Catalog - Heterohelix pachymarginata

CATALOG OF ORIGINAL DESCRIPTIONS: Heterohelix pachymarginata Stenestad 1968

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 -> H -> Heterohelix -> Heterohelix pachymarginata
Other pages this level: H. (Chiloguembelina) pseudotessera directa, H. (Heterohelix) planeobtusa, H. dentata, H. fayose, H. hohenemsensis, H. ivandeklaszi, H. labellosa, H. navarroensis, H. nkporoensis, H. olssoni, H. orientalis, H. pachymarginata, H. pseudoglobulosa, H. pseudoreussi, H. robusta, H. rumseyensis, H. sphenoides, H. stenopos, H. striata aegyptiaca, H. suwalkensis, H. trochospiralis, H. varsoviensis, H. virgata, H. vistulaensis

Heterohelix pachymarginata

Citation: Heterohelix pachymarginata Stenestad 1968
Rank: Species
Described on page(s) : 66-67
Type specimens: Plate 1 fig. 1, 2; Plate 2 fig. 4, 5, 6.

Current identification/main database link: Planoheterohelix planata (Cushman, 1938)


Original Description

Test compressed, rather slender, with subglobular thin-walled chambers. Sutures straight, slightly depressed, in the early stage limbate. The raised sutures turn at the margin of the test in apical direction thus forming an entire, strongly thickened initial margin. Margin indented in the adult. Surface striate, at the initial part of the test strongly striate.

Size:

Etymology:
Describing the broad, thickened initial margin.

Extra details from original publication
Remarks: As shown in plate 2 fig. 4, the thickened margin is not a real carina, but a rather broad girdle around the early part of the test. The proloculum wall is not thickened (Plate 2, fig. 6). Specimens with a true initial coil consisting of at least five chambers are not very abundant. But many specimens have their first chamber after the proloculum placed apically, thus forming a sort of coil with four chambers (Plate 2 fig. 1b). It would actually not be unreasonable to regard such a chamberarrangement as a coil, since the septal foramina are not alternating but all turn to the same side.

The new species differ from H. planata (CUSHMAN) in the surface ornamentation, the more compressed form and the special initialmargin. In Campanian in the borehole Batum 16 A (Sailing, Jutland) some specimens are morphologically rather close to H. striata (EHRENBERG) from which they mainly differ in possessing an entire, thickened initial margin. The strongly carinated H. carinata (CUSHMAN) seems according to CUSHMAN (1938, p. 18, pi. 3 fig. 10 a, 10 b) to have a real carina and to be stronger compressed than the Danish species.

Distribution: Upper Campanian and lowermost Maestrichtian at Hvide Klint (Møn). Upper Campanian in the borehole Batum 16 A (Sailing, Northern Jutland). (White Chalk facies). Lowermost Maestrichtian at Lille Bissinge (Møn).

Stratigraphic Range: Upper Campanian to lowermost Maestricht

Material: About 100 specimens from Upper Campanian and lowermost Maestrichtian in the Danish Embaymen

Editors' Notes

References:

Stenestad, E. (1968). Three new species of Heterohelix Ehrenberg from the upper Senonian of Denmark. Meddelelser fra Dansk Geologisk Forening. 18(1): 64-70. gs


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Heterohelix pachymarginata compiled by the pforams@mikrotax project team viewed: 5-12-2022

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