotalia broedermanni
|
| Synonym list: |
Bolli (1957):
|
| Was used in synonym list of: |
|
|
| References: |
Bolli,H.M. (1957):
Planktonic Foraminifera from the Eocene Navet and San Fernando formations of Trinidad, B.W.I. . Bull. U.S. natl. Mus. Vol. 215 p. 155-172
|
This work is licensed under a Creative Commons Attribution 2.5 License.
|
|
Taxon Concept provided by