Planorotalites pseudoscitula Glaessner 1937 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
Notice: This catalogue page may contain unedited data.
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Species Planorotalites pseudoscitula Glaessner 1937 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRTPTION.
Type of wall: Normal perforate, nonspinose,
weakly muricate.
Test morphology: Peripheral outline oval to
subcircular, weakly lobulate, coiled in low trochospire,
weakly biconvex; in umbilical view 6-8 subtriangular
chambers, compressedlflattened along peripheral
margin, intercameral sutures radial (in early part of last
whorl) to slightly curved in younger chambers, depressed
in terminal 2-3 chambers, umbilicus narrow, shallow,
aperture a low, umbilical-extraumbilical arch bearing a
distinct lip; in spiral view 15- 18 trapezoidal chambers
arranged in 2 1/2-3 whorls, sutures essentially flush with
test chambers, distinctly curved, early part of test
strongly muricate, elevated; in edge view test is
biconvex, with distinct imperforate keel which extends
at least to ante- or preantepenultimate chamber, test
surface penetrated by normal-sized pores which do not
open into distinct pore pits, aperture a typical umbilical-extraumbilical, low slit with distinct lip which extends
to the periphery.
Size: Typical dimension given by Glaessner
(1937, p. 32): 0.2-0.25 mm. |
| Discussion / Comments: |
Toumarkine & Luterbacher (1985):
This small species (0.2 to 0.3 mm) is lenticular, with 5 to 7 tightly coiled chambers in the last whorl. The periphery is circular, slightly lobate and with a faint keel. The surface of the test is rather smooth, but the surface of the chambers of the initial part of the last whorl may be somewhat rugose. The perforation is coarse in the older part of the test, fine in the youngest chambers.
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
The diagnostic
features of Planorotalites pseudoscitula are its small,
weakly biconvex and muricate, distinctly carinate test
(see also under P capdevilensis).
DISCUSSION-
Berggren (1968, 1977), McGowran
(1968), Schmidt and Raju (1973), Hillebrandt (1976)
and Blow (1979) placed renzi Bolli in the synonymy of
pseudoscitula Glaessner and in this most workers have
followed them for the past 20 years. The supposed
synonymy of these two forms as well as G. pseudoscitula
elongata was suggested to one of us (WAB) by
Gohrbandt as early as the mid-1960s based on
examination and illustrations of a topotype of G.
pseudoscitula elongata from Il 'skaya, northern Caucasus
(sent to him by Glaessner) and 3 topotype specimens of
renzi from Trinidad. Pertinent observations made at the
time by Gohrbandt (pers. comm.) include the following: 1. "G. elongata has a more conical last chamber in
axial profile (than G. renzi). G. renzi has a rather
more acute periphery on the later chambers.
However, G. pseudoscitula elongata shows
signs of a 'keel'; and the difference is a minor
one. There are no other significant differences,
so far as can be seen, in the surface texture of
the two forms. The external appearance suggests
that oriented thin sections would show the same
wall structure".
2. In spiral view the specimen of G. pseudoscitula
elongata resembles the type figure of G.
pseudoscitula s.s., whereas the axial profile
resembles the variety elongata.
3. Russian workers no longer recognized elongata
as a formal variety. In gross form G. renzi
resembles the type figure of G. pseudoscitula
very closely indeed. The similarity in surface
texture has been confirmed; it had been strongly
suspected from published data. The SEM was
unavailable to Gohrbandt at the time he made
his observations with the light microscope. SEM
illustrations have shown that there is a difference
in wall texture in the two forms, that of renzi (=capdevilensis, see above) being considerably
more coarsely muricate. Therefore, we have
refrained from concluding that G. renzi/
capdevilensis is a junior subjective synonym of
G. pseudoscitula (see above).
4. Gohrbandt also observed that G. pseudoscitula
(which he regarded as conspecific with G. renzi)
had its lowest occurrence in the lower Eocene
Globorotalia aragonensis Zone (distinctly lower
than the base of Zone P10 as given by Bolli,
1957b; cf. Berggren, 1960 who had noted earlier
an extension into lower Eocene in Nigeria as
well).
