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Late Paleocene Orthophragminae (Foraminfera) from the Haymana-Polatli Basin, CentralTurkey) and Description of a New Taxon, Orbitoclypeus haymanaensisAuthor(s): Ercan Özcan, Ercüment Sirel, Sevinç Özkan Altiner, Sinan ÇolakoǧluSource: Micropaleontology, Vol. 47, No. 4 (Winter, 2001), pp. 339-357Published by: The Micropaleontology Project, Inc.Stable URL: http://www.jstor.org/stable/1486033Accessed: 09/12/2009 05:09

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Late Paleocene Orthophragminae (foranminfera) from the Haymana-Polath Basin, central Turkey) and description of a

new taxon, Orbitoclypeus haymanaensis

Ercan Ozcan', Ercuiment Sirel2, Sevinq Ozkan Altiner3 and Sinan Colakoglu4 1Department of Geological Engineering, Akdeniz University, Topqular, 07200 Antalya, Turkey,

e-mail: [email protected] 2Department of Geological Engineering, Ankara University, Tandogan, 06100 Ankara, Turkey

3Marine Micropaleontology Research Unit, Department of Geological Engineering, Middle East Technical University, 06531 Ankara, Turkey

e-mail: [email protected] 4Department of Geological Engineering, Nigde University, 51100 Nigde, Turkey

ABSTRACT: A transgressive shallow-marine succession suggested as a reference-section for early Thanetian by the 'Early Paleogene working group' (IGCP 286) was studied for its orthophragminid foraminifera from Haymana-Polatli Basin in central Anatolia. Orthophragminae, closely associated withAssilina yvettae and Operculina heberti, have been identified in a friable clastic-carbonate sequence which contains Glomalveolina in its different horizons. Basinal sediments with planktonic taxa overlie the shallow-water deposits and preclude the study of orthophragminae higher in the succession. Orthophragminae, studied in oriented sections, were grouped into four categories considering the qualitative and quantitative aspects of megalospheric embryo and morphologic elements of equatorial and lateral chamberlets in equatorial and partly vertical sections. Thus, Discocyclina seunesi, Orbitoclypeus neumannae and Disco- cyclina sp.l have been identified and a new species, Orbitoclypeus haymanaensis, is erected. These assemblages were dated to Thanetian based upon the calcareous nannofossil and planktonic foraminifera identified in the overlying basinal sediments and also the benthonic foraminifera either associated with orthophragminae or present in different horizons of the shallow-marine succession.

INTRODUCTION

In this study, we introduce and describe Thanetian orthophragminae from the shallow-marine deposits of Haymana- Polatli Basin (central Anatolia). This study basically follows Sirel (1975 and 1992), who first defined the paleontological aspects of marine Paleocene in the region and reported Disco- cyclina from these beds, and Serra-Kiel et al. (1998), who referred these sections as key localities for late Paleocene in Turkey. This study was also prompted by poor information about the Mediterranean orthophragminid foraminifera in Paleocene, realized from previous studies, mainly from that of Less (1987 and 1998) who recently presented the most detailed and up to date information about the biometry and stratigraphy of Mediterranean orthophragminid foraminifera.

Orthophragminae includes the larger foraminifera with an architecture characterized by a layer of equatorial chamberlets arranged in successive annuli and two layers of lateral chamberlets on both sides. In recent studies (Less 1998), Orthophragmininae is divided into two families; Disco- cyclinidae Galloway 1928, comprising the genera Discocyclina Guiimbel 1870, Nemkovella Less 1987, Pseudophragmina Douville 1922, Athecocyclina Bronnimann 1946 and Astero- phragmina Rao 1942, and Asterocyclinidae Bronnimann 1951, comprising the genera Asterocyclina Gtimbel 1870, Orbito- clypeus Silvestri 1907 and Neodiscocyclina Caudri 1972. Mesogean orthophragminids, however, are represented only by Discocyclina Giimbel 1870, Nemkovella Less 1987, Orbito- clypeus Silvestri 1907 and Asterocyclina Giimbel 1870 (Less 1998; Ferrandez-Cafiadell 1998a). The zonation of the Mediter-

ranean late Paleocene and Eocene by orthophragminids, alveolinids, and nummulitids has already been proposed by Serra-Kiel et al. (1998) and 20 shallow benthic zones (SBZ) in Paleocene- Eocene time interval have been suggested by the stratigraphic distribution of these taxa. Less (1998) documented the stratigraphic ranges of tethyan orthophragminid foraminifera in collaboration with these standard zones (table 1).

The Mediterranean Paleocene orthophragminids are poorly understood and all varieties have long been attributed to Disco- cyclina seunesi, originally described from the Aquitaine basin in France (Douville 1922). Original description of this species is primarily based upon the outer test morphology and an illustration of megalospheric embryo in equatorial section, without any measurement of embryo and embryo-related parameters and their variation in the population. Preliminary data regarding the biometry of D. seunesi was first presented by Neumann (1958) from Douville's collection and from her own material. How- ever, the numerical data presented by the author seems to be incorrect, since the figures relating to the size of protoconch and deuteroconch are too big when compared with the measurements of D. seunesi documented either by Less (1998) or with that of our present study. Less (1998) introduced the biometric aspects of this species from different localities in Bulgaria (BELO 0-5 populations) and France (NTSOR and BOUSM populations) and reported its existence in SB Zone 3 (table 1). This author indicated the possibility of further subdivision of this species in subspecific levels by biometry as D. seunesi seunesi and D. seunesi n ssp. Beloslav, the latter one yet not described and figured. Less (1998) also reported the existence of

micropaleontology, vol. 47, no. 4, pp. 339-357, text-figures 1-3, plates 1-4, tables 1-4, 2001 339

E. Ozcan et al.: Late Paleocene Orthophragminae from central Turkey: description of Orbitoclypeus haymanaensis n. sp.

KARAHAMZALI (KAR)

Conglomerate - Shale/Marl

. Sandy Conglromerate Massive Limestone

*" * Sdstone i Sandy Limestone

I SiltonslSandstone Clayey Limestone

Siltne I Limestone

* Alveolinid foramnifera

Gastropoda

Q Pelecypoda

1 Operculinid foraminifera

cSt Plml ktonic foraminifera * Horizns studied for

Orthophragminid foraminifera

=7 _7

... m ~

- --- - sO-=N --- SE~~~_^^--CK SE --- - - - - - - ' _ * I e - - - - - -~_~--

........_._._ - SIgI i

0- 1k

FORS MATIO N I (=T-=

0u j A F O R M A TIO ( D a nia n S ela nd ia ng E arly T h a n etia n) A ltern atio n of C o n glo m erate, M arl, S a n dsto n e a n d Li m esto o o CTIONu- L i -et

o KARAHAMALI o0 0 / 0 1 km 20

[ ] AGASIVRI FORMAnION (Neogene-Rect)- Conglomerate, Marl, argillceousm Lnmestone '- - : -. Alternation of Marl, Sandstone and laminated Limestone

-- KIRKKAVAK Massive Limnestone FORMATON (Thanetian)

.

-- _- Shale/Siltstone, Sandstone, argillaceous Limestone

[0 0 o| KARTAL FORMAnON (Danian-Selandian/Early Thanetian)- Alternation of Conglomerate, Marl, Sandstone and Limestone

MOLLAREMsULFORmAnoN (Late Jurassic-Early Cretaceous)- Limestone

TEXT-FIGURE 1 Geological map of study area south of Polatli, central Anatolia (simplified and partly modified from Sirel 1975) and generalized columnar sections of Paleocene outcrops sampled for Orthophragminae. Numbers on the right of each column refer to the sample numbers and asterisk indicate the horizons studied for Orthophragminae.

