Catalog - Rugotruncana skewesae Catalog - Rugotruncana skewesae

CATALOG OF ORIGINAL DESCRIPTIONS: Rugotruncana skewesae Bronnimann and Brown 1956

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 -> Rugotruncana -> Rugotruncana skewesae
Other pages this level: R. ellisi, R. nothi, R. skewesae, R. tilevi

Rugotruncana skewesae

Citation: Rugotruncana skewesae Bronnimann and Brown 1956
taxonomic rank: Species
Type specimens: 628613
Type age (chronostrat): Maastrichtian
Type locality: From an exposure on the south bank of Walker Creek, about 1 mi. upstream from the intersection of the creek with the Cameron-Clarkson road, and 6 mi. N. 15 degrees E. of Cameron, in Milan County, central TX.
Type repository: Washington; USNM

Linked specimens: USNM-628613

Current identification/main database link: Globotruncana aegyptiaca Nakkady 1950

Original Description

Low trochospirally coiled test is rather smooth on the dorsal side, but it exhibits faint, discontinuous costellae on the early chambers of the last whorl on the ventral side. Its early chambes are inflated and globigerina-like. Later chambers are strongly flattened dorsally, but are somewhat pointed vetnrally, sloping steeply into the umbilius. The last whorl is scalloped and composed of 5-6 chambers, only the dorsal (upper) keel can be observed. The keels of the early chambers of the last whorl show a few rather strong spines. The principal aperture is rounded, interiomarginal, and opens into a rather large umbilicus. Long apertural flaps extent into the umbilicus, and in later chambers form protruded, imperforate, umbilical cover-plated with accessory apertures.

This species is named for the late Helen Jeanne Plummer, née Skewes.

Extra details from original publication

Remarks:  The distinctive feature of Rugotruncana skewesae, n. sp., is its very flat dorsal side. Globotruncana concavata (Brotzen) is the only globotruncanid known to us to have flatter dorsal side. Plummer (1927) referred R. skewesae, n. sp., to Globigerina rosetta Carsey. It differs from Causey's species in possessing faint costellae on the ventral side, rather strong spines on the keels of the early chambers of the last whorl, and a much flatter dorsal side. The holotype of Rugotruncana skewesae, n. sp., is from the same locality as the specimen figured by Plummer. It has been observed in the Prairie Bluff chalk in Alabama.



Brönnimann, P. & Brown, N. K. (1956). Taxonomy of the Globotruncanidae. Eclogae Geologicae Helvetiae. 48: 503-562. gs O


Rugotruncana skewesae compiled by the pforams@mikrotax project team viewed: 3-3-2024

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