However, Blow (1 979) presciently observed that
earlier (early Eocene) and later (middle Eocene) forms
of this plexus are characterized by a coarsening of the
muricate wall texture and gradual enlargement of pores
(similar observations were made on this plexus by
Benjamini, 1980). Blow (1979) was also correct in
surmising that the type level of G. pseudoscitula
Glaessner (and of G. elongata Glaessner) is of early (not
middle) Eocene age as most investigators had thought.
Indeed, the type level is from what was subsequently
designated (Subbotina, 1953) the "Zone of compressed
globorotaliids" (the Abazin Fm.), stratigraphically
equivalent to Zones E4, ?E5. Both he (Blow, 1979, p.
898) and Bolli (1957b, p. 168) gave the stratigraphic
range of G. pseudoscitula s.s. (= G. renzi) as Zones E81
E13 equivalents. However, in his text Blow (1979)
referred to stratigraphically earlier morphotypes as
Globorotalia cf. pseudoscitula with a range of Zones
P7-P9; ? P10 (=E5-E7; ?E8) equivalents. Globorotalia
renzi and G. capdevilensis partim were regarded as junior
synonyms of G. pseudoscitula s.l.. Blow (1979)
suggested that the wall texture pattern changes were one
of degree rather than kind and that Globorotalia
pseudoscitula s.s. (rather than Globorotalia cf.
pseudoscitula based on his earlier, mistaken belief that
the type level of G. pseudoscitula was middle Eocene)
might be appropriate for the older (early Eocene) forms
and G. renzi for the younger (middle Eocene) forms,
while retaining the designationpseudoscitula s.l. for the
entire plexus. Accordingly it is clear that Gohrbandt had
made his observations on elongata (from the basal
Eocene Zone E3-ES), and on renzi from upper middle
Eocene Zone E 1 2-E 13.
At the same time Blow (1 979) considered that
Globorotalia elongata Glaessner is essentially unrelated to the G. pseudoscitula/renzi plexus. This was based
upon the following lines of evidence:
1. Blow (1979) had submitted several specimens
(subsequently illustrated as figures 6 and 7 of
his plate 116 from [his] Zone P7 [=E51 of the
Kilwa area, Tanzania), to Martin Glaessner who
confirmed their identification as Globorotalia
elongata; this led Blow (1 979, p. 890) to assert
that (Paleocene) records of G. elongata by
Loeblich and Tappan (1 957) and Bolli (1 957a)
did not correspond to Glaessner's elongata.
2. G. elongata Glaessner is characterized by an
acute to subacute peripheral margin and "nearly
equally biconvex test". Furthermore, elongata
is a minute (0.15-0.2 mm; Glaessner, 1937;
0.167-0.249 mm: Blow, 1979) form. Confusion
with G. pseudomenardii was not possible
according to Blow because of the less ventrally
inflated chamber surfaces and smaller umbilicus
in pseudomenardii, "which, especially in
stratigraphically younger specimens are
virtually closed (Blow, 1979, p. 891).
3. G. elongata was said to differ from G.
pseudoscitula in having a "more open and lax
trochospire so that the later chambers increase
in size more rapidly than in pseudoscitula"
(Blow, 1979, p. 891).
In the course of our work we have been unable
to recognize a clear differentiation between morphotypes
of elongata and pseudoscitula, considering the minor
differences in coiling to be of degree rather than kind,
and, accordingly, we include elongata in the synonomy
of pseudoscitula.
Phylogenetic relationships within this group
remain enigmatic. McGowran (1968, lineage 6) and
Berggren (1968, lineage 2), in trying to lay a
phylogenetic foundation for distinguishing different
clades of Paleogene "globorotaliids", recognized a
morphologic and stratigraphic separation between
Globanomalina and Planorotalites, although the former
reserved Globanomalina for the planispiral forms (now
referred to Pseudohastigerina) in the erroneous belief
that the type species of Globanomalina (G. ovalis Haque)
is planispiral (cf. Berggren and others, 1968; Banner,
1989, p. 171, 173). Owing to the superficial similarity
among smooth-walled, finely perforate forms in the
Paleocene the generic names Globanomalina and
Planorotalites have been used interchangeably for Paleocene and lower Eocene taxa. Globanomalina has
been adopted by the Working Group for the smoothwalled
Paleocene group typified by G. ovalis and having
its origin in G. archeocompressa in the basal Danian
(Olsson and others, 1999; see also Berggren and Norris,
1997; Fleisher, 1974, p. 1017).