340

KARSAK (KARS)

{--40 - 38 -37 - 36*

I

Micropaleontology, vol. 47, no. 4, 2001

TABLE 1 Stratigraphic distribution of orthophragminae around the Thanetian- Ilerdian boundary (Less 1998) in collaboration with associated benthonic foraminifera only in shallow benthonic zones 3 to 7 (Serra-Kiel et al. 1998).

CD 0

-- .c 05

o

m ,

a n

| | m .e

c i s 1i1 ci

(oc^ - o co ci

c

c I

E

0 0 co

I

.0- 0,

.2

E d

0 0

.a U1) 6. 0.

ci

12 '

I 11

:1 .' ' ----- A------ .

U

i , ; I - , i

- . * * * . . ' I I I I II I, I I 4

I II I I

I I

FORAMINIFERALASSEMBLAGES IN SHALLOW BENTIC ZONES SBZ-3-SBZ-7 DURING THANETIAN- EARLY ILERDIAN

(SERRA-KIEL et al., 1998)

is E 22, aT

I I ; I I I I ' ,

I i I I i = I I

_ I 'I- * - I - = = . I I

3 l l I I III i

I I I I I I

D- Discocyclina Gl- Glomalveolina M- Miscellanea R- Ranikothalia N- Nummulites A- Alveolina V- Vania

Ass- Assilina

P- Periloculina C- Coskinon F- Fallotella Cr- Cribrobulimina Ps- Pseudomiscellanea Da- Daviesina Dic- Dictyokathina 0- Orbitolites

Or. schopeni neumannae, A. moussoulensis, A. subpyrenaica, A. dedolia, A. laxa, N. robustiformis, N. carcasonensis, N. praecursor, N. oblaticus, Ass. arenensis

6 l l A. ellipsoidalis, A. daniensis, A. pasticillata, A. solida, N. minervensis

5 2 I 0 o. gracilis, A. vredenburgi, A. avellana, A. varians, N. gamardensis, IT I . .| Ass. dandotica, Ass. prisca, Da. tenuis 4 GI. levis, M. meandrina, N. catari, H. lucasi, N. catari, Ass. yvettae,

Ass. azilensis, Da. garumnensis, Dic., simplex

1b

3 la

I I -

I * I D. seunesi, GI. primaeva, M. yvettae, R. bermudezi, N. heberti, Pslovenica, C. rajkae, F alavensis, Cr. camiolica, V. anatolica, Ps. primitiva

another species of Discocyclina, D. tenuis, in shallow benthic zones 4-6, corresponding to Late Thanetian (Less 1998) and late Thanetian- early Ilerdian (Serra-Kiel et al. 1998). This species, biometric features of which are given from RUBEC, SPILE and GAMA7 populations, was originally described from Italy (Douville 1922) (Spilecco population of Less 1987 and 1998) without any information about its internal characteristics. However, it is apparent from the biometric data presented by Less (1998) that this species has a large embryo (dmean suggested bigger than 360pm).

The existence of the genus Orbitoclypeus in the late Paleocene has long been debated. This is mainly because of the difficulty either in obtaining the microspheric specimens which bear some morphological features important in generic assignment (see Ferrfandez-Cafiadell 1998b for a full account of criteria for generic and specific assignment) or insufficiency of material from Thanetian. 0. ramaraoi, originally described from Thanetian deposits in India (Samanta 1967), is known to be the only orbitoclypeid species in late Paleocene. Biometric features of the genus in Mediterranean Thanetian deposits were first reported by Less (1987 and 1998) from three localities in France (BOUSM, NTSOR and RUBEC populations of the author). Orbitoclypeus specimens, which are very few in number, in these populations were ascribed to 0. ramaraoi (0. schopeni ramaraoi). Orbitoclypeus neumannae (Toumarkine), regarded as the successor of 0. ramaraoi (Less 1987 and 1998) represents the oldest orbitoclypeid described from Mediterranean region. Less (1987) introduced the biometric aspects of this

species from Spilecco (SPILE) population from Italy. Topotype material of this species, however, was not yet studied.

STRATIGRAPHY, SAMPLE LOCALITIES AND AGE

The late Cretaceous-early Eocene sequence of Haymana- Polatli Basin in central Anatolia comprises a variety of rock types that include basinal marl/shale, turbiditic sandstone, olistostromal horizons in its lower and continental and shallow- water clastics and carbonate units in its upper part. This sequence, interpreted as the fill of a forearc basin by Kocyigit (1991) consists of a rich association of 'orbitoidal' and other benthic foraminifera in many horizons partly accompanied by pelagic organisms. Orbitoides and Lepidorbitoides have been recognized as transported mainly in turbiditic sandstone levels in late Campanian-early Maastrichtian part and possibly in-situ in late Maastrichtian section of the succession (Ozcan and Ozkan-Altmer 1997 and 1999). Paleocene part of the sequence is dominated either by basinal sediments completely devoid of larger foraminifera or continental clastics and shallow-marine clastics and carbonates with orthophragminae, 'operculinids' and alveolinids. Orthophragminid foraminifera closely associated with nummulitids are very common in Eocene part of the succession. Although the benthic foraminiferal inventory of late Paleocene-Eocene sequence was published (Dizer 1968; Sirel 1975, 1976a and b, 1998 and 1999; Sirel and Gundiz 1976; Unalan et al. 1976), orthophragminid foraminifera, very common in late Paleocene- Eocene part of the succession was not studied. As for the late Paleocene, Sirel (1975) noted only the presence of orthophragminae in the same stratigraphic sections,

341

CD 0)

cU)

-

-0

U)

00 0)

o N

"-

I.-

8 8

7 w -J

z

w z I

E. Ozcan et al.: Late Paleocene Orthophragminaefrom central Turkey: description of Orbitoclypeus haymanaensis n. sp.

Number of annuli within 0.5mm wide stripe (nO.5)

Auxiliary chamberlets (A) - arising from the deuteroconch (Adauxiliary chamberlets)

Height (H,h) and width (W,w) of the

auxiliary and peripheral

equatorial chamberlets

TEXT-FIGURE 2 Parameters for the definition of embryo and following equatorial chamberlets in orthophragminae.

which are the subject of present study, and ascribed them to Discocyclina seunesi without any description and illustration.

The study area is located south of the town of Polatli, 75km southwest of Ankara in central Anatolia. This region, which was suggested as one of the key-localities for early Thanetian by Serra-Kiel et al. (1998), was previously mapped by Sirel (1975) (text-fig. 1) who also first described the foraminiferal content of the lithostratigraphic units cropping out in the region. The lower part of Paleocene sequence is represented by continental coarse clastics of Kartal Formation; mainly conglomerate and sandstone beds, which are mostly barren of foraminifera. Sirel (1975) described Rotalia trochidiformis, Mississippina? binkhorsti and Valvulammina sp. in the upper part and assigned 'Montian' age to the unit. Kartal Formation transgressively overlies the Mesozoic carbonates (Mollareus Formation) grades upwards into a shallow marine sequence which comprises basinal sediments in its upper part (Kirkkavak Formation). This unit was dated as Thanetian based on larger foraminifera (Sirel 1975) and Ostracoda (Duru and Gokqen 1985). The lower part of this marine sequence is represented by friable siltstone, sandstone, conglomerate and local argillaceous carbonate horizons and pass upwards into the carbonate-rich units; mainly friable shale/siltstone and sandstone and limestone. A thick cliff-forming marker horizon (known as 'algal limestone' in the literature) composed of massive argillaceous limestone with thin intercalations of friable siltstone and sandstone represents the final phase of shallow-water sedimentation in the region. Sirel (1998) described Glomalveolina primaeva,

Glomalveolina pilula, Operculina cf. heberti, Discocyclina seunesi, Smoutina? subsphaerica, Rotalia trochidiformis, Vania anatolica, Orduella sphaerica and Miscellanea sp. and assigned Thanetian age to these horizons of Kirkkavak Formation. Duru and Gokqen (1985) described Hermanites decoratissima Tambareau, H. praetexta Tambareau, H. alata Ducasse, H. (Hornibrookella) persica Tambareau, Cytherella munsteri (Roemer) and Paleomonsmirabilia paupera Apostolescu in the lower shallow-water part (Alveolina horizon of the authors) of the Kirkkavak Formation and assigned a Thanetian age to the unit.

