Morozovella


Classification: pf_cenozoic -> Truncorotaloididae -> Morozovella
Sister taxa: Acarinina, Praemurica, Igorina, Planorotalites, Astrorotalia, Morozovella, Morozovelloides,
Daughter taxa: (blue => in age window 0-300Ma)
subbotinae-aragonensis group (heavy muricate keel)
This taxon is characterized by having a strongly planoconical test with 6-8 (less commonly 5 at one extreme and 9-10 at the other) chambers in the final whorl, a large open and deep umbilicus whose everted circumumbilical chamber margins are strongly ornamented by fused muricae. It is strongly homeomorphic with M. velascoensis from the late Paleocene-early Eocene (Zone P3b-E2), but M. velascoensis s.s. may be distinguished by its (generally) somewhat larger size, higher conical angle and more pronounced circumumbilical ornament of everted chamber shoulders (tips).
4½ to 5 essentially equidimensional chambers in last whorl, thickened circumumbilical rim of elevated chamber shoulders, strongly limbate sutures on spiral side.
This taxon is characterized by its tightly coiled, nearly circular test (giving the appearance of a truncated cone), narrow umbilicus, distinctly trapezoidal chambers on spiral side and strongly developed muricae on the early chambers.
This taxon is characterized by its subquadrate, involute, biconvex test with narrow umbilicus; test covered by moderately to densely distributed, blunt muricae obscuring, in some instances, the peripheral muricocarina; 4-4½ chambers in last whorl. Later forms exhibit transitional features to plano-convex, multicameral M. aragonensis.
Morozovella subbotinae is distinguished by its relatively large and strongly muricocarinate test, and the circumumbilical elevation/extension of the chambers and weakly ornamented circumumbilical chamber tips.
This morphotype, while exhibiting characters apparently intermediate to other, closely related forms, is characterized by the markedly pronounced peripheral compression of the chambers on the umbilical side which are bordered/ rimmed by a thick and broad peripheral muricocarina formed by the fusion of inordinately large/thick and long muricae.
This taxon is characterized by its relatively large, robust test, 6-7 (rarely 8) chambers and strongly muricate keel. It is distinguished from its antecedent M. gracilis by its larger, more robust test, larger number of chambers in the last whorl and wider umbilicus, and from its partially contemporaneous homeomorph, M. crater, by its more lobulate periphery and larger number of chambers in the final whorl and less ornamented test.
Planoconvex to moderately biconvex test, with lobulate peripheral margin ornamented with a well developed muricocarina; 5-6 essentially equidimensional chambers in last whorl; umbilical intercameral sutures radial, straight, depressed; on spiral side strongly curved, distinctly muricate except for penultimate/ultimate chamber suture which is straight giving cuneiform shape to final chamber (not unlike the shape in Acarinina triplex); umbilical surface covered with muricae, spiral side weakly muricate except for concentration of muricae along intercameral sutures and peripheral margin of ultimate whorl; small sutural openings along margin/junction of ultimate/penultimate whorl resulting from chamber addition along topographically separated/elevated muricate edges; umbilicus narrow, deep; aperture a low interiomarginal, umbilical-extraumbilical arch extending towards, but not to, the peripheral margin.
Subquadrate, plano-convex, muricocarinate test with moderately lobulate peripheral outline and 4 (less commonly 5) chambers in last whorl; intercameral sutures on umbilical side straight, radial; raised, curved on spiral side; umbilicus narrow, bordered by low apertural slit which extends nearly to periphery; test surface generally covered with muricae, particularly on umbilical shoulder and along peripheral margin.
Planoconvex, umbilicoconvex, test with lobulate, weakly muricocarinate periphery; 4-5 chambers in last whorl, inflated to subangular on umbilical side, moderately convex, triangular (lunate) in edge view; intercameral sutures on umbilical side depressed, radially curved and slightly depressed on spiral side; umbilical side distinctly muricate, coarsely perforate on spiral side; umbilicus relatively narrow, deep; aperture an interiomarginal, umbilical-extraumbilical arch with narrow, continuous intraperiumbilical lip.
Muricate, nonspinose angulo-conical test, spiral side flat, early chambers slightly elevated, 10-12 chambers arranged in 2½ whorls, 4-6 chambers in final whorl, periphery lobulate, (sub)acute, imperforate band (muricocarina) developed along peripheral margin; weak circumumbilical collar formed around narrow, deep umbilicus by elevated chambers, particularly last chamber; sutures depressed, straight, radial on umbilical side, strongly recurved on spiral side; aperture, low, interiomarginal, umbilical-extraumbilical low arch with weakly developed lip.
Planoconvex, moderately lobulate test with 5-6 tangentially elongate chambers in last last whorl; umbilical sutures straight to weakly curved, depressed/ incised; spiral intercameral sutures incised, weakly muricate, strongly recurved ; peripheral margin strongly muricate but not muricocarinate; umbilicus narrow, deep with aperture an interiomarginal, umbilical-extraumbilical slit (bordered by a distinct intraperiumbilical lip in well preseved specimens) extending nearly to the peripheral margin.
velascoensis group (weak keel)
This taxon is characterized by its relatively small size, narrow and deep umbilicus, and weakly developed peripheral muricocarina. It bears a close resemblance to juvenile individuals of M. velascoensis from which it is believed to have evolved (Kelly and others, 2001).
This taxon is characterized by varying degrees of axial compression; it is biconvex to mildly planoconvex in edge view; umbilical tips of chambers are relatively rounded and unornamented.
Relatively large (maximum diameter 0.5 mm), robust, plano-convex, nearly circular, moderately lobulate test composed of about 15-16 chambers arranged in 2½ to 3 whorls; last whorl with 6-7 (rarely 8) anguloconical chambers whose tips surround a moderately open umbilicus which is surmounted by an "adumbilical" or circum-umbilical rim (collar) of fused muricae; umbilical sutures radial, depressed, moderately to strongly curved, raised and beaded on spiral side; wall finely perforate, distinctly muricocarinate periphery but the spiral chamber surfaces are often nearly free of muricae; aperture a low, interiomarginal, umbilical-extraumbilical arch.
Conicotruncate, distinctly muricocarinate test with (typically) 5 chambers in last whorl; intercameral sutures radial, depressed on umbilical side and strongly recurved and tangential, distinctly ornamented on, and flush with, spiral side; periumbilical collar weakly to moder- ately well-ornamented with muricae; umbilicus (typically) wide and open but narrow in more tightly coiled individuals; aperture interiomarginal, umbilical-extraumbilical with (typically) well-developed, triangular, circumumbilical "teeth.
Plano-convex to low biconvex, nearly circular test, 4-6 (rarely up to 8) chambers in last whorl, coalescing in a circular, subacute, weakly to moderately muricate umbilical shoulder and forming a narrow, deep umbilicus; umbilical sutures depressed, radial; elevated and beaded, tangentially curved on spiral side; sutures between final and penultimate whorl coarsely muricate; periphery distinctly muricocarinate; aperture an interiomarginal, umbilical-extraumbilical arch.
Relatively large, low umbilico-convex test with flat spiral side, distinctly lobulate, heavily keeled periphery; generally 5-7 (but up to 10, particularly in younger, Zone P4c-P5 horizons), relatively equidimensional chambers in final whorl but with insertion of smaller chambers between larger chambers in some individuals; intercameral sutures depressed, radial on umbilical side; curved, moderately retorse, raised and beaded on spiral side; umbilicus wide but shallow, periumbilical collar only weakly developed; aperture a low slit extending along peri-intraumbilical margin to peripheral margin of last chamber.
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.
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.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Morozovella McGowran in Luterbacher, 1964
Rank: Genus
Type species: Pulvinulina velascoensis Cushman, 1925
Taxonomic discussion: The morozovellids split into two lineages early in their evolution: (1) the M. angulata-M. velascoensis group characterized by the development of muricate adumbilical ridges, a strong muricocarina, and the absence of muricae on parts of the chamber surfaces; and (2) the M. apanthesma-M. subbotinae group whose members are initially unkeeled and entirely covered with fine, thin muricae. [Olsson et al. 1999]