Schmidt and Raju (1973) presented a detailed
analysis of the morphology and evolution of the
pseudoscitula plexus. Pertinent observations/conclusions
include the following:
1. Globorotalia planoconica Subbotina is regarded
as the stem form of the lineage and characterized
by a small, finely perforate, unkeeled
planoconvex test.
2. G. pseudoscitula Glaessner, 1937 is interpreted
as a small, compressed, distinctly (coarsely)
perforate, biconvex form with subcircular
equatorial periphery and faintly keeled margin.
G. pseudoscitula elongata Glaessner, 1937 is
interepreted to represent varietal forms that
develop a large, lobate last chamber.
Globorotalia renzi is considered a junior
synonym of G. pseudoscitula.
3. G. palmerae is considered to have evolved from
pseudoscitula by "prolongation of the chambers
at the axial periphery to a radially elongate shape
terminating in a spine"(Schmidt and Raju, 1973,
p. 179).
4. Globorotalia planoconica is shown to have
originated in the G. velascoensis Zone (Zone
P5 of this paper); G. pseudoscitula in the G.
subbotinae Zone (Zone E3-E4 of this paper) and
G. palmerae in the eponymous zone (i.e.,
within Zone E7).
It would seem that these subtle differences in wall texture are at the root of the disparate lower range
given for the pseudoscitula/renzi group, which spans the interval of Zones P5-E6 (Hillebrandt, 1962; Samuel, 1972; Benjamini, 1980; Fleisher, 1984; Toumarkine and Luterbacher, 1985). Benjamini (1980) suggested that the transition from the relatively larger, typical pseudoscitula
with depressed sutures to the relatively small, coarsely perforate, flush sutured typical renzi took place in the mid-part of the G. palmerae Zone (= Zone E7 of this
work) in the Avedat Group of the northern Negev, Israel. Subbotina (1953) had earlier noted that pseudoscitula extends down into the highest levels of the "Zone of
rotaliid-like globorotaliids" (=Zones P213) in the
Elburgan Formation of the North Caucasus, but we
believe that these references are to members of the
superficially similar Igorina pusilla group. In like
manner, Loeblich and Tappan (1957) identified forms
as pseudoscitula in the mid-late Paleocene of the Gulf
Coast that, while superficially similar to the Eocene
morphotypes, belong to the distinctly different group of
the albearillaevigata plexus (Berggren, 1968).
If the finely perforate, superficially smoothwalled
(but wealtly muricate) to weakly cancellate,
keeled, compressed, test of latest Paleocene-early Eocene
pseudoscitula morphotypes are considered ancestral to
the late early-middle Eocene, biconvex, keeled, coarsely
perforate, muricate renzi, derivation from a juvenile
morozovellid such as Morozovella occlusa would appear
logical (cf. Berggren 1968; McGowran, 1968;
Hillebrandt, 1 976 for earlier, alternate interpretations).
In the course of our studies we have found that
pseudoscitula has its lowest/earliest occurrence at the
base of Zone P5 (i.e, just above the H0 of
Globanomalina pseudomenardii).
The specimen illustrated by Shutskaya (1956,
pl. 4, figs. 5a-c) from the Cherkessk Fm. of the northwest
Caucasus is excluded from this taxon. It would
appear to be a relatively large (maximum diameter 0.43
mm) robust form that was compared by Shutskaya with
Globorotalia subbotinae, G. nartanensis and G.
spinulosa and was recorded from the G. subbotinae Zone
(=Zone E3-4 of this paper), whereas P pseudoscitula is
a relatively small form (with a maximum diameter of
about half that of Shutskaya's specimen; Bolli's [1957a]
holotype of Globorotalia renzi has a maximum diameter
of 0.23 mm) and was shown to have its lowest occurrence
considerably higher, in Zone P 10.
The broadly rounded, seemingly densely muricate form illustrated by Hillebrandt (1962) from Zone P6 (equivalent) appears not to be referable to pseudoscitula/renzi as identified here and is more likely an acarininid referable to esnehensis (or a related form).
PHYLOGENETIC RELATIONSHIPS-
Unresolved;
probably evolved from a juvenile morozovellid (? M. occlusa) by neoteny.
STRATIGRAPHIC RANGE.-
Zone P5-E7.