Three stratigraphic sections representing only the lower shallow-water part of Kirkkavak Formation with larger benthonic foraminifera (Sections Karahamzali-KAR, Kirkkavak-KIRK and Karsak-KARS) were measured and sampled (text-fig. 1). Localities of the sections Kirkkavak and Karahamzali corre- spond to the type- section of Kirkkavak Formation, formerly designated by Rigo de Righi and Cortesini (1959) and together with Karsak, their localities are same with those studied by Sirel (1975). In the succession, Glomalveolina is frequently observed in some levels in the lower and upper part of the succession. In section Kirkkavak (KIRK), which is the most complete section traversing continental clastics down, and lowermost part of basinal sediments up, Orthophragminae has been identified in different horizons above a few-meters-thick argillaceous carbonate clastic level consisting of abundant Glomoalveolina in the lower and massive carbonates with sporadic Glomalveolina in the upper part of the unit. In these horizons, we identified

342

_ ___ ..__....__


KAR.8-1 KAR.9-12

KAR.9-24 KAR.8-9

KIRK.39-27 KIRK.34-21 KIRK.41-15 KIRK.36-22 KIRK.41-1 KIRK.41-10

KIRK.21-2 KIRK.25-2 KIRK.25-20

.'^^ i^^^ \KJRK25-228 KIRK25-24 27-12 OR9

43 KIRK.34-14 KRK27-18 KJRK27-19 KIRK.28-9 RK.28-10 KIRK34-11

KAR.8-13 KAR.8-36 KAR.9-14 KAR.8-3 KAR817 KAR.8-KAR-20

KA - KAR.15-14 KAR.15-10 KAR.15-11 KAR.1 5 KARS.2-12 KARS. t9 ' SKAR.10 K15-1.-2

KAR S2 hCAR.814 KAR.8-15 KAR.8-43 KAR.2 KAR.RM2

KAR.8-58 KAR.9-7 KAR.99 KAR.9-10 A KIRK36-8

KAR.9-39

TEXT-FIGURE 3 Megalospheric embryonic apparatus and first or first several annuli in equatorial section of Orbitoclypeus haymanaensis n. sp. (A), Discocyclina seunesi and Discocyclina sp.l (B) and Orbitoclypeus neumannae (C) from different horizons of Kirkkavak, Karahamzali and Karsak sections. In B, KIRK.25-10-12 and 26 represent Discocyclina sp. and the others belong to Discocyclina seunesi All x60.

343


Glomalveolina primaeva, Glomalveolina cf. levis, Glom- alveolina cf. pilula, Operculina heberti, Vania anatolica, Assilina yvettae, Miscellanea yvettae, Mississippina ? binkhorsti, Valvulina ? sp., Quinqueloculina ? sp., Coskinolina sp., Rotalia sp., Pseudolacasina sp. (PI. 4, figs. 1-21) and abundant Gastropoda, Broyozoa, Bivalves and Corals. Section Kara- hamzali (KAR), measured in the close vicinity of Kirkkavak (KIRK) section, corresponds to the middle-upper part of the shallow-water section of Kirkkavak Formation below the cliff-forming massive limestone horizon. Section Karsak (KARS) corresponding to the clastic-carbonate horizons of Kirkkavak Formation, comprises a rich association Assilina yvettae and Operculina heberti in a few horizons below a massive carbonate horizon rich in Glomalveolina in the uppermost part of the unit.

Massive carbonate horizons of Kirkkavak Formation are over- lain by the basinal sediments, which are represented by fine-siliciclastic levels with sandstone intercalations. These horizons, which are completely devoid of orthophragminae, consist of a moderately diverse fauna of calcareous nannofossil and planktonic foraminifera. We have only studied the lowermost part of the basinal sediments for pelagic organisms (Kirkkavak section, samples KIRK.50-54) (table 2; plate 3). The samples have yielded moderately abundant and diverse calcareous nannofossil assemblages. Cruciplacolithus latipons Romein 1979, Ellipsolithus macellus (Bramlette and Sullivan 1961), Ericsonia cava (Hay and Mohler 1967), Ericsonia ovalis Black 1964, Fasciculithus thomasii Perch-Nielsen 1971, Fascicu- lithus tympaniformis Hay and Mohler 1967, Heliolithus cantabriae Perch-Nielsen 1971, Heliolithus kleinpellii Sullivan 1964, Heliolithus riedelii Bramlette and Sullivan 1961, Mark- alius inversus (Deflandre and Fert 1954), Micrantholithus flos Deflandre 1954, Neochiastozygus chiastus (Bramlette and Sullivan 1961), Neochiastozygus distensus (Bramlette and Sullivan 1961), Neochiastozygus junctus (Bramlette and Sullivan 1961), Neocrepidolithus biskayae Perch-Nielsen 1981, Prinsius bisulcus (Stradner 1963), Rhabdolithus tenuis Bramlette and Sullivan 1961, Scapholithus rhombiformis Hay and Mohler 1967, Sphenolithus primus Perch-Nielsen 1971, Thoracosphaera saxea Stradner 1961, Thoracosphaera opercu- lata Bramlette and Martini 1964, Zygodiscus herlynii Sullivan 1964 dominate the nannofossil assemblages. The presence of all these marker species such as H. riedelii, H. cantabriae, N. chiastus, N. distensus, N. junctus, N. biskayae, P bisulcus in sample KIRK.51 indicates NP 8 calcareous nannoplankton zone (Pierce-Nielsen 1985). Sample KIRK.53 with a diverse planktonic foraminiferal association, represented by Acarinina mckannai (White 1928), Acarinina nitida (Martin 1943), Acarinina primitiva (Finlay 1947), Morozovella aequa (Bolli 1957), Morozovella angulata (White 1928), Morozovella velascoensis (Cushman 1925), Planorotalites pseudomenardii (Bolli 1957). Planorotalites chapmani (Parr 1938), Globigerina velascoensis Cushman 1925 and Globigerina triloculinoides Plummer 1926 suggests P 4 planktonic foraminifera zone (Toumarkine and Luterbacher 1985).

SYSTEMATICS

This work is completely based on the thin sectioning of individ- ual specimens in equatorial and partly vertical sections. In addition, some sections illustrating only the pillar-lateral chamberlet architecture have also been prepared. The majority of the specimens are megalospheric and only a few microspheric specimens have been sectioned. Orthophragminid foraminifera were

first classified based on general shape of the test, pillar-lateral chamberlet network and size of the pillars to correlate the relation of outer morphology with the parameters quantitatively and qualitatively measured and observed in equatorial sections. For the quantitative description of embryo and other features related with the equatorial layer, the parameters; P1 and P2 (diameter of protoconch perpendicular and parallel to P-D axis), Dl and D2 (diameter of deuteroconch perpendicular and parallel to P-D axis), A (number of auxiliary chamberlets directly arising from the deuteroconch; adauxiliary chamberlets), nO.5 (number of annuli within 0.5mm wide stripe measured from the rim of deuteroconch along P-D axis, H and W (height and width of the equatorial chamberlets in the first annulus), h and w (height and width of the equatorial chamberlets around the peripheral part of the equatorial layer), have been measured or counted (text-fig. 2; table 3). The parameter dmean in the text corresponds to the average value of Dl. We use the terminology adopted by Less (1987) to explain different embryo types, which concerns the relation of protoconch and deuteroconch.

