New Paleocene Orbitoidiform era From Punjab Salt Range-Pakistan

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Journal of Foraminiferal Research, v. 32, no. 1, p. 1–21, January 2002

NEW PALEOCENE ORBITOIDIFORM FORAMINIFERA FROM THE PUNJAB SALTRANGE, PAKISTAN

CARLES FERRANDEZ-CANADELL

Dpt. Estratigrafia i Paleontologia, Facultat de Geologia, Universitat de Barcelona, Martı´ Franque`s s/n, 08028-Barcelona, Spain.

ABSTRACT

The orbitoidiform foraminifers from the Paleocene ofthe Pakistan Salt Range, traditionally designated by‘‘ Orbitosiphon’’ or ‘‘ Actinosiphon’’, include two differ-ent genera, both with a concave-convex test shape. Thefirst of these is characterized by a typically orbitoidalgrowth with lateral chamberlet layers on both sides ofthe equatorial layer, and corresponds toLepidocyclina(Polylepidina) punjabensis Davies, the type species of thegenusOrbitosiphon Rao. The second genus, named hereSetia nov. gen., is characterized by orbitoidal chamberletcycles and differentiated dorsal and ventral sides, withlateral chamberlets on the dorsal side and a canal systemresembling that of miogypsinids on the ventral side. Itincludes two species,S. tibetica (Douville 1916) and astratigraphically lower, structurally more simple newspecies,S. primitiva sp. nov. Both genera are found inthe top of the Hangu Formation, the Lockhart Lime-stones, and at the base of Patala Formation from the SaltRange ‘‘Laki Beds’’, which comprise the middle and up-per parts of the Paleocene. The test of the new genusSetia shows a new morphostructural type, resemblingthat of miogypsinids, but with orbitoidal growth. BothSetia and Orbitosiphon became extinct before the arrivalof orthophragminids (Discocyclina and Orbitoclypeus) tothe basin (together with Nummulites, Assilina and Al-veolina), and therefore are never found together with thelatter. The reports of orthophragminids from the Lock-hart Limestones and the lower part of Patala Shales ac-tually correspond to misidentified O. punjabensis or S.tibetica. On the other hand, the American Paleocene ge-nus Actinosiphon cannot be related to either Orbitosi-phon or Setia. Although it is similar to the former, itdiffers in several characters, such as the shape and ar-rangement of equatorial chamberlets and the stolon sys-tem.

INTRODUCTION

The Paleocene foraminiferal fauna of the Salt Range(Punjab, Pakistan) includes a set of orbitoidiform foramin-ifers which have been assigned to a number of genera, in-cluding Lepidorbitoides, Orbitocyclina, Polylepidina, Dis-cocyclina, Orbitosiphon, Actinosiphon and Dictyokathina.Here, a revision of these forms is presented based on ma-terial collected from different locations in the Salt Range.Although very similar in their external appearance, twoforms of differing architecture were recognized. One cor-responds toLepidocyclina (Polylepidina) punjabensis Da-vies 1937, the type species of the genusOrbitosiphon Rao1940. The other form has an architecture that does not cor-

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respond to any known genus, and is assigned to a new one,Setia. The presence of two genera explains the recurrentdescriptions of two forms (A1 and A2, with ‘‘biserial’’ and‘‘quadriserial’’ embryo) found in the literature, often ex-plained as being due to trimorphism.

GEOLOGICAL SETTING

The Salt Range (Fig. 1) is the southernmost edge of theHimalayan foreland fold-and-thrust belt, the result of thecollision of the Indo-Pakistan Plate with the Eurasian Platesince the Paleocene (e.g., Jaume´ and Lillie, 1988). Therange rises up to 1500 m out of the Punjab alluvial plainand is limited, to the north, by the Potwar-Kohat plateau,which separates it from the main Himalayan ranges, and tothe south by the undeformed foreland of the Jhelum plain.The Salt Range thrust is a coherent slab, with at least 20km of southerly displacement (Gee, 1989). Its structure hasbeen strongly influenced by the presence of an evaporiticunit, the Eocambrian Salt Range Formation, up to 1000 mthick (Gee, 1989), which forms the level of dećollement.

In the foreland belt of northern Pakistan, including theSalt Range, four main stratigraphic units have been identi-fied (Khan and others, 1986; Gee, 1989): (1) the igneous-metamorphic Precambrian basement, (2) The EocambrianSalt Range Formation, (3) the ‘‘platform section’’, whichincludes shallow marine sediments from Cambrian to Eo-cene age, with two major unconformities at the base of thePermian and the Paleocene; and (4) the ‘‘molasse section’’,which consists of Miocene to Pleistocene synorogenic mo-lassic sediments of the Rawalpindi and Siwalik groups,reaching thicknesses up to 5000 m.

The Paleogene sediments are represented in the SaltRange by a sequence of mainly shallow-marine sedimentsof Paleocene-Early Eocene age. The stratigraphic sequenceis divided, from bottom to top, into the following units,approved by the Stratigraphic Committee of Pakistan (Gee,1989; Sameeni and Butt, 1996):

(1) Hangu Formation (Dhak Pass beds of Davies and Pin-fold, 1937): sandstone with mudstone and claystone,carbonaceous shale, coal beds, and a few intercalationsof limestone, unconformably lying on the Cambrian toCretaceous basement (Warwick and others, 1995).

(2) Lockhart Limestones (Khairabad Limestone of Gee, inDavies and Pinfold, 1937): shales and nodular lime-stones.

(3) Patala Formation (Patala Shales of Davies and Pinfold,1937): dark-grey, fossiliferous shale interbedded withwhite quartzose sandstone, siltstone, marl, limestone,carbonaceous shale, and with coal beds in the upperpart.

(4) Nammal Formation (Nammal Limestones and Shales ofDavies and Pinfold, 1937): limestones, marls, and shales

2 FERRANDEZ-CANADELL

FIGURE 1. Geological map of the Salt Range and location of Dhak Pass, Nammal Gorge, Makerval, and Dandot village sections.

(5) Sakesar Limestone: massive, cherty limestones.(6) Chor Galy Formation (Bhadrar beds): limestone and

shales, often included in the Sakesar Limestone

The three lowermost units (Hangu Formation, LockhartLimestones and Patala Formation) form the ‘‘Ranikotgroup’’, whereas the three upper units comprise the ‘‘Lakigroup’’.

The Paleogene succession reflects a general deepening se-quence initiated after an approximately 30 million years hi-atus (Warwick and others, 1995) on a paleosurface devel-oped on Paleozoic and Mesozoic beds. The sequence startswith the middle Paleocene shallow marine and deltaic sed-iments of the Hangu Formation that progressively changeinto the shallow-shelf Lockhart Limestone and the Late Pa-leocene shales and limestones of the base of the Patala. Theupper part of the Patala includes carbonaceous shales andcoal beds, reflecting a shallowing of the basin followed, inthe uppermost part of the Patala, which is of early Eoceneage, by a subsequent deepening that continues through theEarly Eocene Nammal Formation and Sakesar Limestone.See Gee (1989) for an overview of the stratigraphy andstructure of the Salt Range.

MATERIALS AND METHODS

After the GEOSAS I Congress, and within the frame ofIGCP Project No. 286,Early Paleogene Benthos, two fieldtrips (1993 and 1995) were carried out in the Salt Range.During these field trips, a stratigraphic framework of thePaleocene-Early Eocene was drawn up and representativesamples were collected. These are now deposited in the Pun-jab University and in the University of Barcelona (Dept. ofStratigraphy and Paleontology). These samples represent arecord of the succession of Paleocene-lower Eocene largerforaminiferal fauna. The succession shows an initial, par-tially endemic fauna, represented by a dominance ofLock-hartia, Daviesina, Miscellanea, Ranikothalia and ‘‘Orbi-tosiphon’’, replaced in the middle part of the Patala For-mation by the subsequent arrival and dominance of westernTethyan genera, such asNummulites, Assilina, Discocycli-na, Orbitoclypeus andAlveolina. The lithostratigraphic andgeneral biostratigraphic (larger foraminifers) framework ofthe area will be published elsewhere.

The samples studied were taken from the Hangu For-mation, Lockhart Limestones and Patala Formation in thePakistan Salt Range. Several sections were sampled alongthe Salt Range. However, the specimens studied come main-ly from the Dhak Pass and Nammal Gorge sections, about7 km apart (Fig. 2). Other specimens shown in the platescome from single samples from the Patala Formation at twoother locations, Dandot Village and Makerval (Fig. 1). Theywere included because of their good state of preservation.

About 350 specimens were studied in oriented thin sec-tions. Due to the concave-convex shape of the test, equa-torial sections are partial, showing the embryo and a fewearly equatorial chamberlet cycles. In equatorial thin sec-tions, eleven embryo parameters (Fig. 3) were measuredfrom about 100 specimens. These eleven measures werethen compared and one,E (largest dimension of the embryothrough its plane of symmetry; Fig. 3), was chosen as themost representative of embryo size. The measurements weremade on drawings (most of them� 300) made from thinsections by means of a projector Leica Pradovit P 2002.

