pforams@mikrotax - Praemurica inconstans pforams@mikrotax - Praemurica inconstans

Praemurica inconstans

Classification: pf_cenozoic -> Truncorotaloididae -> Praemurica -> Praemurica inconstans
Sister taxa: P. uncinata, P. inconstans, P. pseudoinconstans, P. taurica, P. nikolasi, P. sp.


Citation: Praemurica inconstans (Subbotina 1953)
taxonomic rank: Species
Basionym: Globigerina inconstans
Taxonomic discussion: The extensive synonymy above reflects our current understanding and interpretation of this taxon. A variety of morphotypes have been ascribed to inconstans -trinidadensis -praecursoria over the past 40 years and assigned to the genera Globigerina, Globorotalia, Acarinina, Subbotina, and Turborotalia. We include this form in the genus Praemurica following the demonstration by Olsson et al. (1992) of a phylogenetically distinct and homogenous lower Paleocene cancellate, nonspinose lineage. One of us (W AB) has examined the type specimens of inconstans, praecursoria, trinidadensis, and schachdagica and the synonymic listing above is based to a large extent on those studies. The wide range of variation ascribed herein to this morphospecies unifies forms sharing the characteristics of a cancellate, nonspinose test intermediate between the pseudoinconstans -taurica morphology and the typically anguloconical, nonkeeled uncinata morphology. [Olsson et al. 1999]

Catalog entries: Globigerina inconstans, Acarinina praecursoria, Globorotalia trinidadensis, Globigerina schachdagica, Globigerina scabrosa, Globigerina scobinata, Globigerina arabica

Type images:

Distinguishing features:
Parent taxon (Praemurica): Test very low trochospiral, usually 5-6, globular to oval chambers in last whorl, periphery lobulate;
Wall non-spinose, weakly cancellate;

This taxon: 5-7 chambered test; rapidly expanding final whorl; sutures radial; aperture an interiomarginal, umbilical-extraumbilical slit with distinct lipped rim.

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.


Wall type:

Character matrix
test outline:Lobatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Inflatedumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Strongly depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:5-6 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology

Geographic distribution

A cosmopolitan species in northern and southern hemisphere sections (Figure 28). [Olsson et al. 1999]
Aze et al. 2011 summary: Cosmopolitan; based on Olsson et al. (1999)

Isotope paleobiology
Praemurica inconstans has more positive δ13C and more negative δ18O than Subbotina and Globanomalina but has a similar isotopic signature to P. taurica (Boersma and Premoli Silva, 1983; Berggren and Norris, 1997). There is a pronounced increase in δ13C with increased size in P. inconstans (Kelley et al., 1996). [Olsson et al. 1999]
Aze et al. 2011 ecogroup 2 - Open ocean mixed-layer tropical/subtropical, without symbionts. Based on _13C lighter than species with symbionts; also with relatively light _18O. Sources cited by Aze et al. 2011 (appendix S3): Berggren & Norris (1997); Boersma & Premoli Silva (1983)

Phylogenetic relations
This morphospecies evolved from Praemurica pseudoinconstans by the development of umbilical-conical chambers in morphologically advanced forms, development of incised umbilical sutures, and an increase in the number of chambers in the final whorl. [Olsson et al. 1999]

Most likely ancestor: Praemurica pseudoinconstans - at confidence level 4 (out of 5). Data source: Olsson et al. (1999), fig. 5a.
Likely descendants: Praemurica uncinata; plot with descendants

Biostratigraphic distribution

Geological Range:
Notes: Zone Pic to lower Zone P3. [Olsson et al. 1999]
Last occurrence (top): near base of P3a subzone (10% up, 62.2Ma, in Danian stage). Data source: Olsson et al. (1999), fig. 5a
First occurrence (base): at base of P1c subzone (0% up, 63.9Ma, in Danian stage). Data source: Olsson et al. (1999), fig. 5a

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 73


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Leonov, G. P. & Alimarina, V. (1960). Stratigrafiya i planktonnye foraminifery "perekhodnykh" ot mela k paleogeny sloev tsentral'nogo Predkavkazya [Stratigraphy and Plantonic Foraminifera of the Cretaceous-Paleogene "Transition" Beds of the Central Part of the North Caucasus]. In Problema V: Granitsa melovoi i paleogenovoi sistem. Mezhdunarodnyi Geologicheskii Kongress, XXI Sessiya, Doklady Sovetskikh Geologov, Izdatelstvo Akademiya Nauk. 29-60. gs

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

Morozova, V. G. (1957). On the Foraminiferal superfamily Globigerinidea, nov. and some of its representatives (in Russian). Doklady Akademii Nauk SSSR. 114(5): 1109-1112. gs

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

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Shutskaya, E. K. (1970b). 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 Vsesoyuznego Neftyanogo Nauchno-Issledovatel'skogo Geologo-Razvedochnogo Instituta (VNIGRI). 70(1): 256-. gs

Soldan, D. M., Petrizzo, M. R. & Silva, I. P. (2014). Pearsonites, a new Paleogene planktonic foraminiferal genus for the broedermanni lineage. Journal of Foraminiferal Research. 44: 17-27. gs

Stott, L. D. & Kennett, J. P. (1990). The Paleoceanographic and Paleoclimatic signature of the Cretaceous/Paleogene boundary in the Antarctic: Stable isotopic results from ODP Leg 113. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 829-848. gs

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


Praemurica inconstans compiled by the pforams@mikrotax project team viewed: 21-7-2024

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