Most of the specimens in the succession are represented by rela- tively small, thin and flat discoid forms which are very abundant in some horizons. Up in the succession below cliff-forming massive limestone, these specimens are associated with small-sized specimens with inflated central part having comparatively coarser pillars in their elevated central part. These specimens are comparatively rare and constitute a small portion of all orthophragminid foraminifera in a population.

Order FORAMINIFERIDA Eichwald 1830 Family ORBITOCLYPEIDAE Bronnimann 1946 Genus Orbitoclypeus Silvestri 1907

Orbitoclypeus haymanaensis Ozcan, Sirel, Altiner and (Colakoglu, n. sp. Plate 1, figures 1-13; text figure 3A

Etymology: Named after the Haymana-Polati Basin, the region including the type locality.

Holotype: Specimen KAR.8-9, plate 1, figures 1-2; text-figure 3A.

Paratypes: Specimens illustrated in plate 1, figures 3-13.

Type locality: North of Karahamzali village (south of Polatli, Ankara, central Anatolia).

Type level: Thanetian. In the stratigraphic horizons intercalated with Glomalveolina primaeva- bearing beds, possibly SB Zone 3. In Kirkkavak (KIRK) section, Orbitoclypeus haymanaensis n. sp. is identified only in the upper levels of shallow-water part of Kirkkavak Formation below the cliff-forming massive limestone horizon.

Diagnosis: Small-sized forms (less than 3mm) with inflated central part comprising coarse pillars. Embryonic chambers, which are large, are of trybliolepidine-umbilicolepidine and excentrilepidine configuration in equatorial sections. First annulus has 17-33, commonly more than 20, adauxiliary chamberlets. High equatorial chamberlets, which are arranged in irregular annuli rapidly growing towards the edges, are very diagnostic.

344


TABLE 2 Distribution of orthophragminae, other benthonic and planktonic taxa (planktonic foraminifera and calcareous nannofossils) in Kirkkavak section. Numbers on the right of column refer to the sample numbers and asterisk indicate the horizons studied for orthophragminae. See figure 1 for the symbols.

Description

External morphology: Test is small, usually less than 3mm in diameter, inflated to strongly inflated and lenticular in shape (pl. 1, figs. 9-10 ). Sub-circular to circular pillars are coarser in the elevated central part of the test than those in the peripheral part and may be as thick as 150pm in diameter. Peripheral pillars are comparatively small and even indistinct. Pillars in the most central part are usually surrounded by 8-12 lateral chamberlets, whereas, those adjoining ones are surrounded by usually 4-5 open lateral chamberlets having straight walls (pl. 1, fig. 8).

Internal morphology: Megalospheric embryonic apparatus consists of almost spherical protoconch and spherical to sub-spherical deuteroconch (see table 3 and 4 for the measurements of embryo). Considering the relation of protoconch and deuteroconch, three types of configurations have been identified. In some of the specimens, the almost globular deuteroconch encompasses the protoconch with a restricted surface of contact (pl. 1, figs. 1, 4; fig. 3A, KAR. 8-1, 9; KAR. 9-8; KAR. 10-19; KIRK. 34-21; KIRK. 41-1, 15). The protoconch is either embraced by deuteroconch or slightly pushed into the deuteroconch, similar to that of umbilicolepidine configuration of Less (1987). In some of the specimens, both embryonic chambers have no adjoining wall and protoconch is an excentric position (pl. 1, figs. 5-6; fig. 3A, KAR. 9-24, KIRK. 41-10). In

the others, both protoconch and deuteroconch have the trybliolepidine configuration of Less (1987) (pl. 1, fig. 3; fig. 3A, KAR. 9-38, KIRK. 36-22, KIRK. 39-27). Some of these configurations have been observed in the same specimen during successive grinding stages in the equatorial layer. Some specimens revealing umbilicolepidine type configuration at a certain stage of grinding in equatorial layer, for instance, may end up with excentrilepidine configuration of embryonic apparatus with a progressive abrasion in equatorial layer. The equatorial chamberlets are arranged in concentric annuli, almost circular in outline in the central part and highly irregular in the peripheral part of the equatorial layer (pl. 1, fig. 2). The distal parts of equatorial chamberlets in the first and successive annuli are typically arcuate or wedge-like. Chamberlets in the first annulus are numerous and 19-33 chamberlets arising directly from the deuteroconch are observed. Equatorial chamberlets, which are usually 35-50,um high around the embryo, rapidly grow long and may be as high as lOOpm towards the peripheral part of equatorial layer. nO.5 varies between 11 and 18 and is usually less than 15.

In vertical sections, lateral chamberlets having almost flat walls are arranged in regular rows and comprises about 12-17 chamberlets in the central part of the test. Between two pillars, usually one row of lateral chamberlets is observed. The length of the lateral chamberlets varies from 75 to 85pm. The thickness of equatorial layer, which is about 30-40um around the em-

345

E. Ozcan et al: Late Paleocene Orthophragminae from central Turkey: description of Orbitoclypeus haymanaensis n. sp.

TABLE 3 Numeric data for Orthophragminae (see the text for the explanation for abbreviations) in Thanetian section of Haymana- Polatli basin succession.

Orhitoclhpeus neumannae

SAMPLE Test PI P2 Dl 0 A Ns H W NO DIL

KAR.8.2 3030 95 90 150 140 15 22 30 25-35 70-8C

KAR.8.4 - 110 110 165 175 15 - 40 30-40 50

KAR.8.7 2210 85 85 160 165 15 - - - 55

KAR.8.8 3300 120 115 190 165 15-16 18 30-35 20-40 50

KAR..l10 4010 g0 95 160 145 15 19 30 25-40 60

KAR.8.11 2635 125 120 190 155 17-18 17 35 25-35 75

KAR.8.12 3400 120 115 195 160 12 ,18 40-45 40 80

KAR.8.14 2870 145 130 200 185 15 18 30-35 30-40 50

KAR.8.15 3275 11 115 175 155 14 - 30 30-35 55

KAR.8.24 3570 95 95 155 135 13-14 19 30 20-35 55

KAR.8.31 3400 115 110 160 165 14-16 19 30-35 35 55

KAR.8.33 3870 95 95 155 145 14 19 30 25-35 55

K(AR.8.40 3600- 135 130 225 190 16-17 - 30-35 25-35 50-50

KAR.8.43 2820 110 105 175 155 17 18 30 25-30 50-6C

KAR.8.46 2450 105 105 165 145 12-13 - 30 30-35 50-55

KAR.8.50 3650 100 100 170 155 5 - 25-30 25-30 50

KAR.8.52 3100 110 105 185 155 15 16 35 30-40 65-7C

KAR.I.S8 3150 115 110 185 160 14 18 30 30-35

KAR.8.62 2150 85 85 150 125 13 - 30 30-35 55-6C

KAR.8.66 4300 100 100 155 130 13 19 30 25 60-65

KAR.9.2 3200 130 135 220 180 - 14 30-35 30-35

KAR.9.3 3620 120 115 195 180 16 18 25-30 25-30 60

KAR.9.7 3265 95 90 160 135 16 19 35 25-30 55

KAR.9.9 3570 115 110 190 165 - 17 - - 60

KAR.9.10 2700 105 100 175 I35 13-1418 30 30-50 60

KAR.9.14 3570 150 135 225 200 18 15 30-40 25-40 50-75

KAR9.S 15 - 130 130 210 180 19-20 16 30-35 30-35 55-6S

KAR.9.1B 4300 105 105 190 155 - 19 - - 45-50

KAR.9.39 4100 120 120 175 160 14 18 35 30-40 55-65

KAR.9.42 - 110 '00 175 155 - 17 - -

KAR.9.46 4050 95 95 160 140 13 17 25-35 25-40 55-65

KAR.9.49 4460 105 100 190 170 19 35 30-40 50-55

KAR.13.3 - 100 105 185 150

(IRK.36.8 90 85 145 130 11 17

Orbitocl'peus havmanaensis n. sp.