HISTORICAL REVIEW

Douville (1916) described two species of larger foramin-ifers from the upper Paleocene (Davies, 1937) of KampaDzong, Tibet, which he assigned to the genusLepidorbi-toides Silvestri under the new species namesL. tibetica andL. polygonalis. The former was characterized by a concave-convex test of variable size, up to 17 mm in diameter andless than 1 mm in thickness, granulose surface, an equatoriallayer ‘‘thinner than that inOrbitoides’’, and a bilocular em-bryo. The latter species,L. polygonalis, was differentiatedby its larger size, up to 25 mm in diameter, and by the shapeof its equatorial chamberlets, which are more elongated andhexagonal to rectangular in shape. Douville´ regarded thesespecies as transitional forms between the Cretaceous orbi-toidids and the Tertiary orthophragminids.

Davies (1937) studied the larger foraminifers from theSalt Range and found a form which he considered to bevery similar to those described by Douville´ (1916), both inits general appearance and internal measurements, ‘‘asstrongly to suggest identity’’ (Davies, 1937, p. 54). Daviesinterpreted the differences between Tibetan and Salt Range

3PALEOCENE ORBITOIDIFORM FORAMINIFERA FROM PAKISTAN

FIGURE 2. Lithological sections and sample location at Dhak Passand Nammal Gorge. The samples containingOrbitosiphon and Setiaare marked with an square.

specimens as those found between micro- and megalos-pheric forms. However, he proposed a new species for theSalt Range specimens, which he included within the lepi-docyclinids asLepidocyclina (Polylepidina) punjabensis.The specimens figured by Davies (1937, Pl. VII, Figs. 1–8,14, 16, 17, all from the Patala Shales) show two layers oflateral chamberlets and a bilocular embryo followed by asingle first chamber. Davies pointed out the presence of twodifferent forms in this species, which he named ‘‘stout’’ and‘‘thin’’ specimens, and which were said to differ also in the

size of the embryo. He attributed these differences to tri-morphism in the sense of Hofker (1925, 1930, in Daviesand Pinfold, 1937).

Tan Sin Hok (1939) studied a number of specimens fromthe Salt Range (Lockhart Limestones and Patala Formation),and concluded that the megalospheric embryo could be‘‘biserial’’ or ‘‘quadriserial’’ (i.e., followed by either onesingle chamber or by a chamber with two ‘‘auxiliar’’ cham-berlets). He assigned the species to the genusOrbitocyclinaVaughan, asO. punjabensis. This assignment was discussedby Rutten (1940, p. 263, footnote), who considered that sucha variability in the embryo would point to ‘‘a relationshipwith the rather irregular subgenusPolylepidina, and notwith Orbitocyclina or Lepidorbitoides’’. Later, other au-thors also assigned the species described by Davies (1937)to Orbitocyclina (Bronnimann, 1944, though he did ques-tion this assignment; Renz and Ku¨pper, 1947; Hanzawa,1965).

Rao (1940) also questioned the assignment of Davies’species toPolylepidina, because of both the age (the earliestLepidocyclina is of Oligocene age, according to Rao) anddifferences in some structural features, such as the arrange-ment and dimensions of equatorial chamberlets (‘‘homoge-neous’’ and arranged in ‘‘intersecting arcs’’ inL. (P.) pun-jabensis, and ‘‘heterometric’’ and arranged in ‘‘radiatingrows’’ in true Polylepidina (Rao, 1940, p. 414)), and thedimensions and the number of the initial chambers. Rao(1940) proposed a new genus,Orbitosiphon, which in asubsequent study (1944) he characterized in more detail. Heconsidered that the specimens from Tibet described by Dou-ville (1916) and those from the Salt Range described byDavies (1937) belonged to the same species, ‘‘Orbitosiphontibetica’’. Rao (1944) considered this species to be trimor-phic, although he differentiated ‘‘A1’’ and ‘‘A 2’’ megalos-pheric forms not by embryo size (Davies, 1937) but by thetwo kinds of embryo, ‘‘biserial’’ and ‘‘quadriserial’’, as de-scribed by Tan Sin Hok (1939). Following Rao (1944), theforms from Tibet described by Douville´ included micros-pheric and megalospheric A1 forms, whereas those from theSalt Range included megalospheric A1 and A2 forms.

Rao (1944) assigned the TibetanLepidorbitoides poly-gonalis Douville 1916 toDiscocyclina Gumbel on the basisof its ‘‘rectangular to long-hexagonal’’ shape of equatorialchamberlets, and the presence of proximal annular stolons,and of ‘‘inter-septal and inter-mural canals’’.

Rao was the first author to relate these Asian forms tothe American Paleocene genusActinosiphon Vaughan 1929.According to Rao (1944, p. 97),Orbitosiphon was ‘‘an in-termediate form linking the CretaceousLepidorbitoideswith the EoceneActinosiphon’’. Subsequently the AsianOr-bitosiphon has been put in synonymy with the AmericanActinosiphon by most authors, including Cole (in Cushman,1948, p. 358–359), Smout and Haque (1956), Hanzawa(1962, who regarded both forms as having canals), Loeblichand Tappan (1964, 1987), Rajendran and others (1987), andMatsumaru (1991). Only a few authors (Eames, 1952; Wan,1991; Adams, 1987) maintained the genusOrbitosiphon.Finally, a few authors regardedActinosiphon and Orbito-siphon as independent lineages (Adams, 1987; Drooger,1993).

Adams (1987) reinvestigated the types of bothActinosi-


FIGURE 3. The two types of embryo found inSetia and Orbitosiphon, with their ontogeny (left) and the parameters measured (right).Pprotoconch,D deuteroconch,1 chamberlets of the first post-embryonic chamber,2 chamberlets of the second chamber.P1, P2 diameters of theprotoconch,D1, D2 diameters of the deuteroconch,A1, A2 dimensions of the chamberlets of the first chamber,E maximum length of the embryo(� length through its axis of symmetry).

phon andOrbitosiphon and he concluded that they are un-related forms. According to Adams (1987, Table 1), the twogenera differ by several characters, including the relativesize of protoconch and deuteroconch, the number of ‘‘per-yembryonic spires’’, and the type of lateral chamberlets. Ad-ams erected the new family Actinosiphonidae to accom-modate the only species ofActinosiphon he considered tobe valid, A. semmesi Vaughan 1929, whereas he includedOrbitosiphon within the Orbitoididae, including three spe-cies:

(1) O. tibetica (Douville), with lateral chamberlets on bothsides of the test. Following Adams, this species is‘‘based on microspheric specimens seen only in randomsections’’. However the original description includes aclear megalospheric form (Douville´, 1916, Figs. 3a, 3b).

(2) O. punjabensis (Davies), with megalospheric embryoseither ‘‘2-spired’’ or ’’4-spired’’, and lateral chamberletson both sides, and

(3) O. praepunjabensis, a new species, with ‘‘4-spired’’megalospheric embryo and lateral chamberlets on onlyone side.

Adams agreed with Davies (1937) in that the type speci-mens ofL. tibetica are probably microspheric forms ofO.punjabensis, so that the latter were probably a synonym of

the former, but as he considered that final proof to be lackinghe maintained both species. He also stated that ‘‘it is notcertain that the two and four-spired forms are conspecific’’.

The latest revision of these Paleocene forms was under-taken by Matsumaru (1991), who compared the holotypeand topotypes of AmericanActinosiphon semmesi with top-otypes ofL. (P.) punjabensis Davies. He concluded that thethree species ofOrbitosiphon of Adams (1987) were all thesame ‘‘because of the existence of radial stolons in the equa-torial chambers’’ (Matsumaru, 1991, p. 896), and he includ-ed them within the genusActinosiphon as a single species,‘‘ A. tibetica’’.

In sum, the aforementioned authors, in seeking to clarifythe systematics of these larger foraminifers, tended in themain (a) to relate or identify them with other forms, suchas Lepidorbitoides, Orbitocyclina, and Polylepidina; and(b) to unify the different forms into a single genus, relatingthe differences observed to dimorphism or trimorphism.Only Adams (1987) takes into account the presence of lat-eral chamberlets on only one side or on both sides of thetest as a criterion to differentiate species.

The misinterpretation, usually from axial or random thinsections of hard rocks, of these forms as belonging to othergenera, such asDictyokathina Smout orDiscocyclina (e.g.,Butt, 1991; Weiss, 1993), has introduced additional confu-


sion. Such misinterpretations have also had implications forthe biostratigraphical interpretations of the sedimentary se-quences involved.

SYSTEMATICS

Although all specimens have a concavo-convex test shapeand a very similar external appearance, two structurally dif-ferent forms may be identified when studied in thin section.One of these is characterized by a typical orbitoidal test,with arcuate equatorial chamberlets connected by crosswise-oblique stolons, and with lateral chamberlets on both sides.This form corresponds to those described by Davies (1937)asLepidocyclina (Polylepidina) punjabensis, the type spe-cies of Orbitosiphon, and are described here asOrbitosi-phon punjabensis. The second form has an initial orbitoidalgrowth that changes into annular chambers subdivided intorectangular chamberlets. It has lateral chamberlets on onlyone side, the other side containing a canal system similar tothat of Miogypsinoides (De Bock, 1976). This second formcorresponds to those that Douville´ (1916) described as bothLepidorbitoides tibetica andL. polygonalis, and is here as-signed to a new genus, namedSetia.

The embryo ofO. punjabensis is bilocular, and is fol-lowed by a single equatorial ‘‘auxiliary’’ chamberlet. WithinSetia, two species were distinguished based on differencesin the size of the test, in the size and arrangement of theembryo and post-embryonic chamberlets, and on the generaldegree of complexity of the test, mainly the degree of de-velopment of the canal system and the lateral chamberlets.The two species have also a different stratigraphical distri-bution. The stratigraphically later species,Setia tibetica, isfound in the Lockhart Limestones and the base of the PatalaShales, whereas the earlier one,S. primitiva, occurs only inthe Hangu Formation.