Catalog entries: Morozovella;

Type images:

Distinguishing features: Test typically plano-convex, chambers strongly anguloconical.
Wall strongly pustulose (muricate) on parts of spire and umbilicus. Most species with muricocarina.

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: Strongly anguloconical chambers throughout ontogeny. Surface texture strongly pustulose (muricate) on parts of spire and umbilicus. Most species with muricocarina. [Olsson et al. 1999]

Wall type: Normal perforate (pores cylindrical on at least part of the later chambers); some forms with weakly cancellate early chambers (a feature inherited from their praemuricate ancestry); adult chambers strongly pustulose (muricate) on parts of the spire and umbilicus. [Eocene Atlas]

Test morphology: Test low trochospiral, lobulate outline; strongly anguloconical chambers throughout ontogeny; peripheral margin usually bears distinct muricocarina which passes continuously across at least one intercameral suture (absent or rudimentary in apanthesma); primary aperture interiomarginal, umbilical-extraumbilical; secondary apertures may be present on spiral side but typically lack apertural lips.
[Eocene Atlas]

Biogeography and Palaeobiology


Similar species: Genus distinguished by muricate, anguloconical test and peripheral muricocarina (in nearly all taxa) of variable breadth and strength.
[Eocene Atlas]

Most likely ancestor: Praemurica - at confidence level 0 (out of 5). Data source: Olsson et al. 1999.

Biostratigraphic distribution

Geological Range:
Last occurrence (top): in upper part of Lutetian Stage (69% up, 43.2Ma, in Lutetian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Danian Stage (78% up, 62.6Ma, in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 54

References:

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.

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

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.


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Morozovella compiled by the pforams@mikrotax project team viewed: 20-9-2018

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Short stable page link: http://mikrotax.org/pforams/index.php?id=100185Go to Archive.is to create a permanent copy of this page - citation notes



Comments (1)

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François

Hello,

Morozovella was first published as a subgenus of Truncorotaloides. Loeblich and Tappan (1987, p. 478) indicate that the publication of T.(Morozovella) in Luterbacher (1964) is not available because it was published as a synonym of Globorotalia (Opinion of Luterbacher, p. 645)[ICZN art. 11.6]. Therefore T. (Morozovella) was only made available in 1968: McGowran, B. (1968). Reclassification of Early Tertiary Globorotalia. Micropaleontology. 14(2): 179-198.

I hope it helps too,

François

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