SAMPLE Test PI P2 DI D2 A X.t H

NO [ia.

SAMPLE Test P D

NO Dia.

W

Discocvclina sp. I

NSAPL Ta Pt P2 D1 D2 A N5 H W b w

346

Orhitoclspeus hav-manrensis continued

Discocvclitna seunesi

A N,s H W h

. <

.

b


TABLE 4 Correlation of Population-based numeric data (P1, D 1, A and nO.5) for Orthophragminae (see the text for the explanation for abbreviations). '*' mark indicates the measured value only for one specimen. '?' mark denotes that data is not available.

Sample Orthophragminae Pi- Dj A nO.5 Mean({Mn-Max) Mean(Min-Max) Mean(Min-Max) Mean(Min-Max)

KIRK.21 D.seunesi 146.2(140-150) 253.7(250-260) 17.5(15-20) 13.0 KIRK.25 D.seunesi-O.haymanaensis 142.7(125-175)-115.0*' 255.4(225-350)-220.0* 19.0(15-29)-20' 14.0(12-16)-15* KIRK.27 D.seunesi-O.haymanaensis 153.1(145-165)-170.0' 287.7(250-320)-300.0' 22.8(18-25)-? 13.0(11-15)-? KIRK.28 D.seunesi 145.7(125-175) 270.0(230-345) 20.4(17-23) 13.0(12-14) KIRK.34 D.seunesi-O.haymanaensis 147.8(125-180)-148.3(110-170) 258.5(230-280)-286.6(200-350) 23.0(19-26)-22.5(17-28) 13.2(12-15)-12.0(11-13) KIRK.36 D.seunesi-O.haymanaensis 166.0(150-200)-164.3(110-215) 292.5(255-325)-292.5(185-375) 22.6(18-26)-24.8(19-33) 15.3(13-20)-14.4(12-18) KIRK.36 O.haymanaensis-O.neumannae 164.3(110-215)-90.0' 292.5(185-375)-145.0' 24.8(19-33)-11 * 14.4(12-18)-17' KIRK.36 D.seunesi-O.neumannae 166.0(150-200)-90.0' 292.5(255-325)-145.0* 22.6(18-26)-11

* 15.3(13-20)-17*

KIRK.39 D.seunesi-O.haymanaensis 122.5(100-145)-135.0(105-205) 207.5(170-245)-226.0( 160-345) 15.0'-20.8(18-29) 16.5(15-18)-16.0(14-18) KIRK.41 O.haymanaensis , 149.6(135-200) 269.0(215-355) 25.7(20-31) 13.5(11-16) KAR.5 D.seunesi-O.haymanaensis 162.5(150-175)-120.0* 267.5(250-255)-200.0* ?-24.0' 13.5(13-14)-? KAR.8 D.seunesi-O.haymanaensis 171.4(120-205)-161.6(140-175) 280.7(220-335)-280.0(260-310) 22.5(18-281-24.3(23-26) 13.3(11-19)-12.6(11-15) KAR.8 D.seunesi-O.neumannae 171.4(120-205)-108.5(85-145) 280.7(220-335)-183.4(150-225) 22.5118-28)-14.8(12-18) 13.3(11-19)-18.4(16-22) KAR.8 O.haymanaensis-O.neumannae 161.6(140-175)-108.5(85-145) 280.0(260-310)-183.4(150-225) 24.3(23-26)-14.8(12-18) 12.6(11-15)-18.4~16-22) KAR.9 D.seunesi-O.haymanaensis 175.8(150-205)-142.0(105-170) 302.5(280-340)-247.9(210-325) 20.6(17-23)-23.1(19-33) 13.0(131-13.1(11-17) KAR.9 D.seunesi-O.neumannae 175.8(150-205)-115.0(95-150) 302.5(280-340)-188.7(160-225) 20.6(17-23)-15.8(13-20) 13.0(13)-17.2(14-19) KAR.9 O.haymanaensis-O.neumannae 142.0(105-170)-115.0(95-150) 247.9(210-325)-188.7(160-225) 23.1(19-33)-15.8(13-20) 13.111 -17)-17.2(14-19) KAR.10 O.haymanaensis 153.7(145-170) 290.0(275-300) 24.3(23-26) 12.0 12) KAR.13 O.haymanaensis-O.neumannae 147.5(120-175)-100.0' 255.0(225-285)-185.0' 23.0*-? 12.0*-? KAR. 15 O.haymanaensis 142.5(125-160) 267.5(250-285) 28.5(25-32) 11.0' KARS.2 D.seunesi 157.5(135-175) 260.8(215-295) 14.5(12-17) ? 'KARS.13 D.seunesi 147.8(120-170) 247.1(225-270) 19.7(19-21) ?

bryo, increases remarkably towards the peripheral part of the test and varies from 75 to 85pm. The annular walls which are convex outwards in the early stage are distinctly flat in the peripheral part (pl. 1, fig. 11) and annular chamberlets look rectangular in shape.

Remarks and Comparisons: Orbitoclypeus haymanaensis n. sp. differs from 0. ramaraoi and 0. neumannae in having a larger embryonic apparatus, having a larger number of equatorial chamberlets arising from deuteroconch and also in having a different configuration of embryonic chambers. Embryo of 0. haymanaensis n. sp. is characterized by a deuteroconch measur- ing from 160 to 375pm and that of 0. neumannae from 145 to 225pm (table 3 and 4). 0. ramaraoi and 0. neumannae have nephrolepidine and eulepidine type embryonic chambers respectively, whereas, in 0. haymanaensis n sp., embryo presents trybliolepidine-umbilicolepidine and excentrilepidine configurations. The number of adauxiliary chamberlets (A) in the new species is usually more than 20, being 33 at most, which is much greater than that of 0. ramaraoi. 0. ramaraoi on average has about 15 adauxiliary chamberlets. Considering foraminiferal association of Alveolina and Nummulites species reported by Toumarkine (1967) in type locality and other Orbitoclypeus species and Asterocyclina in Spilecco population (Less 1987 and 1998), it is evident that 0. neumannae has a younger stratigraphic position (SB Zone 7) than new species. Orbitoclypeus haymanaensis n. sp. differs from D. seunesi in having an embryo which presents mostly excentrilepidine configuration. Embryonic configuration in D. seunesi is invariably eulepidine-trybliolepidine type. Unlike D. seunesi, the new species has equatorial chamberlets which throughout the ontogeny are arcuate or wedge-like in their distal part and equatorial chamberlets rapidly grow at the peripheral part of the equatorial layer. In D. seunesi, increase in the height of the equatorial chamberlets is progressive and cycles in the peripheral part of equatorial layer is more regular and circular in shape. However, a confusion still may rise in equatorial sections in the distinction of both species when only the embryonic features of those specimens which are not strictly excentrilepidine are compared without considering the development of chamberlets in succes-

sive annuli and outer test morphology. As for the outer morphology, 0. haymanaensis n. sp. differs from D. seunesi and 0. neumannae by having a smaller and inflated test which possesses centrally located large pillars. This new species has some peculiar similarities to 0. schopeni suvlukayensis known from Ilerdian (Less 1987 and 1998). This species with an excentrilepidine embryo ranging from 240 to 300pm in diameter has a younger stratigraphic position (SB Zone 8).