Both genera are considered to be endemic in the India-Pakistan-Tibet region, without being related to other orbi-toidiform genera, and in particular to the American Paleo-cene genusActinosiphon Vaughan 1929 (see below for dis-cussion). Their systematic position at family level is uncer-tain. Proposals regarding new families were avoided untilwe have better structural knowledge of microspheric formsand, thus, of possible phylogenetic relationships. The typesare deposited in the Naturhistorisches Museum of Basel(NHMB), Switzerland.

GenusOrbitosiphon Rao 1940Type species:Orbitosiphon punjabensis (Davies, 1937)

Diagnosis. Bilamellar-perforate orbitoidiform test of dis-coidal, concavo-convex shape, with a single layer of equa-torial arcuate chamberlets arranged in concentric annuli, andlateral chamberlets with piles on both sides. Bilocular me-galospheric embryo, followed by a single ‘‘auxiliary’’chamber. Equatorial chamberlets connected by crosswise-oblique stolons. Annular stolons are also present in distalchamberlets. Microspheric forms up to 1.4 times larger thanmegalospheric forms. Microspheric nepiont not known.

Orbitosiphon punjabensis (Davies) 1937 emend.Figures 3, 4; Plate 1, Figs. 1–26.

Lepidocyclina (Polylepidina) punjabensis; Davies, 1937, p.53, pl. 7, figs. 1–8, 14, 16, text.-fig. 3.

Orbitocyclina punjabensis (Davies); Tan Sin Hok, 1939, p.71, pl. 2, figs. 2, 3.

Orbitosiphon tibetica (Douville, 1916) A2 form; Rao, 1944,p. 95–99, fig. 3.

?Orbitocyclina punjabensis (Davies); Bronnimann, 1944, p.18.

Actinosiphon punjabensis (Davies); Cushman, 1948, p. 359.Orbitocyclina? punjabensis (Davies); Hanzawa, 1965, p.

248, pl. 35, fig. 4b.Actinosiphon tibetica (Douville); Loeblich and Tappan,

1987, p. 649, pl. 737, figs.4–7 (reproduction of pl. VII,figs. 7, 8, 14, and 16 in Davies and Pinfold, 1937).

Emended description. The test ofOrbitosiphon punja-bensis, usually between 2.5 and 4.5 mm in diameter butreaching 6.3 mm in microspheric forms, has a circular tosomewhat elliptical outline, and lenticular to more or lesspronounced concavo-convex shape. Megalospheric formshave a bilocular embryo, with a subspherical protoconchand a rounded deuteroconch of slightly larger size, with amaximum length (parameterE, Fig. 3) ranging from 75 to173 �m (Mean� 112, N � 27). The embryo is followedby a first single ‘‘auxiliary’’ chamber on one side of theembryo. This auxiliary chamber has proximal apertures onboth sides, each connecting with one of the two equatorialchamberlets of the second chamber. The following chambersfollow the orbitoidal type of growth, increasing their num-ber of chamberlets until they form a complete annulus, andannular-cyclic growth is attained. The equatorial chamber-lets are connected by crosswise-oblique stolons, which formspiral alignments in two divergent directions (Pl. 1, Figs. 8,21, 23). In the periphery, the chamberlets of the same an-nulus are connected by annular stolons, proximally located(also noted by Davies, 1937, p. 54). The layers of lateralchamberlets may be symmetrical in respect to the equatorialplane or may be more developed on one side of the test,usually the concave side. Only one clear microspheric spec-imen, with a large test of pronounced concavo-convexshape, 6.3 mm in diameter (Pl. 1, Fig. 6), was found in asample from Dandot, but an equatorial section of the initialchambers could not be obtained.

Type specimen. Geological Survey of India, Calcutta,Type No. 15887 (Davies, 1937, p. 53; pl. 7, figs. 1, 2).

Type level. Thanetian.Stratigraphical range. In the Salt Range,Orbitosiphon

punjabensis occurs in the Lockhart Limestones and at thebase of the Patala Formation, usually associated withLock-hartia, Ranikothalia andMiscellanea.

Distribution. Pakistan and probably Tibet.Remarks. In the Salt RangeOrbitosiphon punjabensis

always occurs associated toSetia tibetica. Also Davies(1937, p. 69), after examining Hayden’s Tibetan collectionsin Calcutta, stated that ‘‘Lepidocyclina (Polylepidina) ti-betica’’ and ‘‘ L. (P.) punjabensis’’ occur together in theTibetan upper Ranikot. However,S. tibetica was observedto be dominant onO. punjabensis in all fossiliferous levelswhere they occur in the section of Nammal Gorge, and inall the other sections studied in the Salt Range, includingDandot Village, also studied by Davies (1937).

In the original description ofO. punjabensis, Davies(1937) stated that the usual diameter of the test ranges from


PLATE 11–26: Orbitosiphon punjabensis (Davies, 1937).1–6 External views,1 convex side, Patala Formation, Dandot Village,� 5; 2–3 External view

of specimens broken in subaxial sections; Patala Formation, Nammal Gorge section (sample NG-93506),� 10; 4 external view (� 10), and detail(� 40) of the lateral surface showing lateral chamberlets and pillars; Patala Formation, Nammal Gorge section (sample NG-93506);5 external view,convex side, Patala Formation, Nammal Gorge section (sample NG-93506), x10;6 external dorsal (left) and ventral (right) view of the samespecimen, Patala Formation, Dandot Village,� 5. 7, 25 Equatorial section (� 25) and detail (� 100) of a specimen with two embryos. Patala


FIGURE 4. A Schematic drawing of structural differences betweenOrbitosiphon andSetia in axial section.B different structural types inSetia,with an increase in the complexity of the canal system from left to right. The development of the ‘‘vacuolar’’ canaliferous cavities, which ressemblelateral chamberlets, often makesSetia difficult to differentiate fromOrbitosiphon in axial section.

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Formation, Nammal Gorge section (sample NG-93504),� 25. 8, 9 Equatorial section (� 25) and detail of the embryo (� 100), Patala Formation,Dandot Village.10 Equatorial section showing the shape of equatorial chamberlets, base of Lockhart Limestones, Dhak Pass section (sample DP-93113),� 50. 11, 26Equatorial section, general view (� 12) and detail of the embryo and initial chambers (� 100). Due to the concavo-convexshape the section shows the embryo and equatorial chamberlets in the central part and lateral chamberlets in the periphery, Patala Formation,Nammal Gorge section (sample NG-95125),� 12. 12, 17 Axial section (� 25) and details (� 50 and� 100). Observe the presence of lateralchamberlets on both sides of the equatorial plane, base of Lockhart Limestones, Dhak Pass section (sample DP-93114).13–16Axial sections.13-15 Dhak Pass section, sample DP-95114 (base of Lockhart Limestones),� 25; 16 base of Patala Formation, Nammal Gorge section (sample NG-93504),� 30. 18 Embryo and initial chambers in equatorial section. Lockhart Limestones, Nammal Gorge section (sample NG-95122),� 100.19Embryo and initial chambers in equatorial section. Patala Formation, Nammal Gorge section (sample NG-93504),� 100. 20 Embryo and initialchambers in equatorial section, bottom of Patala Formation, Nammal Gorge section (sample NG-93503),� 100.21 Equatorial section showing thestolon system. Note the presence of annular stolons, Patala Formation, Dandot Village,� 100. 22 Equatorial section. Due to the concave-convexshape of the test the peripheral part cuts the lateral layers showing the lateral chamberlets and the pillars, base of Patala Formation, Nammal Gorgesection (sample NG-93503),� 25. 23 Equatorial section showing the stolon system, Patala Formation, Dandot Village,� 25.24 Embryo and initialchambers in equatorial section, base of Lockhart Limestones, Dhak Pass section (sample DP-95113),� 100.

4 to 7 mm, and that the larger specimen measured 11 mm.The largest specimen ofO. punjabensis found in our sam-ples (the only microspheric form, Pl. 1, Fig. 6) measured6.3 mm in diameter. Microspheric specimens ofS. tibetica,however, are relatively abundant and can reach 20 mm. Itis possible that, in the original description, Davies (1937)mixed the characters of both species,O. punjabensis andS.tibetica, when referring to sizes and external features. Thefive sectioned specimens figured by Davies correspond toO. punjabensis. However, because of to the very similarexternal appearance of these two species, some of the non-sectioned specimens figured by Davies (1937, pl. VII, figs.3–4), could actually correspond toSetia tibetica. The ho-lotype (Davies, 1937, pl. VII, figs.1–2) is most probably atrue O. punjabensis (compare with Pl. 1, Fig. 6). On the

other hand, because Davies (1937, appendix) distinguished‘‘ L. (P.) tibetica’’ from ‘‘ L. (P.) punjabensis’’ in the sam-ples from Tibet, but did not do so in the Salt Range, prob-ably all of his Salt Range specimens belonged toO. pun-jabensis. Davies instead distinguished between ‘‘stout’’ and‘‘thin’’ specimens within ‘‘L. (P.) punjabensis’’. Such aclear bimodal differentiation in this species was not apparentin the specimens studied here, and it is possibly related toontogeny.

Setia gen. nov.Type species:Setia tibetica (Douville, 1916)

Origin of the species name. After Set, the brother andmurderer of Osiris, regarded as personifying the desert andthe dark side of things.


