Morozovella edgari


Classification: pf_cenozoic -> muricate non-spinose -> Truncorotaloididae -> Morozovella -> Morozovella edgari
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 edgari (Premoli Silva & Bolli 1973)
Rank: Species
Basionym: Globorotalia edgari
Synonyms:
Taxonomic discussion: This minute morozovellid (test diameter ranges from 0.2-0.25 mm) is associated with, and ranges beyond, terminal members of the Morozovella velascoensis group. Kelly and others (2001, p. 507) have suggested that edgari descended from velascoensis by a process called “terminal progenesis” in which the diminutive descendant (edgari) with an adult morphology resembles the juvenile stages of the ancestral form velascoensis.
Morozovella finchi Blow is placed in the synonomy of this taxon. It shares most morphologic features in common with edgari except that the holotype is somewhat larger (0.32 mm) in diameter. It was described from Zone P5 (of Blow, 1979) and said to range to Zone P7 (=E4 of this paper), a range comparable to that ascribed to edgari here. Blow (1979, p. 999-1000) was of the opinion that finchi descended from “Acarininatrichotrocha and even included a paratype from the Hornerstown Formation (Zone P4) of New Jersey (erroneously ascribed to Zone P5) in his new taxon finchi, but our examination of this form at the USNM suggests that this specimen is not ascribable to finchi ( =edgari). [Berggren & Pearson 2006]

Catalog entries: Globorotalia (Morozovella) finchi;
Globorotalia edgari;

Type images:

Distinguishing features: 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).

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: 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). [Berggren & Pearson 2006]

Wall type: Muricate, nonspinose, normal perforate. [Berggren & Pearson 2006]

Test morphology: Low to moderately conical trochospiral; weakly lobulate peripheral outline, 5-6 gradually enlarging , cuneiform-shaped chambers in last whorl, intercameral sutures on umbilical side radial, straight and weakly incised; chambers trapezoidal in shape, separated by distinctly curved sutures which are flush with the test; early part/chambers of the test raised (i.e., the test exhibits an unequal biconvexity); umbilicus narrow, deep; distinct muricocarina extends to final chamber; aperture a low umbilical-extraumbilical arch extending nearly to the periphery; surface distinctly muricate with concentration of pustules decreasing towards terminal chambers. [Berggren & Pearson 2006]

Size: Dimensions of holotype: maximum diameter: 0.21 mm. [Berggren & Pearson 2006]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umb.-extraumbilical
umb chamber shape:Subtriangularcoiling axis:Lowperiphery:Muricocarinateaperture border:N/A
sp chbr shape:Crescenticumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Weakly depressedumb depth:Deepwall texture:Moderately muricateshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Flushdiameter mm:0.21width mm:breadth mm:
final-whorl chambers:5.0-6.0

Biogeography and Palaeobiology


Geographic distribution: Probably widely distributed in (sub)tropical regions (Caribbean, Atlantic Ocean and Pacific Ocean) but records are sparse owing to this taxon having been overlooked heretofore. We have found this form relatively commonly distributed in lower Eocene strata (Esna Shales) of Egypt. [Berggren & Pearson 2006]
Aze et al. 2011 summary: Low latitudes; based on Berggren & Pearson (2006)

Isotope paleobiology: Shallow-intermediate depth-habitat (Kelly and others, 2001). [Berggren & Pearson 2006]
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): Kelly et al. (2001)

Phylogenetic relations: This taxon evolved from Morozovella velascoensis (by means of a gradual decrease in test size and truncation of the ancestral ontogenetic sequence; Kelly and others, 2001) but does not appear to have left any descendants. [Berggren & Pearson 2006]

Most likely ancestor: Morozovella velascoensis - at confidence level 4 (out of 5). Data source: Berggren & Pearson (2006) f11.1.

Biostratigraphic distribution

Geological Range:
Notes: Zone E2 (uppermost part) to Zone E3. [Berggren & Pearson 2006]
Last occurrence (top): at top of E3 zone (100% up, 54.6Ma, in Ypresian stage). Data source: Berggren & Pearson (2006) f11.1
First occurrence (base): in mid part of E2 zone (50% up, 55.5Ma, in Ypresian stage). Data source: Berggren & Pearson (2006) f11.1

Plot of occurrence data:

Primary source for this page: Berggren & Pearson 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 11, p. 362

References:

Berggren, W.A. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Morozovella. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 343-376.

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.

Kelly, D.C.; Bralower, T.J. & Zachos, J.C., (2001). On the demise of the Early Paleogene Morozovella velascoensis lineage: Terminal progenesis in the planktonic foraminifera. Palaios, 16: 507-523, 11 figures, 2 tables, 1 appendix.

Premoli Silva, I. & Bolli, H.M., (1973). Late Cretaceous to Eocene planktonic foraminifera & stratigraphy of Leg 15 Sites in the Caribbean Sea. Initial Results of the Deep Sea Drilling Project, 15: 449-547.

Toumarkine, M. & Luterbacher, H., (1985). Paleocene and Eocene planktic foraminifera. Plankton Stratigraphy. Cambridge Univ. Press, Cambridge, 87-154 pp.


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Morozovella edgari compiled by the pforams@mikrotax project team viewed: 21-7-2018

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