Orbitoclypeus neumannae (Toumarkine) 1967 Plate 1, figures 14-16; plate 2, figures 1-8; text figure 3C

Discocyclina neumannae TOUMARKINE 1967, p. 210-212, PI. 1, figs. 1-8

Orbitoclypeus ramaraoi (Samanta) 1967 subsp. neumannae (Tou- markine). - LESS 1987, p. 198-199, P1.XXVI, figs.1-2, text fig. 30c

External morphology: Test is small, usually less than 4mm in diameter, flat and slightly inflated in the central part. Conical or strongly inflated forms have not been encountered. Pillars are sub-circular to circular, evenly distributed over the test surface and are slightly coarser above the embryo. Pillars in the most central part are usually surrounded by 10-15 and the others by 5-7 lateral chamberlets. The walls of the lateral chamberlets around the pillars are not straight, and look slightly undulose forming comparatively a dense network of lateral chamberlets.

Internal morphology: Bilocular megalospheric embryonic apparatus is conspicuously small and in most of the specimens, the relation of protoconch and almost sub-spherical deuteroconch is of eulepidine configuration (see tables 3 and 4 for the measurements of embryo). In a few specimens, deuteroconch encompasses almost half or 2/3 of the protoconch (fig. 3C, KAR.8-14). The first annulus in the majority of specimens is complete. In incomplete configuration, a complete cycle is observed commonly in the second (fig. 3C, KAR.8-15, 52, KAR.9-39) and occasionally in the third annulus (fig. 3C, KAR.8-14). The number of adauxiliary chamberlets varies from 11 to 19, 20(?) and is generally less than 17. The chamberlets in the first and successive annuli are conspicuously low, with the height of the majority of specimens varying between 25-35pm. The distal parts of these chamberlets in the early ontogenetic part are arcuate or

347


typically wedge-like and are either square in shape or tangentially elongated. nO.5 varies from 14 to 22 and is usually more than 16. The low chamberlets, which have almost the same shape throughout the early part are followed by rectangular peripheral chamberlets which are about two times higher than those near the center (pl. 1, fig. 15; pl. 2, figs. 1-4). These chamberlets may be as high as 70-80pm. Annuli in peripheral part are not circular in outline and irregular annuli with high chamberlets follow regular early cycles. The sudden and remarkable difference in the height of the central and peripheral equatorial chamberlets and corresponding irregularity in the development of annuli are very characteristic features observed in all specimens.

In vertical sections, lateral chamberlets having slightly curved walls of 10- 15pm in thickness, are arranged in regular rows and comprise about 13-16 chamberlets in the central part of the test. The length of the lateral chamberlets varies from 40 to 55pm. The thickness of equatorial layer including the wall, which is about 40-50pm around the embryo, increases remarkably towards the peripheral part of the test and varies between 75-95pm. The annular walls are slightly convex outwards throughout the ontogeny. Pillars, which are 35-60pm in diameter, are coarser in the central part of the test.

Remarks and comparisons: Orbitoclypeus ramaraoi (Samanta) originally described from late Paleocene (?) marine succession of southern India (Samanta 1967), is the only Orbitoclypeus species considered to be late Paleocene in age (Less 1998). This species possesses a small embryonic apparatus with mostly nephrolepidine and partly eulepidine type configuration of protoconch and deuteroconch. In type-material, it is reported to be associated with Ranikothalia sp., Operculina sp., Opercu- linoides sp., Miscellanea ? sp. and Morozovella (Globorotalia) velascoensis. The diameter of spherical protoconch was reported to vary from 70 to 150,um and that of kidney-shaped deuteroconch from 100 to 224pm. The majority of the specimens are characterized by a maximum diameter of deutero-

conch ranging from 150 to 174um. The number of chamberlets in the first annulus, which were reported to be spatulate or square and mostly tangentially elongate near the embryo and ra- dially much elongated towards the periphery, is about 14 to 21. Regular lateral chamberlets are wide and open. Less (1998) introduced biometric aspects of 0. ramaraoi, which are based on only a few specimens, in Mediterranean Paleocene from Pyre- nees (BOUSM, RUBEC and NTSOR populations with dmean=170, 184.5 and 192.5pm respectively). Less (1998) attributed these specimens to 0. schopeni ramaraoi in shallow benthic zones 3 to 6 (table 1) and proposed dmean <195pm for the identification of this taxon.

Orbitoclypeus neumannae (Toumarkine) originally described from Ilerdian, (possibly corresponding to SB zone-7 in Less 1998 and Serra-Kiel et al.,1998) of Mont-Cayla of France has small, almost invariably eulepidine ('eudiscodina') type embryonic configuration. Diameter of almost spherical deuteroconch was reported to vary from 150 to 300gm and that of spherical protoconch from 80 to 170}pm. The majority of the specimens have a diameter of deuteroconch varying from 170 to 200pm (Toumarkine 1967). The height of equatorial chamberlets, which are low in the first annuli (30-50pm), increases with ontogeny and may be as high as 50-100pm in the peripheral part. Other than type-material, biometric aspects of 0. neumannae is known only from the Spilecco population which also consists of other species of Orbitoclypeus and Asterocyclina taramellii (Less 1987 and 1998). 0. neumannae in this population has semi-nephro, eulepidine and excentrilepidine embryo configurations and their biometric features (with deuterococh diameter varying from 170 to 290um and dmean=219.31pm) indicate that these specimens have a larger embryo and possibly represent a further stage of this species in his 0. schopeni lineage. Less (1987) proposed dmean=165-220pm and dmean=195-240pm (Less 1998) for the practical identification of this species under the names Orbitoclypeus ramaraoi neumannae and Orbito- clypeus schopeni neumannae.

PLATE 1 Orbitoclypeus haymanaensis n. sp.

1 equatorial section, sample KAR.8-9, x71


3 equatorial section, sample KIRK.41-24, x71





8 Pillar- lateral chamberlet network after slight abrasion of the test, sample KIRK.36-5, x26

9 external view, sample KAR. 10-17, x 11

10 external view, sample KIRK.39, x l I

11 vertical section, KAR.10-18, x26

12 vertical section, KAR.9-40, x26

13 vertical section, KAR. 10-18, x71

Orbitoclypeus neumannae (Toumarkine)



16 equatorial section, sample KAR.8-43,, x18

348

E. Ozcan et al.

1

3

11

7 6

5 g?'I M- M n..w . .' a; .: . ?. -. s? S ....

.:: :

:.

:U.. ::

13

10

14

12

15

micropaleontology, vol. 47, no. 4, 2001

Plate I

349


Although the specimens in samples KAR.8, KAR.9, KAR.13 and KIRK.36 have an older stratigraphic position than 0. neumannae, they are thought to have a close relationship. These specimens are assigned to 0. neumannae considering the rea- sons documented as follows:

Embryo configuration of studied specimens, which are eulepidine, is different than that of 0. ramaraoi, which are mostly of nephrolepidine type. Although Less (1987) considered that 0. neumannae from Spilecco population has semi- nephro, eulepidine and excentrilepidine embryo, 0. neumannae from the type material was described to have an invariably eulepidine type configuration . Moreover, it is not certain that Spilecco specimens have the same stratigraphic position with 0. neumannae from Mont-Cayla.

Although, a considerable overlap is observed in the diameter of protoconch and deuteroconch of both species, 0. neumannae, on average, has a larger deuteroconch than 0. ramaraoi. Samanta (1967) reported 0 ramaraoi specimens with the diameter of deuteroconch as small as 100lm. Diameter of deuteroconch in samples KAR.8 and KAR.9, which varies from 150 to 225pm and from 160 to 225pm respectively, is larger than that of 0. ramaraoi (table 4) and fall within the given diameter range of 0. neumannae from Mont-Cayla population.

