Subbotina velascoensis


Classification: pf_cenozoic -> Globigerinidae -> Subbotina -> Subbotina velascoensis
Sister taxa: S. projecta, S. tecta, S. jacksonensis, S. corpulenta, S. eocaena, S. gortanii, S. crociapertura, S. yeguaensis, S. senni, S. roesnaesensis, S. utilisindex, S. angiporoides, S. minima, S. linaperta, S. patagonica, S. cancellata, S. hornibrooki, S. velascoensis, S. triloculinoides, S. triangularis, S. trivialis, S. sp.,

Taxonomy

Citation: Subbotina velascoensis (Cushman 1925)
Rank: Species
Basionym: Globigerina velascoensis
Synonyms:
Taxonomic discussion: Although the holotype specimen is deformed, Bolli (1957a) defined the concept of this species, which is followed herein. The species was described from the Velasco Shale from which White (1928) illustrated better preserved specimens that he identified with Cushman's species. White's concept was followed by Bolli. White's figures, although drawings, illustrate a quadrate-shaped test with much compressed chambers. Furthermore, his drawings clearly indicate a symmetrical, coarsely cancellate test wall. Cushman (1925) in his description referred to an evenly reticulate wall, which suggests that he observed the wall texture that characterizes this species.
Bolli (1957a) and Blow (1979) considered that S. velascoensis evolved from S. triangularis at, or near, the Zone P3/P4 boundary and believed that 5. velascoensis represented a dead-end lineage. Subbotina velascoensis has a much different wall texture than does S. triangularis. The latter species has a finer asymmetrical cancellate wall with coalescing spine collars, whereas S. velascoensis has a symmetrical, coarsely cancellate wall texture. In 5. velascoensis, the spines are set at the intersection of the cancellate ridges and are not supported by spine collars (Plate 29: Figure 11) as in S. triangularis (Plate 26: Figures 12, 13). We consider S. velascoensis as the end member of the symmetrical coarsely cancellate lineage that begins with 5. cancellata. Subbotina cancellata, gives rise to S. velascoensis at, or near, the Zone P3/P4 boundary. We agree with Bolli and Blow that S. velascoensis represents a dead-end lineage. Globigerina quadritriloculinoides Khalilov (1956) from the upper Paleocene of Azerbaizhan exhibits the characteristic quadrate-shaped morphology of S. velascoensis. The holotype figures show a coarsely cancellate wall, also typical of S. velascoensis. [Olsson et al. 1999]

Catalog entries: Globigerina velascoensis, Globorotalia tortiva, Globigerina velascoensis compressa, Globigerina quadritriloculinoides, Globigerina triloculinoides nanus

Type images:

Distinguishing features: Test tightly coiled, subquadrate, test with compressed chambers. Final chamber much compressed, elongate, forms about half of the test and typically overhangs the earlier chambers. Aperture umbilical; thin elongate lip along part of aperture with squared-of ends. The test wall is coarsely and symmetrically cancellate, spinose.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description


Diagnostic characters: A tightly coiled test with compressed chambers and a subquadrate test shape with an umbilical aperture. The ultimate chamber is much compressed, an elongate oval shape that makes up about half of the test and typically overhangs the earlier chambers. The aperture is bordered by a thin elongate lip that does not extend along the entire length of the aperture and is squared off where it terminates. The test wall is coarsely and symmetrically cancellate, spinose. [Olsson et al. 1999]

Character matrix

test outline:Quadratechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Inflatedumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Strongly depressedumb depth:Deepwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:3.0-4.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Essentially a worldwide distribution in the low to middle latitudes, with preferential development in the middle to higher latitudes as is common with the subbotinids (Figure 13). [Olsson et al. 1999]
Aze et al. 2011 summary: Cosmopolitan; based on Olsson et al. (1999)

Isotope paleobiology: Subbotina velascoensis has a ∂13C and ∂18O signature similar to P. varianta, G. compressa, and G. pseudomenardii, but it typically has a heavier ∂18O and more negative 8'3C than coexisting Acarinina and Morozovella (Berggren and Norris, 1997). [Olsson et al. 1999]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): Berggren & Norris (1997); Coxall et al. (2000)

Phylogenetic relations: This species evolved from S. cancellata by the development of a more tightly coiled, quadrate test and compressed chambers. [Olsson et al. 1999]

Most likely ancestor: Subbotina triloculinoides - at confidence level 3 (out of 5). Data source: Olsson et al. 1999 f5a (but Olsson et al 2005 f6.2 show it evolving from cancellata).
Likely descendants: Subbotina hornibrooki;

Biostratigraphic distribution

Geological Range:
Notes: Zone P3b to Zone P6a. [Olsson et al. 1999]
Last occurrence (top): within E3 zone (54.61-55.20Ma, top in Ypresian stage). Data source: Olsson et al. 1999
First occurrence (base): within P3b subzone (60.73-61.33Ma, base in Selandian stage). Data source: Olsson et al. 1999

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 33

References:

Bolli, H. M. & Cita, M. B. (1960). Globigerine e Globorotalie del Paleocene di Paderno d'Adda (Italia). Rivista Italiana di Paleontologia e Stratigrafia. LXVI(3): 1-42. gs

Bolli, H. M. (1957d). The genera Globigerina and Globorotalia in the Paleocene-Lower Eocene Lizard Springs Formation of Trinidad. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 61-82. gs

Cushman, J. A. (1925d). Some new foraminifera from the Velasco shale of Mexico. Contributions from the Cushman Laboratory for Foraminiferal Research. 1(6): 18-23. gs

Gohrbandt, K. (1963). Zur Gliederung des Palaeogen im Helvetikum nordlich Salzburg nach planktonischen Foraminiferen. Mitt Geol Ges, Wien. 56(1): 63-. gs

Hillebrandt, A. , von (1962). Das Paleozän und seine Foraminiferenfauna im Becken von Reichenhall und Salzburg. Abhandlungen Bayerischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, Neue Folge. 108: 1-182. gs

Khalilov, D. M. (1956). 0 pelagicheskoy faune foraminifer Paleogenovykh otlozheniy Azerbaydzhana [Pelagic Foraminifera of the Paleogene Deposits of the Azerbaizhan SSR]. Trudy Instituta Geologii, Akademiya Nauk Azerbaidzhanskoi SSR. 17: 234-255. gs

Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. 1-252. gs

Shutskaya, E. K. (1970a). Morphologic groups and descriptions of species of Globigerina and Acarinina in the lower Paleogene of the Crimea, the Caucasus Foreland, and western Central Asia. Trudy Instituta Vsesoyuznyy NauchnoIssledovatel'skiy Geologorazvedochnyy Neftyanot Institut. 69: 79-113. gs

White, M. P. (1928). Some Index Foraminifera of the Tampico Embayment Area of Mexico. Journal of Paleontology. 2(3): 177-215. gs


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Subbotina velascoensis compiled by the pforams@mikrotax project team viewed: 18-10-2019

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