pforams@mikrotax - Morozovella acuta

pforams@mikrotax - Morozovella acuta pforams@mikrotax - Morozovella acuta

Morozovella acuta

Classification: pf_cenozoic -> Truncorotaloididae -> Morozovella -> Morozovella acuta
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.

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Taxonomy

Citation: Morozovella acuta (Toulmin 1941)

taxonomic rank: Species

Basionym: Morozovella

Synonyms:

Globorotalia wilcoxensis Cushman and Ponton var. acuta Toulmin, 1941:608, pl. 82: figs. 6-8 [Zone P4, Salt Mountain Limestone, Wilcox Group, Alabama].—Cushman and Renz, 1942:12, pl. 3: fig. 2a-c [Zone P4, Soldado Fm., Trinidad].—Cushman, 1944a:48,49, pl. 8:fig.5a,b [Zone P3b, Naheola Fm., Alabama]; 1944b: 15, pl. 2: fig. 16a,b [Zone P5, Bashi Fm., Wilcox Group, Alabama].—Shifflett, 1948:73, pl. 4: fig. 23a-c [Zone P4, Aquia Fm. Maryland].
Globorotalia velascoensis (Cushman) var. parva Rey, 1954:209, pl. 12: fig. la,b [Zone P4, Sample TB 450, Well No. 11, Koudiat Bou-Khelif, near Ouezzane, northern Morocco].
Globorotalia acuta Toulmin.—Loeblich and Tappan, 1957a: 185, pl. 47: fig. 5a-c [Zone P4, Salt Mountain Limestone, Wilcox Group, Alabama], pl. 55: figs. 4a-5c [Zone P4, Vincentown Fm., New Jersey], pl. 58: fig. 5a-c [Zone P4, Aquia Fm., Virginia],—Aubert, 1962:54, pl. 1: fig. 3a-c [Zone P4, Koudiat Bou Khelif, Morocco].—Luterbacher, 1964:686-689, text-fig. lOla-c [Zone P4, El Quss Abu Said, Farafrah Oasis, Egypt], text-figs. 102a-104c [Zone P5, Velasco Fm., Ebano, eastern Mexico].
Globorotalia velascoensis parva Rey.—Bolli and Cita, 1960:392-393, pl. 35: fig. 5a-c [Zone P4, Paderno d'Adda, northern Italy],—Aubert, 1963:54, pl. 1: fig. 2a-c [Zone P4, N. Morocco].
Globorotalia velascoensis acuta (Toulmin). —Shutskaya, 1970a: 119-120, pl. 27: fig. l l a - c [Acarinina acarinata Zone, Kachan Stage, Tarkhankut Peninsula, Crimea], pl. 28: fig. 4a-c, pl. 29: fig. 9a-c [Globorotalia aequa Zone, Bakhchisarayan Stage, Tarkhankut Peninsula, Crimea],
Globorotalia (Morozovella) acuta Toulmin.—Jenkins, 1971:106, pl. 9: figs. 205-207 [Globigerina triloculinoides Zone = Zone P4 this paper, Waipawan D Stage, Middle Waipara River section, New Zealand],
Globorotalia (Morozovella) velascoensis parva Rey.—Jenkins, 1971:106, 107, pl. 9: figs. 211-213 [Globigerina triloculinoides Zone = Zone P4 this paper, Waipawan Stage, Middle Waipara River section, New Zealand],—Blow, 1979:1030, 1031, pl. 95: figs. 3-6 [Zone P5, Sample FRCM 1670, Lindi area, Tanzania],
Morozovella acuta (Toulmin).—Toumarkine and Luterbacher, 1985:111, text-fig. 14 (7, reillustration of holotype; 8, reillustration of Loeblich and Tappan, 1957a, pl. 55: fig. 4a-c, from the Vincentown Fm., New Jersey; incorrectly ascribed to the Salt Mountain Fm., Alabama], [Olsson et al. 1999]

Taxonomic discussion: Considerable controversy surrounds the characterization and recognition of this, and closely related, forms of the velascoensis group. The "typical" M. acuta is generally believed to be distinguishable from M. velascoensis in its average smaller size, more rapid increase in chamber growth, proportionately larger final chamber, more subdued periumbilical ornamentation, and reduced number of chambers in the final whorl (Loeblich and Tappan, 1957a; Luterbacher, 1964; Blow, 1979). Other authors (Bolli, 1957a; Hillebrandt, 1962; Proto Decima and Zorzi, 1965, among others) believe these (and other) forms are linked by continuous gradations and consider them synonymous.
At the same time, another commonly cited form is Globorotalia velascoensis parva (auct. non) that we believe shares a close morphologic relationship with M. acuta. Whether the forms illustrated by various authors as parva are, indeed, referable to Rey's taxon is a moot point, however. Luterbacher (1964) showed that the typical parva from the type sample from Morocco has four large, nearly equal-sized chambers in the final whorl, slightly raised and beaded sutures on the spiral side, and a relatively narrow umbilicus lacking the periumbilical ornament characteristic of the velascoensis -acuta forms. We concur with his analysis that forms identified as, parva by Bolli and Cita (1960), Gartner and Hay (1962), and Gohrbandt (1963) differ from the type-level specimens of
parva by possessing a heavy keel and a flat spiral side. The individuals illustrated by Aubert (1962) as velascoensis parva (pl. 1: fig. 2a-c) and acuta (pl. 1: fig. 3a-c), respectively, from Koudiat Bou Khelif, Morocco, are virtually identical, and the individual illustrated as acuta by Blow (1979, pl. 104: fig. 2) is virtually indistinguishable from the one he figured on pl. 95: fig. 6 as parva. We believe that the two morphotypes parva (auct) and acuta are virtually indistinguishable in late Paleocene assemblages.
[Olsson el. 1999]

