Morozovelloides coronatus


Classification: pf_cenozoic -> muricate non-spinose -> Truncorotaloididae -> Morozovelloides -> Morozovelloides coronatus
Sister taxa: M. bandyi, M. coronatus, M. crassatus, M. lehneri,

Taxonomy

Citation: Morozovelloides coronatus (Blow 1979)
Rank: Species
Basionym: Globorotralia (Morozovella) coronata
Synonyms:
Taxonomic discussion: Originally described as coronata, the ending has been changed to agree in gender with the genus Morozovelloides (ICZN, Art. 31.2). Blow (1969, p. 370) differentiated this form based on the circumumbilical muricate ‘coronet’ and indicated it would be described in a forthcoming paper by himself and one of us (WAB). In fact, it was described posthumously by Blow (1979:1016) but not before the name had appeared 5 years earlier in a citation by Fleisher (1974) to what was at the time Blow’s manuscript. Article 13(a) of the ICZN Code of Zoological Nomenclature requires every scientific name published after 1930, in order to be available, to be “(13.1.1) accompanied by a description or definition that states in words characters that are purported to differentiate the taxon, or (13.1.2) accompanied by a bibliographic reference to such a published statement..., or (13.1.3) proposed expressly as a new replacement name....” Fleisher (1974) published an illustration, but included no description of the species; hence (i) is not satisfied (it has to be in words; an illustration is not sufficient), and although he published a citation to Blow, it was to a work not published, and hence (ii) is not satisfied. Fleisher’s use of coronata was, therefore, a nomen nudum and hence not available (see above synonymy; information on status of coronatus provided by R. Fleisher, pers. comm., 1998); the species is correctly attributed to Blow (1979).
While the general morphology of crassatus and coronatus is similar in many respects and the stratigraphic range is comparable, we retain coronatus for those forms distinguished by the muricate coronet, a wider umbilicus and generally more pronouncedly muricate carina. To investigate the range of variability of coronatus, we have illustrated several new specimens from the type locality in Kilwa, Tanzania (Pl.10.2, Figs. 4-7, 15-16). We note that coronatus displays a greater range in the degree of umbilical vaulting (and hence the peripheral angle as seen in edge view) than crassatus. The typical morphology, as shown by the holotype, is a relatively dorso-ventrally compressed form, but other, more highly vaulted variants occur that are reminiscent of lower Eocene Morozovella formosa. Some specimens show a transitional morphology to Morozovelloides lehneri (Pl.10.2, Fig. 12). [Pearson & Berggren 2006]

Catalog entries: Globorotalia (Morozovella) coronata;

Type images:

Short diagnosis: This taxon is distinguished from the closely related M. crassatus by the distinct circumumbilical clustering of muricae on the circumumbilical tips of the chambers resulting in the development of a ‘coronet’ - like ornament. The muricocarina is usually more completely fused than in other species of Morozovelloides.

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 distinguished from the closely related M. crassatus by the distinct circumumbilical clustering of muricae on the circumumbilical tips of the chambers resulting in the development of a ‘coronet’ - like ornament. The muricocarina is usually more completely fused than in other species of Morozovelloides. [Pearson & Berggren 2006]

Wall type: Muricate, normal perforate, with concentration of muricae around periphery and on umbilical shoulders of chambers. [Pearson & Berggren 2006]

Test morphology: Low trochospiral, elongate- oval to subcircular, moderately lobulate peripheral outline; 5-5½ chambers in relatively evolute coil, subtriangular, weakly inflated, increasing gradually in size; umbilical sutures radial, straight to weakly reflexed at junction with peripheral margin; umbilicus relatively wide, deep and rimmed by distinct circumumbilical “coronet” of densely clustered/fused muricae on circumumbilical chamber tips; primary aperture a low arch extending nearly to the periphery and rimmed by a thickened margin; about 11-12 chambers in 2½-3 whorls (muricate overgrowth on early chambers renders differentiation difficult); chambers vary from lens- shaped to trapezoidal (early chambers of last whorl) to subtriangular or subquadrate as a function of disposition of intercameral sutures; flat to slightly concave near peripheral margins; intercameral sutures muricate and limbate, curved, tangential to the periphery in early part of last whorl, radial, straight in terminal part of last whorl, recurved near junction with peripheral, muricocarina; in edge view low, asymmetrically biconvex; umbilico- convex, early whorl(s) of spiral side slightly elevated; distinct and relatively thick marginal muricocarina. [Pearson & Berggren 2006]

