pforams@mikrotax - Planorotalites

Citation: Planorotalites Morozova, 1957

Type species: Globorotalia pseudoscitula Glaessner, 1937

Taxonomic discussion: The Paleogene genera Planorotalia (type species: Planulina membranacea Ehrenberg 1854) and Planorotalites (type species: Globorotalia pseudoscitula Glaessner 1937) were erected by Morozova (1957) for low-trochospiral, normal (finely) perforate, smooth-walled forms whose sole distinction was the presence of a keel in the latter. McGowran (1968) recognized the essential synonymy of these two genera and in his lineage 6 suggested an evolutionary sequence leading from Planorotalites compressa to P. pseudoscitula. The genus Globanomalina was retained for smooth-walled planispiral forms that evolved from either chapmani-pseudomenardii plexus or G. imitata, in the mistaken belief that the type species of Globanomalina is planispiral (cf. Banner, 1989, p. 171-173). In his contemporaneous publication, Berggren (1968) placed these forms in his ‘lineage 2’ (G. pseudobulloides-G. pseudoscitula lineage). (Earlier discussion of this lineage may be found in papers by Bolli, 1957; Berggren, 1962 and Hillebrandt, 1964.)
With the demonstration that the type species of Globanomalina (G. ovalis Haque) is slightly trochoid rather than planispiral (Berggren, 1968; Banner, 1989), that ovalis is closely allied with imitata and the eventual evolution of the planispiral genus Pseudohastigerina near the Paleocene/Eocene boundary from the ovalis -luxorensis group (and not chapmani; Olsson and others, 1999), and that chapmani is part of a separate globanomalinid lineage characterized by low-trochospiral, compressed tests (Olsson and others, 1999), phylogenetic relationships within this group would appear to have been more satisfactorily clarified than heretofore.
Banner (1989, p. 177) drew attention to the fact that the smooth-walled and “microperforate” (actually all forms are normal perforate; see also Olsson and others, 1999) forms of the genus Globanomalina should be “distinguished from the macroperforate (and more distinctly muricate) genus Planorotalites Morozova (e.g., its type species, P. pseudoscitula (Glaessner), Zones P10-13)...” Accordingly we restrict the concept of Planorotalites to the generally small (<0.3mm) normal perforate, muricate forms typified by P. pseudoscitula. As such the genus has its origin in the late Paleocene (Biochron P5) and ranges through the middle Eocene; it probably evolved from a juvenile morozovellid (? M. occlusa) by neoteny. [Berggren et al. 2006]

Distinguishing features:
Parent taxon (Truncorotaloididae): Muricate
This taxon: Biconvex, keeled test with densely perforate surface

Description

Biogeography and Palaeobiology

Most likely ancestor: Morozovella - at confidence level 2 (out of 5). Data source: Berggren et al. 2006; Aze 2011 - see P. pseudoscitula.
Likely descendants: Astrorotalia; plot with descendants

Biostratigraphic distribution

Geological Range:
Last occurrence (top): at top of E14 zone (100% up, 35.9Ma, in Priabonian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within P5 zone (55.96-57.10Ma, base in Thanetian stage). Data source: Total of ranges of species in this database

Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 12, p. 390

References:

Banner, F. T. (1989). The nature of Globanomalina Haque, 1956. Journal of Foraminiferal Research. 19: 171-179. gs

Berggren, W. A. (1962b). Stratigraphic and taxonomic-phylogenetic studies of Upper Cretaceous and Paleogene planktonic foraminifera. Stockholm Contributions in Geology. 9(2): 107-129. gs

Berggren, W. A. (1968). Phylogenetic and taxonomic problems of some Tertiary planktonic foraminiferal lineages. Tulane Studies in Geology and Paleontology. 6(1): 1-22. gs O

Berggren, W. A., Olsson, R. K. & Premoli Silva, I. (2006a). Taxonomy, biostratigraphy and phylogenetic affinities of Eocene Astrorotalia, Igorina, Planorotalites, and Problematica (Praemurica? lozanoi). 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 12): 377-400. gs

Bolli, H. M. (1957a). Planktonic foraminifera from the Eocene Navet and San Fernando formations of Trinidad. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 155-172. gs

Ehrenberg, C. G. (1854). Mikrogeologie: Das Erden und Felsen schaffende Wirken des unsichtbar kleinen selbständigen Lebens auf der Erde. Leopold Voss, Leipzig. 1-374. gs

Glaessner, M. F. (1937a). Planktonforaminiferen aus der Kreide und dem Eozän und ihre stratigraphische Bedeutung. Etyudy po Mikropaleontologiy, Paleontologicheskaya Laboratoriya Moskovskogo Gosudarstvennogo Universiteta. 1(1): 27-46. gs

McGowran, B. J. (1968). Reclassification of Early Tertiary Globorotalia. Micropaleontology. 14: 179-198. gs

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

Daughter taxa (time control age-window is: 0-800Ma)
			Planorotalites capdevilensis Like P. pseudoscitula but stronger pustulation and muricae, higher rate of increase in chambers, more distinct and flush to slightly raised sutures on spiral side, test flatter and more equally biconvex.
			Planorotalites pseudoscitula Test small, weakly biconvex and muricate, distinctly carinate
			Planorotalites sp. Specimens which cannot be assigned to established species

Planorotalites

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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