In 0. ramaraoi, the height of equatorial chamberlets increases gradually with ontogenesis and annuli with high chamberlets in the peripheral part of the test is regular in outline. However, in 0. neumannae, the increase is not gradual and high peripheral chamberlets in irregular annuli follows the low equatorial chamberlets after a certain stage in the development. The development of annuli in our specimens is very similar to that of 0. neumannae.

In vertical sections, lateral chamberlets of 0. ramaraoi is more open and rectangular with usually one row between two pillars. Our specimens closely resemble 0. neumannae in having com-

paratively low chamberlets forming a denser network of lateral chamberlets.

Family DISCOCYCLINIDAE Galloway 1928 Genus Discocyclina Gumbel 1870

Discocyclina seunesi Douville 1922 Plate 2, figures 9-14; plate 3, figures 1-6; text figure 3B

Discocyclina seunesi DOUVILLE 1922, p. 64-65, pl. 4, figs. 1-4, text fig. 1, 6, 15. - NEUMANN 1958, p. 109-110, pl. XXIII, figs. 1-7, pl. XXV. figs. 1-2, text fig. 34

Orbitoclypeus seunesi (Douville). - LESS 1987, p. 194-196, text fig. 30a

External morphology: Test is small, usually less than 5mm in diameter, flat and slightly inflated in the central part (pl. 2, figs. 13-14). Sub-circular to circular pillars, which may be slightly coarser in the central part of the test, are regularly distributed over the test surface and may be as thick as 80- 100pm in diameter. Pillars in the most central part are usually surrounded by 8-15 lateral chamberlets, whereas, those adjoining ones are surrounded by usually 4-5 lateral chamberlets having straight walls.

Internal morphology: Megalospheric embryonic apparatus consists of almost spherical protoconch and spherical to sub- spherical deuteroconch (see table 3 and 4 for the measurements of embryo). The relation of protoconch and deuteroconch is invariably of eulepidine and occasionally very close to trybliolepidine configuration. The equatorial chamberlets are arranged in concentric annuli, almost circular in outline. The distal parts of equatorial chamberlets in the first and occasionally several successive annuli are slightly arcuate (pl. 2, figs. 9, 11-12). This feature is not observed in the following annuli which have typi- cal rectangular chamberlets. The chamberlets of the first cycle, on average, are 35-50pm in height and in the majority of the specimens, these chamberlets are higher than those of second annulus (pl. 2, figs. 9, 12; pl. 3, figs. 4-6). nO.5 varies between

PLATE 2 Orbitoclypeus neumannae (Toumarkine)






7 vertical section, sample KAR.8-55, x26

8 vertical section, Lower half of the specimen cut to ob- serve the embryonal features during sectioning, sample KAR.8-67, x26


Discocyclina seunesi Douville





13 vertical section, sample KIRK.21-7, x26

14 external view, KARS. 13, x 11

350

E. Ozcan et al.

1 2 3

.. .. .. .. 5

7

6

8

14

11 12 13


10

Plate 2

:..

.~

.4 " .

. ...

351


11 and 20 and is usually less than 15. The increase in the height of equatorial chamberlets is progressive and a remarkable size difference between the early and late chamberlets is not observed.

In vertical sections, lateral chamberlets having flat slightly curved walls are arranged in regular rows and comprise about 12-18 chamberlets in the central part of the test. The length of the lateral chamberlets varies from 45 to 55pm. The thickness of equatorial layer, which is about 40-45pm around the embryo, increases towards the peripheral part of the test and varies from 65-75pm. The annular walls are slightly convex outwards throughout the ontogeny.

Remarks and comparisons: Discocyclina seunesi erected by Douville (1922) has long been regarded as the only representa- tive of orthophragminae in Paleocene. This species was erected for the Discocyclina specimens having a small and thin lenticular test usually with a well defined umbo and pillars regularly and closely distributed on the surface of the test. Illustration of this species in equatorial section (Douville 1922; tf. 1) reveals an embryo almost in eulepidine-trybliolepidine configuration of Less (1987) with 16-17 equatorial chamberlets arising from deuteroconch. The slightly arcuate nature of the distal parts of these chamberlets can also be deduced from the figure. The di- mension of protoconch and deuteroconch in the original illustration, which most likely has an incorrect enlargement, is measured to be about 250 and 500pm respectively.

Neumann (1958) illustrated a few megalospheric embryos of D. seunesi from her own material and from the type material of Douville's collection. Equatorial sections illustrated by this au-

thor also reveals eulepidine-trybliolepidine type embryo. The diameter of the protoconch and the deuteroconch were reported to be 240 and 400pm on average respectively. Diameter of the protoconch and the deuteroconch of type equatorial section illustrated by Douville (1922) was reported to be 240 and 440pm respectively. This author reported 23-24 chamberlets around the embryo. Importance of thickening of equatorial layer towards the periphery in vertical sections was noted by Neumann (1958).

Less (1987) attributed all late Paleocene orthophragminid foraminifera to Orbitoclypeus seunesi and gave some measurements of embryo based on bibliographic data. The embryo was described as being of eulepidine-trybliolepidine configuration with the diameter of protoconch varying from 100 to 225pum (with a population average of 110-160pm) and deuteroconch from 190 to 300pm (with a population average of 200-270pm) respectively. The author reported 18-21 chamberlets arising from deuteroconch (adauxiliary chambers of Less 1987) and indicated that their external walls are not straight but arcuate or wedge-like (type varians of Less 1987). Less (1998) later trans- ferred seunesi specimens to Discocyclina in generic level and reported the existence of Orbitoclypeus in Mediterranean Paleocene and thus, extended the stratigraphic range of Orbito- clypeus (Orbitoclypeus schopeni ramaraoi of Less 1998) down into Paleocene (Less 1998). This author (in Serra-Kiel et al. 1998) also reported a new population of Discocyclina above D. seunesi in Early Thanetian (SBZ-4) and Early Ilerdian beds (SBZ-5-7) that he had previously attributed to D. archiaci in Less (1987). Less (1998) ascribed these populations to Discocyclina tenuis which was originally introduced from

PLATE 3

1-6 Discocyclina seunesi Douville, equatorial section: 1, sample KARS.2-6. 2, KIRK.25-22. 3, sample KIRK.25-24. 4, sample KIRK.34-11. 5, sample KIRK.36-22. 6, sample KAR.8-17, x71.

7-8 Discocyclina sp.1, equatorial section: 7, sample KIRK.25-10. 8, sample KIRK.25-12, x71.

9

10

Acarinina mckannii (White), sample KIRK.53, x62.

Globigerina triloculinoides Plummer, sample KIRK.53, x62.