PLATE 21–7, 10–29: Setia tibetica (Douville, 1916);8–9: Discocyclina ranikotensis (Davies, 1937)1–7: External views ofSetia tibetica. 1 ventral side,

Patala Formation, Nammal Gorge section (sample NG-93506),� 5. 2 dorsal side, Patala Formation, Dandot Village,� 5. 3 ventral side, PatalaFormation, Dandot Village,� 7,5. 4 ventral sides, Patala Formation, Nammal Gorge section (sample NG-93506),� 5. 5, 6 ventral sides, PatalaFormation, Dandot Village,� 7.5, and detail of the periphery of the test,� 20. 7 ventral side, Patala Formation, Nammal Gorge section (sample


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NG-93505),� 5. 8–9: Discocyclina ranikotensis (Davies, 1937), Patala Formation, Nammal Gorge section (sample NG-93521),� 5. 10–13Axialsections, Patala Formation, Makerval,� 25 14–21Axial sections, Lockhart Limestones, Dhak Pass section (sample NMS 17), 14–18,� 25; 19–21, �50. 22–29Equatorial sections.22 base of Lockhart Limestones, Dhak Pass section (sample DP-95113),� 100. 23 upper part of LockhartLimestones, Nammal Gorge section (sample NG-95122),� 50. 24 base of Lockhart Limestones, Dhak Pass section (sample DP-95114),� 50. 25Lockhart Limestones, Dhak Pass section (sample NMS-17),� 50.26 Lockhart Limestones, Dhak Pass section (sample NMS-17),� 50.27LockhartLimestones, Dhak Pass section (sample NMS-17),� 100.27 Lockhart Limestones, Dhak Pass (sample NMS-17),� 50.29base of Patala Formation,Nammal Gorge section (sample NG-93505),� 50.

Diagnosis. Bilamellar-perforate test of discoidal, more orless pronounced concavo-convex shape and circular tosomewhat oval outline with lobate margin; with a mainequatorial layer of arcuate to subrectangular chamberlets ar-ranged in concentric annuli. Dorsal and ventral differenti-ated sides, with lateral chamberlets on the dorsal side anda canal system forming a three-dimensional network, some-times with enlarged, ‘‘vacuolar’’ cavities in the ventral side.Piles in both ventral and dorsal side, which produce granulesin the lateral surfaces, arranged in concentric rings. Mega-lospheric forms with bilocular embryo followed either by afirst single ‘‘auxiliar’’ chamber or by a chamber constitutedby two ‘‘auxiliary’’ chamberlets depending on the species,and orbitoidal growth changing progressively into annular-cyclic growth, with annular chambers subdivided into rect-angular chamberlets. Microspheric forms with an initial spi-ral stage. Equatorial chamberlets are connected by three dif-ferent types of communications: those of adjacent annuli bystolons; those of the same annulus, by a distal annular pas-sage; and those of alternate (not adjacent) annuli by radialpassages of the canal system.

Within Setia two species are clearly differentiated by thesize and shape of the embryo:Setia primitiva sp. nov., hasa small, asymmetrical embryo followed by a first single‘‘auxiliary’’ chamber, whereasSetia tibetica (Douville) hasa larger symmetrical bilocular embryo followed by a firstchamber consisting of two ‘‘auxiliary’’ chamberlets.

Setia tibetica (Douville) 1916 emend.Figures 3, 4; Plate 2, Figs. 1–29; Plate 3, Figs. 1–11.

Lepidorbitoides tibetica; Douville, 1916, p. 34, pl. 14, figs1–6.

Lepidorbitoides polygonalis; Douville, 1916, p. 35, pl. 15,figs 1–3.

Lepidocyclina (Polylepidina) tibetica (Douville); Davies,1937, p. 54.

Orbitocyclina punjabensis (Davies); Tan Sin Hok, 1939, p.71–72, pl. 2, fig. 1.

Orbitosiphon punjabensis; Rao, 1940, p. 414–415, fig. 1.Orbitosiphon tibetica (Douville, 1916) A1 form; Rao, 1944,

p. 95–99, text-figs. 1, 2; pl. 1, figs. 2, 3.Discocyclina (Discocyclina) polygonalis (Douville); Rao,

1944, p. 99–100, text-figs. 4, 5; pl. 1, figs. 1, 4.?Orbitocyclina punjabensis (Davies); Bronnimann, 1944, p.

18.Planorbulinella nammalensis; Haque 1956, p. 52, pl. 19,

figs 1–7, 9.Actinosiphon tibetica (Douville); Smout and Haque, 1956,

p. 52, pl. 11, fig. 6.Actinosiphon tibetica (Douville); Hanzawa, 1962, p. 150,

pl. 3, fig. 28.

Orbitocyclina? punjabensis (Davies); Hanzawa, 1965, p.248, pl. 35, fig. 4a.

Orbitosiphon tibetica (Douville); Adams, 1987, p. 310.Orbitosiphon punjabensis (Davies); Adams, 1987, p. 310.Orbitosiphon praepunjabensis; Adams, 1987, p. 310–311,

pl. 4, figs. 7–12.Actinosiphon tibetica (Douville); Loeblich and Tappan,

1987, p. 649, pl. 737, figs. 3, 8 (reproduction of pl. 14,figs. 2b and 3b in Douville´, 1916).

? Actinosiphon sp.; Rajendran and others, 1987, p. 77, fig.2 (the scale is clearly wrong).

Discocyclina ranikotensis Davies; Butt, 1991, pl. 3, fig. g.? Orbitosiphon tibetica (Douville); Wan, 1991, p. 20, pl. 3,

figs. 15, 16.Actinosiphon tibetica (Douville); Matsumaru, 1991, p. 896,

figs. 12–2a, 12–2b, 12–2c, 12–3a, 12–3b.Discocyclina ranikotensis Davies; Weiss, 1993, pl. 1, fig.

3; pl. 4, figs. 5, 6.Dictyokathina simplex Smout; Weiss, 1993, pl. 1, fig. 5; pl.

5, figs. 2, 4.Discocyclina ranikotensis Davies; Akhtar and Butt, 1999,

pl. 2, figs. 1, 2.Actinosiphon tibetica (Douville); Akhtar and Butt, 1999, pl.

4, fig. 2.Actinosiphon tibetica (Douville); Akhtar and Butt, 2000, pl.

3, fig. 12.

Emended description. Test size usually of 2–3 mm indiameter, reaching 4.5 mm in megalospheric forms, andabout 2 cm in microspheric forms. The embryo is bilocular,with a spherical protoconch and a rounded deuteroconch ofsimilar size. The first chamber after the embryo has twoequatorial ‘‘auxiliary’’ chamberlets, one on each side of theembryo in symmetrical arrangement. The first equatorialchamberlets are arcuate, becoming progressively rectangulartowards the periphery of the test. Microspheric forms startwith an initial spiral stage.

Type specimen. Not given by the author of the species,Douville (1916). Rao (1944), who examined the materialstudied by Douville´, refers to two thin sections bearing thenumbers of the Geological Survey of India, Calcutta, No.12,817 (‘‘limestone from top ofOperculina-limestone, Nside of Kam-pa nala’’) and 12819 (‘‘limestone from N. NWof Kam-pa Dzong’’). According to Rao (1944), the formercontains an axial section, and the latter an equatorial sectionof ‘‘ Orbitosiphon tibetica’’. According to Rao’s descrip-tions, these two thin sections correspond most probably tothe Figures 1 and 3 in Douville´ (1916) respectively. Thelocalities given by Rao (1944) of these two thin sectionsalso agree with those given by Douville´ (1916): ‘‘cote norddu ravin de Kampa 1 milles au-dessus du Dzong’’ (for thespecimen in Figure 1), and ‘‘le sommet de la creˆte au


PLATE 31–11: Setia tibetica (Douville, 1916). 11–3 Axial section,1 � 25, and two details,2 � 100, and3 � 150. Lockhart Limestones, Dhak Pass

(sample NMS-17). Note the lateral chamberlets and piles on the dorsal side and the canal system in the ventral side.4–7, 11Equatorial sectionsshowing the structure of the canal system in specimens from Lockhart Limestones, Dhak Pass (sample NMS-17).4 � 60. 5, 6 � 100. 7 � 125.11 � 150. 8 Partially eroded specimen showing the equatorial plane with the septa and the extension of the interlocular cavities, Patala Shales,Dandot Village � 50. 9–10: Slightly oblique equatorial thin section showing the interlocular cavities and their extensions, base of LockhartLimestones, Dhak Pass section (sample DP-95114),9 � 50, 10 � 60. 9 Equatorial thin section, Lockhart Limestones, Dhak Pass section


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(sample NMS-17),� 150. ap annular passage;c connection between canal system and chamber lumen;ex axial extension of the interlocularcavities;ic interlocular cavities;st stolon; tc tubular canals;v extralocular ‘‘vacuolar’’ cavities. White arrows show the direction of growth.

N.N.O. de Kampa Dzong’’ (for the specimen in Figure 3).Consequently, and following the International Code of Zoo-logical Nomenclature, articles 73 and 74, the specimens fig-ured by Douville are syntypes, and one of them is heredesignated as the lectotype, G.S.I. No. 12819, (Douville´,1916, Figs. 3a, 3b), an equatorial section showing the em-bryo.

