Subbotina hornibrooki


Classification: pf_cenozoic -> Globigerinidae -> Subbotina -> Subbotina hornibrooki
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 hornibrooki (Bronnimann 1952)
Rank: Species
Basionym: Globigerina hornibrooki
Synonyms:
Taxonomic discussion: Subbotina hornibrooki has been misinterpreted by workers probably due to the line drawing of the holotype, which presents a generalized morphology. Bronnimann reported the wall to be finely perforate, which somewhat confuses matters. The holotype illustrated for the first time in SEM (Pl.6.12, Figs. 1-3) shows a coarsely perforate sacculifer-type wall texture that places this species in the Subbotina velascoensis group of species. Most of the specimens illustrated by Blow (1979) lack this diagnostic wall texture.
Blow noted the close affinity of Globigerina finlayi Bronnimann, which was described in the same paper as hornibrooki, and we here consider it a synonym. The holotype of Globigerina bacuana Khalilov has been viewed by WAB and questionably referred to this species. [Olsson et al. 2006]

Catalog entries: Globigerina hornibrooki, Globigerina bacuana, Globigerina finlayi

Type images:

Distinguishing features: Test compact, low trochospiral with 3½ to nearly 4 globular embracing chambers in final whorl. Final chamber reduced and directed over the umbilicus. Wall texture coarsely cancellate, sacculifer-type.

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: Subbotina hornibrooki is distinguished by its compact, low trochospiral test with 3½ to nearly 4 globular embracing chambers in the ultimate whorl, reduced ultimate chamber that is directed over the umbilicus, and its coarsely cancellate sacculifer-type wall texture. [Olsson et al. 2006]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umbilical
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Weakly depressedumb depth:Shallowwall texture:Cancellateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:3.5-4.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Global in low to mid latitudes. [Olsson et al. 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (2006a)

Isotope paleobiology: No data available. [Olsson et al. 2006]
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): Coxall et al. (2000)

Phylogenetic relations: Subbotina hornibrooki belongs to the Subbotina velascoensis group of species that developed in the Paleocene from Subbotina cancellata Blow. Subbotina hornibrooki developed from Subbotina velascoensis in Zone P5 by developing a more compact test with a reduced ultimate chamber that is directed over the umbilicus. [Olsson et al. 2006]

Most likely ancestor: Subbotina velascoensis - at confidence level 0 (out of 5). Data source: Olsson et al. 2006 f6.2.
Likely descendants: Globoturborotalita bassriverensis;

Biostratigraphic distribution

Geological Range:
Notes: Upper Paleocene Zone P5 to Zone E4. [Olsson et al. 2006]
Last occurrence (top): within E4 zone (52.54-54.61Ma, top in Ypresian stage). Data source: Eocene Atlas
First occurrence (base): within P5 zone (55.96-57.10Ma, base in Thanetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Olsson et al. 2006 - Eocene Atlas, chap. 6, p. 145

References:

Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs

Brönnimann, P. (1952e). Trinidad Paleocene and lower Eocene Globigerinidae. Bulletin of American Paleontology. 34(143): 1-34. 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., Huber, B. T. & Berggren, W. A. (2006b). Taxonomy, biostratigraphy, and phylogeny of Eocene Globigerina, Globoturborotalita, Subbotina, and Turborotalita. In, Pearson, P. N. , Olsson, R. K. , Hemleben, C. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 6): 111-168. gs

Poag, C. W. & Commeau, J. A. (1995). Paleocene to middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: Biostratigraphy, allostratigraphy, and sequence stratigraphy. Journal of Foraminiferal Research. 25: 134-155. gs


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Subbotina hornibrooki compiled by the pforams@mikrotax project team viewed: 6-12-2019

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