Size: Maximum diameter: 0.43 mm (Blow, 1979, p. 1016). [Pearson & Berggren 2006]

Character matrix

test outline:Lobatecoiling axis:Lowchamber arrangement:Trochospiralumbilicus:Wide
edge view:Inequally biconvexumbilical or test sutures:Moderately depressedspiral sutures:Raised muricateshell porosity:
wall texture:aperture:Umb.-extraumbilicalaperture border:Thin lipaccessory apertures:None
periphery:Muricocarinateumb chamber shape:Subtriangularsp chbr shape:Crescenticperiph margin shape:Subangular
umb depth:Deepdiameter mm:0.43width mm:breadth mm:
final-whorl chambers:4.5-5.5

Biogeography and Palaeobiology


Geographic distribution: Apparently characteristic of (sub)tropical Tethyan areas of the world (Caribbean, Indo-Pacific). Citations of its occurrence are too rare to give an accurate picture of its global geographic distribution. [Pearson & Berggren 2006]
Aze et al. 2011 summary: Low latitudes; based on Pearson & Berggren (2006)

Isotope paleobiology: Oxygen and carbon isotopes are similar to other Morozovelloides and indicate a shallow water, symbiotic habitat (Wade and others, 2001, Wade and Kroon, 2002; recorded as Morozovella spinulosa). [Pearson & Berggren 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): Wade et al. (2001); Wade & Kroon (2002)

Phylogenetic relations: This species evolved from M. crassatus and was ancestral to M. lehneri. [Pearson & Berggren 2006]

Biostratigraphic distribution

Geological Range:
Notes: Zone E8-E12 (middle Eocene; Blow, 1979). [Pearson & Berggren 2006]
Last occurrence (top): within E12 zone (39.97-40.40Ma, top in Bartonian stage). Data source: Eocene Atlas
First occurrence (base): within E8 zone (43.85-45.72Ma, base in Lutetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Pearson & Berggren 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 10, p. 331

References:

Blow, W.H., (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In: Bronnimann, P. and Renz, H.H. (Editors), Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967, Leiden, Netherlands, pp. 380-381.

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

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. 97-124.

Cushman, J.A. & Jarvis, P.W., (1929). New foraminifera from Trinidad. Contributions From the Cushman Foundation for Foraminiferal Reseach, 5: 6-17.

Cushman, J.A., (1927). New and interesting foraminifera from Mexico and Texas. Contributions from the Cushman Laboratory for Foraminiferal Research, 3: 111-119.

Fleisher, R.L., (1974). Cenozoic planktonic foraminifera and biostratigraphy, Arabian Sea, Deep Sea Drilling Project, Leg 23A. Initial Reports of the Deep Sea Drilling Project, 23: 1001-1072.

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

Pearson, P.N. & others, (2004). Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1–5. Journal of African Earth Sciences, 39: 25-62.

Saito, T., (1962). Eocene planktonic foraminifera from Hahajima (Hillsborough Island). Trans. Proc. Pal. Soc. Japan, 1(45): 209-225.

Wade, B.S. & Kroon, D., (2002). Middle Eocene regional climate instability: Evidence from the western North Atlantic. Geology, 30: 1011-1014.

Wade, B.S.; Kroon, D. & Norris, R.D., (2001). Orbitally forced climate change in the Late Middle Eocene at Blake Nose (Leg 171B): Evidence From Stable Isotopes In Foraminifera. Geological Society of London, Special Publications, 183: 273-291.


Morozovelloides coronatus compiled by the pforams@mikrotax project team viewed: 24-6-2017

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