Type level. Thanetian.Stratigraphical range. In the Salt RangeS. tibetica oc-

curs in the Lockhart Limestones (� Khairabad Limestones)and the base of the Patala Formation, always associated withLokchartia and usually withRanikothalia, Miscellanea andDaviesina. In the original description (Douville´, 1916) S.tibetica was reported from the ‘‘Operculina-limestones’’ inKampa Dzong, Tibet, stratigraphically equivalent to theLockhart Limestones (Davies, 1937, p. 70).

Distribution. Pakistan (Davies, 1937; Rao, 1944; Smoutand Haque, 1956; Hanzawa, 1962; Kureshy, 1984b; Butt,1991; Weiss, 1993; Akhtar and Butt, 1999), and Tibet (Dou-ville, 1916; Wan, 1991). Possibly also in SW India (Rajen-dran and others, 1987), and Central Iran (Bizon and others,1972, not fig.).

Remarks. Douville (1916) differentiated ‘‘Lepidorbito-ides’’ polygonalis from ‘‘ Lepidorbitoides’’ tibetica simplyon the basis of its larger test size and the more elongatedshape of the equatorial chamberlets. Although according toDouville L. polygonalis can reach 25 mm in diameter thereare no consistent criteria to divide the specimens of Douvilleínto two species, and they are grouped here into the singlespeciesS. tibetica. The embryonic apparatus ofS. tibeticacorresponds to the ‘‘quadriserial’’ embryo described by TanSin Hok (1939) and Hanzawa (1962, 1965), the A1-form ofRao (1944), and the ‘‘4-spired’’ embryo described by Ad-ams (1987).

The specimens assigned by Haque (1956, p. 211, Pl. 19,Figs. 1–7, 9) to the new speciesPlanorbulinella namma-lensis are most probably juvenile specimens ofSetia. Theembryo cannot be seen in any of the specimens figured byHaque, nor is there a description by this author. The reas-signment toS. tibetica is thus based on their stratigraphicaloccurrence: Haque only found them in the lower part of theKhairabad Limestone, whereS. tibetica occurs, whereasS.primitiva was only found in the Hangu Formation.

Haque (1956, p. 210) defined another new species,P.khairabadensis. This species was only figured with twospecimens (Haque, 1956, Pl. 19, Figs. 8, 10) in which theinternal characters are not visible. Haque (1956, p. 211) stat-ed that the differences withPlanorbulinella nammalensisconsisted ‘‘in the thicker test, smaller size of the chambersof the annular rings, and in the rough surface of the test’’.In his diagnosis of this species, Haque described the earlierchambers as ‘‘slightly coiled’’. These specimens, found inthe upper part of the Lockhart Limestones, could thus cor-respond to microspheric specimens ofS. tibetica, althoughadditional proof is lacking. Finally, in the same plate fig-uring ‘‘P. nammalensis’’ and ‘‘ P. khairabadensis’’ Haque

(1956, Pl. 19, Fig. 11) figured two specimens to which noreference is made in the explanation of the plate, nor in thetext. One of these specimens (Pl. 19, Fig. 11) shows well-developed lateral chamberlets and most probably belongs toOrbitosiphon punjabensis, whereas the second one (Pl. 19,Fig. 12), though not clear from the photograph, probablybelongs toS. tibetica.

The species ‘‘Orbitosiphon praepunjabensis’’ erected byAdams (1987, p. 310), characterized by possessing ‘‘lateralchamberlets only on one side of the median layer and athickened lateral wall on the other’’, and a ‘‘4-spired’’ em-bryonic apparatus, is a junior synonym ofS. tibetica (Dou-ville).

TheActinosiphon sp. reported from subsurface sedimentsof Kerala (S India) by Rajendran and others (1987) couldbelong toSetia tibetica, however, there are several problemsin its taxonomic assignment. First, the short description islimited to the embryo and the presence of ‘‘well developedlateral chambers’’, with no reference to the test shape andsize. The embryonic apparatus, as described by Rajendranand others (bilocular, with a larger subspherical initial cham-ber followed by a smaller chamber, both ‘‘surrounded by aring of about 8 to 9 periembryonic apparatus’’) could in factbelong to Setia. The ‘‘well developed lateral chambers’’could also have been confused with a complex canal systemincluding developed ‘‘vacuolar’’ spaces. Second, they onlyfigured one specimen, a detail of the embryonic apparatusin a rather subequatorial section, including a scale which isclearly erroneous, as the bilocular embryo would measureonly about 6�m. Third, the sample came from a boreholeat a depth of 454–494 m, which the authors interpret as‘‘early Eocene’’, although this interpretation is not justifiedby the occurrence of any other foraminifer. Consequently,this report must be considered inconclusive awaiting con-firmation.

Setia primitiva sp. nov.Plate 4, Figs. 1–14

Origin of the species name. The nameprimitiva is givenbecause of its smaller size and lower degree of complexitycompared to the type species,S. tibetica.

Holotype. NHMB C 37914, megalospheric form, Pl. 4,Figs. 1c, 2, 10, 11.

Figured paratypes. NHMB C 37915, microspheric form(Pl. 4, Figs. 1a, 3, 6); NHMB C 37916, megalospheric form(Pl. 4, Figs. 1b, 7, 8); NHMB C 37917, megalospheric form(Pl. 4, Figs. 4, 13, 14); NHMB C 37918, megalosphericform (Pl. 4, Figs. 5, 9); NHMB C 37919, megalosphericform (Pl. 4, Fig. 1d).

Type locality. Dhak Pass, Salt Range, Pakistan.Type level. Middle part of the Paleocene.Diagnosis. Small-sized species ofSetia with a bilocular

embryo followed by a single ‘‘auxiliary’’ chamber.Description. The test is discoidal, flat, slightly concavo-

convex in shape and up to 3 mm in diameter and 0.3 mm


PLATE 41–14: Setia primitiva sp. nov. All specimens from Hangu Formation, Dhak Pass section sample DP-95115).1c, 2, 10, 11.-Holotype NHMB-C

37914, megalospheric form.1c, external view,� 12,5;2, equatorial section,� 25; 10, equatorial section,� 100; 11, detail of the embryo,� 200.1a, 3, 6.-Paratype NHMB-C 37915, microspheric form.1a, external view,� 12,5;3, equatorial section,� 25; 6, detail of the initial chambers,�200.1b, 7, 8.-Paratype NHMB-C 37916, megalospheric form.1b, external view,� 12,5;7, equatorial section,� 50; 9, detail of embryo,� 100.


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1d Paratype NHMB-C 37919, megalospheric form, external view,� 12,5.4, 13, 14.- Paratype NHMB-C 37917, megalospheric form,4, equatorialsection,� 25; 13, detail of the embryo,� 200; 14, embryo and initial chambers,� 100. 5, 9 Paratype NHMB-C 37918, megalospheric form.5,equatorial section,� 50; 9, detail of the embryo and initial chambers,� 100. 12 Detail an equatorial section showing the canal system,� 200.

in thickness. No dimorphism was observed, the identifiedmicrospheric specimens were rather small, about 1.6 mm indiameter. The surface of the test has small rounded granules.The megalospheric embryo is bilocular, followed by a sin-gle, kidney-shaped ‘‘auxiliary’’ chamber. Microsphericforms start with a proloculus of 20–25�m in diameter, fol-lowed by a spiral stage of about 8 chambers that changesto orbitoidal and then to annular growth. The equatorialchamberlets are arcuate in equatorial section, connected bycrosswise-oblique stolons but also showing a canal system.Lateral chamberlets, small and few, are only present on thedorsal side of the test; the ventral side has a massive ap-pearance. Piles and granules are present on both sides of thetest.

Comparison. The megalospheric embryo ofS. primitivais very similar in shape to that ofOrbitosiphon punjabensis.The equatorial chamberlets are arcuate to rounded in shapeand do not attain the rectangular shape found in distal cham-berlets ofS. tibetica. This makesS. primitiva quite similarto Orbitosiphon from which it can be differentiated by thepresence of canals in equatorial section and by the absenceof lateral chamberlets on one side of the test in axial section.

Stratigraphical range and distribution. This species hasonly been found in the Hangu Formation (� Dhak Beds) inthe section of Dhak Pass, of middle to late Paleocene age.

Remarks. The presence ofSetia in the Hangu Formationwas reported by Smout and Haque (1956), who gave a strat-igraphical range for ‘‘Actinosiphon tibetica’’ correspondingto the Hangu Formation (‘‘Dhak Pass beds’’), LockhartLimestones and Patala Shales.

DISCUSSION

SHELL ARCHITECTURE OFORBITOSIPHON

The architecture of the test ofOrbitosiphon (Fig. 4; Pl.1, Figs 1–26) is very similar to that of other bilamellar-perforate orbitoidiform genera, such asLepidorbitoides orLepidocyclina. From a bilocular embryo and an initial or-bitoidal stage, the growth becomes progressively annular,with annuli of arcuate equatorial chamberlets Pl. 1, Figs. 17,8, 10, 11, 21–23, 26), and with lateral chamberlets on bothsides (Pl. 1, Figs. 12–17). Equatorial chamberlets are con-nected by crosswise-oblique stolons, and also by proximalannular stolons in the distal annuli (Pl. 1, Figs. 21–23). Themain feature which characterizesOrbitosiphon among or-bitoidiform foraminifers is the concavo-convex shape of thetest, which is more pronounced in larger specimens (Pl. 1,Figs. 5, 6). This feature is not easily explained, since fromthe architectural point of view (arrangement of chamberlets,stolons and apertures) the test is completely symmetricalwith respect to the equatorial plane. In structurally similarforaminiferal groups, such as lepidorbitoids or lepidocyclin-ids, the structural symmetry is associated with a symmet-rical (i.e., lenticular) test.