11 Morozovella aequa (Cushman and Renz), sample KIRK.51, x62.

12 Morozovella aequa (Cushman and Renz), sample KIRK.53, x62.

13 Morozovella angulata (White), sample KIRK.51 ,x62.

14 Acarinina mckannii (White), sample KIRK.50,x62.

15 Micrantholithus flos Deflandre, sample KIRK.51, x2150.

16 Neochiastozygus chiastius (Bramlette and Sullivan), sample KIRK.51, x2150.

17 Neochiastozygus junctus (Bramlette and Sullivan), sample KIRK.51, x2150.

18 Neochiastozygus distensus (Bramlette and Sullivan), sample KIRK.51, x2150.

19 Ericsonia cava (Hay and Mohler), sample KIRK.51, x2150.

20 Fasciculithus tympaniformis (Bramlette and Sullivan), sample KIRK.51, x2400.

21 Fasciculithus thomasii (Perch-Nielsen), sample KIRK.51, x2150.

22 Scapholithus rhombiformis (Hay and Mohler), sample KIRK.51, x2150.

23 Rhabdolithus tenuis (Bramlette and Sullivan), sample KIRK.51, x2150.

352

E. Ozcan et al.

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353


Spilecco (Italy), without any illustration of embryo. Less (1998) introduced D. seunesi seunesi from the early Thanetian beds of France and Bulgaria (from the lower part of SBZ-3) for D. seunesi populations with dmean <260um and erected D. seunesi n. spp. Beloslav from the upper horizons (upper part of SBZ-3) for D. seunesi with dmean >260pm. He redefined his D. tenuis populations as D. tenuis n. ssp. Ruisseau de Bec with dmean <360pm in late Thanetian (SBZ-4) and early Ilerdian (SBZ-5-6) and D. tenuis tenuis in Ilerdian (SBZ-7). Thus, He defined D. seunesi seunesi, D. seunesi n. ssp. Beloslav and D. tenuis n. ssp. Ruisseau de Bec as three successive Discocyclina species in Paleoene (SBZ-3-4). Last two subspecies have not yet been figured.

In spite of poor information given for the initial part of D. seunesi in the original description, discocyclinid specimens in the studied material have been attributed to D. seunesi considering the following points:

All discocyclinid specimens in our material present almost the same embryonic configuration, that is, invariably eulepidine- trybliolepidine type configuration as illustrated in original drawing of embryo in type equatorial section. However, a few specimens with trybliolepidine embryo and having comparatively high chamberlets in the first cycle were attributed to Discocyclina sp.1.

The measurements of both protoconch and deuteroconch in our material (Plmean: 122.5- 166.0pm; Dlmean: 207.5- 302.5pm) are not even comparable with those presented either by Neumann (1958) (P, D: 240 and 400,m on average respectively) or the measurements calculated from the original figure (P, D: 250 and 500pm). This is most probably due to the incorrect enlargement of the equatorial sections and must not be in- ferred as the dimensions of embryo. Although a general increase in section KIRK is observed in the mean diameter of deuteroconch, a distinction between D. seunesi seunesi and D. seunesi Beloslav (Less 1998) can not be made.

Although embryonic configuration of both is very similar, D. seunesi is differentiated from 0. neumannae in having a larger embryonic apparatus which is followed by low, arcuate to wedge- like equatorial chamberlets rapidly growing at the periphery of the equatorial layer in 0. neumannae. In addition, some equatorial chamberlets in the early part of 0. neumannae, unlike D. seunesi, are more elongated in annular direction. D. seunesi is differentiated from 0. haymanaensis in having a smaller embryo which only presents transitional embryo configurations between eulepidine and trybliolepidine types. In 0. haymanaensis protoconch is more embraced by the deuteroconch and embryo is usually of umbilicolepidine and excentrilepidine type.

Discocyclina sp. 1 Plate 3, figures 7-8; text figure 3B

A few specimens having similar test morphology with D. seunesi revealed a comparatively larger embryo in which adauxiliary chamberlets are conspicuously high (see table 3 for the measurements of embryo). First cycle may be as high as 70-75pm and there is a pronounced size difference between the chamberlets of first annulus and following ones (text-fig. 3B, KIRK.25-10,12 and 26). In these specimens protoconch is more encompassed by deuteroconch as in the trybliolepidine configuration of Less (1987). These specimens encountered in association with D. seunesi in the lower part of succession were provisionally attributed to Discocyclina sp.1.

CONCLUSIONS

Several shallow- marine localities, formerly proposed as reference- sections for Thanetian in central Anatolia, consist of both orbitoclypeid and discocyclinid genera. Orthophragminae, spa- tially associated with Glomalveolina primaeva, Operculina heberti and Assilina yvettae in the measured sections, is represented mostly by Discocyclina seunesi in the lower part of the sequence. In these populations, several specimens with similar morphological features but with comparatively high chamber-

PLATE 4

14 Assilina yvettae Schaub, 1, axial section, sample KIRK.34-2, x18; 2, axial section, sample KIRK.34-19, x18. 3, equatorial section, sample KIRK.34-17, x18; 4, equatorial section, sample KIRK.34-5, x18.

5-7 Operculina heberti Munier-Chalmas, 5, equatorial section, sample KIRK.36-12, xlO; 6, equatorial section, sample KIRK.36-11, x 18. 7-axial section, sample KIRK.36-16, x18.

8-11 Glomoalveolina primaeva (Reichel), axial section, 8, sample KIRK.5, x26; 9, KARS.24, x26. 10-11, KIRK.5, x26.

12 Glomalveolina sp. slightly off-centered axial section: sample KIRK.5, x26.

13 Glomalveolina cf. levis Hottinger. slightly off- centered axial section, sample KIRK.47,x26.

14 Vania anatolica Sirel and Giinduz, Glomalveolina primaeva (Reichel) and Quinqueloculina sp. sample KARS.24, x18.

15-17 Miscellanea yvettae Leppig. 15, axial section, sample KIRK.39-50, x18; 16, axial section, KIRK.39-40, x18; 17, equatorial section: sample KIRK.39-41, x18.

18 Valvulina ? sp. and Quinqueloculina ? sp. sample KIRK.31, x18.

19-20 Quinqueloculina ? sp. 19, sample KIRK.31, x28; 20, KIRK.45, x26.

21 Coskinolina sp. sample KIRK.5,x26.

354

E. Ozcan et al.

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lets in the first annulus and larger embryo were attributed to Discocyclina sp.l. Both D. seunesi and Discocyclina sp. 1, invariably revealing an eulepidine-trybliolepidine and trybliolepidine type configurations of embryo respectively in equatorial sections possess rectangular chamberlets which are slightly arcuate in their distal part in the first few annuli. Fol- lowing equatorial chamberlets are arranged in comparatively regular and circular annuli in which a progressive, but a slight increase in the height of the chamberlets is observed.

Higher up in the section, two distinct orthophragminid foraminifera, 0. haymanaensis and 0. neumannae, coexist together with D. seunesi. 0. haymanaensis has a large embryo, transitional between trybliolepidine and excentrilepidine configurations, and arcuate to wedge-like high equatorial chamberlets which rapidly grow at late ontogenetic part. These small-sized and inflated specimens with centrally located coarse pillars belong to a new species, Orbitoclypeus haymanaensis, 0. neumannae has an smaller embryo of invariably eulepidine type configuration and low equatorial chamberlets which grow rapidly at the peripheral part of the equatorial layer. 0. neumannae, known only from the Ilerdian in a few Mediter- ranean locality, has conspicuously low, arcuate to wedge- like early equatorial chamberlets, some of which are more elongated in annular direction. The specimens of 0. haymanaensis having small, inflated test with characteristically large pillars in the central part and very thin and even indistinct pillars at the mar- ginal part of the test can be easily differentiated from D. seunesi and 0. neumannae, which have rather thin and lenticular test. Pillars, slightly coarser in the central part of 0. neumannae, are regularly distributed over the surface of the test in both species.

ACKNOWLEDGMENTS

This paper was supported by the Scientific and Technical Coun- cil of Turkey (Project no TUBITAK-YDAB~AG 198Y046). We are indebted to Dr. Gudmumdur Gudmundsson, chairman of Collection and Systematics Department and Curator of Foraminifera and Marine Invertebrates, Icelandic Institute and Museum of Natural History (Iceland), who critically read the first draft of this manuscript and suggested a number of useful changes.

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Manuscript received December 18, 2000 Manuscript accepted August 1, 2001

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