Morozovella acutispira


Classification: pf_cenozoic -> Truncorotaloididae -> Morozovella -> Morozovella acutispira
Sister taxa: M. caucasica, M. crater, M. aragonensis, M. lensiformis, M. subbotinae, M. marginodentata, M. formosa, M. gracilis, M. aequa, M. apanthesma, M. angulata, M. praeangulata, M. edgari, M. allisonensis, M. velascoensis, M. acuta, M. occlusa, M. pasionensis, M. acutispira, M. conicotruncata, M. sp.,

Taxonomy

Citation: Morozovella acutispira (Bolli and Cita 1960)
Rank: Species
Basionym: Globorotalia acutispira
Synonyms:
Taxonomic discussion: This species has been little used in the literature on Paleocene morozovellids. The distinctive character of this form is the raised early part of the test containing the neanic chambers; this feature canvary considerably among individuals in a given sample. Our studies support the diagnosis of Blow (1979) of a biconvex test with a very narrow umbilicus linking it with M. occlusa. If Globorotalia californica Smith, 1957, is indeed a homonym of Globorotalia californica Cushman and Todd, 1946 (according to Blow, 1979), and a senior synonym of Globorotalia acutispira Bolli and Cita, 1960, it should be renamed, although we can agree (provisonally) with Blow that this may be unnecessary.
A closely related, if not identical, morphospecies is M. kolchidica ( Morozova). Morozova (1961) referred to theflator weakly convex central part of the spiral side of the test, which we have confirmed by examinaton of the holotype (3510/12 in the micropaleontological collections of GAN, Moscow). Comparison with the refigured holotype of M. acutispira Bolli and Cita (in Luterbacher, 1964, text-fig. 72a-c) reveals two virtually identical forms. Blow's (1979) interpretation of M. kolchidica as a junior synonym of G. (M.) formosa gracilis Bolli is considered anomalous and incorrect (although the two forms are clearly homeomorphic in the same manner as are M. velascoensis and M. caucasica). Morozovella kolchidica was described from (and is characteristic of) Zone P3 (as well as Zone P4); M. gracilis was described from (and is characteristic of) Zone P6 (as well as Zone P7). Morozovella acutispira is also homeomorphic with M. marginodentata (Subbotina), but the latter bears a consistently more massive muricocarina and lacks the apiculate early portion of the test (see also Berggren,
1977).
Illustrated on Plate 11: Figures 13-15 is a specimen from the collections of Shutskaya (no. 645) in VNIGRI (St. Petersburg), which is probably referable to M. acutispira. Although the slide containing this specimen is labeled as Globorotalia angulata var. kubanensis Shutskaya, the illustration of the holotype resembles M. conicotruncata (Subbotina); however, because the holotype in Moscow is lost, the identity of this taxon cannot be determined. Further confusing the taxonomic status of Shutskaya's taxon is the other specimen from the same slide (no. 645) illustrated on Plate 11: Figures 10-12. This specimen is probably referable to M. apanthesma. [Olsson et al. 1999]

Catalog entries: Globorotalia acutispira;
Globorotalia californica Smith;
Globorotalia kolchidica;

Type images:

Distinguishing features: Lenticular to subcircular, plano-convex to biconvex test with apiculate early whorls and lobulate outline, 4-6 chambers in last whorl; umbilical sutures radial, slightly curved, depressed; spiral sutures curved, raised and ornamented by the extension of the strongly muricate keel; chambers tend to be flattened along the peripheral margin; aperture a low, interiomarginal, umbilical-extraumbilical arch extending from a narrow, deep umbilicus.

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

Character matrix

test outline:Circularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:-
umb chamber shape:Subtriangularcoiling axis:Highperiphery:Muricocarinateaperture border:N/A
sp chbr shape:Petaloidumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Moderately muricateshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Raised muricatediameter mm:width mm:breadth mm:
final-whorl chambers:4.0-6.0

Biogeography and Palaeobiology


Geographic distribution: The geographic distribution of this morphospecies appears characteristic of subtropical to tropical regions as does that of occlusa. [Olsson et al. 1999]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology: The ∂13C of Morozovella acutispira is similar to that of coexisting morozovellids but is more positive than that of Subbotina and Globanomalina. The ∂18O ofM acutispira is lighter than that of Globanomalina and Subbotina (Berggren and Norris, 1997). [Olsson et al. 1999]
Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy δ13C and relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): Berggren & Norris (1997)

Phylogenetic relations: This morphospecies is closely related to, and probably evolved from, M. pasionensis by an increase in spire height, development of a biconvex test, a decrease in the number of chambers in the final whorl, and a decrease in the size of the umbilicus. Morozovella acutispira is closely related to M. occlusa as herein described. [Olsson et al. 1999]

Most likely ancestor: Morozovella pasionensis - at confidence level 4 (out of 5). Data source: Olsson et al. (1999) f5a.

Biostratigraphic distribution

Geological Range:
Notes: Near the Zone P3/P4 boundary to the top of Zone P4b. [Olsson et al. 1999]
Last occurrence (top): at top of P4b subzone (100% up, 57.8Ma, in Thanetian stage). Data source: Olsson et al. (1999) f5a
First occurrence (base): at top of P3b subzone (95% up, 60.8Ma, in Selandian stage). Data source: Olsson et al. (1999) f5a

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 56

References:

Belford, D.J., (1984). Tertiary foraminifera and age of sediments, Ok Tedi-Wabag, Papua New Guinea. Bureau of Mineral Resources, Australia, Bulletin, 216: 1-52.

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

Cushman, J.A. & Todd, R., (1946). A Foraminiferal Fauna from the Paleocene of Arkansas. Contributions from the Cushman Laboratory for Foraminiferal Research, 22: 45-65.

Luterbacher, H.P., (1964). Studies in some Globorotalia from the Paleocene and Lower Eocene of the Central Apennines. Eclogae Geologicae Helvetiae, 57: 631-730.

Morozova, V.G., (1961). Datsko-Montskie planktonnye foraminifery yuga SSSR [Danian-Montian Planktonic Foraminifera of the Southern USSR]. Paleontologicheskiy Zhurnal, 2(8-19).

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology, 85. Smithsonian Institution Press, Washington, DC, 1-252 pp.

Shutskaya, E.K., (1970). Stratigrafiya, foraminifery i paleogeografiya nizhnego paleogena Kryma, predkavkaz'ya i zapadnoi chadsti srednei azii [Stratigraphy, Foraminifera and Paleogeography of the Lower Paleogene in the Crimea, Precaucasus and the Western Part of Central Asia]. Trudy, Vsesoyuznyi Nauchno-lssledovadetel 'skii Geologorazvedochnyi Neftyanoi Institut (VNIGNI), 70: 256 pages.

Smith, B.Y., (1957). Lower Tertiary foraminifera from Contra Costa county, California. University of California Publications in Geological Sciences, 32(3): 127-242.


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Morozovella acutispira compiled by the pforams@mikrotax project team viewed: 18-9-2018

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