Globanomalina luxorensis Nakkady 1950 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.
|
Species Globanomalina luxorensis Nakkady 1950 |
|
|
|
| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Smooth, normal perforate.
Test morphology: Test very low trochospiral,
compressed, tightly coiled, oval in outline, slightly
lobulate; chambers inflated, globular; in umbilical view
normally 6-7 chambers in ultimate whorl, increasing
rapidly in size, sutures moderately depressed, straight
to slightly curved, umbilicus small, circular in shape; in
spiral view 6-7, occasionally 5 or up to 8, chambers in
ultimate whorl, increasing rapidly in size, sutures
moderately depressed, straight to slightly curved, inner
whorl of chambers depressed, evolute to partly involute;
in edge view primary aperture an oval, umbilical-extraumbilical
high arch bordered by a narrow lip which
extends slightly onto the spiral side but not to the spiral suture; test compressed with a rounded periphery;
peripheral margin perforate.
Size: Maximum diameter of holotype 0.25 mm,
thickness 0.15 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
Globanomalina
luxorensis is characterized by its very low trochospiral
test, globular chambers, rounded axial periphery, and
an arched aperture that extends over the axial periphery
to the spiral side, but not to the trace of the spiral suture.
The species is regarded as representing the transitional
morphology from a trochospiral to a planispiral test, but
is not planispiral according to the criterion of Blow
(1979, p. 1060; discussed above).
DISCUSSION.-
Globanomalina luxorensis has been a
poorly known species since it was first described. This
may, in part, be due to its limited occurrence and
abundance in the stratigraphic record and, perhaps, to
its having been overlooked or included in
Globanomalina chapmani, Globanomalina ovalis
Haque, 1956, or Pseudohastigerina wilcoxensis. Banner
(1989) concluded that G. luxorensis could be separated
from G. ovalis, although he earlier (Banner, 1982) had
considered G. luxorensis as the senior synonym of G.
ovalis. He regarded G. luxorensis as the immediate
ancestor of P. wilcoxensis. Recently, Speijer and Samir
(1997) noted the association of G. luxorensis with the
negative ò13C excursion in the middle part of Zone P5
(of Berggren and others, 1995), which they suggested
as the point for marking the boundary between the
Paleocene and the Eocene in a Global Stratotype Section and Point (GSSP). However, they concluded, in contrast
to Banner (1 989), that G. ovalis was a junior synonym
of G. luxorensis and found that in Egypt G. luxorensis
was extremely rare below the ò13C excursion. We would
agree with Banner that the two species can be separated,
but part of the confusion appears to be due to poor preservation (see Banner, 1989) and to lack of sufficient
specimens below the 6I3C excursion. Globanomalina
ovalis is common in Zone P4 in southern India (Olsson
and others, 1999), which suggests that the species was
common in the Indian Ocean region, and records of the
species in New Zealand indicate its widespread
distribution in the late Paleocene.
Globanomalina ovalis usually has 5 chambers
in the ultimate whorl in contrast to G. luxorensis which
usually has 6-7 chambers in the ultimate whorl.
Occasionally, 6-chambered forms and 5-chambered
forms are found in assemblages of each species,
respectively (see Speijer and Samir, pl. 2, figs. 2a-c as
an example). The chambers in G. ovalis in edge view
are oval in shape, and wider than high. Because of this,
the chambers tend to extend over the spiral side
presenting a planispiral appearance and, as Banner
(1989) noted, the spiral "side becomes incompletely
evolute and slightly concave in shape" (p. 177). The
aperture, however, only extends extraumbilically to the
medium point of the axial periphery, in contrast to G.
luxorensis where the aperture extends slightly over the
axial periphery but not to the trace of the spiral suture.
In edge view the chambers in G. luxorensis are more
globular, equidimensional, or even slightly compressed.
Given these morphological criteria the morphotype
recorded as ex interc G.(T.)chapmani Parr and
Pseudohastigerina wilcoxensis (Cushman and Ponton)
by Blow (1979, pl. lll: fig. 5) is more appropriately placed in G. luxorensis rather than in G. ovalis (as
recorded by Olsson and others, 1999).