SHELL ARCHITECTURE OFSETIA

The architecture of the test ofSetia (Figs. 4, 5; Plates 2,3) differs from that of any other known foraminiferal group.The equatorial layer, starting with orbitoidal growth fromthe embryo, is made of arcuate equatorial chamberlets con-nected by crosswise-oblique stolons, which progressivelybecome rectangular chamberlets in annular arrangementconnected by radial stolons. Equatorial chamberlets are alsoconnected to a complex canal system developed only on theventral side, resembling the canal system of miogypsinids.Whereas the ventral side has a massive appearance of su-perposed outer lamellae only crossed by pores and a net-work of canals and ‘‘vacuolar’’ extralocular spaces, the dor-sal side lacks a canal system and is occupied by true lateralchamberlets connected by stolons. Piles develop on the dor-sal side, where they are clearly visible between lateral cham-berlets (Pl. 2, Figs. 10–21). Piles can also be observed onthe ventral side, where they are not so conspicuous becauseof the massive, imperforate structure (without lateral cham-berlets), although they also produce granules on the lateralsurface (Pl. 2, Figs. 2, 11–13, 17, 20).

Three types of canal elements can be differentiated in thetest of Setia all of which are located on the ventral side(Plate 3, Figs. 1–11; Figs. 4, 5):

1.- Interlocular cavities. Located on the lateral walls ofequatorial chamberlets. Interlocular cavities are extralocularspaces formed between equatorial chamberlets (hence theterm interlocular) by the superposition of outer lamellae ofnew chambers on the reliefs of previous equatorial cham-berlets in the ventral side of the test (Fig. 5; Pl. 3, Figs. 2,3, 9). The interlocular cavities extend in axial direction to-wards the equatorial plane, forming a rounded extension lo-cated on the distal wall of the equatorial chamberlets of theprevious annulus. Theseextensions of the interlocular cav-ities (Fig. 5; Pl. 3, Figs. 4, 6, 8–11) are limited to the prox-imal part of the annuli, thus leaving anannular passage inthe distal part of the annuli (Fig. 5; Pl. 3, Figs. 4, 8, 10,11). Interlocular cavities inSetia are similar to those de-scribed in Miogypsinoides as ‘‘intraseptal canal system(ICS)’’ and ‘‘vertical canal system (VCS)’’ by De Bock(1976).

2.- Extralocular ‘‘vacuolar’’ cavities. Located in the lat-eral thickening of the ventral side, extralocular ‘‘vacuolar’’cavities are formed by the local detachment of the involuteouter lamellae, creating an expanded cannaliferous ‘‘vacu-ole’’ (Pl. 2, Figs. 12, 13; Pl. 3, Figs, 1–3). The number, sizeand shape of these extralocular cavities is highly variable inSetia, and may be absent in stratigraphically lower speciesor in smaller megalospheric forms. When they are well-developed, their appearance in axial section ressembles thatof narrow lateral chamberlets.

3.- Tubular canals. Cylindrical cannaliferous passageswhich form a three-dimensional network, connecting the in-terlocular cavities and the extralocular ‘‘vacuolar’’ cavities.


FIGURE 5. Schematic tangential section inSetia showing the dif-ferent structural elements that can be seen in different planes.ap an-nular passage;c connection between canal system and chamber lumen;ex axial extension of the interlocular cavities;ic interlocular cavities;st stolon;v extralocular ‘‘vacuolar’’ cavities.

Tubular canals are either parallel or normal to the equatorialplane (Pl. 2, Figs. 20, 21; Pl. 3, Figs. 1–3).

The connections between the canal system and the cham-ber lumina are stolon-like apertures located in the septa, inthe distal edge of each equatorial chamberlet, connectingwith an extension of the interlocular cavities (Pl. 3, Figs. 7,11). The formation of the canal system starts in the firstchamber after the embryo.

Although Orbitosiphon and Setia have not previouslybeen differentiated, it is clear that some authors describedthis ‘‘vacuolar’’ canal system ofSetia as lateral chamberlets.Thus, when defining the genusOrbitosiphon, Rao (1940,1944) described the ‘‘lateral chambers’’ as ‘‘small and com-pressed’’. Also Smout and Haque (1956, p. 52) stated intheir description of ‘‘Actinosiphon tibetica’’, from NammalGorge that ‘‘the lateral chambers are very compressed andinconspicuous’’.

The canal system ofSetia, constituted by both tubularpassages and enlarged cavities, is different from canal sys-tems in other groups, such as nummulitids, in which thecanal system is constituted exclusively by tubular canals. Itis strikingly similar to the canal system of miogypsinids (seeFigs. 12, 22 and 23 in De Bock, 1976). Canal systems areusually associated with rotaliid tests, characterized by spiralgrowth, with one exception,Droogerinella (Popescu andBrotea, 1995), which lacks lateral chamberlets. Some rota-liid forms with canal systems may change into orbitoidalgrowth (e.g., miogypsinids), or develop lateral chamberletson one side of the test (e.g.,Sirtina, Vanderbeekia, Iranitesand Neumannites; Bronnimann and Wirz, 1962; Rahaghi,1992). The canal system ofSetia is unique because it hasdeveloped in a non-spiral foraminifer. The similarity be-tween the canal systems ofSetia and Miogypsina is prob-ably due to the similar orbitoidal growth of their equatorialchamberlets (i.e., the arrangement of chambers and cham-berlets). The detailed morphostructure ofSetia will be de-scribed in a further paper.

INTERSPECIFICVARIABILITY AND EVOLUTIONARY TRENDS

The study of a succession of samples through the Hangu,Lockhart and Patala formations revealed a clear increase insize of the embryo in bothSetia andOrbitosiphon through-out the Lockhart Limestones and Patala Shales (Figs. 6, 7).The increase in embryo size runs parallel to a general in-crease in test size in bothOrbitosiphon andSetia, and alsoto a general increase in structural complexity in the canalsystem inSetia.

The plot of measurements of the parameterE (maximumdiameter of the embryo, Fig. 6) showed the following re-sults:

(1) The general increase in embryo size is parallel inOr-bitosiphon andSetia.

(2) The general increase in embryo size is obscured by ahigh intraspecific variability, up to 75% in the value ofE in Setia. In this genus the variability seems to belarger than inOrbitosiphon. Although this could be anartifact due to the different number of specimens mea-sured, it could also be due to the larger size and greatercomplexity of the embryo inSetia.

(3) There is a sudden shift in the dimensions of the embryo


FIGURE 6. Plot of measurements of parameterE (maximum diameter of the embryo in equatorial section) in specimens from different samples.Observe the general trend in embryo size increase and the break at the boundary between Lockhart Limestones and Patala Formation. The samplesare ordered stratigraphically, from lower (left) to upper (right), though intervals between samples are not regular (see location of sections andsamples in Figures 1 and 2).


FIGURE 7. Table comparing the embryos of the species studied from different samples from Nammal Gorge and Dhak Pass sections (drawnfrom thin sections by means of a projector Leica Pradovit P 2002). All embryos at the same magnification (x 75).


FIGURE 8. Biostratigraphical distribution ofSetia, Orbitosiphon,Nummulites, Assilina and orthophragminids in the Paleocene-Early Eo-cene of the Salt Range.

of Setia at the boundary between the Hangu Formationand the Lockhart Limestones, that corresponds to thereplacement ofS. primitiva by S. tibetica.

(4) There is a break in the general trend of size increase,coinciding with a hardground that was taken as theboundary between the Lockhart Limestones and the Pa-tala Formation (Figs. 2, 8). The break implies a drop inthe range of dimensions. Thus, the size of the embryoin the specimens from the base of Patala Formation issmaller than in specimens from the top of the underly-ing Lockhart Limestones. After the hardground, the em-bryo sizes of bothSetia and Orbitosiphon continue toincrease in size, although they do not reach the sizesattained by the specimens from the upper part of theLockhart Limestones (Figs. 6, 7).

In Orbitosiphon there is a curious feature. Although thereis a considerable increase in embryo size from lower toupper samples (Figs. 6, 7), the embryo maintains its config-uration, with only one aperture in the deuteroconch and afirst single ‘‘auxiliary’’ chamber (Fig. 3; Pl. 1, Figs. 9, 18–20, 24–26). The increase in size concerns the embryo (pro-

toconch and deuteroconch) and the first chamber, the sizeof the following chambers remains largely constant in allspecimens. This is unsusual in orbitoidiform foraminifers(e.g., lepidorbitoids, discocyclinids, lepidocyclinids), inwhich an increase in embryo size is normally associatedwith a change in embryonic configuration, with a deutero-conch growing larger and developing additional apertures.It contrasts also with the embryonic configuration ofSetia,in which a change from uniapertural to biapertural deuter-oconchs occurs associated with an increase in embryo sizefrom S. primitiva to S. tibetica. Thus, uniapertural embryosof Orbitosiphon from the upper part of the Lockhart Lime-stones may be larger than biapertural embryos ofSetia fromthe lower part (Figs. 6, 7).