GEOGRAPHIC DISTRIBUTION.-
Ranges from
tropics to temperate regions; central equatorial Pacific
(ODP Site 865), New Jersey Coastal Plain (Bass River
Borehole where it is a common form in Zone El),
Tethyan deposits of northern Africa (Egypt where it
appears in the lower part of the Esna Shale Fm. in basal
Zone P5) and northern Caucasus; not reliably reported
(to date) from high austral or northern latitudes to our
knowledge.
STABLE ISOTOPE PALEOBIOL0GY.-
No data
available. |
| Systematics: |
15
Classis Foraminifera
Genus Planorotalites
Species Hantkenina alabamensis
Species Planorotalites pseudoscitula
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Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Truncorotaloididae
Genus Planorotalites
Species Planorotalites pseudoscitula
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| Synonym list: |
Toumarkine & Luterbacher (1985):
Pearson et al. (2006):
1937 Globorotalia pseudoscitula Glaessner. - Glaessner : p.32 text-fig. 3a-c [lower Eocene, holotype VNIGRI No. 4076, Lower
Foraminiferal Beds, Suite F 1, Il'skaya, Northwest
Caucasus]
1947 Globorotalia pseudoscitula Glaessner. - Subbotina : 121-122 pl. 9; fig. 18-22 [Lower Eocene Globorotalia ex. gr. canariensis Zone,
Abazin Fm., Khieu River section, northwest Caucasus]
1953 Globorotalia pseudoscitula Glaessner. - Subbotina : p.208 pl. 16; fig. 17a-c (reillustration of
holotype No. 4076 of Glaessner, 1937) [Zone of
compressed globorotaliids];
pl. 16, fig. 18a-c [Zone of thin-walled pelagic foraminifera, Foraminiferal Beds, Suite F2, North Caucasus];
pl. 17, fig. la-c [lower Eocene Zone of conical globorotaliids, Foraminiferal Beds, Suite F2, Khieu River section, North Caucasus]
? 1956 Globorotalia pseudoscitula Glaessner. - Shutskaya : p. 95, 96 pl. 4; fig. 5a-c [lower Eocene Globorotalia subbotinae
Zone, Cherkessk Fm., near town of Nal'chik, northern
Caucasus, FSU]
non 1957 Globorotalia pseudoscitula Glaessner. - Loeblich & Tappan : p. 193-194 pl. 46, fig. 4a-c;
pl. 48, fig. 3ac;
pl. 53, fig. 5a-c;
pl. 59, fig. 2a-c;
pl. 63, fig. 6a-c [=Igorina albeari (Cushman and Bermudez)]
1973 Globorotalia pseudoscitula Glaessner. - Schmidt & Raju : p. 181, 182 pl. 1; fig. 3a-c, 4 [lower Eocene Globorotalia palmerae
Zone, MNG-1, CC 18, Cauvery Basin, southeastern India]
1979 Globorotalia (Globorotalia) pseudoscitula sensu lato Glaessner. - Blow : p.897 pl. 116, fig. 8-10 [lower Eocene
Zone P7, Kilwa area, Tanzania, East Africa, referred to as G.(G.) cf. pseudoscitula];
pl. 173, fig. 1-8 [middle
Eocene Zone P1 l, sample RS24, Kilwa area, Tanzania, East Africa]
1979 Globorotalia (Globorotalia) elongata Glaessner. - Blow : p.889 pl. 105, fig. 1-2, 4-6 [lower Eocene Zone P6,
DSDP Hole 20C, South Atlantic Ocean];
pl. 116, fig. 6-7 [lower Eocene Zone P7, Sample RS 80, Kilwa area, Tanzania, East Africa]
p 1985 Planorotalites pseudoscitula Glaessner. - Toumarkine & Luterbacher : p.118 fig. 20.5 (holotype of Glaessner refigured);
fig. 20.6 [lower Eocene Acarinina pentacamerata Zone, Richmond Fm., Jamaica];
fig. 20. 7-10 [Acarinina pentacamerata Zone, Cauvery Basin, South India, sample]
1993 Planorotalites pseudoscitula Glaessner. - Lu & Keller : p.114 pl. 5; fig. 5-7 [lower Eocene
Pseudohastigerina wilcoxensis (AP6a) Zone, ODP Hole
738C, Kerguelen Plateau, southern Indian Ocean]
1995 Planorotalites pseudoscitula Glaessner. - Lu & Keller : p.100 pl. 6; fig. 15-17 [lower Eocene Zone
P6b, DSDP Site 577, Shatksy Rise, northwest Pacific
Ocean]
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| Was used in synonym list of: |
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| Specimen: |
VNIGRI collections, St. Petersburg, Inventory number: 4076
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| References: |
Glaessner,M.F. (1937):
Planktonische Foraminiferen aus der Kreide und dem Eozän und ihre stratigraphische Bedeutung.
