Globoturborotalita bassriverensis Olsson & Hemleben 2006 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
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Species Globoturborotalita bassriverensis Olsson & Hemleben 2006 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Cancellate, normal perforate,
spinose, sacculifer-type wall structure.
Test morphology: Test moderately low
trochospiral, globular, lobulate in outline, chambers
globular; in spiral view 4 globular, slightly embracing
chambers in ultimate whorl, increasing moderately in
size, sutures depressed, straight, last 4 chambers make
up about 1/2 of the test size; in umbilical view 4 globular, slightly embracing chambers, increasing moderately in size, sutures depressed, straight, umbilicus small, open, enclosed by surrounding chambers, aperture umbilical, a rounded arch, bordered by a narrow lip that is thickened in some specimens; in edge view chambers globular in
shape, slightly embracing, initial spire of chambers
slightly elevated.
Size: Maximum diameter of holotype 0.16 mm,
thickness 0.12 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
ETYMOLOGY.-
Named after the borehole at Bass
River, New Jersey, from which the holotype is described.
DISTlNGUISHING FEATURES.-
The species is
characterized by its small size, 4 globular, slightly
embracing chambers in the final whorl, umbilical
aperture, and cancellate wall texture. It is distinguished
from G. ouachitaensis, which it most closely resembles,
by its thicker, more prominent lip which it shares with
its ancestral genus Subbotina.
DISCUSSION.
Globoturborolalita bassriverensis is
described from an exceptionally well-preserved
assemblage of planktonic foraminifera from a Zone El
section in the Bass River Borehole, ODP 174AX, New
Jersey Coastal Plain. The assemblage from which this
species is described is associated with the carbon isotope
excursion (CIE) and the Paleocene-Eocene Thermal
Maximum (PETM). In addition, the excursion taxa
(Kelly and others, 1996), Acarinina africana, A.
sibaiyaensis, and Morozovella allisonensis also occur
in this El assemblage. The bassriverensis morphology
has not been observed in the Paleocene (Olsson and
others, 1999). Thus, it appears that the origin of
Globoturborotalita is related to climate-induced changes
in the structure of water masses during the PETM. The
genus was apparently derived from Subbotina because
of its symmetrical sacculifer-type, spinose wall texture
and umbilically directed aperture. Specimens are quite
common but have probably been overlooked because of
their small size.
PHYLOGENETIC RELATIONSHIPS.-
Globoturborotalita
bassriverensis is the first species in a generic
line that extends to the Recent. The probable ancestor
is Subbotina hornibrooki.
GEOGRAPHIC DISTRIBUTION.-
Distributed in mid- to low latitudes.
STABLE ISOTOPE PALEOBIOLOGY-
Recorded (as
'small globigeriniforms') by Pearson and others (2001)
from the middle Eocene of Tanzania with relatively
negative ò180 indicating a shallow water habitat. |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Globigerinidae
Genus Globoturborotalita
Species Globoturborotalita bassriverensis
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| Synonym list: |
Pearson et al. (2006):
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| Specimen: |
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 521867
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 521868
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| References: |
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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