PHYLOGENETlC RELATIONSHIPS.-
Globanomalina
luxorensis evolved from G. ovalis by an
increase of number of chambers in the final whorl,
development of more globular equidimensional
chambers, and by the migration of the aperture slightly
over the axial periphery onto the spiral side. In turn, G. luxorensis gave rise to Pseudohastigerina wileoxensis
through the development of an equatorial aperture and
a planispiral test. The species is the end-member of the
Globanomalina imitata-G. ovalis-G. luxorensis lineage which
led to the genus Pseudohastigerina.
STRATIGRAPHIC RANGE.-
Zone P5 to top of Zone
E3.
GEOGRAPHIC DISTRIBUTION.-
Global in low to
mid latitudes.
STABLE ISOTOPE PALEOBIOL0GY.-
Our data
show relatively negative oxygen values that suggest a
shallow habitat above the thermocline (R. K. Olsson,
unpublished data). |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Hedbergellidae
Genus Globanomalina
Species Globanomalina luxorensis
|
| Synonym list: |
Pearson et al. (2006):
1950 Anomalina luxorensis Nakkady. - Nakkady : p.691 pl. 90; fig. 39-41 [upper Paleocene, Esna Shale, Abu Durba, Western Sinai,
Egypt]
1950 Anomalina luxorensis Nakkady. - Nakkady : p.465 pl. 5; fig. 1a-c [upper
Paleocene, Gabal Um Elghanayem, Kharga Oasis, Western
Desert, Egypt]
p 1967 Pseudohastigerina wilcoxensis Cushman & Ponton. - Berggren et al. : p.278 text-fig. 2.d-f, m-r [lower Eocene Zone P6, Manasquan Fm.,
New Jersey]
1975 Pseudohastigerina wilcoxensis Cushman & Ponton. - Stainforth et al. : p.243 fig. 99.6a-c (reillustration of Berggren and others, 1967, text-fig.
2: p-r)
1979 Globorotalia (Turborotalia) sp . - Blow : p.1061 pl. 111; fig. 5 [lower Eocene Zone P7, Moogli Mudstones, Kagua,
Papua]; [recorded as ex interc G. (T.) chapmani
and Pseudohastigerina wilcoxensis]
1990 Pseudohastigerina wilcoxensis Cushman & Ponton. - Stott & Kennett : p.560 pl. 5; fig. 5, 6 [lower Eocene Zone AP6, ODP Hole 6908, Maud Rise,
Antarctic Ocean]; [Not Cushman and Ponton, 1932]
p 1997 Globanomalina luxorensis Nakkady. - Speijer & Samir : p.53 pl. l, fig. 4a-5c [lower Eocene, 4a-c, Gebel Aweina, Egypt; 5a-c, Gebel Duwi, Egypt];
pl. 2, fig. la-4c [lower Eocene, la-c,
Pyramidal Hill, Egypt; 2a-c, Darb Daga; 3a-4c, Gebel Aweina, Egypt] (not pl. l, fig. 6a-c)
|
| Specimen: |
Natural History Museum, London, Inventory number: P.42400
|
| References: |
Nakkady,S.E. (1950):
A new foraminiferal fauna from the Esna shales and Upper Cretaceous chalk of Egypt . Journal of Paleontology Vol. 24 p. 675-692
Berggren,W.A.; Olsson,R.K. and Reyment,R.A. (1967):
Origin and Development of the Foraminiferal Genus Pseudohastigerina Banner and Blow, 1959 . Micropaleontology Vol. 13 p. 265-288
Stainforth,R.M.; Lamb,J.L.; Luterbacher,H.P.; Beard,J.H. and Jeffords,R.M. (1975):
Cenozoic planktonic foraminiferal zonation and characteristics of index forms . Paleontological ContributionsArticle 62 p. 425
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
Stott,L.D. and Kennett,J.P. (1990):
Antarctic Paleogene planktonic foraminifer biostratigraphy: ODP Leg 113, Sites 689 and 690.
In: Proceedings of the Ocean Drilling Program Vol. 113 p. 549-569
Speijer,R.P.. and Samir,A.M.. (1997):
Globanomalina luxorensis, a Tethyan biostratigraphic marker of latest Paleocene global events . Micropaleontology Vol. 43 p. 51-62
Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
|
This work is licensed under a Creative Commons Attribution 2.5 License.
|
|
Taxon Concept provided by