Catalog - Steineckia steinecki Catalog - Steineckia steinecki

CATALOG OF ORIGINAL DESCRIPTIONS: Steineckia steinecki Georgescu 2009

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Higher levels: pf_cat -> S -> Steineckia -> Steineckia steinecki
Other pages this level: S. steinecki

Steineckia steinecki

Citation: Steineckia steinecki Georgescu 2009
taxonomic rank: Species
Type specimens: Holotype. Specimen WKB-F00501. Paratypes. Seven specimens WKB-000502.
Type sample (& lithostrat): Sample DSDP 79-511-47-5, 13.5– 14.5 cm.
Type age (chronostrat): Upper Turonian
Type locality: DSDP Site 511, Falkland Plateau. Geographic coordinates: 51°00’ S, 47°58’ W.
Type repository: Alberta; Willi Karl Braun Micropaleontological Collection at the University of Calgary (Calgary, Alberta, Canada.)

Current identification:

Original Description

Test is biserial throughout, consisting of 10 to 11 chambers that increase gradually in size; earlier chambers are globular, the last formed ones reniform. Proloculus is small (9.8–16.3 μm). Sutures are straight to slightly curved, depressed and oblique to the test axis of growth. Periphery is broadly rounded, without peripheral structures. Aperture is a medium-high arch situated at the base of the last-formed chamber and is bordered by two well-developed, symmetrical anges. Chamber surface is ornamented with large pore mounds (D = 4.0–6.4 μm, rarely as small as 3.3 μm in juvenile specimens in less than 4% of the measured structures). No periapertural pustulose area is present. Test wall is calcitic, hyaline, nannoperforate to microperforate, pore diameter ranging between 0.43 and 0.76 μm.

Dimensions of the holotype. Length: L = 0.169 mm; width: W = 0.116 mm; W/L = 0.686; thickness: T = 0.058 mm; T/L = 0.343.

As for the genus

Extra details from original publication
Remarks. Ontogenetic trajectories based on chamber increase in size apparently indicate that the ancestor of Steineckia steinecki is among the smooth small-sized heterohelicid species of the Cenomanian and Turonian (Figure 10). The diameters of the pore mounds in S. steinecki (D = 4.0–6.4 μm, rarely as small as 3.3 μm) are much larger than those of the biserial L. pulchra (D = 1.7–2.8 μm, occasionally as large as 3.9 μm). However, there is an overlap area between the two taxa, which might suggest the existence of an evolutionary relationship between them. The absence of costae in S. steinecki and presence of vestigial costae in L. pulchra indicate different evolutionary origins for the two taxa.

Stratigraphic range. Upper Turonian (lower part of the Whiteinella baltica Biozone).

Geographic distribution. South Atlantic (Falkland Plateau).


Georgescu, M. D. (2009b). Taxonomic revision and evolutionary classification of the biserial Cretaceous planktic foraminiferal genus Laeviheterohelix Nederbragt, 1991. Revista Mexicana de Ciencias Geológicas. 26: 315-334. gs


Steineckia steinecki compiled by the pforams@mikrotax project team viewed: 20-4-2024

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