Catalog entries: Globorotalia wilcoxensis acuta, Globorotalia velascoensis parva

Type images:

holotype: G. wilcoxensis acuta

Distinguishing features:
Parent taxon (Morozovella): Test typically plano-convex, chambers strongly anguloconical.
Wall strongly pustulose (muricate) on parts of spire and umbilicus. Most species with muricocarina.
This taxon: Like M. velascoensis but wth smaller umbilicus, weaker ornament and fewer chambers in final whorl (usually 5).

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: Lobate chamber arrangement: Trochospiral edge view: Planoconvex aperture: Umbilical-extraumbilical
sp chamber shape: Petaloid coiling axis: High periphery: Muricocarinate aperture border: Thin flange
umb chbr shape: Subtriangular umbilicus: Narrow periph margin shape: Subangular accessory apertures: None
spiral sutures: Raised muricate umb depth: Deep wall texture: Coarsely muricate shell porosity: Finely Perforate: 1-2.5µm
umbilical or test sutures: Strongly depressed final-whorl chambers: 4-5 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology

Geographic distribution

Morozovella acuta is an essentially subtropical to tropical form with somewhat narrower biogeographic distribution than M. velascoensis (see also Loeblich and Tappan, 1957a). [Olsson el. 1999]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology

Morozovella acuta has δ180 and δ13C similar to other species of Morozovella (M. occlusa, M. velascoensis). Morozovella acuta has more positive δ13C and more negative δ18O than Subbotina spp. (Shackleton et al., 1985). [Olsson el. 1999]
Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy _¹³C and relatively light _¹⁸O. Sources cited by Aze et al. 2011 (appendix S3): Shackleton et al. (1985)

Phylogenetic relations

This species evolved from M. velascoensis through a reduction in umbilical size and ornament and chamber number [Olsson el. 1999]

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

Biostratigraphic distribution

Geological Range:
Notes: Zone P4b to Zone E2 (top). [Berggren & Pearson 2006]
Zone P4b to Zone P5 (top). Several authors suggest that M. acuta occurs somewhat higher than M. velascoensis. We record its lowest occurence in Zone P4b and have not found it to extend above M. velascoensis at DSDP Site 213 (Indian Ocean). Shutskaya (1970a) gave the range of M. acuta as extending from the A. acarinata Zone (= Subzone P4b this paper) to the top of the G. aequa Zone (= top of Zone P5 this paper), which is, essentially, the same as observed herein. [Olsson el. 1999]
Last occurrence (top): at top of E2 zone (100% up, 55.2Ma, in Ypresian stage). Data source: Berggren & Pearson (2006) f11.1
First occurrence (base): near base of P4b subzone (10% up, 60.2Ma, in Selandian stage). Data source: Berggren & Pearson (2006) f11.1

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Taxon plotted: Morozovella acuta, synonyms included - Globorotalia acuta; Morozovella acuta;
See also space-time plot :: Samples map :: Parent: Morozovella

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 55

References:

Berggren, W. A. & Pearson, P. N. (2006a). Taxonomy, biostratigraphy, and phylogeny of Eocene Morozovella. 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 11): 343-376. gs O

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

Rey, M. (1954). Description de quelques espèces nouvelles de foraminifères dans le Nummulitique nord-marocain. Bulletin de la Société Géologique de France. 4(4-6): 1-209. gs

Toulmin, L. (1941). Eocene Smaller Foraminifera from the Salt Mountain Limestone of Alabama. Journal of Paleontology. 15(6): 567-611. gs

Morozovella acuta compiled by the pforams@mikrotax project team viewed: 9-9-2024

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test outline:	Lobate	chamber arrangement:	Trochospiral	edge view:	Planoconvex	aperture:	Umbilical-extraumbilical
sp chamber shape:	Petaloid	coiling axis:	High	periphery:	Muricocarinate	aperture border:	Thin flange
umb chbr shape:	Subtriangular	umbilicus:	Narrow	periph margin shape:	Subangular	accessory apertures:	None
spiral sutures:	Raised muricate	umb depth:	Deep	wall texture:	Coarsely muricate	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Strongly depressed	final-whorl chambers:	4-5	N.B. These characters are used for advanced search. N/A - not applicable