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Acarinina praetopilensis Blow 1979 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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Anonymous: Unedited TaxonConcept data
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Species Acarinina praetopilensis Blow 1979


Diagnosis / Definition:
Pearson et al. (2006):
DESCRIPTION. Type of wall: Strongly muricate, nonspinose, normal perforate. Test morphology: Low-trochospiral, sutures radial, straight, sunk (depressed) between overlapping junctionts) of juxtaposed inflated chambers; umbilicus deep and wide with no circum-umbilical muricate rim/ collar; weakly rimmed aperture extends towards (but does not reach) the periphery; 9-10 chambers in 2-2 1/2 whorls on spiral side; chambers tangentially longer than radially broad; last chamber distinctly disjunct, cuneate or mitriform, subacute margin with profusion/ concentration of partially fused muricae; supplementary apertures usually present between the last two chambers in well preserved individuals; spiral sutures radial to weakly curved; in edge view high, angulo-conical. Size: Maximum diameter of holotype: 0.3 8mm (Blow, 1979, p. 1043).
Discussion / Comments:
Pearson et al. (2006):
DISTINGUISHTNG FEATURES.- Distinguished by its strongly muricate, subquadrate test, disjunct, cuneate to mitriform last chamber which bears heavy circum-peripheral concentration of partially fused muricae. DISCUSSION.- Acarinina praetopilensis was named by Blow (1979) for middle Eocene descendants of A. pseudotopilensis that show more closely appressed chambers in the last whorl leading to laterally angulate chambers and enhanced circum-peripheral concentration of partially fused muricae into a muricocarina on the last chamber. PHYLOGENETIC RELATIONSHIPS.- Probably evolved from Acarinina mcgowrani n. sp. by greater lateral compression of, and concomitant concentration of partially fused muricae on, margins of last chamber, greater laxity in coiling mode and resulting larger and deeper umbilicus, and development of rimmed supplementary apertures between (at least) the last two chambers (Blow, 1979). It gave rise to Acarinina topilensis by developing a more distinctly lobate periphery, disjunct chamber margins on later chambers which exhibit pronounced cuneate or mitriform shape, stronger/heavier concentration of thick muricae on chambers of the last whorl, looser coiling resulting in even wider umbilicus than in praetopilensis and larger and greater number of supplementary apertures on spiral side. STRATIGRAPHIC RANGE.- Zone E7 (upper part) to Zone E 1 2. GEOGRAPHIC DISTRIBUTION.- Widespread distribution in Tethyan and South Atlantic regions. STABLE ISOTOPE PALEOBIOLOGY.- Relatively negative ò18O and positive ò13C indicate a mixed layer habitat. Size fraction data shows a large change in ò13C through ontogeny suggestive of a symbiotic relationship like other muricate forms (Boersma and others, 1987; Pearson and others, 1993; recorded as pseudotopilensis).
Systematics:

35
 Ordo Foraminiferida
  Superfamilia Globigerinaceae
   Familia Truncorotaloididae
    Genus Acarinina
     Species Acarinina praetopilensis
Synonym list:
Pearson et al. (2006):
1979 Globorotalia (Truncorotaloides) topilensis praetopilensis Blow. - Blow : p.1043 pl. 155, fig. 9; pl. 203, fig. 1-2 (detail of pl. 155: fig. 9), [Zone P10, KANE 9, piston-core 42,95 cm, Endeavor Seamount, equatorial Atlantic Ocean]; pl. 169, fig. 1-9 (8=holotype); pl. 207, fig. 1 (detail of. pl. 178, fig. 9), fig. 2 (=detail of pl. 169, fig. 7); pl. 208, fig. 1-4 (=detail of pl. 169, fig. 4); pl. 208, fig. 5 (=detail of pl., 169, fig. 7), [Zone P1 1, Sample RS. 24, Kilwa area, Tanzania]; pl. 178, fig. 6-9; pl. 185, fig. 7-8 [Zone Pll, DSDP Hole 21A, South Atlantic Ocean]; pl. 187, fig. l - 2 and pl. 208, fig. 6 (=detail of pl. 187, fig. 2), [Zone P12, DSDP Site 19, South Atlantic Ocean]; pl. 187, fig. 3-4 [Zone P12, DSDP Hole 21A, South Atlantic Ocean]
non 2001 Acarinina praetopilensis Blow. - Wade & Norris : p.277 fig. 3f-3h
2004 Acarinina praetopilensis Blow. - Pearson et al. : p.37 pl. 2; fig. 7-9 (details of muricae) [Zone P 1 1, Tanzania Drilling Project Site 2/9/CC]
non 2004 Acarinina praetopilensis Blow. - Wade : p.28 pl. 1; fig. g-h (=A. mcgowrani)
2006 Acarinina praetopilensis Blow. - Pearson et al. : p.301 pl. 9.16; fig. 1-16 (Pl. 9.16, Figs. 1-3: reillustration of holotype and paratypes of Globorotalia (Truncorotaloides) topilensis praetopilensis Blow)
Was used in synonym list of:
Specimen:
Natural History Museum, London, Inventory number: BP Cat. NO. 64/2
References:

Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp

Wade,B.S.. and Norris,R.D. (2001):
Orbitally forced climate change in the late Middle Eocene at Blake Nose (Leg 171B): Evidence from stable isotopes in foraminifera.
In: Western North Atlantic Palaeogene and Cretaceous Palaeoceanography Vol. 183 Eds: Kroon, D.Norris, R.D.Klaus, A.. p. 273-291

Wade,B.S.. (2004):
Planktonic foraminiferal biostratigraphy and mechanisms in the extinction of Morozovella in the late Middle Eocene . Marine Micropaleontology Vol. 51 p. 23-38

Pearson,P.N.; Nicholas,C.J..; Singano,J.M..; Bown,P.R..; Coxali,H.K..; van Dongen,B.E..; Huber,B.T.; Karega,A..; Lees,J.A..; Misaky,E..; Pancost,R.D..; Pearson,M.. and Roberts,A.P.. (2004):
Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1-5 . Journal of African Earth Sciences Vol. 39 p. 25-62

Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
Anonymous: Unedited TaxonConcept data
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