However, in Setia there is only a single change in theembryonic configuration, from uniapertural inS. primitiva(Pl. 4, Figs. 8–11, 13, 14) to biapertural inS. tibetica (Pl.2, Figs. 22–29). Large embryos ofSetia, with E up to morethan 250�m, maintain only two apertures, from which twolarge ‘‘auxiliary’’ chamberlets, with a size similar to that ofembryonic chambers, are formed in the first postembryonicchamber (Figs. 3, 7). Another particular feature ofSetia isthe large size of the protoconch. The increase in embryosize is isometric, that is, both the protoconch and the deu-teroconch increase in size, maintaining a similar diameter(Fig. 7; Pl. 2, Figs. 22–29). This also contrasts with theusual trend in orbitoidiform foraminifers, in which the in-crease in embryo size leads to a change from isolepidine toeulepidine, trybliolepidine and, eventually, to centrolepidineembryonic configurations (e.g.,Lepidocyclina, Discocycli-na).

INCREASE IN STRUCTURAL COMPLEXITY IN SETIA

Together with the increase in test and embryo size, a pro-gressive increase in structural complexity can be observedin Setia. A major break occurs at the boundary betweenHangu Formation and the Lockhart Limestones, with thereplacement ofS. primitiva by S. tibetica. From the base ofthe Lockhart Limestones until the last occurrence, in thelower part of the Patala Shales, a gradual change in thecomplexity of the test, mainly in the canal system, was ob-served inS. tibetica. In the stratigraphically lower speci-mens, the canal system is reduced to tubular passages withsmall interlamellar spaces. Specimens from upper samplesshow an increase of ‘‘vacuolar’’ canal system, to the extentthat it becomes difficult to differentiate the genus fromOr-bitosiphon in axial section. Although there is a general in-crease in complexity of the canal system, it is obscured bya high intraspecific variability, and simple and complexspecimens are found together in the same sample.

The species ‘‘Orbitosiphon praepunjabensis’’ ( � S. ti-betica) erected by Adams (1987, p. 310), characterized by‘‘lateral chamberlets only on one side of the median layerand a thickened lateral wall on the other’’, and a ‘‘4-spired’’embryonic apparatus, seems to be based on those specimensof S. tibetica with a canal system consisting mainly of tu-bular canals, lacking the developed ‘‘vacuolar’’ cavities thatgive the test ofSetia the appearance of having lateral cham-berlets on both sides.


RELATIONSHIP BETWEEN TEST SIZE AND EMBRYO SIZE

In the original description ofO. punjabensis, Davies(1937) distinguished two forms within ‘‘L. (P.) punjaben-sis’’, which he called ‘‘stout’’ and ‘‘thin’’ specimens. Theformer are larger, thicker and of concavo-convex shape, thelatter are smaller, thinner and flatter. Davies found differ-ences in embryo size between stout and thin specimens.Following Davies, the ‘‘largest primordial cell’’ (i.e., thefirst chamber after the bilocular embryo) measured 100 x50 �m in the thin specimens, and 150 x 100�m in the stoutspecimens.

On our field trips to the Salt Range, samples were col-lected from every level where orbitoidiform foraminiferswere found. These samples revealed that bothO. punjaben-sis andS. tibetica show a considerable degree of variabilityin test size and shape. This variability was most clearly ob-served inS. tibetica as it was more abundant in all thesamples. The preparation of many specimens in thin sectionand the measurement and comparison between test diameterand embryo size in a number of specimens revealed thatthese two parameters were not related. It is thus concludedthat the populations studied included specimens of a rangeof different ontogenetic stages, but without a clear bimodaldifferentiation as that described by Davies (1937).

STRATIGRAPHICAL DISTRIBUTION

Douville (1916) regarded ‘‘Lepidorbitoides tibetica’’ and‘‘ L. polygonalys’’ ( � S. tibetica) as Danian. This age wasreinterpreted for both ‘‘L. tibetica’’ ( � S. tibetica) and ‘‘L.(P.) punjabensis’’ ( � O. punjabensis) as upper Ranikot(� Late Paleocene) by Davies (1937, appendix). Both spe-cies are considered as ‘‘Paleocene’’ by most authors. Recentstudies on calcareous nannofossils, planktic foraminiferaand palynomorphs, carried out mainly in the Salt Range,have produced a biostratigraphical framework for the Paleo-cene-Eocene, which allows us to determine the biostrati-graphical setting ofOrbitosiphon andSetia more accurately(Fig. 8).

S. primitiva occurs in the Hangu Formation, andO. pun-jabensis andS. tibetica in the Lockhart Limestones and thebase of the Patala Formation (Fig. 7). The upper part of thePatala Formation clearly corresponds to the biozone NP 9(Kothe and others, 1988; Bybell and Self-Trail, 1993, inpress; Gibson, 1994). Calcareous nannoplankton ages areconfirmed by planktic foraminifers (Gibson in Bybell andSelf-Trail, 1993; Weiss, 1993; Afzal and Butt, 2000), largerforaminifers (Hottinger and others, 1998, SBZ 5), and di-noflagellates (Edwards, in Bybell and Self-Trail, 1993).

The base of the Patala corresponds to NP 8 (Ko¨the andothers, 1988), although Bybell and Self-Trail (1993) failedto find calcareous nannofossils in its lower part. The firstdatable sample of Bybell and Self-Trail, already NP 9, co-incides with the levels where the first orthophragminids,Nummulites and Assilina occur (Fig. 7), which are charac-teristic for SBZ 5 (‘‘Early Ilerdian 1’’, Serra-Kiel and others,1998). Such levels have been dated as P5 from plankticforaminifers (Weiss, 1993; Afzal and Butt, 2000).

Calcareous nannofossils and dinoflagellates give an agefor the Lockhart Limestones of NP 6 (Ko¨the and others,1988; Bybell and Self-Trail, 1993). The age of the Hangu

Formation is more controversial. It is considered early or‘‘middle’’ Paleocene by most authors (e.g., Butt, 1991;Weiss, 1993; Akhtar and Butt, 1999). The palynostratigraph-ical study of Warwick and others (1995) gives an age forthe Hangu Formation of middle Paleocene. Ko¨the and others(1988) include the upper part of the Hangu Formation, to-gether with the Lockhart Limestones in the Nammal Gorgesection within their biozone PAK D-I, approximately equiv-alent to biozone NP 6.

Orbitosiphon punjabensis always occurs together withSetia tibetica (Fig. 7). The latter species was observed tobe dominant in all the fossiliferous levels in which theyoccur in the Salt Range. Both species are found associatedto Lockhartia, Daviesina, Miscellanea and Ranikothalia.The second species ofSetia, S. primitiva was found asso-ciated to the same genera except forRanikothalia.

In summary,S. primitiva is found in NP 6 (early LatePaleocene). The range ofS. tibetica and O. punjabensis isNP 7-NP 8 (Thanetian). In the Salt Range, the first ortho-phragminids,Nummulites andAssilina occur in NP 9.

ORBITOSIPHON, SETIA, AND ACTINOSIPHON

Setia and Orbitosiphon, previously grouped under onesingle genus, have been considered by some authors as sur-vival forms of Cretaceous genera (eitherOrbitoides, Lepi-dorbitoides or Orbitocyclina), or as intermediate forms be-tween Cretaceous and Tertiary forms, mainly orthophrag-minids (e.g., Douville´, 1916; Mac Gillavry, 1963; Drooger,1993).

Rao (1944) regarded ‘‘Orbitosiphon’’ as an intermediateform linking the CretaceousLepidorbitoides with the ‘‘Eo-cene’’ American genusActinosiphon Vaughan. Adams(1987) thought that the similarities between ‘‘Orbitosi-phon’’ ( � Setia andOrbitosiphon) andOrbitoides, and be-tween the AmericanActinosiphon and Orbitocyclina were‘‘too great to be fortuitous’’, and that these Paleocene generawere descendants of the Cretaceous ones. A similar idea wasfollowed by Drooger (1993, p. 160, 162) who stated thatActinosiphon andOrbitosiphon could be ‘‘independent linesof unknown ancestry’’, although he did not rule out a re-lationship of the former with the Upper Cretaceous lepidor-bitoids. Grimsdale (1959) considered thatActinosiphonsemmesi had no feature by which it could be ‘‘satisfactorilydifferentiated fromLepidocyclina s.l.’’. In contrast, Hanza-wa (1962) put in synonymy ‘‘Orbitosiphon tibetica’’ withActinosiphon on the basis of the presence of an interseptalcanal system in both forms, although he stated that ‘‘L. (P.)punjabensis Davies is not likely to be congeneric withAc-tinosiphon tibetica (Douville)’’.

Most authors put in synonymy the Asian forms with theAmerican genusActinosiphon (Cole, in Cushman, 1948;Smout and Haque, 1956; Cole, 1960; Hanzawa, 1962; Loeb-lich and Tappan, 1964, 1987; Rajendran and others, 1987;Matsumaru, 1991; Akhtar and Butt, 1999). As stated above,Setia has a particular mosphostructure which has not beenobserved in any other group of previously described largerforaminifer. Consequently, it cannot be related to Cretaceouslepidorbitoids, neither to the PaleoceneActinosiphon. Withregard toOrbitosiphon, the differences withActinosiphonare not so obvious, although the two genera clearly differ


in many characters. First, in the test shape, as the test ofActinosiphon has not the concavo-convex shape present, toa variable degree, in all specimens ofOrbitosiphon.