In: Studies in Micropaleontology Vol. 1(1) p. 27-46
Subbotina,N.N. (1947):
Foraminifery datskikh i paleogenovykh otlozhenii severnogo Kavkaza.
In: Mikrofauna neftyanykh mestorozhdenii Kavkaza, Emby I Srednei Azii Vol. 1 p. 39-160
Subbotina,N.N. (1953):
Iskopaemye foraminifery SSSR (Globigerinidy, Khantkenininidy i Globorotaliidy) . Trudy Vsesoyznogo Nauchno-Issledovatel'skogo Geologo-razvedochnogo Instituta (VNIGRI) Vol. 76 p. 296
Shutskaya,E.K. (1956):
Stratigrafiya nizhnikh gorizontov paleogena Tsentral'nogo Predkavkaz'ya po foraminiferam . Trudy Instituta Geologii Nauk Akademiya SSSR Vol. 164(70) p. 3-114
Loeblich,A.R. and Tappan,H. (1957):
Planktonic Foraminifera of Paleocene and Early Eocene Age from the Gulf and Atlantic Coastral Plains.
In: Studies in Foraminifera, United States National Museum Bulletin Vol. 215 p. 173-198
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Planktonic Foraminifera from the Eocene Navet and San Fernando formations of Trinidad, B.W.I. . Bull. U.S. natl. Mus. Vol. 215 p. 155-172
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Das Paleozän und seine Foraminiferenfauna im Becken von Reichenhall und Salzburg . Bayerische Akademie Wissenschaft, Mathematischen-Naturwissenschaften Klasse Vol. 108 p. 188 p.
Samuel,O.. (1972):
New species of planktonic foraminifers from the Paleogene of the west Carpathian in Slovakia (Czechoslovakia) . Zbornik Geologick"ck Vied Západné Karpaty Vol. 17 p. 165-221
Schmidt,R. and Raju,D.S.N. (1973):
Globorotalia palmerae Cushman & Bermudez and closely related species from the Lower Eocene, Cauvery Basin, South India . Proc. Koninkl. Nederlandse Akad. wetenschapen ser B Vol. 76 p. 167-178
Hillebrandt,A. (1976):
Los formainiferos planctonicos, nummulitidos y coccolitoforidos de las zona de Globorotalia palmerae del Cuisiense (Eoceno inferior) en el ES de Espana (Provincias de Murcia y Alicante) . Revista Espanol de Micropaleontologia Vol. 8 p. 323-394
Berggren,W.A. (1977):
Atlas of Paleogene planktonic foraminifera. Some species of the genera Subbotina, Planorotalites, Morozovella, Acarinina and Truncorotaloides.
In: Oceanic Micropaleontology Eds: Ramsay, A.T.S. p. 205-299
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
Benjamini,C.. (1980):
Plankton foraminiferal biostratigraphy of the Avedat Group (Eocene in the northern Negev, Israel) . Journal of Paleontology Vol. 54 p. 325-358
Toumarkine,M. and Luterbacher,H.P. (1985):
Paleocene and Eocene Planktic Foraminifera.
In: Plankton Stratigraphy p. 87-154
Loeblich,A.R. and Tappan,H. (1988):
Foraminiferal Genera and their Classification. 2 volumes. p. 970 pp
Lu,G. and Keller,G. (1993):
The Paleocene-Eocene Transition in the Antarctic Indian Ocean: Inference from Planktic Foraminifera . Marine Micropaleontology Vol. 21 p. 101-142
Lu,G. and Keller,G. (1995):
Planktic Foraminiferal Faunal Turnovers in the Subtropical Pacific during the Late Paleocene to Early Eocene . Journal of Foraminiferal Research Vol. 25 p. 97-116
Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
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