Morozovella allisonensis Kelly et al. 1998 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 Morozovella allisonensis Kelly et al. 1998 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.-
Type of wall: Normal perforate, muricate,
nonspinose.
Test morphology: Low to medium trochospiral
test, subcircular, weakly to non-lobulate peripheral
outline, chambers triangular on umbilical side,
trapezoidal to subquadrate oispiral side as a function
of degree of curvature of intercameral sutures; in
umbilical view primary aperture low arch to subcircular,
umbilical to extraumbilical in position extending to
peripheral margin; typically 5-9 chambers in the final
whorl; sutures depressed, straight to slightly curved,
radial; umbilicus generally small, deep varying with
tightness of coiling; chambers with unornanlented
rounded umbilical shoulders, slight tendency to be
umbilically inclined as a function of axial compression;
on the spiral side approximately 12-17 chambers
arranged in about 3 whorls; chambers flattened to
moderately inflated; gradual increase in chamber size
throughout; sutures muricate, strongly to weakly curved,
varying from raised to slightly depressed; in edge view
umbilico-convex to planar; spiral side flat to slightly
convex; test periphery subrounded to acute; weakly
muricate keel.
Size: Holotype maximum diameter:
approximately 0.35 to 0.40 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
This taxon is
characterized by varying degrees of axial compression;
it is biconvex to mildly planoconvex in edge view;
umbilical tips of chambers are relatively rounded and
unornamented.
DISCUSSION.- This taxon exhibits a wide range of
morphological plasticity that is a function of degree of
axial compression. We have observed the relatively high
conical morphotypes intermediate between the typical
end members of the veluscoensis-allisonensis group
within the CIE in the Dababiya and Qreiya sections in
Egypt.
PHYLOGENETIC RELATIONSHIPS.-
This
ephemeral taxon intergrades with more ornate
morphotypes of its ancestor, M. velascoensis, and has
no descendants.
STRATIGRAPHIC RANGE.-
Zone El ; restricted to
Carbon Isotope Excursion (CIE) interval of Paleocene-
Eocene Thermal Maximum(P ETM).
GEOGRAPHIC DISTRIBUTION.-
This taxon is most
abundant in warm-water, (sub)tropical regions; common
in central-equatorial Pacific Ocean (ODP Site 865) and
in northern (Spain) and southern (Egypt) Tethyan
deposits; rare occurrences recorded on Blake Ridge of
North Atlantic (ODP Site 105 1).
STABLE ISOTOPE PALEOBIOL0GY.-
Inferred
depth-habitat varies over time; initially occupied deeper
portions of mixed-layer to upper thermocline and
subsequently inhabited shallow mixed-layer; carbon
isotope signature exhibits strong covariance with shell
size, while oxygen isotope composition displays a
modest negative correlation with shell size (overall stable isotopic signature is analogous to that of modern,
symbiotic species) (Kelly and others, 1998). |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Truncorotaloididae
Genus Morozovella
Species Morozovella allisonensis
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| Synonym list: |
Pearson et al. (2006):
1996 Morozovella allisonensis Kelly et al.. - Kelly et al. : p.424 fig. 2.7a-2.7b (nomen nudum); [Zone P5 (from a part equivalent to Zone E1 in
this work, from within carbon isotope excursion of
Paleocene-Eocene Thermal Maximum), ODP Hole 865C
Allison Guyot, equatorial Pacific Ocean].
1998 Morozovella allisonensis Kelly et al.. - Kelly et al. : p.158 fig. 5A [holotype], 5B [paratype];
fig. 8D-G [Zone P5; (from a part equivalent to Zone El in this work,
from within carbon isotope excursion of Paleocene-Eocene
Thermal Maximum), ODP Hole 865C Allison Guyot,
equatorial Pacific Ocean].
2006 Morozovella allisonensis Kelly et al.. - Pearson et al. : p.348 pl. 11.2; fig. 4-16 (Pl. 11.2, Figs. 4-8, 12: SEMs of holotype and
paratype of Morozovella allisonensis Kelly, Bralower,
and Zachos)
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| Specimen: |
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 494824
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 494825
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| References: |
Kelly,D.C.; Bralower,T.J.; Zachos,J.C.; Premoli Silva,I. and Thomas,E. (1996):
Rapid diversification of planktonic foraminifera in the tropical Pacific (ODP Site 865) during the late Paleocene thermal maximum . Geology Vol. 24 p. 423-426
Kelly,.; Bralower,. and Zachos,. (1998):
On the demise of the Early Paleogene Movozovella velascoensis lineage: terminal progenesis in the planktonic foraminifera . Palaios Vol. 16 p. 507-523
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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