Morozovella conicotruncata


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

Taxonomy

Citation: Morozovella conicotruncata (Subbotina 1947)
Rank: Species
Basionym: Globorotalia conicotruncata
Synonyms:
Taxonomic discussion: This is a distinct middle Paleocene planoconvex morozovellid species characterized by 5-7 equidimensional chambers in the last whorl. Our studies support Blow's (1979) observation that this form appears virtually simultaneously with typical angulata-types (cf. Bolli, 1957a); however, we do not agree with the extended range given this taxon by Blow (1979) of mid-Zone P3 through Zone P4, extending possibly into Zone P5. Our studies support, rather, the range given by Bolli (1957a) of its extension into the lower part of the Globorotalia pseudomenardii Zone. [Olsson et al. 1999]

Catalog entries: Globorotalia (Truncorotalia) angulata; Globorotalia angulata abundocamerata;
Globorotalia conicotruncata;

Type images:

Distinguishing features: Like M. angulata (White) but test more planoconvex; umbilucs more open; and with a low rate of chamber enlargement, and so (5-7) equidimensional chambers in the final whorl.

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: Subcircular, moderately lobulate, low trochospiral test with 5-7 subangular, inflated, essentially equidimensional chambers in last whorl, spiral side flat to slightly convex in early whorls; umbilical sutures straight to weakly curved, radial, incised; spiral sutures distinctly curved, incised; axial periphery (sub)acute, peripheral muricocarina variable, generally fused on early chambers of last whorl while later chambers generally subrounded (although muricocarinae fuse consistently along peripheral margin on individuals of this form as it transforms into M. velascoensis in Zone P3b); umbilicus narrow, deep; aperture a low interiomarginal, umbilical-extraumbilical slit. [Olsson et al. 1999]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Planoconvexaperture:Interiomarginal
umb chamber shape:Subtriangularcoiling axis:Moderate-highperiphery:Muricocarinateaperture border:N/A
sp chbr shape:Crescenticumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Strongly depressedumb depth:Deepwall texture:Spinoseshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Weakly depressedfinal-whorl chambers:4.5-5.5

Biogeography and Palaeobiology


Geographic distribution: As with its closely related sister taxon angulata, this form has a predominantly tropical to temperate distribution (< 45° N and S) and has not been reliably reported from high northern or southern (subantarctic) latitudes. It is a common and distinct form in our material and is observed to grade into M. velascoensis in Subzone P3b. [Olsson et al. 1999]
Aze et al. 2011 summary: Low latitudes; based on Olsson et al. (1999)

Isotope paleobiology: Morozovella conicotruncata has ∂13C similar to M. angulata and more positive than Subbotina and Globanomalina (Boersma and Premoli Silva, 1983; Berggren and Norris, 1997). The ∂18O of M. conicotruncata is slightly lighter than M. angulata in samples from DSDP Site 384 (Berggren and Norris, 1997) and is distinctly lighter than coexisting Globanomalina and Subbotina (Boersma and Premoli Silva, 1983; 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): Boersma & Premoli Silva (1983); Berggren & Norris (1997)

Phylogenetic relations: This morphospecies evolved from Morozovella angulata (White) in the lower part of Zone P3 by the development of a distinctly planoconvex test, a more open umbilicus than M. angulata, and a characteristic low rate of chamber enlargement, which results in equidimensional chambers throughout the final whorl. [Olsson et al. 1999]

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

Biostratigraphic distribution

Geological Range:
Notes: Zone P3 to lower Zone P4. [Olsson et al. 1999]
Last occurrence (top): at top of P4 zone (100% up, 57.1Ma, in Thanetian stage). Data source: Olsson et al. (1999) f5a
First occurrence (base): near base of P3 zone (10% up, 62.1Ma, in Danian 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. 60

References:

Berggren, W.A., (1971). Paleogene planktonic foraminiferal faunas on Legs I-IV (Atlantic Ocean) JOIDES Deep Sea Drilling Program: a synthesis. In: Farinacci, A. (Editor), Proceedings of the II Planktonic Conference, Roma 1970. Edizioni Tecnoscienza, Rome, pp. 57-77.

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

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.

Bolli, H.M., (1957). The genera Globigerina and Globorotalia in the Paleocene-Lower Eocene Lizard Springs Formation of Trinidad. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 61-82.

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

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., (1956). Stratigraphy of the lower horizons of the Paleogene of the central Precaucasus according to the foraminifera. Akad Nauk SSSR, Inst Geol Nauk, Trudy, vypusk 164, Geol. Ser., 71: 3-119.

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.

Subbotina, N.N., (1947). Danian and Paleogene foraminifera of the northern Caucasus. Vses Neft Nauchno-Issled . Geol . -Razved . Inst. (VNIGRI) [All-Union Petroleum Scientific Research Geological Prospecting Institute], Microfauna of the oilfields of the Caucasus, Emba, and Central Asia, 1947: 39-160.

Subbotina, N., (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres, 2239: 1-144.


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Morozovella conicotruncata compiled by the pforams@mikrotax project team viewed: 16-11-2018

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