The embryonic apparatus ofO. punjabensis differs fromthat inA. semmesi (Vaughan) andA. vichayalensis (Rutten).Differences in the embryonic apparatus are not particularlyimportant, because they may change within one genus fromone species to another (e.g., fromS. primitiva to S. tibetica).However, the embryo ofActinosiphon is rather unusual,characterized by a larger circular protoconch and a smallerkidney-shaped deuteroconch with two apertures (see Pl. 4,Figs. 1, 2, 5, 6 in Adams, 1987), whereas inOrbitosiphonboth embryonic chambers are of about the same size andthere is a single aperture in the deuteroconch.

The shape of equatorial chamberlets also differs in thetwo genera. InOrbitosiphon the equatorial chamberlets areogival, giving the appearance of spirals in opposite direc-tions, whereas inActinosiphon they are more rounded andwithout spiral appearance but rather with radial alignmentsof chamberlets of alternate annuli (Vaughan, 1929, Pl. 21,Fig. 1, reproduced in Loeblich and Tappan, 1987, Pl. 737,Fig. 2; Rutten, 1935, Figs. 1, 2; Caudri, 1996, Pl. 12, Fig.1; Adams, 1987, Pl. 4, Figs 1, 5). Such a difference can beproduced simply by the arrangement and shape of chambers,as was observed by Adams (1987), who stated that ‘‘whenadjacent chamberlets of the same cycle are not contiguouslaterally, they form radiating rows’’, and he exemplified thisfeature withPseudolepidina trimera Barker and Grimsdale(Adams, 1987, Pl. 3, Fig. 11). This would be the case forActinosiphon as well.

The arrangement of equatorial chamberlets is closely re-lated to stolon systems. InActinosiphon there are distal ra-dial stolons connecting equatorial chamberlets of alternaterings (see Fig. 2 in Rutten, 1935; and Pl. 737, Fig. 2 inLoeblich and Tappan, 1987), a feature clearly absent inOr-bitosiphon. On the other hand, and due to the non-contig-uous arrangement of equatorial chamberlets of the same an-nulus (that is, chamberlets do not touch),Actinosiphon lacksannular stolons, which are present inOrbitosiphon (Pl. 1,Fig. 21).

Both genera have in common the fact that they are or-bitoidiform foraminifers of Paleocene age.Actinosiphon isknown only in the Caribbean region, andOrbitosiphon onlyin south central Asia. Here, it is concluded that they are twodifferent, phylogenetically unrelated genera.

CO-OCCURRENCE OFSETIA AND ORBITOSIPHON WITH

ORTHOPHRAGMINIDS

Several authors have reported the co-occurrence of ‘‘Or-bitosiphon’’ or Actinosiphon’’ with orthophragminids (Dis-cocyclina) (e.g., Davies, 1937; Rao, 1944; Butt, 1991; Ah-kar and Butt, 1999), and such co-occurrence has usuallybeen included in biostratigraphical syntheses (e.g., Nagappa,1959; Cole, 1960; Adams, 1970; Kureshy, 1978, 1984b).

The reports of co-occurrence are actually due to the er-roneous determination ofDiscocyclina. Rao (1944) reas-signedLepidorbitoides polygonalis (Douville, 1916) toDis-cocyclina which, consequently, was contemporaneous to‘‘ Orbitosiphon’’ tibetica. Rao (1944, p. 95) justified the as-signment ofL. tibetica to Discocyclina from the rectangular

shape of equatorial chamberlets, but also because of the‘‘presence of inter-septal and inter-mural canals’’, a featurewhich was previously thought to be present inDiscocyclina(see Ferra`ndez-Canãdell and Serra-Kiel, 1992).

The ‘‘Discocyclina ranikotensis’’ reported by some au-thors either from the Lockhart Limestones (e.g., Butt, 1991;Weiss, 1993) or the lower part of the Patala Formation (e.g.,Akhtar and Butt, 1999) are actually specimens ofSetia ti-betica (see Pl. 3, Fig. g in Butt, 1991; Pl. 1, Fig. 3, and Pl.4 Figs. 5, 6 in Weiss, 1993; Pl. 2, Figs. 1, 2 in Akhtar andButt, 1999; and Pl. 3, Fig. 12 in Akhtar and Butt, 2000).Weiss (1993) also assigned specimens ofSetia tibetica toDictyokathina simplex (see Pl. 1, Fig. 5 and Pl. 5, Figs. 2,4 in Weiss, 1993). These misinterpretations of specimens ofSetia and their assignment toDiscocyclina are explained bythe ‘‘vacuolar’’ canaliferous cavities in the former, that res-semble lateral chamberlets, and also by the similarity in theexternal appearance ofS. tibetica and D. ranikotensis (Pl.2, Figs. 1, 2, 7–9). Other reports ofD. ranikotensis fromthe Lokhart Limestones are actually axial sections which donot allow a confident assigment and might belong toOr-bitosiphon punjabensis (e.g., Pl. 3, Fig. 10 in Akhtar andButt, 2000)

The study of a sequence of samples from different sec-tions in the Salt Range, mainly in the Nammal Gorge sec-tion, revealed that both groups are never found together(Fig. 8). The last occurrence of bothSetia andOrbitosiphonis located in the lower part of the Patala Shales (sampleNG-93506, Fig. 2). The first orthophragminids (D. broen-nimanni, Orbitoclypeus ramaraoi, D. ranikotensis; unpub-lished data, still under study) are found 27 m above in theNammal Gorge section. The first occurrence of orthophrag-minids coincides with that ofNummulites (N. gamardensis)andAssilina (A. ranikoti, A. patalensis) (determinations byJ. Tosquella) suggesting a replacement of foraminiferal fau-na.

The 27 m interval between the last occurrence ofSetiaand the first appearance of orthophragminids in the NammalGorge section consists of marls and clays without largerforaminifers (Figs. 2, 8). This interval marks a major shiftin the foraminiferal fauna, changing from an endemic as-semblage dominated byLockhartia, Daviesina, Miscella-nea, Ranikothalia, Setia and Orbitosiphon to the entranceof Tethyan genera includingNummulites, Assilina, Disco-cyclina, Orbitoclypeus and Alveolina. Such a change in-cludes the extinction of the endemic orbitoidiform generaSetia and Orbitosiphon, although Lockhartia, Daviesina,Miscellanea andRanikothalia continue.

Whereas within the lower assemblageSetia and Orbito-siphon are true endemic forms, the other genera are alsofound in the western Tethys and some of them,Rhaniko-thalia and Lockhartia, are even found in America as well(e.g., Cole, 1942; Caudri, 1944; Butterlin, 1981; Berlanga,1997). A certain degree of endemism in this region has alsobeen suggested for microbenthic foraminifers by Kureshy(1984a), although restricted to the Upper Indus Basin.

Cole (1960) interpreted the speciesLepidocyclina (Po-lylepidina) zeilmansi described by Tan Sin Hok (1936) fromthe Paleocene-Upper Eocene Mahakam Formation in Bor-neo as a possible synonym of ‘‘Actinosiphon tibetica’’. Ihave been unable to find Tan’s paper in order to verify the


identity of this species. If it is actually a synonym ofSetiatibetica then the geographical range of this species wouldextend considerably. However, the Mahakam Formation hasbeen object of discussion because of the supposed contem-poraneous occurrence ofLepidocyclina and Discocyclina.Rutten (1948) revised the material deposited in the UtrechtGeological Institute and concluded that it included redepos-ited Eocene species together with Neogene species.

CONCLUSIONS

The Paleocene foraminifers from Pakistan previously as-signed to ‘‘Orbitosiphon’’ or ‘‘ Actinosiphon’’ actually in-clude two different genera. One corresponds to the speciesdescribed by Davies (1937) as ‘‘Lepidocyclina (Polylepi-dina) punjabensis’’, type species of the genusOrbitosiphon.The second corresponds to the species described by Dou-ville (1916) as ‘‘Lepidorbitoides tibetica’’ and ‘‘ L. poly-gonalis’’, and is reassigned here to a new genus,Setia.Within Setia two species are distinguished:S. tibetica,which occurs together withOrbitosiphon punjabensis in theLockhart Limestones and the lower part of the Patala For-mation, andS. primitiva sp. nov., which occurs in the HanguFormation.

The genusOrbitosiphon is characterized by a typical or-bitoidiform test but with an asymmetrical, concavo-convexshape. The genusSetia has a unique test architecture, withorbitoidal growth but also with a canal system on the ventralside of the test.

Both genera are considered endemic of the south-centralAsian region. They are not related to the American genusActinosiphon and do not occur together with orthophrag-minids (Discocyclina andOrbitoclypeus), which arrived tothe basin together withNummulites and Assilina after theextinction ofOrbitosiphon andSetia.

ACKNOWLEDGMENTS

This research was supported by the DGICYT project PB98-1263 and a F.P.U. grant of the Ministerio de Educaciońy Cultura of the Spanish Goverment, and is a contributionto the IGCP Project No. 393. I wish to thank Prof. A.A.Butt for the organization and guidance of fieldtrips in Pak-istan; J. Tosquella for the determination ofNummulites andAssilina species; L.M. Bybell for kindly sending the prelim-inary report of her paper with J.M. Self-Trail (in press); andL. Hottinger, E. Caus, and D. Basi for their critical reviewand useful comments on the manuscript. The stratigraphicalframework was elaborated with the help of L. Hottinger, J.Serra-Kiel, A. Trave´ and J.M. Samso´.

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Submitted 2 June 2000Accepted 8 May 2001

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New Paleocene Orbitoidiform era From Punjab Salt Range-Pakistan