Tenuitella insolita Jenkins 1966 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 Tenuitella insolita Jenkins 1966 |
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Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Microperforate, monolamellar,
surface smooth to finely pustulose, pustules irregularly
scattered on umbilical and spiral sides of test.
Test morphology: Test small, subquadrate to
subcircular and lobate in axial view, equatorial margin rounded; chambers inflated to subglobular, coiled in a
moderate trochospire, sometimes becoming nearly
planispiral in the final whorl, increasing gradually in size,
4-6 in the final whorl; sutures depressed, curved on the
spiral side, radial on umbilical side; umbilicus small;
aperture in early chambers subcircular to circular (Pl.
16.5, Fig. 10), in adult final chambers it is a distinct,
high, sometimes triangular arch that may be aligned with
the equatorial periphery (e.g., P1. 16.5, Figs. 5, 12) or
offset toward the umbilicus (Pl. 16.5, Figs. 2, 8, 17).
Size: Holotype maximum diameter: 0.16 mm,
breadth 0.10 mm. Hypotype maximum diameter 0.19
mm, breadth 0.1 0 mm. |
Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
Distinguished from
other tenuitellids by its highly arched and narrow
aperture and smooth test surface.
DISCUSSION-
Li and Radford (1992) and Li and
others (1 995) distinguished T. impariapertura Li from
T. insolita by suggesting the latter species has a more
circular test, a more convex dorsal side, and a narrower
umbilicus. Given that Jenkins's (1966) type illustrations
shows a triangular to highly arched aperture in his
holotype and paratype illustrations, and in light of the
morphological variability of specimens illustrated on
Plate 16.5, we consider impariapertura to be a junior
synonym of insolita. Some of the specimens identified
as Praetenuitella patefacta by Li and others (1995, pl.
4, figs. 1-3) exhibit triangular, highly arched apertures
that are nearly centered on the equatorial peripheral plane
and are therefore here designated as T. insolita.
Poorly preserved upper Eocene specimens
identified as Globorotalia insolita by Jenkins and Orr
(1972) from DSDP Site 77B (eastern Equatorial Pacific)
are considered misidentified as the presence of elongate
umbilical flaps, axially compressed tests with a weakly
lobate equatorial periphery are not characteristic. We are
uncertain of the species identity of their illustrated
specimens. Dissected specimens of T. insolita (e.g., PI. 16.5,
Fig. 10) reveal that a highly arched aperture rimmed by
a narrow lip is present in all final whorl chambers in
adult specimens. This dissected specimen also shows
that the wall microstructure is monolamellar, as observed
in the wall of T. praegemma (Pl. 16.6, Fig.9) and T.
gemma (Pl. 16.7, Fig. 15).
PHYLOGENETIC RELATIONSHIPS.-
The suggestion by Li and others (1995) that T. insoliter
(=Praetenuitella impariapertura Li) descended directly
from Pseudohastigerina is rejected since the latter
species is planispiral and normal perforate whereas T.
insolita is trochospiral and microperforate. Li and
McGowran (l996) observed that Teniutella insolita
shares a number of morphological features with Cassigerinella eocaenica ( C. winniana in their study)
including a smooth, microperforate wall structure,
minute test size, and high, narrowly arched aperture, but
it differs in having a low trochospiral rather than a
biserially enrolled coiling mode. The possible
relationship between these two species needs further
study and other phylogenetic hypotheses for the origin
of the tenuitellids need to be explored. Tenuitella praegemma and T. patefacta probably evolved from T. insolita during the latest Eocene.
STRATIGRAPHIC RANGE.-
Upper Eocene Zone
E 15; nominate species for the T. insolia Taxon Range
Zone (Zone AE9) at southern high latitudes(Huber and Quillévéré, 2005). Originally described from the Port
Elizabeth section in New Zealand where it ranges from
just above the extinction of Acarinina collactea to just
below the extinction of Globigerinatheka spp. (Jenkins, 1971). In the Ocean View Borehole (New Jersey Coastal
Plain) the lowest occurrence of T. insolita was recorded
within the upper 30 feet of the 200 Soot stratigraphic
range of Globigerinatheka index (Miller and others, 2003).
GEOGRAPHIC DISTRIBUTION.-
Originally
described from the Port Elizabeth section (upper Eocene)
in New Zealand; also identified in upper Eocene
sequences in southern Australia (McGowran, 1987),
Japan (Kaiho, 1984), southern South Atlantic Ocean
(ODP Site 703; Nocchi and others, 1991) and southern
Indian Ocean (ODP Sites 737, 738C, 747 and 749;
Huber, 1991; Li and others, 1992). At low latitudes
reported from the equatorial Pacific (DSDP Site 77;
Jenkins and Orr, 1972) and central Pacific Ocean (DSDP
Site 321; Quilty, 1976).
