CATALOG OF ORIGINAL DESCRIPTIONS: Rugoglobigerina (Rugoglobigerina) plana Belford 1960

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> R -> Rugoglobigerina (Rugoglobigerina) -> Rugoglobigerina (Rugoglobigerina) plana
Other pages this level: R. (Rugoglobigerina) arwae, R. (Rugoglobigerina) badryi, R. (Rugoglobigerina) bronnimanni, R. (Rugoglobigerina) browni, R. (Rugoglobigerina) bulbosa, R. (Rugoglobigerina) pilula, R. (Rugoglobigerina) plana

Rugoglobigerina (Rugoglobigerina) plana

Citation: Rugoglobigerina (Rugoglobigerina) plana Belford 1960
Rank: Species
Type locality: Toolonga Point, Murchison River area, W. Australia
Type age (chronostrat): 8 feet above base of Toolonga Calcilutite (Santonian)
Type specimens: Holotype (C.P.C. 3403), paratypes A to C (C.P.C. 3404 to 3406), and thin section (C.P.C. 3407)
Type repository: Canberra, Australia; Commonwealth Palaeontological Collection

Current identification/main database link: Costellagerina pilula (Belford, 1960)


Original Description
Diagnosis: Test trochoid, spiral surface usually flat, chambers globular, inflated, 5-6 in last whorl. Sutures straight, depressed, test ornamented with small ridges, sometimes in a meridional pa'ttern, or in plane of coiling. Aperture interiomarginal umbilical large.

Description: Test trochoid, both dextrally and sinistrally coiled forms occurring; umbilicus wide, circular, usually infilled. Chambers globular, inflated, forming 2½-3 whorls, successive whorls strongly but not completely overlapping, spiral surface only slightly if at all convex; 5-6 chambers in last whorl. Sutures straight and strongly depressed on both spiral and umbilical sides. Test ornamented with small discontinuous ridges, not strongly developed, often difficult to observe on earlier whorls, where they are irregularly arranged. Meridional pattern developed on chambers of last whorl of some specimens, on others weakly developed, the ridges mainly arranged parallel to plane of coiling. Wall of test calcareous, finely perforate, radiate in structure. Aperture interiomarginal, umbilical, large and arcuate, not always observed. Well-preserved specimens show small tegilla extending into umbilicus.

Size: Holtype 0.37 x 0.20 mm; Partypes 0.29-0.33mm long x 0.18-0.21 mm wide.

Etymology: The specific name is the Latin planus, even, flat, level.

Extra details from original publication

Remarks: This is the least common species of Rugoglobigerina in the Upper Cretaceous of Western Australia; it occurs in the Santonian and basal Canipanian bed G of the Toolonga Calcilutite in the Murchison River area, and in the Gingin Chalk. Ten sinistrally coiled and six dextrally coiled specimens have been found, but this is not sufficient to indicate a preferred direction of coiling in this species.

Other described species of Rugoglobigerina have a preference for dextral coiling; Bronnimann (1952) observed only dextrally coiled specimens. Bolli, Loeblich, & Tappan (1957) stated that" All known species of Globotruncana and Rugoglobigerina tend to develop an almost exclusive preference for dextral coiling". Bolli (1951), investigating some Globorotalidae from Trinidad, found that random coiling is usually restricted to the early representatives of a species, whereas stratigraphically younger forms prefer a single direction, either dextral or sinistral.

It has not been possible to investigate the relative frequencies of the direction of coiling of the present species throughout their total range. The random coiling may indicate that these are early representatives of the species. By analogy with investigated lineages of planktonic foraminifera it is probable that a preferred direction of coiling would be developed by stratigraphically younger specimens.

Several subspecies of Rugoglobigerina have been established by Bronnimann (1952) in the Upper Cretaceous of Trinidad and by Gandolfi (1955) in the Upper Cretaceous of north-eastern Colombia. With more material and more detailed study it may be possible to recognise finer taxonomic divisions within the species here described from the Upper Cretaceous of Western Australia.

References:

Belford, D. J. (1960). Upper Cretaceous foraminifera from the Toolonga Calcilutite and Gingin Chalk, Western Australia. Australia Bureau of Mineral Resources, Geology and Geophysics Bulletin. 57: 1-198. gs


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Rugoglobigerina (Rugoglobigerina) plana compiled by the pforams@mikrotax project team viewed: 27-11-2020

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