STABLE, ISOTOPE PALEOBIOL0GY.-
An oxygen
and carbon isotope cross-plot showing values from T. insolita relative to those from co-occurring benthic and planktonic species is presented in Figure 163 for an
upper Eocene (~Zone F15-16) sample from Cape May, New Jersey. These data suggest that T. insolita was a
relatively deep dwelling planktonic species that either
preferred living within the oxygen minimum zone of
the water column or had a considerable vital effect
causing preferential fractionation of the lighter carbon
isotope. The carbon and oxygen isotope values of T. insolita
are near those of Dipsidripella danvillensis, suggesting that these species had similar ecological
ecological and/or vital effect offset from equilibrium
fractionation.
REPOSITORY.-
Holotype and paratypes deposited in
the Geological and Nuclear Research Institute, Lower
Hutt, New Zealand. |
Systematics: |
35 Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Cassigerinellidae
Genus Tenuitella
Species Tenuitella insolita
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Synonym list: |
Pearson et al. (2006):
1966 Globorotalia insolita Jenkins. - Jenkins : p.1120 fig. 13, nos 113-118 [upper Eocene, Port Elizabeth, New Zealand]
1991 Praetenuitella insolita Jenkins. - Huber : pl. 7; fig. 9, 10 [upper Eocene Zone AP12, ODP Hole 738B,
Kerguelen Plateau, southern Indian Ocean]
1991 Praetenuitella insolita Jenkins. - Nocchi et al. : p.269 pl. 4; fig. 24-26 [upper Eocene, ODP Hole
703A, South Atlantic Ocean]
1992 Praetenuitella insolita Jenkins. - Li & Radford : p.578 pl. 1; fig. 1-3 [upper Eocene, ODP Hole 749B,
Kerguelen Plateau, southern Indian Occan]
1995 Praetenuitella insolita Jenkins. - Li et al. : p.132 pl. 3; fig. 1-7, 9, 10 [upper Eocene, Brown's Creek Fm., Otway Basin,
southern Australia]
1995 Praetenuitella impariapertura Li. - Poag & Commeau : p.155 pl. 9; fig. 16-17 [Upper Eocene Zone P15, U.S. Geological Survey
Exmore Core, Virgina Coastal Plain]
1995 Praetenuitella patefacta Li. - Li et al. : p.127 pl. 4; fig. 1-3 [upper Eocene, ODP Hole 749B, Kerguelen
Plateau, southern Indian Ocean];
[Not Li, 1987]
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References: |
Jenkins,D.G. (1966): Planktonic foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. . N. Z. J. Geol. Geophys. Vol. 8 p. 1088-1126
Jenkins,D.G. (1971): New Zealand Cenozoic Planktonic Foraminifera . New Zealand Geological Survey Paleontological Bulletin Vol. 42
Jenkins,D.G. and Orr,W.N. (1972): Planktonic foraminiferal biostratigraphy of the eastern equatorial Pacific—DSDP Leg 9. In: Initial Reports of the Deep Sea Drilling Project Vol. 9 Eds: Hays, J.D.et al. p. 1059-1193
Li,Q. (1987): Origin, phylogenetic development and systematic taxonomy of the Tenuitella plexus (Globigerinitidae Globigerininina) . Journal of Foraminiferal Research Vol. 17 p. 298-320
Nocchi,M.; Amici,E. and Premoli Silva,I. (1991): Planktonic Foraminiferal Biostratigraphy and Paleoenvironmental Interpretation of Paleocene Faunas from the Subantartic Transect, Leg 114. In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 114 Eds: Ciesielski, P.F.Kristoffersen, Y.Al, E. p. 233-279
Huber,B.T. (1991): Paleogene and early Neogene planktonic foraminifer biostratigraphy of Sites 738 and 744, Kerguelen Plateau (southern Indian Ocean). In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 119 Eds: Leckie, R.M.Sigurdsson, H.Acton, G.D.Draper, G. p. 427-449
Li,Q. and Radford,S.S.. (1992): Morphology and affinity of the planktonic foraminifer Cassigerinelloita amekiensis Stolk and reclassification of Cassigerinelloita Stolk. In: Proceedings of the Ocean Drilling Program, Scientific Results, Ocean Drilling Program Vol. 120 Eds: Wise, J.S.W..Schlich, R..and others p. 595-602
Poag,C.W.. and Commeau,J.A.. (1995): Paleocene to middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: biostratigraphy, allostratigraphy, and sequence stratigraphy . Journal of Foraminiferal Research Vol. 25 p. 134-155
Li,Q.; McGowran,B. and Boersma,A. (1995): Early Palaeocene Parvularuglobigerina and late Eocene Praetenuitella; does evolutionary convergence imply similar habitat? . Journal of Micropalaeontology Vol. 14 p. 119-134
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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